CODES

ADOPTS WITH AMENDMENTS:

International Energy Conservation Code 2015 (IECC 2015)

Chapter 1 [CE] Scope and Administration

Chapter 2 [CE] Definitions

Chapter 3 [CE] General Requirements

Chapter 4 [CE] Commercial Energy Efficiency

Chapter 5 [CE] Existing Buildings

Chapter 6 [CE] Referenced Standards

Chapter 1 [RE] Scope and Administration

Chapter 2 [RE] Definitions

Chapter 3 [RE] General Requirements

Chapter 4 [RE] Residential Energy Efficiency

Chapter 5 [RE] Existing Buildings

Chapter 6 [RE] Referenced Standards

The provisions in this chapter are applicable to commercialbuildings and their building sites.

C401.2 Application

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Commercial buildings shall comply with one of the following:

  1. The requirements of ANSI/ASHRAE/IESNA 90.1.
  2. The requirements of Sections C402 through C405. In addition, commercial buildings shall comply with Section C406 and tenant spaces shall comply with Section C406.1.1, C403, C404, C405, C406, C408, C409 and C410.
  3. The requirements of Sections C402.5, C403.2, C404, C405.2, C405.3, C405.5, C405.6 and C407, C408, C409, C410, C402.5, C403.2, C404, C405.2, C405.3, C405.4, C405.6 and C405.7. The building energy cost consumption shall be equal to or less than 85 87, 90 or 93 percent of the standard reference design building, depending on the option selected per Section C407.3.

C401.2.1 Application to replacement fenestration products

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Where some or all of an existing fenestration unit is replaced with a new fenestration product, including sash and glazing, the replacement fenestration unit shall meet the applicable requirements for U-factor and SHGC in Table C402.4.

Exception: An area-weighted average of the U-factor of replacement fenestration products being installed in the building for each fenestration product category listed in Table C402.4 shall be permitted to satisfy the U-factor requirements for each fenestration product category listed in Table C402.4. Individual fenestration products from different product categories listed in Table C402.3 shall not be combined in calculating the area-weighted average U-factor.

C401.2.1 Application to existing buildings

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Work on existing buildings shall comply with Chapter 5 in addition to the applicable provisions of Chapter 4.

C402.1 General (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Building thermal envelope assemblies for buildings that are intended to comply with the code on a prescriptive basis, in accordance with the compliance path described in Item 2 1 of Section C401.2, shall comply with the following:

  1. The opaque portions of the building thermal envelope shall comply with the specific insulation requirements of Section C402.2 and the thermal requirements of either the R-value-based method of Section C402.1.3;, the U-, C-and F-factor-based method of Section C402.1.4;, or the component performance alternative of Section C402.1.5.
  2. Roof solar reflectance and thermal emittance shall comply with Section C402.3.
  3. Fenestration in the building envelope assemblies shall comply with Section C402.4, or the component performance alternative of Section C402.1.5.
  4. Air leakage of building envelope assemblies shall comply with Section C402.5.

Alternatively, where buildings have a vertical fenestration area or skylight area exceeding that allowed in Section C402.4, the building and building thermal envelope shall comply with Section C401.2, Item 1 or Section C401.2, Item 3.

Walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers shall comply with Section C403.2.15 or C403.2.16.

C402.1.1 Low-energy buildings

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The following low-energy buildings, or portions thereof, separated from the remainder of the building by building thermal envelope assemblies complying with this section, code shall be exempt from the building all thermal envelope provisions of Section C402.this code:

  1. Those that are heated and/or cooled with a peak design rate of energy usage less than 3.4 Btu/h x ft2 (10.7 W/m2) or 1.0 watt/ft2 per square foot (10.7 W/m2) of floor area for space conditioning purposes.
  2. Those that do not contain conditioned space.
  3. Greenhouses where cooling does not include a condensing unit and that are isolated from any other conditioned space.
  4. Unstaffed equipment shelters or cabinets used solely for personal wireless service facilities.

C402.1.1.1 Semi-heated buildings and spaces

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The building envelope of semi-heated buildings, or portions thereof, shall comply with the same requirements as that for conditioned spaces in Section C402, except as modified by this section. Building envelope assemblies separating conditioned space from semi-heated space shall comply with the exterior envelope insulation requirements. Semi-heated spaces heated by mechanical systems that do not include electric resistance heating equipment are not required to comply with the opaque wall insulation provisions of Section C402.2.3 for walls that separate semi-heated spaces from the exterior or low energy spaces. Semi-heated spaces shall be calculated separately from other conditioned spaces for compliance purposes. Opaque walls in semi-heated spaces shall be calculated as fully code compliant opaque walls for both the target and proposed for the Target UA calculations for the component performance alternative in Section C402.1.5, and for the Standard Reference Design for Total Building Performance compliance per Section C407.

C402.1.2 Equipment buildings

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Buildings that comply with all of the following shall be exempt from the building thermal envelope provisions of this code:

  1. Are separate buildings with floor area not more than 500 square feet (50 m2).
  2. Are intended to house electronic equipment with installed equipment power totaling not less than at least 7 watts per square foot (75 W/m2) and not intended for human occupancy.
  3. Have a heating system capacity not greater than (17,000 Btu/hr) (5 kW) and a heating thermostat set point that is restricted to not more than 50°F (10°C).
  4. Have an average wall and roof U-factor less than 0.200 in Climate Zones 1 through 5 and less than 0.120 in Climate Zones 6 through 8.
  5. Comply with the roof solar reflectance and thermal emittance provisions for Climate Zone 1.

C402.1.3 Insulation component R -value-based method

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Building thermal envelope opaque assemblies shall meet the requirements of Sections C402.2 and C402.4 based on the climate zone specified in Chapter 3. For opaque portions of the building thermal envelope intended to comply on an insulation component R-value basis, the R-values for insulation in framing cavities areas, where required, and for continuous insulation, where required, shall be not be less than that specified in Table C402.1.3, based on the climate zone specified in Chapter 3. Commercial buildings or portions of commercial buildings enclosing Group R occupancies shall use the R-values from the “Group R” column of Table C402.1.3. Commercial buildings or portions of commercial buildings enclosing occupancies other than Group R shall use the R-values from the “All other” column of Table C402.1.3. The thermal resistance or R-value of the insulating material installed in, or continuously within or on, the below-grade exterior walls of the building envelope required in accordance with Table C402.1.3 shall extend to a depth of not less than 10 feet (3048 mm) below the outside finished ground level, or to the level of the lowest floor of the conditioned space enclosed by the below-grade wall, whichever is less. Doors having less than 50 percent opaque glass area shall be considered opaque doors. Opaque swinging doors shall comply with the Table C402.1.4 and opaque nonswinging doors shall comply with Table C402.1.3 or C402.1.4.

TABLE C402.1.3
OPAQUE THERMAL ENVELOPE INSULATION COMPONENT MINIMUM REQUIREMENTS, R-VALUE METHODa,g

CLIMATE ZONE1234 EXCEPT MARINE5 AND MARINE 4678
All otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup R
Roofs
Insulation entirely
above roof deck
R-20ciR-25ciR-25ciR-25ciR-25ciR-25ciR-30ciR-30ciR-30ciR-30ciR-30ciR-30ciR-35ciR-35ciR-35ciR-35ci
Metal buildingsb R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R-11 LS
R-25 +
R-11 LS
R-25 +
R-11 LS
R-30 +
R-11 LS
R-30 +
R-11 LS
R-30 +
R-11 LS
R-30 +
R-11 LS
Attic and otherR-38R-38R-38R-38R-38R-38R-38R-38R-38R-49R-49R-49R-49R-49R-49R-49
Walls, above grade
MassR-5.7cicR-5.7cicR-5.7cicR-7.6ciR-7.6ciR-9.5ciR-9.5ciR-11.4ciR-11.4ciR-13.3ciR-13.3ciR-15.2ciR-15.2ciR-15.2ciR-25ciR-25ci
Metal buildingR-13+
R-6.5ci
R-13 +
R-6.5ci
R13 +
R-6.5ci
R-13 +
R-13ci
R-13 +
R-6.5ci
R-13 +
R-13ci
R-13 +
R-13ci
R-13 +
R-13ci
R-13 +
R-13ci
R-13 +
R-13ci
R-13 +
R-13ci
R-13 +
R-13ci
R-13 +
R-13ci
R-13 +
R-19.5ci
R-13 +
R-13ci
R-13 +
R-19.5ci
Metal framedR-13 +
R-5ci
R-13 +
R-5ci
R-13 +
R-5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-7.5ci
R-13 +
R-15.6ci
R-13 +
R-7.5ci
R-13 +
R17.5ci
Wood framed and
other
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-3.8ci or
R-20
R-13 +
R-7.5ci or
R-20 +
R-3.8ci
R-13 +
R-7.5ci or
R-20 +
R-3.8ci
R-13 +
R-7.5ci or
R-20 +
R-3.8ci
R-13 +
R-7.5ci or
R-20 +
R-3.8ci
R-13 +
R-7.5ci or
R-20 +
R-3.8ci
R13 +
R-15.6ci or
R-20 +
R-10ci
R13 +
R-15.6ci or
R-20 +
R-10ci
Walls, below grade
Below-grade walldNRNRNRNRNRNRR-7.5ciR-7.5ciR-7.5ciR-7.5ciR-7.5ciR-7.5ciR-10ciR-10ciR-10ciR-12.5ci
Floors
MasseNRNRR-6.3ciR-8.3ciR-10ciR-10ciR-10ciR-10.4ciR-10ciR-12.5ciR-12.5ciR-12.5ciR-15ciR-16.7ciR-15ciR-16.7ci
Joist/framingNRNRR-30R-30R-30R-30R-30R-30R-30R-30R-30R-30fR-30fR-30fR-30fR-30f
Slab-on-grade floors
Unheated slabsNRNRNRNRNRNRR-10 for
24″ below
R-10 for
24″ below
R-10 for
24″ below
R-10 for
24″ below
R-10 for
24″ below
R-15 for
24″ below
R-15 for
24″ below
R-15 for
24″ below
R-15 for
24″ below
R-20 for
24″ below
Heated slabsR-7.5 for
12″ below
R-7.5 for
12″ below
R-7.5 for
12″ below
R-7.5 for
12″ below
R-10 for
24″ below
R-10 for
24″ below
R-15 for
24″ below
R-15 for
24″ below
R-15 for
36″ below
R-15 for
36″ below
R-15 for
36″ below
R-20 for
48″ below
R-20 for
24″ below
R-20 for
48″ below
R-20 for
48″ below
R-20 for
48″ below
Opaque doors
NonswingingR-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75R-4.75
CLIMATE ZONE 5 AND MARINE 4
All other Group R
  Roofs
Insulation entirely above roof deck R-30ciR-38ci R-30ciR-38ci
Metal buildingsb R-19 R-25 +
R-11 LS
R-19 R-25 +
R-11 LS
Attic and other R-38 R-49 R-49
Walls, Above Grade
Mass R-11.4ciR-9.5c ci R-13.3ci
Metal building R-13 + R-13ci R-19ci R-13 + R-13ciR-19ci
Metal Steel framed R-13 +
R-7.5ciR-10ci
R-13R-19 +
R-7.5ciR-8.5ci
Wood framed and other R-13 + R-3.8ci or R-20 R-21 int R-13 + R-7.5ci or R-20 + R-3.8ciR-21 int
Walls, Below Grade
Below-grade walld R-7.5ciSame as above gradeR-7.5ciSame as above grade
Floors
Massef R-10ciR-30ci R-12.5ciR-30ci
Joist/framing R-30e R-30e
Slab-on-Grade Floors
Unheated slabs R-10 for
24″ below
R-10 for
24″ below
Heated slabsd R-15 for 36″ below R-10 perimeter & under entire slab R-15 for 36″ below R-10 perimeter & under entire slab
Opaque Doors
Nonswinging R-4.75 R-4.75

For SI: 1 inch = 25.4 mm, 1 pound per square foot = 4.88 kg/m2, 1 pound per cubic foot = 16 kg/m3.

ci = Continuous insulation, NR = No requirement, LS = Liner system.

  1. Assembly descriptions can be found in ANSI/ASHRAE/IESNA Chapter 2 and Appendix A.
  2. Where using R-value compliance method, a thermal spacer block with minimum thickness of 1/2 -inch and minimum R-value of R-3.5 shall be provided, otherwise use the U-factor compliance method in Table C402.1.4.
  3. R-5.7ci is allowed to be substituted with concrete block walls complying with ASTM C 90, ungrouted or partially grouted at 32 inches or less on center vertically and 48 inches or less on center horizontally, with ungrouted cores filled with materials having a maximum thermal conductivity of 0.44 Btu-in/h-f2 °F. Exception: Integral insulated concrete block walls complying with ASTM C90 with all cores filled and meeting both of the following:
    1. At least 50 percent of cores must be filled with vermiculite or equivalent fill insulation; and
    2. The building thermal envelope encloses one or more of the following uses: Warehouse (storage and retail), gymnasium, auditorium, church chapel, arena, kennel, manufacturing plant, indoor swimming pool, pump station, water and waste water treatment facility, storage facility, storage area, motor vehicle service facility. Where additional uses not listed (such as office, retail, etc.) are contained within the building, the exterior walls that enclose these areas may not utilize this exception and must comply with the appropriate mass wall R-value from Table C402.1.3/U-factor from Table C402.1.4.
  4. Where heated slabs are below grade, below-grade walls they shall comply with the exterior insulation requirements for heated slabs.
  5. Steel floor joist systems shall be insulated to R-38 + R-10ci.
  6. “Mass floors” shall include floors weighing not less than:

    1. 35 pounds per square foot of floor surface area; or
    2. 25 pounds per square foot of floor surface area where the material weight is not more than 120 pounds per cubic foot.
  7. For roof, wall or floor assemblies where the proposed assembly would not be continuous insulation, an alternate nominal R-value compliance option for assemblies with isolated metal penetrations of otherwise continuous insulation is:

    Assemblies with
    continuous insulation
    (see definition)
    Alternate option for assemblies with
    metal penetrations, greater than 0.04%
    but less than 0.08%
    Alternate option for assemblies with
    metal penetrations, greater than or equal to 0.08%
    but less than 0.12%
    R-9.5ci R-11.9ci R-13ci
    R-11.4ci R-14.3ci R-15.7ci
    R-13.3ci R-16.6ci R-18.3ci
    R-15.2ci R-19.0ci R-21ci
    R-30ci R-38ci R-42ci
    R-38ci R-48ci R-53ci
    R-13 + R-7.5ci R-13 + R-9.4ci R-13 + R-10.3ci
    R-13 + R-10ci R-13 + R-12.5ci R-13 + R-13.8ci
    R-13 + R-12.5ci R-13 + R-15.6ci R-13 + R-17.2ci
    R-13 + R-13ci R-13 + R-16.3ci R-13 + R-17.9ci
    R-19 + R-8.5ci R-19 + R-10.6ci R-19 + R-11.7ci
    R-19 + R-14ci R-19 + R-17.5ci R-19 + R-19.2ci
    R-19 + R-16ci R-19 + R-20ci R-19 + R-22ci
    R-20 + R-3.8ci R-20 + R-4.8ci R-20 .+ R-5.3ci
    R-21 + R-5ci R-21 + R-6.3ci R-21 + R-6.9ci

    This alternate nominal R-value compliance option is allowed for projects complying with all of the following:

    1. The ratio of the cross-sectional area, as measured in the plane of the surface, of metal penetrations of otherwise continuous insulation to the opaque surface area of the assembly is greater than 0.0004 (0.04%), but less than 0.0012 (0.12%).
    2. The metal penetrations of otherwise continuous insulation are isolated or discontinuous (e.g., brick ties or other discontinuous metal attachments, offset brackets supporting shelf angles that allow insulation to go between the shelf angle and the primary portions of the wall structure). No continuous metal elements (e.g., metal studs, z-girts, z-channels, shelf angles) penetrate the otherwise continuous portion of the insulation.
    3. Building permit drawings shall contain details showing the locations and dimensions of all the metal penetrations (e.g., brick ties or other discontinuous metal attachments, offset brackets, etc.) of otherwise continuous insulation. In addition, calculations shall be provided showing the ratio of the cross-sectional area of metal penetrations of otherwise continuous insulation to the overall opaque wall area.
    For other cases where the proposed assembly is not continuous insulation, see Section C402.1.4 for determination of U-factors for assemblies that include metal other than screws and nails.

C402.1.4 Assembly U -factor, C -factor or F -factor-based method

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Building thermal envelope opaque assemblies intended to comply on an assembly U-, C-, or F-factor basis shall have a U-, C-, or F-factor not greater than that specified in Table C402.1.4. Commercial buildings or portions of commercial buildings enclosing Group R occupancies shall use the U-, C-, or F-factor from the “Group R” column of Table C402.1.4. Commercial buildings or portions of commercial buildings enclosing occupancies other than Group R shall use the U-, C-, or F-factor from the “All Other” column of Table C402.1.4. The C-factor for the below-grade exterior walls of the building envelope, as required in accordance with Table C402.1.4, shall extend to a depth of 10 feet (3048 mm) below the outside finished ground level, or to the level of the lowest conditioned floor, whichever is less. Opaque swinging doors shall comply with Table C402.1.4 and opaque non-swinging doors shall comply with Table C402.1.3 or C402.1.4. The U-factors for typical construction assemblies are included in Appendix A. These values shall be used for all calculations. Where proposed construction assemblies are not represented in Appendix A, values shall be calculated in accordance with the ASHRAE Handbook of Fundamentals using the framing factors listed in Appendix A where applicable and shall include the thermal bridging effects of framing materials.

TABLE C402.1.4
OPAQUE THERMAL ENVELOPE ASSEMBLY MAXIMUM REQUIREMENTS, U-FACTOR METHODa, bf

CLIMATE ZONE 1234 EXCEPT MARINE5 AND MARINE 4678
All otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup RAll otherGroup R
Roofs
Insulation entirely above roof deck U-0.048 U-0.039 U-0.039 U-0.039 U-0.039 U-0.039 U-0.032 U-0.032 U-0.032 U-0.027 U-0.032 U-0.027 U-0.032 U-0.032 U-0.028U-0.028U-0.028U-0.028
Metal buildings U-0.044 U-0.035 U-0.035 U-0.035 U-0.035 U-0.035 U-0.035 U-0.035 U-0.035 U-0.031 U-0.035 U-0.031 U-0.031 U-0.031 U-0.029U-0.029U-0.029U-0.029
Attic and other U-0.027 U-0.027 U-0.027 U-0.027 U-0.027 U-0.027 U-0.027 U-0.027 U-0.027 U-0.021 U-0.021 U-0.021 U-0.021 U-0.021 U-0.021 U-0.021 U-0.021
Joist or single rafter U-0.027 U-0.027
Walls, above grade
Mass U-0.151 U-0.151 U-0.151 U-0.123 U-0.123 U-0.104 U-0.104 U-0.090 U-0.090 U-0.104d U-0.080 U-0.078 U-0.080U-0.071U-0.071U-0.061U-0.061U-0.061
Mass transfer deck slab edge U-0.20 U-0.20
Metal buildingU-0.079U-0.079U-0.079U-0.079U-0.079U-0.052U-0.052U-0.052U-0.052U-0.052U-0.052U-0.052U-0.052U-0.039U-0.052U-0.039
Metal Steel framed U-0.077 U-0.077 U-0.077 U-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.064U-0.055 U-0.064U-0.055U-0.057U-0.064U-0.052U-0.045U-0.045
Wood framed and othercU-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.054 U-0.064 U-0.054 U-0.051U-0.051U-0.051U-0.051U-0.036U-0.036
Walls, below grade
Below-grade wallcb C-1.140e C-1.140e C-1.140e C-1.140e C-1.140e C-1.140e C-0.119 C-0.119 C-0.119 Same as above grade C-0.119 Same as above grade C-0.119 C-0.119C-0.092C-0.092C-0.092C-0.092
Floors
Massde U-0.322e U-0.322e U-0.107 U-0.087 U-0.076 U-0.076 U-0.076 U-0.074 U-0.074 U-0.031 U-0.064 U-0.031 U-0.064 U-0.057U-0.055U-0.051U-0.055U-0.051
Joist/framing U-0.066e U-0.066e U-0.033 U-0.033 U-0.033 U-0.033 U-0.033 U-0.033 U-0.033 U-0.029 U-0.033 U-0.029 U-0.033 U-0.033U-0.033U-0.033U-0.033U-0.033
Slab-on-grade floors
Unheated slabs F-0.73e F-0.73e F-0.73e F-0.73e F-0.73e F-0.73e F-0.54 F-0.54 F-0.54 F-0.54F-0.54F-0.52F-0.40F-0.40F-0.40F-0.40
Heated slabsfc F-0.70 F-0.70 F-0.70 F-0.70 F-0.70 F-0.70 F-0.65 F-0.65 F-0.65 F-0.55 F-0.65 F-0.55F-0.58F-0.58F-0.55F-0.55F-0.55F-0.55
Opaque doors
SwingingU-0.61U-0.61U-0.61U-0.61U-0.61U-0.61U-0.61U-0.61U-0.37U-0.37U-0.37U-0.37U-0.37U-0.37U-0.37U-0.37
Nonswinging U-0.34 U-0.34
CLIMATE ZONE 5 AND MARINE 4
All Other Group R
Roofs
Insulation entirely above roof deck U-0.032 U-0.027 U-0.032 U-0.027
Metal buildings U-0.035 U-0.031 U-0.035 U-0.031
Attic and other U-0.027 U-0.021 U-0.021
Joist or single rafter U-0.027 U-0.027
Walls, Above Grade
Mass U-0.090 U-0.104d U-0.080 U-0.078
Mass transfer deck slab edge U-0.20 U-0.20
Metal building U-0.052 U-0.052
Metal Steel framed U-0.064U-0.055 U-0.064U-0.055
Wood framed and other c U-0.064 U-0.054 U-0.064 U-0.054
Walls, Below Grade
Below-grade wallcb C-0.119 Same as above grade C-0.119 Same as above grade
Floors
Massde U-0.074 U-0.031 U-0.064 U-0.031
Joist/framing U-0.033 U-0.029 U-0.033 U-0.029
Slab-on-Grade Floors
Unheated slabs F-0.54 F-0.54
Heated slabsfc F-0.65 F-0.55 F-0.65 F-0.55
Opaque Doors
Swinging U-0.37 U-0.37
Nonswinging U-0.34 U-0.34

For SI: 1 pound per square foot = 4.88 kg/m2, 1 pound per cubic foot = 16 kg/m3.

ci = Continuous insulation, NR = No requirement, LS = Liner system.

  1. Use of opaque assembly U-factors, C-factors, and F-factors from ANSI/ASHRAE/IESNA 90.1 Appendix A shall be permitted, provided the construction, excluding the cladding system on walls, complies with the appropriate construction details from ANSI/ASHRAE/ISNEA 90.1 Appendix A is required unless otherwise allowed by Section C402.1.4..
  2. Opaque assembly U-factors based on designs tested in accordance with ASTM C1363 shall be permitted. The R-value of continuous insulation shall be permitted to be added to or subtracted from the original tested design.
  3. Where heated slabs are below grade, below-grade walls they shall comply with the F-factor requirements for heated slabs.
  4. Heated slab F-factors shall be determined specifically for heated slabs. Unheated slab factors shall not be used.
  5. Exception: Integral insulated concrete block walls complying with ASTM C90 with all cores filled and meeting both of the following:

    1. At least 50 percent of cores must be filled with vermiculite or equivalent fill insulation; and
    2. The building thermal envelope encloses one or more of the following uses: Warehouse (storage and retail), gymnasium, auditorium, church chapel, arena, kennel, manufacturing plant, indoor swimming pool, pump station, water and waste water treatment facility, storage facility, storage area, motor vehicle service facility. Where additional uses not listed (such as office, retail, etc.) are contained within the building, the exterior walls that enclose these areas may not utilize this exception and must comply with the appropriate mass wall R-value from Table C402.1.3/U-factor from Table C402.1.4.
  6. “Mass floors” shall include floors weighing not less than:

    1. 35 pounds per square foot of floor surface area; or
    2. 25 pounds per square foot of floor surface area where the material weight is not more than 120 pounds per cubic foot.
  7. These C-, F- and U-factors are based on assemblies that are not required to contain insulation.
  8. Evidence of compliance with the F -factors indicated in the table for heated slabs shall be demonstrated by the application of the unheated slab F-factors and R-values derived from ASHRAE 90.1 Appendix A.
  9. Opaque assembly U-factors based on designs tested in accordance with ASTM C1363 shall be permitted. The R-value of continuous insulation shall be permitted to be added to or subtracted from the original tested design.

U-factors of walls with cold-formed steel studs shall be permitted to be determined in accordance with Equation 4-1:

(Equation 4-1)

where:

Rs =The cumulative R-value of the wall components along the path of heat transfer, excluding the cavity insulation and steel studs.
ER =The effective R-value of the cavity insulation with steel studs.

TABLE C402.1.4.1

EFFECTIVE R-VALUES FOR STEEL STUD WALL ASSEMBLIES

NOMINAL
STUD
DEPTH
(inches)
SPACING
OF
FRAMING
(inches)
CAVITY
R-VALUE
(insulation)
CORRECTION
FACTOR
(Fc)
EFFECTIVE
R-VALUE (ER)
(Cavity R-Value × Fc)
31/216130.465.98
150.436.45
31/224130.557.15
150.527.80
616190.377.03
210.357.35
624190.458.55
210.439.03
816250.317.75
24250.389.50

C402.1.5 Component performance alternative

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Building envelope values and fenestration areas determined in accordance with Equation 4-2 shall be permitted in lieu of compliance with the U-, F- and C-factors and F-factors in Tables C402.1.3 and C402.1.4 and C402.4 and the maximum allowable fenestration areas in Section C402.4.1.

(Equation 4-2)

Where:

A = Sum of the (UA Dif) values for each distinct assembly
type of the building thermal envelope, other than slabs
on grade and below-grade walls.:
    UA Dif = UA Proposed - UA Table
    UA Proposed = Proposed U-value x Proposed Area
    UA Table = (U-factor from Table C402.1.3 or Table C402.1.4 or C402.4) x Area
B = Sum of the (FL Dif) values for each distinct slab-on-grade perimeter condition of the building thermal envelope.:
    FL Dif = FL Proposed - FL Table.
    FL Proposed = Proposed F-value x Proposed Perimeter length.
    FL Table = (F-factor specified in Table C402.1.4) x Proposed Perimeter length.
C = Sum of the (CA Dif) values for each distinct below-
grade wall assembly type of the building thermal
envelope.
    CA Dif = CA Proposed - CA Table.
    CA Proposed = Proposed C-value Area.
    CA Table = (Maximum allowable C-factor specified in Table C402.1.4) Area.

The maximum allowed prescriptive vertical fenestration area, identified as “Vertical Fenestration Area allowed” in factor CA below, is the gross above-grade wall area times either:
  1. 30%
  2. 40% if the building complies with Section C402.4.1.1 or Section C402.4.1.4; or
  3. 40% if the U-values used in calculating A for vertical fenestration are taken from Section C402.4.1.3 rather than Table C402.4

Where the proposed vertical glazing fenestration area is less than or equal to Vertical Fenestration Area allowed, glazing area allowed by Section C402.4.1 the value of D C (Excess Vertical Glazing Value) shall be zero. Otherwise:

C = (CA x UV) – (CA x UWall), but not less than zero
CA = (Proposed Vertical Fenestration Area) – (Vertical Fenestration Area allowed)
UAW = Sum of the (UA table) values for each above-grade wall assembly
UWall = UAW/(sum of Proposed wall area + CA)
UAV = Sum of the (UA table) values for each vertical fenestration assembly
UV = UAV/Total Vertical Fenestration Area allowed

Where the proposed skylight area is less than or equal to the skylight area allowed by Section C402.4.1, the value of E D (Excess Skylight Value) shall be zero. Otherwise:

E D = (EA DA x US) - (EA DA x URoof), but not less than zero.
   EA DA = (Proposed Skylight Area) - (Allowable Skylight Area as specified in from Section C402.4.1).
   UAR = Sum of the (UA Table) values for each roof assembly
   URoof = Area-weighted average U-value of all roof assemblies.UAR/sum of Proposed roof area
   UAS = Sum of the (UA Table) values for each skylight assembly.
   US = UAS/the Allowable Skylight Area from Section C402.4.1.


Where required by other sections of the code, Proposal Total Envelope UA and Allowed Total Envelope UA shall be calculated as:

Proposed Total Envelope UA
= Sum of UA Proposed and FL Proposed for each distinct envelope assembly
Allowed Total Envelope UA

= Sum UA Table – C – D
Where:
Sum UA Table

= Sum of UA Table and FL Table for each distinct envelope assembly

C402.1.5.1 Component U-factors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The U-factors for typical construction assemblies are included in Chapter 3 and Appendix A. These values shall be used for all calculations. Where proposed construction assemblies are not represented in Chapter 3 or Appendix A, values shall be calculated in accordance with the ASHRAE Handbook of Fundamentals, using the framing factors listed in Appendix A.

For envelope assemblies containing metal framing, the U-factor shall be determined by one of the following methods:
  1. Results of laboratory measurements according to acceptable methods of test.
  2. ASHRAE Handbook of Fundamentals where the metal framing is bonded on one or both sides to a metal skin or covering.
  3. The zone method as provided in ASHRAE Handbook of Fundamentals.
  4. Effective framing/cavity R-values as provided in Appendix A. When return air ceiling plenums are employed, the roof/ceiling assembly shall:
    1. For thermal transmittance purposes, not include the ceiling proper nor the plenum space as part of the assembly; and
    2. For gross area purposes, be based upon the interior face of the upper plenum surface.
  5. Tables in ASHRAE 90.1 Normative Appendix A.

C402.1.5.2 SHGC rate calculations

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Fenestration SHGC values for individual components and/or fenestration are permitted to exceed the SHGC values in Table C402.4 and/or the maximum allowable fenestration areas in Section C402.4.1 where the proposed values result in SHGCAp less than SHGCAt as determined by Equations 4-3 and 4-4.

EQUATION 4-3
TARGET SHGCAT
SHGCAt = SHGCogt(Aogt) + SHGCvgt(Avgt + Avgmt + Avgmot + Avgdt)
Where:
SHGCAt = The target combined specific heat gain of the target fenestration area.
SHGCogt = The solar heat gain coefficient for skylight fenestration found in Table C402.4.
Aogt = The target skylight area.
SHGCvgt = The solar heat gain coefficient for fenestration found in Table C402.4 which corresponds to the proposed total fenestration area as a percent of gross exterior wall area.
Avgt = The target vertical fenestration area with nonmetal framing
Avgmt _vertical_align_top">=d> ss="uc_vertical_align_top">The target vertical fenestration area with fixed metal framing
Avgmot = The target vertical fenestration area with operable metal framing
Avgdt = The proposed entrance door area
NOTE: The vertical fenestration area does not include opaque doors and opaque spandrel panels.

   If the proposed vertical fenestration area does not exceed the Vertical Fenestration Area allowed, the target area for each vertical fenestration type shall equal the proposed area. If the proposed vertical fenestration area exceeds the Vertical Fenestration Area allowed, the target area of each vertical fenestration element shall be reduced in the base envelope design by the same percentage and the net area of each above-grade wall type increased proportionately by the same percentage so that the total vertical fenestration area is exactly equal to the Vertical Fenestration Area allowed.

   If the proposed skylight area does not exceed the Allowable Skylight Area from Section C402.4.1, the target area shall equal the proposed area. If the proposed skylight area exceeds the Allowable Skylight Area from Section C402.4.1, the area of each skylight element shall be reduced in the base envelope design by the same percentage and the net area of each roof type increased proportionately by the same percentage so that the total skylight area is exactly equal to the allowed percentage per Section C402.3.1 of the gross roof area.

EQUATION 4-4
PROPOSED SHGCAP
SHGCAp = SHGCogAog + SHGCvgAvg
Where:
SHGCAt = The combined proposed specific heat gain of the proposed fenestration area.
SHGCog = The solar heat gain coefficient of the skylights.
Aog = The skylight area.
SHGCvg = The solar heat gain coefficient of the vertical fenestration.
Avg = The vertical fenestration area.
NOTE: The vertical fenestration area does not include opaque doors and opaque spandrel panels.

C402.2 Specific building thermal envelope insulation requirements (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Insulation in building thermal envelope opaque assemblies shall comply with Sections C402.2.1 through C402.2.6 and Table C402.1.3.

Where this section refers to installing insulation levels as specified in Section C402.1.3, assemblies complying with Section C402.1.5 are allowed to install alternate levels of insulation so long as the U-factor of the insulated assembly is less than or equal to the U-factor required by the respective path.

C402.2.1 Multiple layers of continuous insulation board

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where two or more layers of continuous insulation board are used in a construction assembly, the continuous insulation boards shall be installed in accordance with Section C303.2. Where If the continuous insulation board manufacturer’s installation instructions do not address installation of two or more layers, the edge joints between each layer of continuous insulation boards shall be staggered.

C402.2.2 Roof assembly

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The minimum thermal resistance (R-value) of the insulating material installed either between the roof framing or continuously on the roof assembly shall be as specified in Table C402.1.3, based on construction materials used in the roof assembly. Skylight curbs shall be insulated to the level of roofs with insulation entirely above deck or R-5, whichever is less.

Exceptions:

  1. Continuously insulated roof assemblies where the thickness of insulation varies 1 inch (25 mm) or less and where the area-weighted U-factor is equivalent to the same assembly with the R-value specified in Table C402.1.3.
  2. Where tapered insulation is used with insulation entirely above deck, the R-value where the insulation thickness varies 1 inch (25 mm) or less from the minimum thickness of tapered insulation shall comply with the R-value specified in Table C402.1.3 those roof assemblies shall show compliance on a U-factor basis per Section C402.1.4. The effective U-factor shall be determined through the use of Tables A102.2.6(1), A102.2.6(2) and A102.2.6(3).
  3. Unit skylight curbs included as a component of a skylight listed and labeled in accordance with NFRC 100 shall not be required to be insulated.

Insulation installed on a suspended ceiling with removable ceiling tiles shall not be considered part of the minimum thermal resistance of the roof insulation.

C402.2.3 Thermal resistance of above-grade walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The minimum thermal resistance (R-value) of materials installed in the wall cavity between the framing members and continuously on the walls shall be as specified in Table C402.1.3, based on framing type and construction materials used in the wall assembly. The R-value of integral insulation installed in concrete masonry units (CMU) shall not be used in determining compliance with Table C402.1.3.

“Mass walls” shall include walls:

  1. Weighing not less than 35 psf (170 kg/m2) of wall surface area.
  2. Weighing not less than 25 psf (120 kg/m2) of wall surface area where the material weight is not more than 120 pounds per cubic foot (pcf) (1,900 kg/m3).
  3. Having a heat capacity exceeding 7 Btu/ft2 x °F (144 kJ/m2 x K).
  4. Having a heat capacity exceeding 5 Btu/ft2 x °F (103 kJ/m2 x K), where the material weight is not more than 120 pcf (1900 kg/m3).

C402.2.4 Floors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The thermal properties (component R-values or assembly U-, C- or F-factors) of floor assemblies over outdoor air or unconditioned space shall be as specified in Table C402.1.3 or C402.1.4 based on the construction materials used in the floor assembly. Floor framing cavity insulation or structural slab insulation shall be installed to maintain permanent contact with the underside of the subfloor decking or structural slabs.

Exceptions:

  1. The floor framing cavity insulation or structural slab insulation shall be permitted to be in contact with the top side of sheathing or continuous insulation installed on the bottom side of floor assemblies where combined with insulation that meets or exceeds the minimum R-value in Table C402.1.3 for “Metal framed” or “Wood framed and other” values for “Walls, Above Grade” and extends from the bottom to the top of all perimeter floor framing or floor assembly members.
  2. Insulation applied to the underside of concrete floor slabs shall be permitted an airspace of not more than 1 inch (25 mm) where it turns up and is in contact with the underside of the floor under walls associated with the building thermal envelope.

C402.2.4 Thermal resistance of below-grade walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The minimum thermal resistance (R-value) of the insulating material installed in, or continuously on, the below-grade walls shall be as specified in Table C402.1.3.

C402.2.5 Slabs-on-grade perimeter insulation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Where the slab on grade is in contact with the ground, the minimum thermal resistance (R-value) of the insulation around the perimeter of unheated or heated slab-on-grade floors designed in accordance with the R-value method of Section C402.1.3 shall be as specified in Table C402.1.3. The insulation shall be placed on the outside of the foundation or on the inside of the foundation wall. The insulation shall extend downward from the top of the slab for a minimum distance as shown in the table or to the top of the footing, whichever is less, or downward to at least the bottom of the slab and then horizontally to the interior or exterior for the total distance shown in the table. Insulation extending away from the building shall be protected by pavement or by not less than of 10 inches (254 mm) of soil.

Exception: Where the slab-on-grade floor is greater than 24 inches (61 mm) below the finished exterior grade, perimeter insulation is not required.

C402.2.6 Insulation of radiant heating systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Radiant heating system panels, and their associated components that are installed in interior or exterior assemblies shall be insulated with a minimum of R-3.5 (0.62 m2/K W) on all surfaces not facing the space being heated. Radiant heating system panels that are installed in the building thermal envelope shall be separated from the exterior of the building or unconditioned or exempt spaces by not less than the R-value of insulation installed in the opaque assembly in which they are installed or the assembly shall comply with Section C402.1.4.

Exception: Heated slabs on grade insulated in accordance with Section C402.2.5.

C402.2.5 Floors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The thermal properties (component R-values or assembly U- or F-factors) of floor assemblies over outdoor air or unconditioned space shall be as specified in Table C402.1.3 or C402.1.4 based on the construction materials used in the floor assembly. Floor framing cavity insulation or structural slab insulation shall be installed to maintain permanent contact with the underside of the subfloor decking or structural slabs.

Exceptions:
  1. The floor framing cavity insulation or structural slab insulation shall be permitted to be in contact with the top side of sheathing or continuous insulation installed on the bottom side of floor assemblies where combined with insulation that meets or exceeds the minimum R-value in Table C402.1.3 for “Metal framed” or “Wood framed and other” values for “Walls, Above Grade” and extends from the bottom of the top of all perimeter floor framing or floor assembly members.
  2. Insulation applied to the underside of concrete floor slabs shall be permitted an air space of not more than 1 inch where it turns up and is in contact with the underside of the floor under walls associated with the building thermal envelope.

C402.2.6 Slabs-on-grade perimeter insulation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where the slab-on-grade is in contact with the ground, the minimum thermal resistance (R-value) of the insulation around the perimeter of unheated or heated slab-on-grade floors designed in accordance with the R-value method of Section C402.1.3 shall be as specified in Table C402.1.3.

The insulation shall be placed on the outside of the foundation or on the inside of the foundation wall. The insulation shall extend downward from the top of the slab for a minimum distance as shown in the table or to the top of the footing, whichever is less, or downward to at least the bottom of the slab and then horizontally to the interior or exterior for the total distance shown in the table. Insulation extending away from the building shall be protected by pavement or by a minimum of 10 inches (254 mm) of soil. Insulation complying with Table C402.1.3 shall be provided under the entire area of heated slabs-on-grade.

Exception: Where the slab-on-grade floor is greater than 24 inches (61 mm) below the finished exterior grade, perimeter insulation is not required.

C402.2.7 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C402.2.8 Insulation of radiant heating systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Radiant heating system panels and their associated components that are installed in interior or exterior assemblies shall be insulated with a minimum of R-3.5 (0.62 m2/K × W) on all surfaces not facing the space being heated. Radiant heating system panels that are installed in the building thermal envelope shall be separated from the exterior of the building or unconditioned or exempt spaces by not less than the R-value of the insulation installed in the opaque assembly in which they are installed or the assembly shall comply with Section C402.1.4.

Exception: Heated slabs-on-grade insulated in accordance with Section C402.2.6.

C402.3 Roof solar reflectance and thermal emittance

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Low-sloped roofs directly above cooled conditioned spaces in Climate Zones 1, 2 and 3 shall comply with one or more of the options in Table C402.3.

Exceptions: The following roofs and portions of roofs are exempt from the requirements of Table C402.3:

  1. Portions of the roof that include or are covered by the following:

    1. 1.1. Photovoltaic systems or components.
    2. 1.2. Solar air or water-heating systems or components.
    3. 1.3. Roof gardens or landscaped roofs.
    4. 1.4. Above-roof decks or walkways.
    5. 1.5. Skylights.
    6. 1.6. HVAC systems and components, and other opaque objects mounted above the roof.
  2. Portions of the roof shaded during the peak sun angle on the summer solstice by permanent features of the building or by permanent features of adjacent buildings.
  3. Portions of roofs that are ballasted with a minimum stone ballast of 17 pounds per square foot [74 kg/m2] or 23 psf [117 kg/m2] pavers.
  4. Roofs where not less than 75 percent of the roof area complies with one or more of the exceptions to this section.

TABLE C402.3

MINIMUM ROOF REFLECTANCE AND EMITTANCE OPTIONSa

Three-year aged solar reflectanceb of 0.55 and 3-year aged thermal emittancec of 0.75
Three-year-aged solar reflectance indexd of 64
  1. The use of area-weighted averages to comply with these requirements shall be permitted. Materials lacking 3-year-aged tested values for either solar reflectance or thermal emittance shall be assigned both a 3-year-aged solar reflectance in accordance with Section C402.3.1 and a 3-year-aged thermal emittance of 0.90.
  2. Aged solar reflectance tested in accordance with ASTM C 1549, ASTM E 903 or ASTM E 1918 or CRRC-1 Standard.
  3. Aged thermal emittance tested in accordance with ASTM C 1371 or ASTM E 408 or CRRC-1 Standard.
  4. Solar reflectance index (SRI) shall be determined in accordance with ASTM E 1980 using a convection coefficient of 2.1 Btu/h ft2 °F (12W/m2 K). Calculation of aged SRI shall be based on aged tested values of solar reflectance and thermal emittance.

C402.3 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C402.3.1 Aged roof solar reflectance

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Where an aged solar reflectance required by Section C402.3 is not available, it shall be determined in accordance with Equation 4-3.

(Equation 4-3)

where:

Raged =The aged solar reflectance.
Rinitial =The initial solar reflectance determined in accordance with CRRC-1 Standard.

C402.4 Fenestration (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Fenestration shall comply with Sections C402.4 through C402.4.4 and Table C402.4. Daylight responsive controls shall comply with this section and Section C405.2.3.1 C405.2.4.1.

TABLE C402.4
BUILDING ENVELOPE FENESTRATION
MAXIMUM U-FACTOR AND SHGC REQUIREMENTS

CLIMATE ZONE 1 2 3 4 EXCEPT
MARINE
5 AND
MARINE 4
6 7 8
Vertical fenestration
U-factor
Nonmetal framing (all)a         0.30      
Metal framing (Fixed fenestration)b 0.50 0.50 0.46 0.38 0.38 0.36 0.29 0.29
Metal framing (operable fenestration)c 0.65 0.65 0.60 0.45 0.450.40 0.43 0.37 0.37
Metal framing (entrance doors)d 1.10 0.83 0.77 0.77 0.770.60 0.77 0.77 0.77
SHGC
Orientationa SEW N SEW N SEW N SEW N SEW N SEW N SEW N SEW N
PF < 0.2 0.25 0.33 0.25 0.33 0.25 0.33 0.40 0.53 0.40 0.53 0.40 0.53 0.45 NR 0.45 N
0.2 ≤ PF < 0.5 0.30 0.37 0.30 0.37 0.30 0.37 0.48 0.58 0.48 0.58 0.48 0.58 NR NR NR NR
PF ≥ 0.5 0.40 0.40 0.40 0.40 0.40 0.40 0.64 0.64 0.64 0.64 0.64 0.64 NR NR NR NR
Skylights
U-factor 0.75 0.65 0.55 0.50 0.50 0.50 0.50 0.50
SHGC 0.35 0.35 0.35 0.40 0.400.35 0.40 NR NR
CLIMATE ZONE 5 AND MARINE 4
Vertical Fenestration
U-factor
Nonmetal framing (all)a 0.30
Metal framing (fixed fenestration)b 0.38
Metal framing (operable fenestration)c 0.450.40
Metal framing (entrance doors)d 0.770.60
SHGC
Orientationa SEW N
PF < 0.2 0.40 0.53
0.2 ≤ PF < 0.5 0.48 0.58
PF ≥ 0.5 0.64 0.64
Skylights
U-factor 0.50
SHGC 0.400.35

NR = No requirement, PF = Projection factor.
  1. “N” indicates vertical fenestration oriented within 45 degrees of true north. “SEW” indicates orientations other than “N.” For buildings in the southern hemisphere, reverse south and north. Buildings located at less than 23.5 degrees latitude shall use SEW for all orientations.
  2. "Nonmetal framing" includes framing materials other than metal, with or without metal reinforcing or cladding.
  3. "Metal framing" includes metal framing, with or without thermal break. "Fixed" includes curtain wall, storefront, picture windows, and other fixed windows.
  4. "Metal framing" includes metal framing, with or without thermal break. "Operable" includes openable fenestration products other than "entrance doors."
  5. "Metal framing" includes metal framing, with or without thermal break. "Entrance door" includes glazed swinging entrance doors. Other doors which are not entrance doors, including sliding glass doors, are considered "operable."

C402.4.1 Maximum area

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The vertical fenestration area (not including opaque doors and opaque spandrel panels) shall not be greater than exceed 30 percent of the gross above-grade wall area. The skylight area shall not be greater than exceed 3 percent of the gross roof area.

C402.4.1.1 Increased vertical fenestration area with daylight responsive controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
In Climate Zones 1 through 6, not more than A maximum of 40 percent of the gross above-grade wall area shall be permitted to be vertical fenestration for the purpose of prescriptive compliance with Section C402.1.4 or for the component performance alternative in Section C402.1.5, provided all of the following requirements are met:

  1. In buildings not greater than two stories above grade, not less than 50 percent of the net conditioned floor area is within a daylight zone.
  2. In buildings three or more stories above grade, not less than 25 percent of the net floor area is within a daylight zone.
  3. Daylight responsive controls complying with Section C405.2.3.1 C405.2.4.1 are installed in daylight zones.
  4. Visible transmittance (VT) of vertical fenestration is not less greater than or equal to 1.1 times solar heat gain coefficient (SHGC).
Exception: Fenestration that is outside the scope of NFRC 200 is not required to comply with Item 4.

C402.4.1.2 Increased skylight area with daylight responsive controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The skylight area shall be permitted to be not more than 5 percent of the roof area provideddaylight responsive controls complying with Section C405.2.3.1 are installed in daylight zones under skylights.

C402.4.1.2 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C402.4.1.3 Increased vertical fenestration area with high-performance fenestration

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The vertical fenestration area (not including opaque doors and opaque spandrel panels) is permitted to exceed 30% but shall not exceed 40% of the gross above grade wall area, for the purpose of prescriptive compliance with Section C402.1.3 provided that each of the following conditions are met:
  1. The vertical fenestration shall have the following U-factors:
    1. Non-metal framing (all) = 0.28
    2. Metal framing (fixed) = 0.34
    3. Metal framing (operable) = 0.36
    4. Metal framing (entrance doors) = 0.60
  2. The SHGC of the vertical fenestration shall be less than or equal to 0.35, adjusted for projection factor in compliance with C402.4.3.
An area-weighted average shall be permitted to satisfy the U-factor requirement for each fenestration product category listed in Item 1 of this section. Individual fenestration products from different fenestration product categories shall not be combined in calculating the area-weighted average U-factor.

The compliance path described in this section is not permitted to be used for the Total Building Performance compliance path in Section C407. The compliance path described in this section is permitted to be used for the component performance alternative in Section C402.1.5, provided that the requirements of Section C402.1.5 are met.

C402.4.1.4 Increased vertical fenestration area with high-performance mechanical systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The vertical fenestration area (not including opaque doors and opaque spandrel panels) is permitted to exceed 30 percent but shall not exceed 40 percent of the gross above-grade wall area, for the purpose of prescriptive compliance with Section C402.1.4 or for the component performance alternative in Section C402.1.5, provided that the mechanical system complies with all requirements of Section C403.6, dedicated outdoor air systems (DOAS) without utilizing the exceptions to Section C403.6. This increased glazing fraction is not permitted to be used to establish the reference case for the Total Building Performance compliance path in Section C407.

C402.4.2 Minimum skylight fenestration area

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

For single story buildings only, in an enclosed space greater than 2,500 square feet (232 m2) in floor area, directly under a roof with not less than 75 percent of the ceiling area with a ceiling heights greater than 15 feet (4572 mm), and used as an office, lobby, atrium, concourse, corridor, storage space, gymnasium/exercise center, convention center, automotive service area, space where manufacturing occurs, nonrefrigerated warehouse, retail store, distribution/sorting area, transportation, depot or workshop, the total daylight zone under skylights are required to provide shall be not less than half the floor area and shall a total toplight daylight zone area not less than half the floor area and shall provide one of the following:

  1. A minimum ratio of skylight area to toplight daylight zone area under skylights of not less than 3 percent where all skylights have a VT of at least 0.40 as determined in accordance with Section C303.1.3.
  2. A minimum skylight effective aperture of at least 1 percent, determined in accordance with Equation 4-45.


(Equation 4-45)

where:

Skylight area=Total fenestration area of skylights.
Skylight VT=Area weighted average visible transmittance of skylights.
WF=Area weighted average well factor, where well factor is 0.9 if light well depth is less than 2 feet (610 mm), or 0.7 if light well depth is 2 feet (610 mm) or greater.
Light well depth=Measure vertically from the underside of the lowest point of the skylight glazing to the ceiling plane under the skylight.

Exception: Skylights above daylight zones of enclosed spaces are not required in:

  1. Buildings in Climate Zones 6 through 8 Reserved.
  2. Spaces where the designed general lighting power densities are less than 0.5 W/ft2 (5.4 W/m2).
  3. Areas where it is documented that existing structures or natural objects block direct beam sunlight on at least half of the roof over the enclosed area for more than 1,500 daytime hours per year between 8 a.m. and 4 p.m.
  4. Spaces where the daylight zone under rooftop monitors is greater than 50 percent of the enclosed space floor area.
  5. Spaces where the total floor area minus the sidelightarea of daylight zones adjacent to vertical fenestration area is less than 2,500 square feet (232 m2), and where the lighting in the daylight zone is controlled according to in accordance with Section C405.2.3.1.

C402.4.2.1 Lighting controls in daylight zones under skylights

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Daylight responsive controls complying with Section C405.2.3.1 C405.2.4.1 shall be provided to control all electric lights within daylight zones under skylights.

C402.4.2.2 Haze factor

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Skylights in office, storage, automotive service, manufacturing, nonrefrigerated warehouse, retail store, and distribution/sorting area spaces shall have a glazing material or diffuser with a haze factor greater than 90 percent when tested in accordance with ASTM D 1003.

Exception: Skylights designed and installed to exclude direct sunlight entering the occupied space by the use of fixed or automated baffles, or the geometry of skylight and light well.

C402.4.3 Maximum U-factor and SHGC

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The maximum U-factor and solar heat gain coefficient (SHGC) for fenestration shall be as specified in Table C402.4.

The window projection factor shall be determined in accordance with Equation 4-56.

(Equation 4-56)

Where:

PF =Projection factor (decimal).
A =Distance measured horizontally from the furthest continuous extremity of any overhang, eave, or permanently attached shading device to the vertical surface of the glazing.
B =Distance measured vertically from the bottom of the glazing to the underside of the overhang, eave, or permanently attached shading device.

Where different windows or glass doors have different PF values, they shall each be evaluated separately.

C402.4.3.1 Increased skylight SHGC

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
InClimate Zones 1 through 6, skylights shall be permitted a maximum SHGC of 0.60 where located above daylight zones provided with daylight responsive controls .

C402.4.3.1 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C402.4.3.2 Increased skylight U -factor

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where skylights are installed abovedaylight zones provided with daylight responsive controls , a maximum U -factor of 0.9 shall be permitted in Climate Zones 1 through 3 and a maximum U -factor of 0.75 shall be permitted in Climate Zones 4 through 8.

C402.4.3.2 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Where dynamic glazing is intended to satisfy the SHGC and VT requirements of Table C402.4, the ratio of the higher to lower labeled SHGC shall be greater than or equal to 2.4, and the dynamic glazing shall be automatically controlled to modulate the amount of solar gain into the space in multiple steps. Dynamic glazing shall be considered separately from other fenestration, and area-weighted averaging with other fenestration that is not dynamic glazing shall not be permitted.

Exception: Dynamic glazing is not required to comply with this section where both the lower and higher labeled SHGC already comply with the requirements of Table C402.4.

C402.4.3.4 Area-weighted U-factor

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
An area-weighted average shall be permitted to satisfy the U -factor requirements for each fenestration product category listed in Table C402.4. Individual fenestration products from different fenestration product categories listed in Table C402.4 shall not be combined in calculating area-weighted average U -factor.

C402.4.4 Doors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Opaque doors shall comply with the applicable requirements for doors as specified in Tables C402.1.3 and C402.1.4 and be considered part of the gross area of above- grade walls that are part of the building thermal envelope. Other doors shall comply with the provisions of Section C402.4.3 for vertical fenestration and the entire door area, including the frame, shall be considered part of the fenestration area of the building thermal envelope.

C402.5 Air leakage—thermal envelope (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The thermal envelope of buildings shall comply with Sections C402.5.1 through C402.5.8, or the building thermal envelope shall be tested in accordance with ASTM E 779 at a pressure differential of 0.3 inch water gauge (75 Pa) or an equivalent method approved by the code official and deemed to comply with the provisions of this section when the tested air leakage rate of the building thermal envelope is not greater than 0.40 cfm/ft 2 (0.2 L/s m 2 ). Where compliance is based on such testing, the building shall also comply with Sections C402.5.5, C402.5.6 and C402.5.7.

C402.5.1 Air barriers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

A continuous air barrier shall be provided throughout the building thermal envelope. The air barriers shall be permitted to be located on the inside or outside of the building envelope, located within the assemblies composing the envelope, or any combination thereof. The air barrier shall comply with Sections C402.5.1.1 and C402.5.1.2.

Exception: Air barriers are not required in buildings located in Climate Zone 2B.

C402.5.1.1 Air barrier construction

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The continuous air barrier shall be constructed to comply with the following:

  1. The air barrier shall be continuous for all assemblies that are the thermal envelope of the building and across the joints and assemblies.
  2. Air barrier joints and seams shall be sealed, including sealing transitions in places and changes in materials. The joints and seals shall be securely installed in or on the joint for its entire length so as not to dislodge, loosen or otherwise impair its ability to resist positive and negative pressure from wind, stack effect and mechanical ventilation.
  3. Penetrations of the air barrier shall be caulked, gasketed or otherwise sealed in a manner compatible with the construction materials and location. Joints and seals associated with penetrations shall be sealed in the same manner or taped or covered with moisture vapor-permeable wrapping material. Sealing materials shall be appropriate to the construction materials being sealed and shall be securely installed around the penetrations so as not to dislodge, loosen or otherwise impair the penetrations’ ability to resist positive and negative pressure from wind, stack effect, and mechanical ventilation. Sealing of concealed fire sprinklers, where required, shall be in a manner that is recommended by the manufacturer. Caulking or other adhesive sealants shall not be used to fill voids between fire sprinkler cover plates and walls or ceilings.
  4. Recessed lighting fixtures shall comply with Section C402.5.8. Where similar objects are installed that which penetrate the air barrier, provisions shall be made to maintain the integrity of the air barrier.
  5. Construction documents shall contain a diagram showing the building’s pressure boundary in plan(s) and section(s) and a calculation of the area of the pressure boundary to be considered in the test.

C402.5.1.2 Air barrier compliance options

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A continuous air barrier for the opaque building envelope shall comply with Section C402.5.1.2.1 or C402.5.1.2.2.

C402.5.1.2 Building test

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The completed building shall be tested and the air leakage rate of the building envelope shall not exceed 0.40 cfm/ft2 at a pressure differential of 0.3 inches water gauge (2.0 L/s x m2 at 75 Pa) at the upper 95 percent confidence interval in accordance with ASTM E 779 or an equivalent method approved by the code official. A report that includes the tested surface area, floor area, air by volume, stories above grade, and leakage rates shall be submitted to the building owner and the Code Official. If the tested rate exceeds that defined here, a visual inspection of the air barrier shall be conducted and any leaks noted shall be sealed to the extent practicable. An additional report identifying the corrective actions taken to seal air leaks shall be submitted to the building owner and the Code Official and any further requirement to meet the leakage air rate will be waived.

  1. Test shall be accomplished using either (1) both pressurization and depressurization or (2) pressurization alone, but not depressurization alone. The test results shall be plotted against the correct P for pressurization in accordance with Section 9.4 of ASTM E779.
  2. The test pressure range shall be from 25 Pa to 80 Pa per Section 8.10 of ASTM E779, but the upper limit shall not be less than 50 Pa, and the difference between the upper and lower limit shall not be less than 25 Pa.
  3. If the pressure exponent n is less than 0.45 or greater than 0.85 per Section 9.6.4 of ASTM E779, the test shall be rerun with additional readings over a longer time interval.

C402.5.1.2.1 Materials

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Materials with an air permeability not greater than 0.004 cfm/ft2 (0.02 L/s m2) under a pressure differential of 0.3 inch water gauge (75 Pa) when tested in accordance with ASTM E 2178 shall comply with this section. Materials in Items 1 through 16 shall be deemed to comply with this section, provided joints are sealed and materials are installed as air barriers in accordance with the manufacturer’s instructions.

  1. Plywood with a thickness of not less than 3/8 inch (10 mm).
  2. Oriented strand board having a thickness of not less than 3/8 inch (10 mm).
  3. Extruded polystyrene insulation board having a thickness of not less than 1/2 inch (12.7 mm).
  4. Foil-back polyisocyanurate insulation board having a thickness of not less than 1/2 inch (12.7 mm).
  5. Closed-cell spray foam a minimum density of 1.5 pcf (2.4 kg/m3) having a thickness of not less than 11/2 inches (38 mm).
  6. Open-cell spray foam with a density between 0.4 and 1.5 pcf (0.6 and 2.4 kg/m3) and having a thickness of not less than 4.5 inches (113 mm).
  7. Exterior or interior gypsum board having a thickness of not less than 1/2 inch (12.7 mm).
  8. Cement board having a thickness of not less than 1/2 inch (12.7 mm).
  9. Built-up roofing membrane.
  10. Modified bituminous roof membrane.
  11. Fully adhered single-ply roof membrane.
  12. A Portland cement/sand parge, or gypsum plaster having a thickness of not less than 5/8 inch (15.9 mm).
  13. Cast-in-place and precast concrete.
  14. Fully grouted concrete block masonry.
  15. Sheet steel or aluminum.
  16. Solid or hollow masonry constructed of clay or shale masonry units.

C402.5.1.2.1 Building test for mixed-use buildings

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where a building is three or fewer stories above grade plane and contains both commercial and residential uses, the air barrier of the R-2 and R-3 occupancy areas of the building is permitted to be separately tested according to Section R402.4.1.2. Alternatively, it is permissible to test the air barrier of the entire building according to Section C402.5.1.2, provided that the tested air leakage rate does not exceed the rate specified in Section C402.5.1.2.

C402.5.1.2.2 Assemblies

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Assemblies of materials and components with an average air leakage not greater than 0.04 cfm/ft2 (0.2 L/s m2) under a pressure differential of 0.3 inch of water gauge (w.g.)(75 Pa) when tested in accordance with ASTM E 2357, ASTM E 1677 or ASTM E 283 shall comply with this section. Assemblies listed in Items 1 through 3 shall be deemed to comply, provided joints are sealed and the requirements of Section C402.5.1.1 are met.

  1. Concrete masonry walls coated with either one application of block filler or two applications of a paint or sealer coating.
  2. Masonry walls constructed of clay or shale masonry units with a nominal width of 4 inches (102 mm) or more.
  3. A Portland cement/sand parge, stucco or plaster not less than 1/2 inch (12.7 mm) in thickness.


C402.5.2 Air leakage of fenestration

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The air leakage of fenestration assemblies shall meet the provisions of Table C402.5.2. Testing shall be in accordance with the applicable reference test standard in Table C402.5.2 by an accredited, independent testing laboratory and labeled by the manufacturer.

Exceptions:

  1. Field-fabricated fenestration assemblies that are sealed in accordance with Section C402.5.1.
  2. Fenestration in buildings that comply with the testing alternative of Section C402.5 are not required to meet the air leakage requirements in Table C402.5.2.

TABLE C402.5.2

MAXIMUM AIR LEAKAGE RATE FOR FENESTRATION ASSEMBLIES

FENESTRATION ASSEMBLYMAXIMUM
RATE (CFM/FT2)
TEST PROCEDURE
Windows0.20 aAAMA/WDMA/CSA 101/I.S.2/A440 or NFRC 400
Sliding doors0.20 a
Swinging doors0.20 a
Skylights – with condensation
weepage openings
0.30
Skylights – all other0.20 a
Curtain walls0.06NFRC 400
or
ASTM E 283 at 1.57 psf
(75 Pa)
Storefront glazing0.06
Commercial glazed
swinging entrance doors
1.00
Revolving doors1.00
Garage doors0.40ANSI/DASMA 105,
NFRC 400, or
ASTM E 283 at 1.57 psf
(75 Pa)
Rolling doors1.00
High-speed doors1.30

For SI: 1 cubic foot per minute = 0.47 L/s, 1 square foot = 0.093 m2.

  1. The maximum rate for windows, sliding and swinging doors, and skylights is permitted to be 0.3 cfm per square foot of fenestration or door area when tested in accordance with AAMA/WDMA/CSA101/I.S.2/A440 at 6.24 psf (300 Pa).

C402.5.2 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C402.5.3 Rooms containing fuel-burning appliances

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

In Climate Zones 3 through 8, Where open combustion air ducts provide combustion air to open combustion space conditioning fuel-burning appliances, the appliances and combustion air openings shall be located outside of the building thermal envelope or enclosed in a room isolated from inside the thermal envelope. Such rooms shall be sealed and insulated in accordance with the envelope requirements of Table C402.1.3 or C402.1.4, where the walls, floors and ceilings shall meet the minimum of the below-grade wall R-value requirement. The door into the room shall be fully gasketed, and any water lines and ducts in the room insulated in accordance with Section C403. The combustion air duct shall be insulated, where it passes through conditioned space, to a minimum of R-8.


Exceptions:

  1. Direct vent appliances with both intake and exhaust pipes installed continuous to the outside.
  2. Fireplaces and stoves complying with Sections 901 through 905 of the International Mechanical Code, and Section 2111.13 of the International Building Code.

C402.5.4 Doors and access openings to shafts, chutes, stairways and elevator lobbies

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Doors and access openings from conditioned space to shafts, chutes, stairways, and elevator lobbies not within the scope of the fenestration assemblies covered by Section C402.5.2 shall be gasketed, weatherstripped or sealed.


Exceptions:

  1. Door openings required to comply with Section 716 715 or 716.5 715.4 of the International Building Code.
  2. Doors and door openings required to comply with UL 1784 by the International Building Code.
Stairway enclosures, elevator shaft vents and other outdoor air intakes and exhaust openings integral to the building envelope shall be provided with dampers in accordance with Section C403.2.4.3.
Cargo doors and loading dock doors shall be equipped with weatherseals to restrict infiltration when vehicles are parked in the doorway.

C402.5.7 Vestibules

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

All building entrances shall be protected with an enclosed vestibule, with all doors opening into and out of the vestibule equipped with self-closing devices. Vestibules shall be designed so that in passing through the vestibule it is not necessary for the interior and exterior doors to open at the same time. The installation of one or more revolving doors in the building entrance shall not eliminate the requirement that a vestibule be provided on any doors adjacent to revolving doors. For the purposes of this section, “building entrances” shall include exit-only doors in buildings where separate doors for entering and exiting are provided.


Interior and exterior doors shall have a minimum distance between them of not less than 7 feet. The exterior envelope of conditioned vestibules shall comply with the requirements for a conditioned space. Either the interior or exterior envelope of unconditioned vestibules shall comply with the requirements for a conditioned space. The building lobby is not considered a vestibule.

Exceptions: Vestibules are not required for the following:

  1. Buildings in Climate Zones 1 and 2.
  2. Doors not intended to be used by the public, such as doors to mechanical or electrical equipment rooms, or intended solely for employee use as building entrances.
  3. Unfinished ground-level space greater than 3,000 square feet (298 m2) if a note is included on the permit documents at each exterior entrance to the space stating “Vestibule required at time of tenant build-out if entrance serves a space greater than 3,000 square feet in area.”
  4. Doors opening directly from a sleeping unit or dwelling unit.
  5. Doors that open directly from between a space less smaller than 3,000 square feet (298 m2) in area and the exterior of the building or the building entrance lobby, where those doors do not comprise one of the primary entrance paths to the remainder of the building.
  6. Revolving doors.
  7. Doors used primarily to facilitate vehicular movement or material handling and adjacent personnel doors.
  8. In buildings less than three stories above grade or in spaces that do not directly connect with the building elevator lobby, doors that have an air curtain with a velocity of not less than 6.56 feet per second (2 m/s) at the floor that have been tested in accordance with ANSI/AMCA 220 and installed in accordance with the manufacturer’s instructions. Manual or automatic controls shall be provided that will operate the air curtain with the opening and closing of the door. Air curtains and their controls shall comply with Section C408.2.3.
  9. Building entrances in buildings that are less than four stories above grade and less than 10,000 square feet in area.
  10. Elevator doors in parking garages provided that the elevators have an enclosed lobby at each level of the garage.
  11. Entrances to semi-heated spaces.

C402.5.8 Recessed lighting

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Recessed luminaires installed in the building thermal envelope shall be all of the following:

  1. IC- Rated.
  2. Labeled as having an air leakage rate of not more than 2.0 cfm (0.944 L/s) when tested in accordance with ASTM E 283 at a 1.57 psf (75 Pa) pressure differential.
  3. Sealed with a gasket or caulk between the housing and interior wall or ceiling covering.

Section C403 Building Mechanical Systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C403.1 General

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Mechanical systems and equipment serving the building heating, cooling, or ventilating, and other needs shall comply with Section C403.2 and shall comply with Sections C403.3 and C403.4 based on the equipment and systems provided.

Walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers shall comply with Section C403.2.15 or C403.2.16.


Exception: Energy using equipment used by a manufacturing, industrial or commercial process other than for conditioning spaces or maintaining comfort and amenities for the occupants and not otherwise regulated by C403.2.3, Tables C403.2.3 (1) through (10) inclusive, C403.2.4.5, C403.2.4.6, C403.2.7, C403.2.9, C403.5.4, C404.2, Table C404.2, C405.8, and C410. Data center HVAC equipment is not covered by this exception.

C403.2 Provisions applicable to all mechanical systems (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Mechanical systems and equipment serving the building heating, cooling or ventilating needs shall comply with Sections C403.2.1 through C403.2.16 C403.2.13.

C403.2.1 Calculation of heating and cooling loads

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Design loads associated with heating, ventilating and air conditioning of the building shall be determined in accordance with the procedures described in ANSI/ASHRAE/ACCA Standard 183 or by anapproved equivalent computational procedure using the design parameters specified in Chapter 3. Heating and cooling loads shall be adjusted to account for load reductions that are achieved where energy recovery systems are utilized in the HVAC system in accordance with the ASHRAE HVAC Systems and Equipment Handbook by an approved equivalent computational procedure.

C403.2.2 Equipment and system sizing

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The output capacity of heating and cooling equipment shall be not greater than that of the smallest available equipment size that exceeds the loads calculated in accordance with Section C403.2.1. A single piece of equipment providing both heating and cooling shall satisfy this provision for one function with the capacity for the other function as small as possible, within available equipment options.


Exceptions:

  1. Required standby equipment and systems provided with controls and devices that allow such systems or equipment to operate automatically only when the primary equipment is not operating.
  2. Multiple units of the same equipment type with combined capacities exceeding the design load and provided with controls that have the capabilityare configured to sequence the operation of each unit based on load.

C403.2.3 HVAC equipment performance requirements

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Equipment shall meet the minimum efficiency requirements of Tables C403.2.3(1), C403.2.3(2), C403.2.3(3), C403.2.3(4), C403.2.3(5), C403.2.3(6), C403.2.3(7), C403.2.3(8) and C403.2.3(9) when tested and rated in accordance with the applicable test procedure. Plate-type liquid-to-liquid heat exchangers shall meet the minimum requirements of Table C403.2.3(10). The efficiency shall be verified through certification and listed under an approved certification program or, where aif no certification program does not exists, the equipment efficiency ratings shall be supported by data furnished by the manufacturer. Where multiple rating conditions or performance requirements are provided, the equipment shall satisfy all stated requirements. Where components, such as indoor or outdoor coils, from different manufacturers are used, calculations and supporting data shall be furnished by the designer that demonstrates that the combined efficiency of the specified components meets the requirements herein.

Gas-fired and oil-fired forced air furnaces with input ratings of 225,000 Btu/h (65 kW) or greater and all unit heaters shall also have an intermittent ignition or interrupted device (IID), and have either mechanical draft (including power venting) or a flue damper. A vent damper is an acceptable alternative to a flue damper for furnaces where combustion air is drawn from the conditioned space. All furnaces with input ratings of 225,000 Btu/h (65 kW) or greater, including electric furnaces, that are not located within the conditioned space shall have jacket losses not exceeding 0.75 percent of the input rating.

Chilled water plants and buildings with more than 500 tons total capacity shall not have more than 100 tons provided by air-cooled chillers.

Exceptions:
  1. Where the designer demonstrates that the water quality at the building site fails to meet manufacturer's specifications for the use of water-cooled equipment.
  2. Air-cooled chillers with minimum efficiencies at least 10 percent higher than those listed in Table C403.2.3(7).
  3. Replacement of existing equipment.

TABLE C403.2.3(1)A
MINIMUM EFFICIENCY REQUIREMENTS:
ELECTRICALLY OPERATED UNITARY AIR CONDITIONERS AND CONDENSING UNITS

EQUIPMENT TYPE SIZE CATEGORY HEATING
SECTION TYPE
SUBCATEGORY OR
RATING CONDITION
MINIMUM EFFICIENCYBefore 1/1/2016As of 1/1/2016 TEST
PROCEDUREa
Air conditioners,
air cooled
< 65,000 Btu/hb All Split System 13.0 SEER13.0 SEER AHRI 210/240
Single Package 13.0 SEER14.0 SEERc
Through-the-wall
(air cooled)
≤ 30,000 Btu/hb All Split system 12.0 SEER12.0 SEER
Single Package 12.0 SEER12.0 SEER
Small-duct high- velocity,
(air cooled)
≤ 65,000 Btu/hb All Split system 11.0 SEER11.0 SEER
Air conditioners,
air cooled
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.2 EER
11.4 IEER
11.2 EER
12.8
12.9 IEER
 
AHRI 340/360
All other Split System and
Single Package
11.0 EER
11.2 IEER
11.0 EER
12.6 12.7 IEER
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.0 EER
11.2 IEER
11.0 EER
12.4 IEER
All other Split System and
Single Package
10.8 EER
11.0 IEER
10.8 EER
12.2 IEER
≥ 240,000 Btu/h
and
< 760,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
10.0 EER
10.1 IEER
10.0 EER
11.6 IEER
All other Split System and
Single Package
9.8 EER
9.9 IEER
9.8 EER
11.4 IEER
≥ 760,000 Btu/h Electric Resistance
(or None)
Split System and
Single Package
9.7 EER
9.8 IEER
9.7 EER
11.2 IEER
All other Split System and
Single Package
9.5 EER
9.6 IEER
9.5 EER
11.0
11.6 IEER 
Air conditioners,
water cooled
< 65,000 Btu/hb All Split System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
12.3 IEER
AHRI 210/240
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
13.9 IEER
AHRI 340/360
All other Split System and
Single Package
11.9 EER
12.1 IEER
11.9 EER
13.7 IEER
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.5 EER
12.5 IEER
12.5 EER
13.9 IEER
 
All other Split System and
Single Package
12.3 EER
12.5 IEER
12.3 EER
13.7 IEER
≥ 240,000 Btu/h
and
< 760,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.4 EER
12.6 IEER
12.4 EER
13.6 IEER
 
All other Split System and
Single Package
12.2 EER
12.4 IEER
12.2 EER
13.4 IEER
≥ 760,000 Btu/h Electric Resistance
(or None)
Split System and
Single Package
12.2 EER
12.4 IEER
12.2 EER
13.5 IEER
All other Split System and
Single Package
12.0 EER
12.2 IEER
12.0 EER
13.3 IEER
Air conditioners,
evaporatively cooled
< 65,000 Btu/hb All Split System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
12.3 IEER
AHRI 210/240
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
12.3 IEER
AHRI 340/360
All other Split System and
Single Package
11.9 EER
12.1 IEER
11.9 EER
12.1 IEER
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.0 EER
12.2 IEER
12.0 EER
12.2 IEER
All other Split System and
Single Package
11.8 EER
12.0 IEER
11.8 EER
12.0 IEER
≥ 240,000 Btu/h
and
< 760,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.9 EER
12.1 IEER
11.9 EER
12.1 IEER
All other Split System and
Single Package
11.7 EER
11.9 IEER
11.7 EER
11.9 IEER
≥ 760,000 Btu/h Electric Resistance
(or None)
Split System and
Single Package
11.7 EER
11.9 IEER
11.7 EER
11.9 IEER
All other Split System and
Single Package
11.5 EER
11.7 IEER
11.5 EER
11.7 IEER
Condensing units,
air cooled
≥ 135,000 Btu/h     10.5 EER
11.8 IEER
10.5 EER
11.8 IEER
AHRI 365
Condensing units,
water cooled
≥ 135,000 Btu/h     13.5 EER
14.0 IEER
13.5 EER
14.0 IEER
Condensing units,
evaporatively cooled
≥ 135,000 Btu/h     13.5 EER
14.0 IEER
13.5 EER
14.0 IEER

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Chapter 6 of the referenced standard contains a complete specification of the referenced test procedure, including the reference year version of the test procedure.
  2. Single-phase, air-cooled air conditioners less than 65,000 Btu/h are regulated by NAECA. SEER values are those set by NAECA.
  3. Minimum efficiency as of January 1, 2015.
TABLE C403.2.3(1)B
MINIMUM EFFICIENCY REQUIREMENTS:
ELECTRICALLY OPERATED VARIABLE REFRIGERANT FLOW AIR CONDITIONERS
Equipment Type Size Category Heating Section Type Sub-Category or
Rating Condition
Minimum Efficiency Test Procedure
Before
1/1/2017
After
1/1/2017
VRF
Air Conditioners,
Air Cooled
<65,000 Btu/h All VRF Multi-split System 13.0 SEER 13.0 SEER AHRI 1230
≥65,000 Btu/h and <135,000 Btu/h Electric Resistance (or none) VRF Multi-split System 11.2 EER
13.1 IEER
11.2 EER
15.5 IEER
≥135,000 Btu/h and <240,000 Btu/h Electric Resistance (or none) VRF Multi-split System 11.0 EER
12.9 IEER
11.0 EER
14.9 IEER
≥240,000 Btu/h Electric Resistance (or none) VRF Multi-split System 10.0 EER
11.6 IEER
10.0 EER
13.9 EER

TABLE C403.2.3(1)C
MINIMUM EFFICIENCY REQUIREMENTS: ELECTRICALLY OPERATED VARIABLE REFRIGERANT FLOW AIR-TO-AIR AND APPLIED HEAT PUMPS
Equipment Type Size Category Heating Section Type Sub-Category or
Rating Condition
Minimum Efficiency Test Procedure
Before
1/1/2017
After
1/1/2017
VRF
Air Cooled,
(cooling mode)
<65,000 Btu/h All VRF Multi-split System 13.0 SEER 13.0 SEER AHRI 1230
≥65,000 Btu/h and
<135,000 Btu/h
Electric Resistance
(or none)
VRF Multi-split System 11.0 EER
12.9 IEER
11.0 EER
14.6 IEER
≥65,000 Btu/h and <135,000 Btu/h Electric Resistance
(or none)
VRF Multi-split System
with Heat Recovery
10.8 EER
12.7 IEER
10.8 EER
14.4 IEER
≥135,000 Btu/h and <240,000 Btu/h Electric Resistance
(or none)
VRF Multi-split System 10.6 EER
12.3 IEER
10.6 EER
13.9 IEER
≥135,000 Btu/h and <240,000 Btu/h Electric Resistance
(or none)
VRF Multi-split System
with Heat Recovery
10.4 EER
12.1 IEER
10.4 EER
13.7 IEER
≥240,000 Btu/h Electric Resistance
(or none)
VRF Multi-split System 9.5 EER
11.0 IEER
9.5 EER
12.7 IEER
≥240,000 Btu/h Electric Resistance
(or none)
VRF Multi-split System with Heat Recovery 9.3 EER
10.8 IEER
9.3 EER
12.5 IEER
VRF
Water source
(cooling mode)
<65,000 Btu/h All VRF Multi-split systems
86°F entering water
12.0 EER AHRI 1230
<65,000 Btu/h All VRF Multi-split systems
with Heat Recovery
86°F entering water
11.8 EER
≥65,000 Btu/h and
<135,000 Btu/h
All VRF Multi-split System
86°F entering water
12.0 EER
≥65,000 Btu/h and<135,000 Btu/h All VRF Multi-split System
with Heat Recovery
86°F entering water
11.8 EER
≥135,000 Btu/h All VRF Multi-split System
86°F entering water
10.0 EER
≥135,000 Btu/h All VRF Multi-split System
with Heat Recovery
86°F entering water
9.8 EER
VRF Ground
water source
(cooling mode)
<135,000 Btu/h All VRF Multi-split System
59°F entering water
16.2 EER AHRI 1230
<135,000 Btu/h All VRF Multi-split System
with Heat Recovery
59°F entering water
16.0 EER
≥135,000 Btu/h All VRF Multi-split System
59°F entering water
13.8 EER
≥135,000 Btu/h All VRF Multi-split System
with Heat Recovery
59°F entering water
13.6 EER
VRF
Ground source
(cooling mode)
<135,000 Btu/h All VRF Multi-split System
77°F entering water
13.4 EER AHRI 1230
<135,000 Btu/h All VRF Multi-split System
with Heat Recovery
77°F entering water
13.2 EER
≥135,000 Btu/h All VRF Multi-split System
77°F entering water
11.0 EER
≥135,000 Btu/h All VRF Multi-split System
with Heat Recovery
77°F entering water
10.8 EER
VRF
Air Cooled
(heating mode)
<65,000Btu/h
(cooling capacity)
- - - VRF Multi-split System 7.7 HSPF AHRI 1230
≥65,000 Btu/h and
<135,000 Btu/h
(cooling capacity)
- - - VRF Multi-split system


47°F db/43°F wb Outdoor Air 3.3 COP
17°F db/15°F wb Outdoor Air 2.25 COP
≥135,000 Btu/h
(cooling capacity)
- - - VRF Multi-split System
47°F db/43°F wb Outdoor Air 3.2 COP
17°F db/15°F wb Outdoor Air 2.05 COP
VRF
Water source
(heating mode)
<135,000 Btu/h
(cooling capacity)
--- VRF Multi-split System
68°F entering water
4.2 COP AHRI 1230
≥135,000 Btu/h
(cooling capacity)
--- VRF Multi-split System
68°F entering water
3.9 COP
VRF
Groundwater source
(heating mode)
<135,000 Btu/h
(cooling capacity)
--- VRF Multi-split System
50°F entering water
3.6 COP AHRI 1230
≥135,000 Btu/h
(cooling capacity)
--- VRF Multi-split System
50°F entering water
3.3 COP
VRF
Ground source
(heating mode)
<135,000 Btu/h
(cooling capacity)
--- VRF Multi-split System
32°F entering water
3.1 COP AHRI 1230
≥135,000 Btu/h
(cooling capacity)
--- VRF Multi-split System
32°F entering water
2.8 COP


TABLE C403.2.3(2)
MINIMUM EFFICIENCY REQUIREMENTS: ELECTRICALLY OPERATED UNITARY AND APPLIED HEAT PUMPS

EQUIPMENT TYPE SIZE CATEGORY HEATING
SECTION TYPE
SUBCATEGORY OR
RATING CONDITION
MINIMUM
EFFICIENCY
TEST
PROCEDUREa
Before 1/1/2016 As of 1/1/2016
Air cooled
(cooling mode)
< 65,000 Btu/hb All Split System 13.0 SEERc 14.0 SEERc AHRI 210/240
Single Packaged 13.0 SEERc 14.0 SEERc
Through-the-wall, air cooled (cooling mode) ≤ 30,000 Btu/hb All Split System 12.0 SEER 12.0 SEER
Single Packaged 12.0 SEER 12.0 SEER
Single- Small duct high- velocity, air cooled < 65,000 Btu/hb All Split System 11.0 SEER 11.0 SEER
Air cooled
(cooling mode)
≥ 65,000 Btu/h and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.0 EER
11.2 IEER
11.0 EER
12.0 12.2 IEER
AHRI 340/360
All other Split System and
Single Package
10.8 EER
11.0 IEER
10.8 EER
11.8 12.0 IEER
≥ 135,000 Btu/h and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
10.6 EER
10.7 IEER
10.6 EER
11.6 IEER
All other Split System and
Single Package
10.4 EER
10.5 IEER
10.4 EER
11.4 IEER
≥ 240,000 Btu/h Electric Resistance
(or None)
Split System and
Single Package
9.5 EER
9.6 IEER
9.5 EER
10.6 IEER
All other Split System and
Single Package
9.3 EER
9.4 IEER
9.3 EER
9.410.4 IEER
Water to Air: Water Loop source
(cooling mode)
< 17,000 Btu/h All 86°F entering water 12.2 EER 12.2 EER ISO 13256-1
≥ 17,000 Btu/h and
< 65,000 Btu/h
All 86°F entering water 13.0 EER 13.0 EER
≥ 65,000 Btu/h and
< 135,000 Btu/h
All 86°F entering water 13.0 EER 13.0 EER
Water to Air: Ground water source
(cooling mode)
< 135,000 Btu/h All 59°F entering water 18.0 EER 18.0 EER ISO 13256-1
Brine to Air: Ground Loop source
(cooling mode)
< 135,000 Btu/h All 77°F entering water 14.1 EER 14.1 EER ISO 13256-1
Water-source water to water: Water Loop
(cooling mode)
< 135,000 Btu/h All 86°F entering water 10.6 EER 10.6 EER ISO 13256-2
59°F entering water 16.3 EER 16.3 EER
Ground water source
Brine to water: Ground Loop
(cooling mode)
< 135,000 Btu/h All 77°F entering fluid 12.1 EER 12.1 EER
Air cooled
(heating mode)
< 65,000 Btu/hb Split System 7.7 HSPFc 8.2 HSPFc AHRI 210/240
Single Package 7.7 HSPFc 8.0 HSPFc
Through-the-wall,
(air cooled, heating mode)
≤ 30,000 Btu/hb (cooling capacity) Split System 7.4 HSPF 7.4 HSPF
Single Package 7.4 HSPF 7.4 HSPF
Small-duct high velocity
(air cooled, heating mode)
< 65,000 Btu/hb Split System 6.8 HSPF 6.8 HSPF
Air cooled
(heating mode)
≥ 65,000 Btu/h and
< 135,000 Btu/h
(cooling capacity)
47°F db/43°F wb
outdoor air
3.3 COP 3.3 COP AHRI 340/360
17°Fdb/15°F wb
outdoor air
2.25 COP 2.25 COP
≥ 135,000 Btu/h
(cooling capacity)
47°F db/43°F wb
outdoor air
3.2 COP 3.2 COP
17°Fdb/15°F wb
outdoor air
2.05 COP 2.05 COP
Water to Air: Water Loop source
(heating mode)
< 135,000 Btu/h
(cooling capacity)
68°F entering water 4.3 COP 4.3 COP ISO 13256-1
Water to Air: Ground water source
(heating mode)
< 135,000 Btu/h
(cooling capacity)
50°F entering water 3.7 COP 3.7 COP
Brine to Air: Ground Loop source
(heating mode)
< 135,000 Btu/h
(cooling capacity)
32°F entering fluid 3.2 COP 3.2 COP
Water-source
water to water: Water Loop
(heating mode)
< 135,000 Btu/h
(cooling capacity)
68°F entering water 3.7 COP 3.7 COP ISO 13256-2
Water to Water: Ground Water
(heating mode)
< 135,000 Btu/h
(cooling capacity)
50°F entering water 3.1 COP 3.1 COP
Ground source
brine to water: Ground Loop
(heating mode)
< 135,000 Btu/h
(cooling capacity)
32°F entering fluid 2.5 COP 2.5 COP

For SI: 1 British thermal unit per hour = 0.2931 W, °C = [(°F) - 32]/1.8.

  1. Chapter 6 of the referenced standard contains a complete specification of the referenced test procedure, including the reference year version of the test procedure.
  2. Single-phase, air-cooled air conditioners less than 65,000 Btu/h are regulated by NAECA. SEER values are those set by NAECA.
  3. Minimum efficiency as of January 1, 2015.

TABLE C403.2.3(3)
MINIMUM EFFICIENCY REQUIREMENTS: ELECTRICALLY OPERATED PACKAGED TERMINAL AIR CONDITIONERS, PACKAGED TERMINAL HEAT PUMPS, SINGLE-PACKAGE VERTICAL AIR CONDITIONERS, SINGLE-PACKAGE VERTICAL HEAT PUMPS, ROOM AIR CONDITIONERS AND ROOM AIR-CONDITIONER HEAT PUMPS

EQUIPMENT TYPESIZE CATEGORY (INPUT)SUBCATEGORY OR
RATING CONDITION
MINIMUM EFFICIENCYTEST
PROCEDUREa
PTAC (cooling mode)
new construction
All Capacities95°F db outdoor air14.0 — (0.300 × Cap/1000) EERcAHRI 310/380
PTAC (cooling mode)
replacementsb
All Capacities95°F db outdoor air10.9 - (0.213 × Cap/1000) EER
PTHP (cooling mode)
new construction
All Capacities95°F db outdoor air14.0 - (0.300 × Cap/1000) EER
PTHP (cooling mode)
replacementsb
All Capacities95°F db outdoor air10.8 - (0.213 × Cap/1000) EER
PTHP (heating mode)
new construction
All Capacities3.23.7 - (0.0260.052 × Cap/1000) COP
PTHP (heating mode)
replacementsb
All Capacities2.9 - (0.026 × Cap/1000) COP
SPVAC
(cooling mode)
< 65,000 Btu/h95°F db/ 75°F wb outdoor air9.0 10.0 EERAHRI 390
≥ 65,000 Btu/h and
< 135,000 Btu/h
95°F db/ 75°F wb outdoor air8.9 10.0 EER
≥ 135,000 Btu/h and
< 240,000 Btu/h
95°F db/ 75°F wb outdoor air8.6 10.0 EER
SPVHP
(cooling mode)
< 65,000 Btu/h95°F db/ 75°F wb outdoor air9.0 10.0 EER
≥ 65,000 Btu/h and
< 135,000 Btu/h
95°F db/ 75°F wb outdoor air8.9 10.0 EER
≥ 135,000 Btu/h and
< 240,000 Btu/h
95°F db/ 75°F wb outdoor air8.6 10.0 EER
SPVHP
(heating mode)
< 65,000 Btu/h47°F db/ 43°F wb outdoor air3.0 COPAHRI 390
≥ 65,000 Btu/h and
< 135,000 Btu/h
47°F db/ 43°F wb outdoor air3.0 COP
≥ 135,000 Btu/h and
< 240,000 Btu/h
47°F db/ 7543°F wb outdoor air2.9 3.0 COP
Room air conditioners,
with louvered sides
< 6,000 Btu/h 9.7 SEER ANSI/AHAM RAC-1
≥ 6,000 Btu/h and
< 8,000 Btu/h
9.7 SEER
≥ 8,000 Btu/h and
< 14,000 Btu/h
9.8 EER
≥ 14,000 Btu/h and
< 20,000 Btu/h
9.7 SEER
≥ 20,000 Btu/h 8.5 EER
Room air conditioners,
without louvered sides
< 8,000 Btu/h 9.0 EER
≥ 8,000 Btu/h and
< 20,000 Btu/h
8.5 EER
≥ 20,000 Btu/h 8.5 EER
Room air-conditioner
heat pumps with
louvered sides
< 20,000 Btu/h 9.0 EER ANSI/AHAM RAC-1
≥ 20,000 Btu/h 8.5 EER
Room air-conditioner
heat pumps without
louvered sides
< 14,000 Btu/h 8.5 EER
≥ 14,000 Btu/h 8.0 EER
Room air conditioner casement only All capacities 8.7 EER
Room air conditioner casement-slider All capacities 9.5 EER

For SI: 1 British thermal unit per hour = 0.2931 W, °C = [(°F) - 32]/1.8, wb = wet bulb, db = dry bulb.

“Cap” = The rated cooling capacity of the project product in Btu/h. Where If the unit’s capacity is less than 7000 Btu/h, use 7000 Btu/h in the calculation. WhereIf the unit’s capacity is greater than 15,000 Btu/h, use 15,000 Btu/h in the calculations.

  1. Chapter 6 of the referenced standard contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. Replacement unit shall be factory labeled as follows: “MANUFACTURED FOR REPLACEMENT NONSTANDARD SIZE APPLICATIONS ONLY: NOT TO BE INSTALLED IN NEW STANDARD PROJECTS” or MANUFACTURED FOR REPLACEMENT APPLICATIONS ONLY: NOT TO BE INSTALLED IN NEW CONSTRUCTION PROJECTS.” Replacement efficiencies apply only to units with existing sleeves less than 16 inches (406 mm) in height and less than 42 inches (1067 mm) in width.
  3. Before January 1, 2015 the minimum efficiency shall be 13.8 - (0.300 x Cap/1000) EER.

TABLE 403.2.3(4)
WARM- AIR FURNACES AND COMBINATION WARM- AIR FURNACES/AIR-CONDITIONING UNITS, WARM- AIR DUCT FURNACES AND UNIT HEATERS, MINIMUM EFFICIENCY REQUIREMENTS

EQUIPMENT TYPESIZE CATEGORY
(INPUT)
SUBCATEGORY OR
RATING CONDITION
MINIMUM
EFFICIENCYd, e
TEST PROCEDUREa
Warm-air furnaces,
gas fired
< 225,000 Btu/h78% AFUE or
80%Etc
DOE 10 CFR Part 430 or
ANSI Z21.47
≥ 225,000 Btu/hMaximum capacityc80%EtfANSI Z21.47
Warm-air furnaces,
oil fired
< 225,000 Btu/h78% AFUE or
80%Etc
DOE 10 CFR Part 430 or
UL 727
≥ 225,000 Btu/hMaximum capacityb81%EtgUL 727
Warm-air duct furnaces,
gas fired
All capacitiesMaximum capacityb80%EcANSI Z83.8
Warm-air unit heaters,
gas fired
All capacitiesMaximum capacityb80%EcANSI Z83.8
Warm-air unit heaters,
oil fired
All capacitiesMaximum capacityb80%EcUL 731

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Chapter 6 of the referenced standard contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. Minimum and maximum ratings as provided for and allowed by the unit’s controls.
  3. Combination units not covered by the National Appliance Energy Conservation Act of 1987 (NAECA) (3-phase power or cooling capacity greater than or equal to 65,000 Btu/h [19 kW]) shall comply with either rating.
  4. Et = Thermal efficiency. See test procedure for detailed discussion.
  5. Ec = Combustion efficiency (100% less flue losses). See test procedure for detailed discussion.
  6. Ec = Combustion efficiency. Units shall must also include an IID, have jackets not exceeding 0.75 percent of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.
  7. Et = Thermal efficiency. Units shall must also include an IID, have jacket losses not exceeding 0.75 percent of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.

TABLE C403.2.3(5)
MINIMUM EFFICIENCY REQUIREMENTS: GAS- AND OIL-FIRED BOILERS

EQUIPMENT TYPEaSUBCATEGORY OR
RATING CONDITION
SIZE CATEGORY (INPUT)MINIMUM EFFICIENCYd, eTEST PROCEDURE
Boilers, hot waterGas-fired< 300,000 Btu/h80%82% AFUE10 CFR Part 430
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
80% Et10 CFR Part 431
> 2,500,000 Btu/ha82% Ec
Oil-firedc< 300,000 Btu/h80%84% AFUE10 CFR Part 430
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
82% Et10 CFR Part 431
> 2,500,000 Btu/ha84% Ec
Boilers, steamGas-fired< 300,000 Btu/h75% 80% AFUE10 CFR Part 430
Gas-fired- all, except natural draft≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
79% Et10 CFR Part 431
> 2,500,000 Btu/ha79% Et
Gas-fired-natural draft≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
77% Et
> 2,500,000 Btu/ha77% Et
Oil-firedc< 300,000 Btu/h80%82% AFUE10 CFR Part 430
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
81% Et10 CFR Part 431
> 2,500,000 Btu/ha81% Et

For SI: 1 British thermal unit per hour = 0.2931 W.
Ec = Combustion efficiency (100 percent less flue losses). Et = Thermal efficiency. See referenced standard document for detailed information.

  1. These requirements apply to boilers with rated input of 8,000,000 Btu/h or less that are not packaged boilers and to all packaged boilers. Minimum efficiency requirements for boilers cover all capacities of packaged boilers.
  2. Maximum capacity – minimum and maximum ratings as provided for and allowed by the unit’s controls.
  3. Includes oil-fired (residual).
  4. Ec = Combustion efficiency (100 percent less flue losses).
  5. Et = Thermal efficiency. See referenced standard for detailed information.
TABLE C403.2.3(6)

MINIMUM EFFICIENCY REQUIREMENTS: CONDENSING UNITS, ELECTRICALLY OPERATED

RESERVED
EQUIPMENT TYPESIZE CATEGORYMINIMUM EFFICIENCYbTEST PROCEDUREa
Condensing units, air cooled≥ 135,000 Btu/h10.1 EER
11.2 IPLV
AHRI 365
Condensing units, water or evaporatively cooled≥ 135,000 Btu/h13.1 EER
13.1 IPLV

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. IPLVs are only applicable to equipment with capacity modulation.

TABLE C403.2.3(7)
MINIMUM EFFICIENCY REQUIREMENTS:
WATER CHILLING PACKAGES — EFFICIENCY REQUIREMENTSa, b, d
EQUIPMENT TYPESIZE CATEGORYUNITSBEFORE 1/1/2015AS OF 1/1/2015bTEST
PROCEDUREc
Path APath BPath APath B
FULL LOADIPLVFULL LOADIPLV
Air-cooled chillers < 150 TonsEER
(Btu/W)
≥ 9.562 FLNAc≥ 10.100 FL≥ 9.700 FLAHRI 550/590
≥ 12.500 IPLV≥ 13.700 IPLV≥ 15,800 IPLV
≥ 150 Tons≥ 9.562 FLNAc≥ 10.100 FL≥ 9.700 FL
≥ 12.500 IPLV≥ 14.000 IPLV≥ 16.100 IPLV
Air-cooled chillers < 150 tons EER ≥ 10.100 ≥ 13.700 ≥9.700 ≥15.800 AHRI 550/5904
≥150 tons EER ≥ 10.100 ≥14.000 ≥9.700 ≥16.100
Air cooled
without condenser,
electrically operated
All capacitiesEER(Btu/W) Air-cooled chillers without condensers shall be rated with
matching condensers and complying comply with the air-cooled chiller
efficiency requirements
Water cooled, electrically operated, reciprocatingAll capacitieskW/ton Reciprocating units shall comply with water cooled positive displacement efficiency requirements
Water cooled, electrically operated, positive displacement < 75 tons kW/ton ≤ 0.780 FL ≤ 0.750 ≤ 0.800 FL ≤ 0.600≤ 0.750 FL ≤ 0.780≤ 0.780 FL ≤0.500
≤ 0.630 IPLV≤ 0.600 IPLV≤ 0.600 IPLV≤ 0.500 IPLV
≥ 75 tons and < 150 tons kW/ton ≤ 0.775 FL ≤ 0.720≤ 0.790 FL ≤ 0.560≤ 0.720 FL ≤ 0.750≤ 0.750 FL ≤ 0.490
≤ 0.615 IPLV≤ 0.586 IPLV≤ 0.560 IPLV≤ 0.490 IPLV
≥ 150 tons and < 300 tons kW/ton ≥ 0.680 FL ≤ 0.660≥ 0.718 FL ≤0.540≥ 0.660 FL ≤ 0.680≥ 0.680 FL ≤ 0.440
≥ 0.580 IPLV≥ 0.540 IPLV≥ 0.540 IPLV≥ 0.440 IPLV
≥ 300 tons and < 600 tons kW/ton ≤ 0.620 FL ≤ 0.610≤ 0.639 FL ≤ 0.520≤ 0.610 FL ≤ 0.625≤ 0.625 FL ≤ 0.410
≤ 0.540 IPLV≤ 0.490 IPLV≤ 0.520 IPLV≤ 0.410 IPLV
≥ 600 tons kW/ton ≤ 0.620 FL ≤ 0.560≤ 0.639 FL ≤ 0.500≤ 0.560 FL ≤ 0.585≤ 0.585 FL≤ 0.380
≤ 0.540 IPLV≤ 0.490 IPLV≤ 0.500 IPLV≤ 0.380 IPLV
Water cooled, electrically operated, centrifugal< 150 tonskW/ton≤ 0.634 FL ≤ 0.610≤ 0.639 FL ≤ 0.550≤ 0.610 FL ≤ 0.695≤ 0.695 FL ≤ 0.440
≤ 0.596 IPLV≤ 0.450 IPLV≤ 0.550 IPLV≤ 0.440 IPLV
≥ 150 tons and < 300 tons kW/ton≤ 0.634 FL≤ 0.639 FL≤ 0.610 FL≤ 0.635 FL
≤ 0.596 IPLV≤ 0.450 IPLV≤ 0.550 IPLV≤ 0.400 IPLV
≥ 300 tons and < 400 tons kW/ton ≤ 0.576 FL ≤ 0.560≤ 0.600 FL ≤ 0.520≤ 0.560 FL ≤ 0.595≤ 0.595 FL ≤ 0.390
≤ 0.549 IPLV≤ 0.400 IPLV≤ 0.520 IPLV≤ 0.390 IPLV
≥ 400 tons and < 600 tons kW/ton0.576 FL ≤0.560≤ 0.600 FL ≤ 0.500≤ 0.560 FL ≤ 0.585≤ 0.585 FL ≤0.380
≤ 0.549 IPLV≤ 0.400 IPLV≤ 0.500 IPLV≤ 0.380 IPLV
≥ 600 Tons≤ 0.570 FL≤ 0.590 FL≤ 0.560 FL≤ 0.585 FL
≤ 0.539 IPLV≤ 0.400 IPLV≤ 0.500 IPLV≤ 0.380 IPLV
Air cooled, absorption, single effect All capacitiesCOP≥ 0.600 FL NAcNR ≥ 0.600 FL NANAcAHRI 560
Water cooled, absorption, single effectAll capacitiesCOP≥ 0.700 FLNAc NR≥ 0.700 FL NANAc
Absorption, double effect, indirect firedAll capacitiesCOP≥ 1.000 FLNAc ≥ 1.050≥ 1.000 FL NANAc
≥ 1.050 IPLV≥ 1.050 IPLV
Absorption double effect, direct firedAll capacitiesCOP≥ 1.000 FLNAc≥ 1.000≥ 1.000 FL NANAc
≥ 1.000 IPLV≥ 1.050 IPLV

For SI: 1 ton = 3517 W, 1 British thermal unit per hour = 0.2931 W, °C = [(°F) - 32]/1.8.
NA = Not applicable, not to be used for compliance; NR = No requirement.
  1. The requirements for centrifugal chiller shall be adjusted for nonstandard rating conditions in accordance with Section C403.2.3.1 and are only applicable for the range of conditions listed in Section C403.2.3.1. The requirements for air-cooled, water-cooled positive displacement and absorption chillers are at standard rating conditions defined in the reference test procedure.The centrifugal chiller equipment requirements, after adjustment in accordance with Section C403.2.3.1 or Section C403.2.3.2, do not apply to chillers used in low-temperature applications where the design leaving fluid temperature is less than 36°F. The requirements do not apply to positive displacement chillers with leaving fluid temperatures less than or equal to 32°F. The requirements do not apply to absorption chillers with design leaving fluid temperatures less than 40°F.
  2. Both the full-load and IPLV requirements shall be met or exceeded to comply with this standard. Where there is a Path B, compliance can be with either Path A or Path B for any application.Compliance with this standard can be obtained by meeting the minimum requirements of Path A or B. However, both the full load and IPLV shall be met to fulfill the requirements of Path A or B.
  3. NA means the requirements are not applicable for Path B and only Path A can be used for compliance.
  4. FL represents the full-load performance requirements and IPLV the part-load performance requirements.
  5. Chapter 6 of the referenced standard contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

TABLE C403.2.3(8)
MINIMUM EFFICIENCY REQUIREMENTS: HEAT REJECTION EQUIPMENT


EQUIPMENT TYPEaTOTAL SYSTEM
HEAT REJECTION
CAPACITY AT RATED
CONDITIONS
SUBCATEGORY OR RATING CONDITIONiPERFORMANCE
REQUIREDb, c, d, g, h
TEST PROCEDUREe, f
Propeller or axial fan open- circuit cooling towersAll95°F Entering Water
85°F Leaving Water
75°F Entering wb
40.2 38.2 gpm/hpCTI ATC-105 and
CTI STD-201
Centrifugal fan open- circuit cooling towersAll95°F Entering Water
85°F Leaving Water
75°F Entering wb
≥ 20.0 gpm/hpCTI ATC-105 and
CTI STD-201
Propeller or axial fan closed- circuit cooling towersAll102°F Entering Water
90°F Leaving Water
75°F Entering wb
≥ 14.0 gpm/hpCTI ATC-105S and
CTI STD-201
Centrifugal fan closed- circuit cooling towersAll102°F Entering Water
90°F Leaving Water
75°F Entering wb
≥ 7.0 gpm/hpCTI ATC-105S and
CTI STD-201
Propeller or axial fan evaporative condensers All Ammonia R-507A Test Fluid 140 165°F Entering Gas Temperature
96.3 105°F Entering db Condensing Temperature
75°F Entering wb
134,000157,000 Btu/h•hp CTI ATC-106
Centrifugal fan evaporative condensers Propeller or axial fan evaporative condensers All Ammonia Test Fluid
140°F Entering Gas Temperature
96.3°F Entering db Condensing Temperature
75°F Entering wb
> 110,000≥ 134,000 Btu/h•hp CTI ATC-106
Propeller or axial fan evaporative condensersCentrifugal fan evaporative condensersAllR-507A Test Fluid
165°F Entering Gas Temperature
105°F Entering db Condensing Temperature
75°F Entering wb
157,000135,000 Btu/h•hpCTI ATC-106
Centrifugal fan evaporative condensersAllR-507A Ammonia Test Fluid
165 140°F Entering Gas Temperature
105 96.3°F Entering db Condensing Temperature
75°F Entering wb
135,000 110,000 Btu/h•hpCTI ATC-106
Air-cooled condensersAll125°F Entering dbCondensing Temperature
R-22 Test Fluid
190°F Entering Gas Temperature
15°F Subcooling
95°F Entering db
≥ 176,000 Btu/h•hpAHRI 460

For SI: °C = [(°F)-32]/1.8, L/s kW = (gpm/hp)/(11.83), COP = (Btu/h • hp)/(2550.7),

db = dry bulb temperature, °F, wb = wet bulb temperature, °F.

  1. The efficiencies and test procedures for both open- and closed- circuit cooling towers are not applicable to hybrid cooling towers that contain a combination of wet and dry heat exchange sections.
  2. For purposes of this table, open circuit cooling tower performance is defined as the water flow rating of the tower at the thermal rating condition listed in Table 403.2.3(8) divided by the fan nameplate- rated motor power.
  3. For purposes of this table, closed- circuit cooling tower performance is defined as the water flow rating of the tower at the thermal rating condition listed in Table 403.2.3(8) divided by the sum of the fan nameplate- rated motor power and the spray pump nameplate- rated motor power.
  4. For purposes of this table, air-cooled condenser performance is defined as the heat rejected from the refrigerant divided by the fan nameplate- rated motor power.
  5. Chapter 6 of the referenced standard contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure. The certification requirements do not apply to field-erected cooling towers.
  6. Where a certification program exists for a covered product, and it includes provisions for verification and challenge of equipment efficiency ratings, then the product shall be listed in the certification program, or, if a certification program exists for a covered product, and it includes provisions for verification and challenge of equipment efficiency ratings, but the product is not listed in the existing certification program, the ratings shall be verified by an independent laboratory test report.
  7. Cooling towers shall comply with the minimum efficiency listed in the table for that specific type of tower with the capacity effect of any project-specific accessories and/or options included in the capacity of the cooling tower
  8. For purposes of this table, evaporative condenser performance is defined as the heat rejected at the specified rating condition in the table, divided by the sum of the fan motor nameplate power and the integral spray pump nameplate power
  9. Requirements for evaporative condensers are listed with ammonia (R-717) and R-507A as test fluids in the this table. Evaporative condensers intended for use with halocarbon refrigerants other than R-507A shall must meet the minimum efficiency requirements listed in this table above with R-507A as the test fluid.

TABLE C403.2.3(9)
MINIMUM EFFICIENCY REQUIREMENTS:
AIR CONDITIONERS AND CONDENSING UNITS SERVING COMPUTER ROOMS

EQUIPMENT TYPE NET SENSIBLE COOLING CAPACITYa MINIMUM SCOP-127b EFFICIENCY
DOWNFLOW UNITS/UPFLOW UNITS
TEST PROCEDURE
Air conditioners, air cooled < 65,000 Btu/h
(<19 kW)
2.20 / 2.09 ANSI/ASHRAE 127
≥ 65,000 Btu/h and
< 240,000 Btu/h
(≥19kW and < 70 kW)
2.10 / 1.99
≥ 240,000 Btu/h
(≥ 70 kW)
1.90 / 1.79
Air conditioners, water cooled < 65,000 Btu/h
(<19 kW)
2.60 / 2.49 ANSI/ASHRAE 127
≥ 65,000 Btu/h and
< 240,000 Btu/h
(≥19kW and < 70 kW)
2.50 / 2.39
≥ 240,000 Btu/h
(≥ 70 kW)
2.40 / 2.29
Air conditioners, water cooled with
fluid economizer
< 65,000 Btu/h
(<19 kW)
2.55 / 2.44 ANSI/ASHRAE 127
≥ 65,000 Btu/h and
< 240,000 Btu/h
(≥19kW and < 70 kW)
2.45 / 2.34
≥ 240,000 Btu/h
(≥ 70 kW)
2.35 / 2.24
Air conditioners, glycol cooled
(rated at 40% propylene glycol)
< 65,000 Btu/h
(<19 kW)
2.50 / 2.39 ANSI/ASHRAE 127
≥ 65,000 Btu/h and
< 240,000 Btu/h
(≥19kW and < 70 kW)
2.15 / 2.04
≥ 240,000 Btu/h
(≥ 70 kW)
2.10 / 1.99
Air conditioners, glycol cooled
(rated at 40% propylene glycol)
with fluid economizer
< 65,000 Btu/h
(<19 kW)
2.45 / 2.34 ANSI/ASHRAE 127
≥ 65,000 Btu/h and
< 240,000 Btu/h
(≥19kW and < 70 kW)
2.10 / 1.99
≥ 240,000 Btu/h
(≥ 70 kW)
2.05 / 1.94

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Net sensible cooling capacity: The total gross cooling capacity less the latent cooling less the energy to the air movement system. (Total Gross – latent – Fan Power).
  2. Sensible coefficient of performance (SCOP-127): a ratio calculated by dividing the net sensible cooling capacity in watts by the total power input in watts (excluding re-heaters and humidifiers) at conditions defined in ASHRAE Standard 127. The net sensible cooling capacity is the gross sensible capacity minus the energy dissipated into the cooled space by the fan system.

TABLE C403.2.3(10)
MINIMUM EFFICIENCY REQUIREMENTS: HEAT TRANSFER EQUIPMENT

EQUIPMENT TYPESUBCATEGORYMINIMUM EFFICIENCYTEST PROCEDUREa
Liquid-to-liquid heat exchangersPlate typeNRAHRI 400

NR = No Requirement.

  1. Chapter 6 of the referenced standard contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

C403.2.3.1 Water-cooled centrifugal chilling packages

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Equipment not designed for operation at AHRI Standard 550/590 test conditions of 44°F (7°C) leaving chilled-water temperature and 2.4 gpm/ton evaporator fluid flow and 85°F (29°C) entering condenser water temperature with 3 gpm/ton (0.054 IL/s x kW) condenser water flow shall have maximum full-load kW/ton (FL) and part-load ratings requirements adjusted using Equations 4-67 and 4-78.

FLadj = FL/Kadj (Equation 4-67)

PLVadj = IPLV/Kadj (Equation 4-8)

Where:

Kadj = A × B
FL = Full-load kW/ton values as specified in Table C403.2.3(7).
FLadj = Maximum full-load kW/ton rating, adjusted for nonstandard conditions.
IPLV = Values as specified in Table C403.2.3(7).
PLVadj = Maximum NPLV rating, adjusted for nonstandard conditions.
A = 0.00000014592 x (LIFT)4 – 0.0000346496 x (LIFT)3 + 0.00314196 x (LIFT)2 – 0.147199 x (LIFT) + 3.9302
B = 0.0015 x Lvg Evap (°F) + 0.934
LIFT = LvgCondLvg Evap
LvgCond = Full-load condenser leaving fluid temperature (°F).
LvgEvap = Full-load evaporator leaving temperature (°F).

The FLadj and PLVadj values are only applicable for centrifugal chillers meeting all of the following full-load design ranges:

  1. Minimum evaporator leaving temperature: 36°F.
  2. Maximum condenser leaving temperature: 115°F.
  3. 20°F ≤ LIFT ≤ 80°FLIFT is not less than 20°F and not greater than 80°F.
Equipment with a leaving fluid temperature higher than 32°F (0°C) and water-cooled positive displacement chilling packages with a condenser leaving fluid temperature below 115°F (46°C) shall meet the requirements of Table C403.2.3(7) when tested or certified with water at standard rating conditions, in accordance with the referenced test procedure.

C403.2.3.3 Packaged electric heating and cooling equipment

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Packaged electric equipment providing both heating and cooling with a total cooling capacity greater than 6,000 Btu/h shall be a heat pump.

Exception: Unstaffed equipment shelters or cabinets used solely for personal wireless service facilities.

C403.2.3.4 Humidification

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
If an air economizer is required on a cooling system for which humidification equipment is to be provided to maintain minimum indoor humidity levels, then the humidifier shall be of the adiabatic type (direct evaporative media or fog atomization type).

Exceptions:
  1. Health care facilities licensed by the state where Chapter 246-320 or 246-330 WAC requires steam injection humidifiers in duct work downstream of final filters.
  2. Systems with water economizer.
  3. 100% outside air systems with no provisions for air recirculation to the central supply fan.
  4. Nonadiabatic humidifiers cumulatively serving no more than 10% of a building's air economizer capacity as measured in cfm. This refers to the system cfm serving rooms with stand-alone or duct mounted humidifiers.

C403.2.4 HVAC system controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each heating and cooling system shall be provided with thermostatic controls as specified in Section C403.2.4.1, C403.2.4.1.3, C403.2.4.2, C403.2.4.3, C403.3.1, C403.4, C403.4.1 or C403.4.4. HVAC systems shall be provided with controls as defined in this section and shall be capable of and configured to implement all required control functions in this code.

C403.2.4.1 Thermostatic controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The supply of heating and cooling energy to each zone shall be controlled by individual thermostatic controls capable of responding to temperature within the zone. Controls in the same zone or in neighboring zones connected by openings larger than 10 percent of the floor area of either zone shall not allow for simultaneous heating and cooling. At a minimum, each floor of a building shall be considered as a separate zone. Controls on systems required to have economizers and serving single zones shall have multiple cooling stage capability and activate the economizer when appropriate as the first stage of cooling. See Section C403.3.1 for further economizer requirements. Where humidification or dehumidification or both is provided, at least one humidity control device shall be provided for each humidity control system.


Exceptions:

  1. Independent perimeter systems that are designed to offset only building envelope heat losses, or gains or both serving one or more perimeter zones also served by an interior system provided:

    1. The perimeter system includes at least one thermostatic control zone for each building exposure having exterior walls facing only one orientation (within +/-45 degrees) (0.8 rad) for more than 50 contiguous feet (15,240 mm); and
    2. The perimeter system heating and cooling supply is controlled by a thermostats located within the zones served by the system.; and
    3. Controls are configured to prevent the perimeter system from operating in a different heating or cooling mode from the other equipment within the zones or from neighboring zones connected by openings larger than 10 percent of the floor area of either zone.
  2. Any interior zone open to a perimeter zone shall have setpoints and deadbands coordinated so that cooling in the interior zone shall not operate while the perimeter zone is in heating until the interior zone temperature is 5°F (2.8°C) higher than the perimeter zone temperature, unless the interior and perimeter zones are separated by a partition whose permanent openings are smaller than 10 percent of the perimeter zone floor area.

C403.2.4.1.1 Heat pump supplementary heat

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heat pumps having supplementary electric resistance heat shall have controls that, except during defrost, prevent supplementary heat operation where the heat pump can provide the heating load.Unitary air cooled heat pumps shall include microprocessor controls that minimize supplemental heat usage during start-up, set-up, and defrost conditions. These controls shall anticipate need for heat and use compression heating as the first stage of heat. Controls shall indicate when supplemental heating is being used through visual means (e.g., LED indicators). Heat pumps equipped with supplementary heaters shall be installed with controls that prevent supplemental heater operation above 40°F.

Exception: Packaged terminal heat pumps (PTHPs) of less than 2 tons (24,000 Btu/hr) cooling capacity provided with controls that prevent supplementary heater operation above 40°F.

C403.2.4.1.2 Deadband

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Where used to control both heating and cooling, zone thermostatic controls shall be capable of providing configured to provide a temperature range or deadband of at least 5°F (2.8°C) within which the supply of heating and cooling energy to the zone is capable of being shut off or reduced to a minimum.


Exceptions:

  1. Thermostats requiring manual changeover between heating and cooling modes.
  2. Occupancies or applications requiring precision in indoor temperature control as approved by the code official.

C403.2.4.1.3 Setpoint overlap restriction

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where a zone has a separate heating and a separate cooling thermostatic control located within the zone, a limit switch, mechanical stop or direct digital control system with software programming shall be provided with the capability configured to prevent the heating set point from exceeding the cooling setpoint and to maintain a deadband in accordance with Section C403.2.4.1.2.

C403.2.4.2 Off-hour controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

For all occupancies other than Group R, each zone shall be provided with thermostatic setback controls that are controlled by either an automatic time clock or programmable control system.


Exceptions:

  1. Zones that will be operated continuously.
  2. Zones with a full HVAC load demand not exceeding 6,800 Btu/h (2 kW) and having a readily accessible manual shutoff switch.

C403.2.4.2.1 Thermostatic setback capabilities

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Thermostatic setback controls shall have the capability be configured to set back or temporarily operate the system to maintain zone temperatures down to 55°F (13°C) or up to 85°F (29°C).

C403.2.4.2.2 Automatic setback and shutdown capabilities

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Automatic time clock or programmable controls shall be capable of starting and stopping the system for seven different daily schedules per week and retaining their programming and time setting during a loss of power for at least 10 hours. Additionally, the controls shall have a manual override that allows temporary operation of the system for up to 2 hours; a manually operated timer capable of being adjusted configured to operate the system for up to 2 hours; or an occupancy sensor.
Automatic start controls shall be provided for each HVAC system. The controls shall be capable of automatically adjusting the daily start time of the HVAC system in order to bring each space to the desired occupied temperature immediately prior to scheduled occupancy.

C403.2.4.3 Shutoff dampers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Outdoor air supply, intake and exhaust openings and relief outlets and stairway and shaft vents shall be provided with Class I motorized dampers.

Return air openings used for airside economizer operation shall be equipped with Class I motorized dampers.

The dampers shall have an air Class I dampers shall have a maximum leakage rate not greater than of 4 cfm/ft2 (20.3 L/s x m2) of damper surface area at 1.0 inch water gauge (w.g.) (249 Pa) and shall be labeled by an approved agency when tested in accordance with AMCA 500D and shall be labeled by an approved agency for such purpose.

Exception: Motorized dampers on return air openings in unitary packaged equipment that have the minimum leakage rate available from the manufacturer shall be deemed to comply.

Outdoor air intake and exhaust dampers shall be installed with automatic controls configured to close when the systems or spaces served are not in use or during unoccupied period warm-up and setback operation, unless the systems served require outdoor or exhaust air in accordance with the International Mechanical Code or the dampers are opened to provide intentional economizer cooling.

Stairway and shaft vent dampers shall be installed with automatic controls configured to open upon the activation of any fire alarm initiating device of the building’s fire alarm system or the interruption of power to the damper.

Exceptions:

  1. Gravity (nonmotorized) dampers shall be permitted to be used as follows:
    1. In buildings less than three stories in height above grade plane.
    2. In buildings of any height located in Climate Zones 1, 2 or 3.
    3. Where the design exhaust capacity is not greater than 300 cfm (142 L/s).
    4. Relief dampers serving systems less than 5,000 cfm total supply shall be permitted in buildings less than three stories in height.
    5. Gravity (nonmotorized) dampers in Group R occupancies where the design outdoor air intake or exhaust capacity does not exceed 400 cfm (189 L/s).
    6. Combustion air intakes.
Gravity (nonmotorized) dampers shall have an air leakage rate not greater than 20 cfm/ft2 (101.6 L/s x m2) where not less than 24 inches (610 mm) in either dimension and 40 cfm/ft2 (203.2 L/s x m2) where less than 24 inches (610 mm) in either dimension. The rate of air leakage shall be determined at 1.0 inch water gauge w.g. (249 Pa) when tested in accordance with AMCA 500D for such purpose. The dampers shall be labeled by an approved agency. Gravity dampers for ventilation air intakes shall be protected from direct exposure to wind.

HVAC systems serving zones that are over 25,000 square feet (2323 m2) in floor area or that span more than one floor and are designed to operate or be occupied nonsimultaneously shall be divided into isolation areas. Each isolation area shall be equipped with isolation devices and controls configured to automatically shut off the supply of conditioned air and outdoor air to and exhaust air from the isolation area. Each isolation area shall be controlled independently by a device meeting the requirements of Section C403.2.4.2.2. Central systems and plants shall be provided with controls and devices that will allow system and equipment operation for any length of time while serving only the smallest isolation area served by the system or plant.

Exceptions:

  1. Exhaust air and outdoor air connections to isolation areas where the fan system to which they connect is not greater than 5,000 cfm (2360 L/s).
  2. Exhaust airflow from a single isolation area of less than 10 percent of the design airflow of the exhaust system to which it connects.
  3. Isolation areas intended to operate continuously or intended to be inoperative only when all other isolation areas in a zone are inoperative.

C403.2.4.5 Snow- and ice-melt system controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Snow- and ice-melting systems, supplied through energy service to the building, shall include automatic controls capable ofconfigured to shutting off the system when the pavement temperature is above 50°F (10°C) and no precipitation is falling and an automatic or manual control that will allow is configured to shut off when the outdoor temperature is above 40°F (4°C) so that the potential for snow or ice accumulation is negligible.
Freeze protection systems, such as heat tracing of outdoor piping and heat exchangers, including self-regulating heat tracing, shall include automatic controls configured to shut off the systems when outdoor air temperatures are above 40°F (4°C) or when the conditions of the protected fluid will prevent freezing.

C403.2.4.7 Economizer fault detection and diagnostics (FDD)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Air-cooled unitary direct-expansion units with a cooling capacity of 54,000 Btu/h or greater listed in Tables C403.2.3(1) through C403.2.3(3) and variable refrigerant flow (VRF) units that are equipped with an economizer in accordance with Section C403.3 shall include a fault detection and diagnostics (FDD) system complying with the following:

  1. The following temperature sensors shall be permanently installed to monitor system operation:

    1. 1.1. Outside air.
    2. 1.2. Supply air.
    3. 1.3. Return air.
  2. Temperature sensors shall have an accuracy of ±2°F (1.1°C) over the range of 40°F to 80°F (4°C to 26.7°C).
  3. Refrigerant pressure sensors, where used, shall have an accuracy of ±3 percent of full scale.
  4. The unit controller shall be capable ofconfigured to providingprovide system status by indicating the following:

    1. 4.1. Free cooling available.
    2. 4.2. Economizer enabled.
    3. 4.3. Compressor enabled.
    4. 4.4. Heating enabled.
    5. 4.5. Mixed air low limit cycle active.
    6. 4.6. The current value of each sensor.
  5. The unit controller shall be capable of manually initiating each operating mode so that the operation of compressors, economizers, fans and the heating system can be independently tested and verified.
  6. The unit shall be capable of reporting configured to report faults to a fault management application accessible by day-to-day operating or service personnel, or annunciated locally on zone thermostats.
  7. The FDD system shall be capable of detecting configured to detect the following faults:

    1. 7.1. Air temperature sensor failure/fault.
    2. 7.2. Not economizing when the unit should be economizing.
    3. 7.3. Economizing when the unit should not be economizing.
    4. 7.4. Damper not modulating.
    5. 7.5. Excess outdoor air.

C403.2.4.8 Combustion heating equipment controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Combustion heating equipment with a capacity over 225,000 Btu/h shall have modulating or staged combustion control.

Exceptions:
  1. Boilers.
  2. Radiant heaters.

C403.2.4.9 Group R-1 hotel/motel guest rooms

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For hotel and motel guest rooms, a minimum of one of the following control technologies shall be required in hotels/motels with over 50 guest rooms such that the space temperature would automatically setback (winter) or set up (summer) by no less than 5°F (3°C) when the occupant is not in the room:

  1. Controls that are activated by the room occupant via the primary room access method - Key, card, deadbolt, etc.
  2. Occupancy sensor controls that are activated by the occupant's presence in the room.

C403.2.4.10 Group R-2 and R-3 dwelling units

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The primary space conditioning system within each dwelling unit shall be provided with at least one programmable thermostat for the regulation of space temperature. The thermostat shall allow for, at a minimum, a 5-2 programmable schedule (weekdays/weekends) and be capable of providing at least two programmable setback periods per day.

Each additional system provided within the dwelling unit shall be provided with at least one adjustable thermostat for the regulation of temperature.

Exceptions:
  1. Systems controlled by an occupant sensor that is configured to shut the system off when no occupant is sensed for a period of up to 30 minutes.
  2. Systems controlled solely by a manually operated timer configured to operate the system for no more than two hours.
  3. Ductless heat pumps.
Each thermostat shall be capable of being set by adjustment or selection of sensors as follows:
  1. When used to control heating only: 55°F to 75°F.
  2. When used to control cooling only: 70°F to 85°F.
  3. All other: 55°F to 85°F with an adjustable deadband of not less than 10°F.

C403.2.4.11 Group R-2 sleeping units

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The primary space conditioning system within each sleeping unit shall be provided with at least one programmable thermostat for the regulation of space temperature. The thermostat shall allow for, at a minimum, a 5-2 programmable schedule (weekdays/weekends) and be capable of providing at least two programmable setback periods per day.

Each additional system provided within the sleeping unit shall be provided with at least one adjustable thermostat for the regulation of temperature.

Exceptions:
  1. Systems controlled by an occupant sensor that is configured to shut the system off when no occupant is sensed for a period of up to 30 minutes.
  2. Systems controlled solely by a manually operated timer configured to operate the system for no more than two hours.
  3. Zones with a full HVAC load demand not exceeding 3,400 Btu/h (1 kW) and having a readily accessible manual shutoff switch.
  4. Ductless heat pumps.
Each thermostat shall be capable of being set by adjustment or selection of sensors as follows:
  1. When used to control heating only: 55°F to 75°F;
  2. When used to control cooling only: 70°F to 85°F;
  3. All other: 55°F to 85°F with an adjustable deadband of not less than 10°F.

C403.2.4.12 Direct digital control systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Direct digital control (DDC) shall be required as specified in Sections C403.2.4.12.1 through C403.2.4.12.3.

C403.2.4.12.1 DDC applications

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
DDC shall be provided in the applications and qualifications listed in Table C403.2.4.12.1.

TABLE C403.2.4.12.1
DDC APPLICATIONS AND QUALIFICATIONS
Building Status Application Qualifications
New Building Air-handling system and all zones served by the system All air-handling systems in buildings with building cooling capacity greater than 780,000 Btu/h
Air-handling system and all zones served by the system Individual systems supplying more than three zones and with fan system bhp of 10 hp and larger
Chilled-water plant and all coils and terminal units served by the system Individual plants supplying more than three zones and with design cooling capacity of 300,000 Btu/h and larger
Hot-water plant and all coils and terminal units served by the system Individual plants supplying more than three zones and with design heating capacity of 300,000 Btu/h and larger
Alteration or addition Zone terminal units such as VAV box Where existing zones served by the same air-handling, chilled-water, or hot-water system have DDC
Air-handling system or fan coil Where existing air-handling system(s) and fan coil(s) served by the same chilled- or hot-water plant have DDC
New air-handling system and all new zones served by the system Individual systems with fan system bhp 10 hp and larger and supplying more than three zones and more than 75% of zones are new
New or upgraded chilled-water plant Where all chillers are new and plant design cooling capacity is 300,000 Btu/h and larger
New or upgraded hot-water plant Where all boilers are new and plant design heating capacity is 300,000 Btu/h and larger

C403.2.4.12.2 DDC controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where DDC is required by Section C403.2.4.12.1, the DDC system shall be capable of all of the following, as required to provide the system and zone control logic required in Sections C403.2, C403.3 and C403.4:

  1. Monitoring zone and system demand for fan pressure, pump pressure, heating and cooling.
  2. Transferring zone and system demand information from zones to air distribution system controllers and from air distribution systems to heating and cooling plant controllers.

C403.2.4.12.3 DDC display

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where DDC is required by Section C403.2.4.12.1 for new buildings, the DDC system shall be capable of trending and graphically displaying input and output points.
Hot water boilers that supply heat to the building through one- or two-pipe heating systems shall have an outdoor setback control that lowers the boiler water temperature based on the outdoor temperature.

C403.2.6 Ventilation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ventilation, either natural or mechanical, shall be provided in accordance with Chapter 4 of the International Mechanical Code. Where mechanical ventilation is provided, the system shall be configured to provide the capability to reduce the outdoor air supply to the no greater than 150 percent of the minimum outdoor air required by Chapter 4 of the International Mechanical Code or other applicable code or standard, whichever is greater.

Exceptions:
  1. The mechanical system may supply outdoor air at rates higher than the limit above when it is used for particulate or VOC dilution, economizer, night flushing, dehumidification, pressurization, exhaust make-up, or other process air delivery. Outdoor air shall be reduced to the minimum ventilation rates when not required for the preceding uses.
  2. Air systems supplying Group R-1, R-2 or I-2 occupancies.
  3. Alterations that replace less than half of the total heating and cooling capacity of the system.
  4. Systems with energy recovery complying with the requirements of Section C403.5.1.

C403.2.6.1 Demand controlled ventilation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Demand control ventilation (DCV) shall be provided for spaces larger than 500 square feet (46.5 m2) and with an average occupant load of 25 people per 1,000 square feet (93 m2) of floor area (as established in Table 403.3.1.1 of the International Mechanical Code) and served by systems with one or more of the following:

  1. An air-side economizer.
  2. Automatic modulating control of the outdoor air damper.
  3. A design outdoor airflow greater than 3,000 cfm (1416 L/s).

Exception: Demand control ventilation is not required for systems and spaces as follows:

  1. Systems with energy recovery complying with Section C403.2.7.
  2. Multiple-zone systems without direct digital control of individual zones communicating with a central control panel.
  3. Systems with a design outdoor airflow less than 1,200 cfm (566 L/s).
  4. Spaces where the supply airflow rate minus any makeup or outgoing transfer air requirement is less than 1,200 cfm (566 L/s).
  5. Ventilation provided for process loads only.

C403.2.6.1 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C403.2.6.2 Enclosed parking garage ventilation controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Enclosed parking garages used for storing or handling automobiles operating under their own power shall employ contamination-sensing devices and automatic controls configured to stage fans or modulate fan average airflow rates to 50 percent or less of design capacity, or intermittently operate fans less than 20 percent of the occupied time or as required to maintain acceptable contaminant levels in accordance with International Mechanical Code provisions. Failure of contamination sensing devices shall cause the exhaust fans to operate continuously at design airflow.

Exceptions:

  1. Garages with a total exhaust capacity less than 22,500 cfm (10 620 L/s) with ventilation systems that do not utilize heating or mechanical cooling.
  2. Garages that have a garage area to ventilation system motor nameplate power ratio that exceeds 1125 cfm/hp (710 L/s/kW) and do not utilize heating or mechanical cooling.

C403.2.6.2 Demand controlled ventilation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Demand control ventilation (DCV) shall be provided for spaces larger than 500 square feet (50 m2) and with an occupant load greater than or equal to 25 people per 1000 square feet (93 m2) of floor area (as established in Table 403.3.1.1 of the International Mechanical Code) and served by systems with one or more of the following:

  1. An air-side economizer.
  2. Automatic modulating control of the outdoor air damper.
  3. A design outdoor airflow greater than 3,000 cfm (1416 L/s).
Exception: Demand control ventilation is not required for systems and spaces as follows:
  1. Systems with energy recovery complying with Section C403.5.1.
  2. Multiple-zone systems without direct digital control of individual zones communicating with a central control panel.
  3. System with a design outdoor airflow less than 750 cfm (354 L/s).
  4. Spaces where the supply airflow rate minus any makeup or outgoing transfer air requirement is less than 1,200 cfm (566 L/s).
  5. Ventilation provided for process loads only.
  6. Spaces with one of the following occupancy categories (as defined by the International Mechanical Code): Correctional cells, daycare sickrooms, science labs, barbers, beauty and nail salons, and bowling alley seating.

C403.2.6.3 Occupancy sensors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Classrooms, gyms, auditoriums and conference rooms larger than 500 square feet of floor area shall have occupancy sensor control that will either close outside air dampers or turn off serving equipment when the space is unoccupied except where equipped with another means to automatically reduce outside air intake below design rates when spaces are partially occupied.

C403.2.6.4 Enclosed loading dock and parking garage exhaust ventilation system control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Mechanical ventilation systems for enclosed loading docks and parking garages shall be designed to exhaust the airflow rates (maximum and minimum) determined in accordance with the International Mechanical Code.

Ventilation systems shall be equipped with a control device that operates the system automatically by means of carbon monoxide detectors applied in conjunction with nitrogen dioxide detectors. Controllers shall be configured to shut off fans or modulate fan speed to 50 percent or less of design capacity, or intermittently operate fans less than 20 percent of the occupied time or as required to maintain acceptable contaminant levels in accordance with the International Mechanical Code provisions.

Gas sensor controllers used to activate the exhaust ventilation system shall stage or modulate fan speed upon detection of specified gas levels. All equipment used in sensor controlled systems shall be designed for the specific use and installed in accordance with the manufacturer’s recommendations. The system shall be arranged to operate automatically by means of carbon monoxide detectors applied in conjunction with nitrogen dioxide detectors. Garage and loading docks shall be equipped with a controller and a full array of carbon monoxide (CO) sensors set to maintain levels of carbon monoxide below 35 parts per million (ppm).

Additionally, a full array of nitrogen dioxide detectors shall be connected to the controller set to maintain the nitrogen dioxide level below the OSHA standard for eight hour exposure.

Spacing and location of the sensors shall be installed in accordance with manufacturer recommendations.

C403.2.6.4.1 System activation devices for enclosed loading docks

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ventilation systems for enclosed loading docks shall be activated by one of the following:
  1. Gas sensors installed in accordance with the International Mechanical Code; or
  2. Occupant detection sensors used to activate the system that detects entry into the loading area along both the vehicle and pedestrian pathways.

C403.2.6.4.2 System activation devices for enclosed parking garages

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ventilation systems for enclosed parking garages shall be activated by gas sensors.

Exception: A parking garage ventilation system having a total design capacity under 8,000 cfm may use occupant sensors

C403.2.7 Energy recovery ventilation systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Where the supply airflow rate of a fan system exceeds the values specified in Tables C403.2.7(1) and C403.2.7(2), the system shall include an energy recovery system. The energy recovery system shall have the capability to provide a change in the enthalpy of the outdoor air supply of not less than 50 percent of the difference between the outdoor air and return air enthalpies, at design conditions. Where an air economizer is required, the energy recovery system shall include a bypass or controls which permit operation of the economizer as required by Section C403.3.

Exception: An energy recovery ventilation system shall not be required in any of the following conditions:

  1. Where energy recovery systems are prohibited by the International Mechanical Code.
  2. Laboratory fume hood systems that include at least one of the following features:

    1. 2.1. Variable-air-volume hood exhaust and room supply systems capable of reducing exhaust and makeup air volume to 50 percent or less of design values.
    2. 2.2. Direct makeup (auxiliary) air supply equal to at least 75 percent of the exhaust rate, heated not warmer than 2°F (1.1°C) above room setpoint, cooled to not cooler than 3°F (1.7°C) below room setpoint, no humidification added, and no simultaneous heating and cooling used for dehumidification control.
  3. Systems serving spaces that are heated to less than 60°F (15.5°C) and are not cooled.
  4. Where more than 60 percent of the outdoor heating energy is provided from site-recovered or site solar energy.
  5. Heating energy recovery in Climate Zones 1 and 2.
  6. Cooling energy recovery in Climate Zones 3C, 4C, 5B, 5C, 6B, 7 and 8.
  7. Systems requiring dehumidification that employ energy recovery in series with the cooling coil.
  8. Where the largest source of air exhausted at a single location at the building exterior is less than 75 percent of the design outdoor air flow rate.
  9. Systems expected to operate less than 20 hours per week at the outdoor air percentage covered by Table C403.2.7(1).
  10. Systems exhausting toxic, flammable, paint or corrosive fumes or dust.
  11. Commercial kitchen hoods used for collecting and removing grease vapors and smoke.

TABLE C403.2.7(1)

ENERGY RECOVERY REQUIREMENT (Ventilation systems operating less than 8,000 hours per year)

CLIMATE ZONEPERCENT (%) OUTDOOR AIR AT FULL DESIGN AIRFLOW RATE
≥ 10% and < 20%≥ 20% and < 30%≥ 30% and < 40%≥ 40% and <
50%
≥ 50% and <
60%
≥ 60% and <
70%
≥ 70% and <
80%
≥ 80%
DESIGN SUPPLY FAN AIRFLOW RATE (cfm)
3B, 3C, 4B, 4C, 5BNRNRNRNRNRNRNRNR
1B, 2B, 5CNRNRNRNR≥ 26,000≥ 12,000≥ 5,000≥ 4,000
6B≥ 28,000≥ 26,5000≥ 11,000≥ 5,500≥ 4,500≥ 3,500≥ 2,500≥ 1,500
1A, 2A, 3A, 4A,
5A, 6A
≥ 26,000≥ 16,000≥ 5,500≥ 4,500≥ 3,500≥ 2,000≥ 1,000>0
7,8≥ 4,500≥ 4,000≥ 2,500≥ 1,000>0>0>0>0

For SI: 1 cfm = 0.4719 L/s.

NR = Not Required.

TABLE C403.2.7(2)

ENERGY RECOVERY REQUIREMENT (Ventilation systems operating not less than 8,000 hours per year)

CLIMATE ZONEPERCENT (%) OUTDOOR AIR AT FULL DESIGN AIRFLOW RATE
≥ 10% and
< 20%
≥ 20% and
< 30%
≥ 30% and
< 40%
≥ 40% and
< 50%
≥ 50% and
< 60%
≥ 60% and
< 70%
≥ 70% and
< 80%
≥ 80%
Design Supply Fan Airflow Rate (cfm)
3CNRNRNRNRNRNRNRNR
1B, 2B, 3B, 4C, 5CNR≥ 19,500≥ 9,000≥ 5,000≥ 4,000≥ 3,000≥ 1,500> 0
1A, 2A, 3A, 4B, 5B≥ 2,500≥ 2,000≥ 1,000≥ 500> 0> 0> 0> 0
4A, 5A, 6A, 6B, 7, 8> 0> 0> 0> 0> 0> 0> 0> 0

For SI: 1 cfm = 0.4719 L/s.

NR = Not required

C403.2.7 Exhaust systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C403.2.7.1 Kitchen hoods

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Replacement air introduced directly into the exhaust hood cavity shall not be greater than 10 percent of the hood exhaust airflow rate. Conditioned supply air delivered to any space shall not exceed the greater of the following:
  1. The ventilation rate required to meet the space heating or cooling load.
  2. The hood exhaust flow minus the available transfer air from adjacent space where available transfer air is considered that portion of outdoor ventilation air not required to satisfy other exhaust needs, such as restrooms, and not required to maintain pressurization of adjacent spaces.
Where total kitchen hood exhaust airflow rate is greater than 2,000 cfm each hood shall be a factory built commercial exhaust hood listed by a nationally recognized testing laboratory in compliance with UL 710. Each hood shall have a maximum exhaust rate as specified in Table C403.2.7.1 and shall comply with one of the following:
  1. Not less than 50 percent of all replacement air shall be transfer air that would otherwise be exhausted.
  2. Demand ventilation systems on not less than 75 percent of the exhaust air that are configured to provide not less than a 50-percent reduction in exhaust and replacement air system airflow rates, including controls necessary to modulate airflow in response to appliance operation and to maintain full capture and containment of smoke, effluent and combustion products during cooking and idle.
  3. Listed energy recovery devices with a sensible heat recovery effectiveness of not less than 40 percent on not less than 50 percent of the total exhaust airflow.
Where a single hood, or hood section, is installed over appliances with different duty ratings, the maximum allowable flow rate for the hood or hood section shall be based on the requirements for the highest appliance duty rating under the hood or hood section.

Exceptions:
  1. Where not less than 75 percent of all the replacement air is transfer air that would otherwise be exhausted.
  2. Certified grease extractor hoods that require a face velocity no greater than 60 fpm.

TABLE C403.2.7.1
MAXIMUM NET EXHAUST FLOW RATE,
CFM PER LINEAR FOOT OF HOOD LENGTH

TYPE OF HOOD LIGHT-DUTY EQUIPMENT MEDIUM-DUTY EQUIPMENT HEAVY-DUTY EQUIPMENT EXTRA-HEAVY-DUTY EQUIPMENT
Wall-mounted canopy 140 210 280 385
Single island 280 350 420 490
Double island (per side) 175 210 280 385
Eyebrow 175 175 NA NA
Backshelf/Pass-over 210 210 280 NA

For SI: 1 cfm = 0.4719 L/s; 1 foot = 305 mm.
NA = Not Allowed

C403.2.7.2 Laboratory exhaust systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Buildings with laboratory exhaust systems having a total exhaust rate greater than 5,000 cfm (2,360 L/s) shall include heat recovery systems to preconditioned makeup air from laboratory exhaust. The heat recovery system shall be capable of increasing the outside air supply temperature at design heating conditions by 25°F (13.9°C). A provision shall be made to bypass or control the heat recovery system to permit air economizer operation as required by Section C403.3.

Exceptions:
  1. Variable air volume laboratory exhaust and room supply systems configured to reduce exhaust and make-up air volume to 50% or less of design values; or
  2. Direct make-up (auxiliary) air supply equal to at least 75% of the exhaust rate, heated no warmer than 2°F (1.1°C) below room set point, cooled to no cooler than 3°F (1.7°C) above room set point, no humidification added, and no simultaneous heating and cooling used for dehumidification control; or
  3. Combined energy reduction method: VAV exhaust and room supply system configured to reduce exhaust and makeup air volumes and a heat recovery system to precondition makeup air from laboratory exhaust that when combined will produce the same energy reduction as achieved by a heat recovery system with a 50% sensible recovery effectiveness as required above. For calculation purposes, the heat recovery component can be assumed to include the maximum design supply airflow rate at design conditions. The combined energy reduction (QER) shall meet the following:
QER ≥ QMIN
    QMIN = CFMS x (TR - TO) x 1.1 x 0.6
  QER = CFMS x (TR - TO) x 1.1(A+B)/100
Where:  
  QMIN = Energy recovery at 60% sensible effectiveness (Btu/h)
  QER = Combined energy reduction (Btu/h)
  CFMS = The maximum design supply airflow rate to conditioned spaces served by the system in cubic feet per minute
  TR = Space return air dry bulb at winter design conditions
  TO = Outdoor air dry bulb at winter design conditions
  A = Percentage that the exhaust and makeup air volumes can be reduced from design conditions
  B = Percentage sensible heat recovery effectiveness

C403.2.8 Kitchen exhaust systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Replacement air introduced directly into the exhaust hood cavity shall not be greater than 10 percent of the hood exhaust airflow rate. Conditioned supply air delivered to any space shall not exceed the greater of the following:

  1. The ventilation rate required to meet the space heating or cooling load.
  2. The hood exhaust flow minus the available transfer air from adjacent space where available transfer air is considered that portion of outdoor ventilation air not required to satisfy other exhaust needs, such as restrooms, and not required to maintain pressurization of adjacent spaces.

Where total kitchen hood exhaust airflow rate is greater than 5,000 cfm (2360 L/s), each hood shall be a factory-built commercial exhaust hood listed by a nationally recognized testing laboratory in compliance with UL 710. Each hood shall have a maximum exhaust rate as specified in Table C403.2.8 and shall comply with one of the following:

  1. Not less than 50 percent of all replacement air shall be transfer air that would otherwise be exhausted.
  2. Demand ventilation systems on not less than 75 percent of the exhaust air that are capable of not less than a 50-percent reduction in exhaust and replacement air system airflow rates, including controls necessary to modulate airflow in response to appliance operation and to maintain full capture and containment of smoke, effluent and combustion products during cooking and idle.
  3. Listed energy recovery devices with a sensible heat recovery effectiveness of not less than 40 percent on not less than 50 percent of the total exhaust airflow.

Where a single hood, or hood section, is installed over appliances with different duty ratings, the maximum allowable flow rate for the hood or hood section shall be based on the requirements for the highest appliance duty rating under the hood or hood section.

Exception: Where not less than 75 percent of all the replacement air is transfer air that would otherwise be exhausted

TABLE C403.2.8

MAXIMUM NET EXHAUST FLOW RATE, CFM PER LINEAR FOOT OF HOOD LENGTH

TYPE OF HOODLIGHT-DUTY
EQUIPMENT
MEDIUM-DUTY
EQUIPMENT
HEAVY-DUTY
EQUIPMENT
EXTRA-HEAVY-DUTY
EQUIPMENT
Wall-mounted canopy140210280385
Single island280350420490
Double island (per side)175210280385
Eyebrow175175NANA
Backshelf/Pass-over210210280NA

For SI: 1 cfm = 0.4719 L/s; 1 foot = 305 mm.

NA = Not Allowed.

C403.2.8 Duct and plenum insulation and sealing

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C403.2.8.1

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ducts, shafts and plenums conveying outside air from the exterior of the building to the mechanical system shall meet all air leakage and building envelope insulation requirements of Section C402, plus building envelope vapor control requirements from the International Building Code, extending continuously from the building exterior to an automatic shutoff damper or heating or cooling equipment. For the purposes of building envelope insulation requirements, duct surfaces shall meet the requirements for metal framed walls per Table C402.1.4. Duct surfaces included as part of the building envelope shall not be used in the calculation of maximum glazing area as described in Section C402.4.1.

Exceptions:
  1. Outside air ducts serving individual supply air units with less than 2,800 cfm of total supply air capacity, provided these are insulated to R-7.
  2. Unheated equipment rooms with combustion air louvers, provided they are isolated from conditioned space at sides, top and bottom of the room with R-11 nominal insulation.

C403.2.8.2

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
All other supply and return air ducts and plenums shall be insulated with a minimum of R-6 insulation where located in unconditioned spaces and where located outside the building with a minimum of R-8 insulation in Climate Zone 4 and R-12 insulation in Climate Zone 5. Where located within a building envelope assembly, the duct or plenum shall be separated from the building exterior or unconditioned or exempt spaces by minimum insulation value as required for exterior walls by Section C402.1.3.

Exceptions:
  1. Where located within equipment.
  2. Where the design temperature difference between the interior and exterior of the duct or plenum does not exceed 15°F (8°C).
Where located within conditioned space, supply ducts which convey supply air at temperatures less than 55°F or greater than 105°F shall be insulated with a minimum of R-3.3 insulation.

Exception: Ductwork exposed to view within a zone that serves that zone is not required to be insulated.

All ducts, air handlers, and filter boxes shall be sealed. Joints and seams shall comply with Section 603.9 of the International Mechanical Code.

C403.2.8.3 Duct construction

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ductwork shall be constructed and erected in accordance with the International Mechanical Code.

C403.2.8.3.1 Low-pressure duct systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
All longitudinal and transverse joints, seams and connections of supply and return ducts operating at a static pressure less than or equal to 2 inches water gauge (w.g.) (500 Pa) shall be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus embedded-fabric systems or tapes installed in accordance with the manufacturer's installation instructions. Pressure classifications specific to the duct system shall be clearly indicated on the construction documents in accordance with the International Mechanical Code.

Exception: Continuously welded and locking-type longitudinal joints and seams on ducts operating at static pressures less than 2 inches water gauge (w.g.) (500 Pa) pressure classification.

C403.2.8.3.2 Medium-pressure duct systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
All ducts and plenums designed to operate at a static pressure greater than 2 inches water gauge (w.g.) (500 Pa) but less than 3 inches w.g. (750 Pa) shall be insulated and sealed in accordance with Section C403.2.8. Pressure classifications specific to the duct system shall be clearly indicated on the construction documents in accordance with the International Mechanical Code.

C403.2.8.3.3 High-pressure duct systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ducts designed to operate at static pressures in excess of 3 inches water gauge (w.g.) (750 Pa) shall be insulated and sealed in accordance with Section C403.2.8. In addition, ducts and plenums shall be leak-tested in accordance with the SMACNA HVAC Air Duct Leakage Test Manual and shown to have a rate of air leakage (CL) less than or equal to 4.0 as determined in accordance with Equation 4-9.

CL = F/P0.65 (Equation 4-9)
Where:
F = The measured leakage rate in cfm per 100 square feet of duct surface.
P = The static pressure of the test.

Documentation shall be furnished by the designer demonstrating that representative sections totaling at least 25 percent of the duct area have been tested and that all tested sections meet the requirements of this section.

C403.2.9 Duct and plenum insulation and sealing

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Supply and return air ducts and plenums shall be insulated with a minimum of R-6 insulation where located in unconditioned spaces and where located outside the building with a minimum of R-8 insulation in Climate Zones 1 through 4 and a minimum of R-12 insulation in Climate Zones 5 through 8. Where located within a building envelope assembly, the duct or plenum shall be separated from the building exterior or unconditioned or exempt spaces by a minimum of R-8 insulation in Climate Zones 1 through 4 and a minimum of R-12 insulation in Climate Zones 5 through 8.

Exceptions:

  1. Where located within equipment.
  2. Where the design temperature difference between the interior and exterior of the duct or plenum is not greater than 15°F (8°C).

Ducts, air handlers and filter boxes shall be sealed. Joints and seams shall comply with Section 603.9 of the International Mechanical Code.

C403.2.9 Piping insulation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
All piping serving as part of a heating or cooling system shall be thermally insulated in accordance with Table C403.2.9.

Exceptions:
  1. Factory-installed piping within HVAC equipment tested and rated in accordance with a test procedure referenced by this code.
  2. Factory-installed piping within room fan-coils and unit ventilators tested and rated according to AHRI 440 (except that the sampling and variation provisions of Section 6.5 shall not apply) and 840, respectively.
  3. Piping that conveys fluids that have a design operating temperature range between 60°F (15°C) and 105°F (41°C).
  4. Piping that conveys fluids that have not been heated or cooled through the use of fossil fuels or electric power.
  5. Strainers, control valves, and balancing valves associated with piping 1 inch (25 mm) or less in diameter.
  6. Direct buried piping that conveys fluids at or below 60°F (15°C).

TABLE C403.2.9
MINIMUM PIPE INSULATION THICKNESS (thickness in inches)a

FLUID OPERATING
TEMPERATURE
RANGE AND USAGE
(°F)
INSULATION CONDUCTIVITY NOMINAL PIPE OR TUBE SIZE (inches)
Conductivity
Btu • in./(h • ft2 • °F)b
Mean Rating Temperature, °F < 1 1 to < 1-1/2 1-1/2 to < 4 4 to < 8 ≥ 8
> 350 0.32 – 0.34 250 4.5 5.0 5.0 5.0 5.0
251 – 350 0.29 – 0.32 200 3.0 4.0 4.5 4.5 4.5
201 – 250 0.27 – 0.30 150 2.5 2.5 2.5 3.0 3.0
141 – 200 0.25 – 0.29 125 1.5 1.5 2.0 2.0 2.0
105 – 140 0.21 – 0.28 100 1.0 1.0 1.5 1.5 1.5
40 – 60 0.21 – 0.27 75 0.5 0.5 1.0 1.0 1.0
< 40 0.20 – 0.26 75 0.5 1.0 1.0 1.0 1.5
  1. For piping smaller than 11/2 inch (38 mm) and located in partitions within conditioned spaces, reduction of these thicknesses by 1 inch (25 mm) shall be permitted (before thickness adjustment required in footnote b) but not to a thickness less than 1 inch (25 mm).
  2. For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows:

    T = r{(1 + t/r)K/k – 1}

    where:

    T=minimum insulation thickness,
    r=actual outside radius of pipe,
    t=insulation thickness listed in the table for applicable fluid temperature and pipe size,
    K=conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu x in/h x ft2 x °F) and
    k=the upper value of the conductivity range listed in the table for the applicable fluid temperature.
  3. For direct-buried heating and hot water system piping, reduction of these thicknesses by 11/2 inches (38 mm) shall be permitted (before thickness adjustment required in footnote b but not to thicknesses less than 1 inch (25 mm).

C403.2.9.1 Duct construction

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ductwork shall be constructed and erected in accordance with theInternational Mechanical Code .

C403.2.9.1 Protection of piping insulation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Piping insulation exposed to weather shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind, and shall provide shielding from solar radiation that can cause degradation of the material. Adhesives tape shall not be permitted.

C403.2.9.1.1 Low-pressure duct systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Longitudinal and transverse joints, seams and connections of supply and return ducts operating at a static pressure less than or equal to 2 inches water gauge (w.g.) (498 Pa) shall be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems or tapes installed in accordance with the manufacturer’s instructions. Pressure classifications specific to the duct system shall be clearly indicated on the construction documents in accordance with the International Mechanical Code.

Exception: Locking-type longitudinal joints and seams, other than the snap-lock and button-lock types, need not be sealed as specified in this section.

C403.2.9.1.2 Medium-pressure duct systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ducts and plenums designed to operate at a static pressure greater than 2 inches water gauge (w.g.) (498 Pa) but less than 3 inches w.g. (747 Pa) shall be insulated and sealed in accordance with Section C403.2.9. Pressure classifications specific to the duct system shall be clearly indicated on the construction documents in accordance with theInternational Mechanical Code .

C403.2.9.1.3 High-pressure duct systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Ducts and plenums designed to operate at static pressures greater than 3 inches water gauge (747 Pa) shall be insulated and sealed in accordance with Section C403.2.9. In addition, ducts and plenums shall be leak tested in accordance with the SMACNA HVAC Air Duct Leakage Test Manual and shown to have a rate of air leakage (CL) less than or equal to 4.0 as determined in accordance with Equation 4-8.

(Equation 4-8)

where:

F=The measured leakage rate in cfm per 100 square feet of duct surface.
SL =The static pressure of the test.

Documentation shall be furnished by the designer demonstrating that representative sections totaling at least 25 percent of the duct area have been tested and that all tested sections comply with the requirements of this section.

C403.2.10 Piping insulation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Piping serving as part of a heating or cooling system shall be thermally insulated in accordance with Table C403.2.10.

Exceptions:

  1. Factory-installed piping within HVAC equipment tested and rated in accordance with a test procedure referenced by this code.
  2. Factory-installed piping within room fan-coils and unit ventilators tested and rated according to AHRI 440 (except that the sampling and variation provisions of Section 6.5 shall not apply) and AHRI 840, respectively.
  3. Piping that conveys fluids that have a design operating temperature range between 60°F (15°C) and 105°F (41°C).
  4. Piping that conveys fluids that have not been heated or cooled through the use of fossil fuels or electric power.
  5. Strainers, control valves, and balancing valves associated with piping 1 inch (25 mm) or less in diameter.
  6. Direct buried piping that conveys fluids at or below 60°F (15°C).

TABLE C403.2.10

MINIMUM PIPE INSULATION THICKNESS (in inches)a, c

FLUID OPERATING
TEMPERATURE RANGE
AND USAGE (°F)
INSULATION CONDUCTIVITYNOMINAL PIPE OR TUBE SIZE (inches)
Conductivity
Btu in./(h ft2 °F)b
Mean Rating Temperature, °F< 11 to < 1 1/21 1/2 to < 44 to < 8≥ 8
> 3500.32 – 0.342504.55.05.05.05.0
251 – 3500.29 – 0.322003.04.04.54.54.5
201 – 2500.27 – 0.301502.52.52.53.03.0
141 – 2000.25 – 0.291251.51.52.02.02.0
105 – 1400.21 – 0.281001.01.01.51.51.5
40 – 600.21 – 0.27750.50.51.01.01.0
< 400.20 – 0.26500.51.01.01.01.5

For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8.

  1. For piping smaller than 11/2 inches and located in partitions within conditioned spaces, reduction of these thicknesses by 1 inch shall be permitted (before thickness adjustment required in footnote b) but not to a thickness less than 1 inch.
  2. For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows:
  3. where:

    T=minimum insulation thickness,
    r=actual outside radius of pipe,
    t=insulation thickness listed in the table for applicable fluid temperature and pipe size,
    K=conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu in/h ft2 °F) and
    k=the upper value of the conductivity range listed in the table for the applicable fluid temperature.
  4. For direct-buried heating and hot water system piping, reduction of these thicknesses by 11/2 inches (38 mm) shall be permitted (before thickness adjustment required in footnote b but not to thicknesses less than 1 inch (25 mm).

C403.2.10 Mechanical systems commissioning and completion requirements

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Mechanical systems shall be commissioned and completed in accordance with Section C408.

C403.2.10.1 Protection of piping insulation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Piping insulation exposed to the weather shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind, and shall provide shielding from solar radiation that can cause degradation of the material. Adhesive tape shall not be permitted.

C403.2.11 Mechanical systems commissioning and completion requirements

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Mechanical systems shall be commissioned and completed in accordance with Section C408.2.

C403.2.11 Air system design and control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each HVAC system having a total fan system motor nameplate horsepower (hp) exceeding 5 hp (3.7 kW) shall comply with the provisions of Sections C403.2.11.1 through C403.2.11.3.

The airflow requirements of Section C403.2.11.5 shall apply to all fan motors. Group R occupancy exhaust fans shall also comply with Section C403.2.11.4.

C403.2.11.1 Allowable fan motor horsepower

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each HVAC system at fan system design conditions shall not exceed the allowable fan system motor nameplate hp (Option 1) or fan system bhp (Option 2) as shown in Table C403.2.11.1(1). This includes supply fans, exhaust fans, return/relief fans, and fan-powered terminal units associated with systems providing heating or cooling capability. Single zone variable-air-volume systems shall comply with the constant volume fan power limitation.

Exceptions:
  1. Hospital, vivarium and laboratory systems that utilize flow control devices on exhaust and/or return to maintain space pressure relationships necessary for occupant health and safety or environmental control shall be permitted to use variable volume fan power limitation.
  2. Individual exhaust fans with motor nameplate horsepower of 1 hp or less are exempt from the allowable fan motor horsepower requirements.

TABLE C403.2.11.1(1)
FAN POWER LIMITATION

LIMITCONSTANT VOLUMEVARIABLE VOLUME
Option 1: Fan system motor nameplate hpAllowable nameplate motor hphp ≤ CFMs x 0.0011hp ≤ CFMs x 0.0015
Option 2: Fan system bhpAllowable fan system bhpbhp ≤ CFMS x 0.00094 + Abhp ≤CFMS x 0.0013 + A

For SI: 1 bhp = 735.5 W, 1 hp = 745.5 W, 1 cfm = 0.471 L/s.

where:

CFMS=The maximum design supply airflow rate to conditioned spaces served by the system in cubic feet per minute.
Hp=The maximum combined motor nameplate horsepower.
Bhp=The maximum combined fan brake horsepower.
A=Sum of [PD × CFMD/4131]

where:

PD=Each applicable pressure drop adjustment from Table C403.2.10.1(2) in. w.c.
CFMD=The design airflow through each applicable device from Table C403.2.10.1(2) in cubic feet per minute.

TABLE C403.2.11.1(2)
FAN POWER LIMITATION PRESSURE DROP ADJUSTMENT

DEVICEADJUSTMENT
Credits
Fully ducted return and/or exhaust air systems0.5 inch w.c. (2.15 inches w.c. for laboratory and vivarium systems)
Return and/or exhaust air flow control devices0.5 inch w.c.
Exhaust filters, scrubbers, or other exhaust treatmentThe pressure drop of device calculated at fan system design condition
Particulate filtration credit: MERV 9 - 120.5 inch w.c.
Particulate filtration credit: MERV 13 - 15 0.9 inch w.c.
Particulate filtration credit: MERV 16 and greater and
electronically enhanced filters
Pressure drop calculated at 2x clean filter pressure drop at
fan system design condition
Carbon and other gas-phase air cleanersClean filter pressure drop at fan system design condition
Biosafety cabinetPressure drop of device at fan system design condition
Energy recovery device, other than coil runaround loop(2.2 × energy recovery effectiveness) – 0.5 inch w.c. for each airstream
Coil runaround loop0.6 inch w.c. for each airstream
Evaporative humidifier/cooler in series with another
cooling coil
Pressure drop of device at fan system design conditions
Sound attenuation section (fans serving spaces with design
background noise goals below NC35)
0.15 inch w.c.
Exhaust system serving fume hoods0.35 inch w.c.
Laboratory and vivarium exhaust systems in high-rise buildings0.25 inch w.c./100 feet of vertical duct exceeding 75 feet
Deductions
Systems without central cooling device- 0.6 inch w.c.
Systems without central heating device- 0.3 inch w.c.
Systems with central electric resistance heating- 0.2 inch w.c.

For SI: 1 inch w.c. = 249 Pa, 1 inch = 25.4 mm.

w.c. = water column, NC = Noise criterion.

C403.2.11.2 Motor nameplate horsepower

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For each fan, the selected fan motor shall be no larger than the first available motor size greater than the brake horsepower (bhp). The fan bhp shall be indicated on the design documents to allow for compliance verification by the code official.

Exceptions:
  1. For fans less than 6 bhp (4413 W), where the first available motor larger than the brake horsepower has a nameplate rating within 50 percent of the bhp, selection of the next larger nameplate motor size is allowed.
  2. For fans 6 bhp (4413 W) and larger, where the first available motor larger than the bhp has a nameplate rating within 30 percent of the bhp, selection of the next larger nameplate motor size is allowed.
  3. For fans used only in approved life safety applications such as smoke evacuation.

C403.2.11.3 Fan efficiency

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Fans shall have a fan efficiency grade (FEG) of 67 or higher based on manufacturers’ certified data, as defined by AMCA 205. The total efficiency of the fan at the design point of operation shall be within 15 percentage points of the maximum total efficiency of the fan.

Exception: The following fans are not required to have a fan efficiency grade:
  1. Fans of 5 hp (3.7 kW) or less as follows:

    1. Single fan with a motor nameplate horsepower of 5 hp (3.7 kW) or less, unless Exception 1.2 applies.
    2. Multiple fans in series or parallel that have a combined motor nameplate horsepower of 5 hp (3.7 kW) or less and are operated as the functional equivalent of a single fan.
  2. Fans that are part of equipment covered under Section C403.2.3.
  3. Fans included in an equipment package certified by an approved agency for air or energy performance.
  4. Powered wall/roof ventilators.
  5. Fans outside the scope of AMCA 205.
  6. Fans that are intended to operate only during emergency conditions

C403.2.11.4 Group R occupancy exhaust fan efficacy

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The Group R occupancies of the building shall be provided with ventilation that meets the requirements of the International Mechanical Code, as applicable, or with other approved means of ventilation. Mechanical ventilation system fans with 400 cfm or less in capacity shall meet the efficacy requirements of Table C403.2.11.4.

Exceptions:
  1. Group R heat recovery ventilator and energy recovery ventilator fans that are less than 400 cfm.
  2. Where whole house ventilation fans are integrated with forced-air systems that are tested and listed HVAC equipment, they shall be powered by an electronically commutated motor where required by Section C405.8
  3. Domestic clothes dryer booster fans, domestic range rood exhaust fans, and domestic range booster fans that operate intermittently.

TABLE C403.2.4.11.4
MECHANICAL VENTILATION SYSTEM FAN EFFICACY
Fan location Air Flow Rate Minimum (cfm) Minimum Efficacy (cfm/watt) Air Flow Rate Minimum (cfm)
Exhaust fan: Bathroom, utility room, whole house 10 1.4 cfm/watt < 90
Exhaust fan: Bathroom, utility room, whole house 90 2.8 cfm/watt Any

C403.2.11.5 Fan airflow control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each cooling system listed in Table C403.2.11.5 shall be designed to vary the indoor fan airflow as a function of load and shall comply with the following requirements:

  1. Direct expansion (DX) and chilled water cooling units that control the capacity of the mechanical cooling directly based on space temperature shall have not fewer than two stages of fan control. Low or minimum speed shall not be greater than 66 percent of full speed. At low or minimum speed, the fan system shall draw not more than 40 percent of the fan power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  2. Other units including DX cooling units and chilled water units that control the space temperature by modulating the airflow to the space shall have modulating fan control. Minimum speed shall be not greater than 50 percent of full speed. At minimum speed, the fan system shall draw no more than 30 percent of the power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  3. Units that include an airside economizer in accordance with Section C403.3 shall have not fewer than two speeds of fan control during economizer operation.
Exceptions:
  1. Modulating fan control is not required for chilled water and evaporative cooling units with fan motors of less than 1 hp (0.746 kW) where the units are not used to provide ventilation air and the indoor fan cycles with the load.
  2. Where the volume of outdoor air required to comply with the ventilation requirements of the International Mechanical Code at low speed exceeds the air that would be delivered at the minimum speed defined in this section, the minimum speed shall be selected to provide the required ventilation air.

TABLE C403.2.4.11.5
FAN CONTROL
Cooling System Type Fan Motor Size Mechanical Cooling Capacity
DX cooling Any ≥65,000 Btu/h
Chilled water and evaporative cooling ≥ 5 hp Any
1/4 hp Any

C403.2.12 Air system design and control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each HVAC system having a total fan system motor nameplate horsepower (hp) exceeding 5 hp (3.7 kW) shall comply with the provisions of Sections C403.2.12.1 through C403.2.12.3.

C403.2.12 Heating outside a building

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Systems installed to provide heat outside a building shall be radiant systems.

Such heating systems shall be controlled by an occupancy sensing device or a timer switch, so that the system is automatically deenergized when no occupants are present.

C403.2.12.1 Allowable fan motor horsepower

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Each HVAC system at fan system design conditions shall not exceed the allowable fan system motor nameplate hp (Option 1) or fan system bhp (Option 2) as shown in Table C403.2.12.1(1). This includes supply fans, exhaust fans, return/relief fans, and fan-powered terminal units associated with systems providing heating or cooling capability.

Single-zone variable air volume systems shall comply with the constant volume fan power limitation.

Exceptions:

  1. Hospital, vivarium and laboratory systems that utilize flow control devices on exhaust or return to maintain space pressure relationships necessary for occupant health and safety or environmental control shall be permitted to use variable volume fan power limitation.
  2. Individual exhaust fans with motor nameplate horsepower of 1 hp (0.746 kW) or less are exempt from the allowable fan horsepower requirement.

TABLE C403.2.12.1(1)

FAN POWER LIMITATION

LIMITCONSTANT VOLUMEVARIABLE VOLUME
Option 1: Fan system motor nameplate hpAllowable nameplate motor hphp ≤ CFMs 0.0011hp ≤ CFMs 0.0015
Option 2: Fan system bhpAllowable fan system bhpbhp ≤ CFMS 0.00094 + Abhp ≤CFMS 0.0013 + A

For SI: 1 bhp = 735.5 W, 1 hp = 745.5 W, 1 cfm = 0.4719 L/s.

where:

CFMS=The maximum design supply airflow rate to conditioned spaces served by the system in cubic feet per minute.
hp=The maximum combined motor nameplate horsepower.
Bhp=The maximum combined fan brake horsepower.
A=Sum of [PD × CFMD/4131]

where:

PD=Each applicable pressure drop adjustment from Table C403.2.12.1(2) in. w.c.
CFMD=The design airflow through each applicable device from Table C403.2.12.1(2) in cubic feet per minute.

TABLE C403.2.12.1(2)

FAN POWER LIMITATION PRESSURE DROP ADJUSTMENT

DEVICEADJUSTMENT
Credits
Fully ducted return and/or exhaust air systems0.5 inch w.c. (2.15 in w.c. for laboratory and vivarium systems)
Return and/or exhaust airflow control devices0.5 inch w.c.
Exhaust filters, scrubbers or other exhaust treatmentThe pressure drop of device calculated at fan system design condition
Particulate filtration credit: MERV 9 thru 120.5 inch w.c.
Particulate filtration credit: MERV 13 thru 150.9 inch. w.c.
Particulate filtration credit: MERV 16 and greater and
electronically enhanced filters
Pressure drop calculated at 2x clean filter pressure drop at
fan system design condition.
Carbon and other gas-phase air cleanersClean filter pressure drop at fan system design condition.
Biosafety cabinetPressure drop of device at fan system design condition.
Energy recovery device, other than coil runaround loop(2.2 × energy recovery effectiveness) – 0.5 inch w.c. for each airstream.
Coil runaround loop0.6 inch w.c. for each airstream.
Evaporative humidifier/cooler in series with another
cooling coil
Pressure drop of device at fan system design conditions.
Sound attenuation section (fans serving spaces with design
background noise goals below NC35)
0.15 inch w.c.
Exhaust system serving fume hoods0.35 inch w.c.
Laboratory and vivarium exhaust systems in high-rise buildings0.25 inch w.c./100 feet of vertical duct exceeding 75 feet.
Deductions
Systems without central cooling device- 0.6 in. w.c.
Systems without central heating device- 0.3 in. w.c.
Systems with central electric resistance heat- 0.2 in. w.c.

For SI: 1 inch w.c. = 249 Pa, 1 inch = 25.4 mm.

w.c. = water column, NC = Noise criterion.

C403.2.12.2 Motor nameplate horsepower

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

For each fan, the fan brake horsepower shall be indicated on the construction documents and the selected motor shall be not larger than the first available motor size greater than the following:

  1. For fans less than 6 bhp (4413 W), 1.5 times the fan brake horsepower.
  2. For fans 6 bhp (4413 W) and larger, 1.3 times the fan brake horsepower.
  3. Systems complying with Section C403.2.12.1fan system motor nameplate hp (Option 1).

C403.2.12.3 Fan efficiency

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Fans shall have a fan efficiency grade (FEG) of not less than 67 when determined in accordance with AMCA 205 by an approved, independent testing laboratory and labeled by the manufacturer. The total efficiency of the fan at the design point of operation shall be within 15 percentage points of the maximum total efficiency of the fan.

Exception: The following fans are not required to have a fan efficiency grade:

  1. Fans of 5 hp (3.7 kW) or less as follows:

    1. 1.1. Single fan with a motor nameplate horsepower of 5 hp (3.7 kW) or less, unless Exception 1.2 applies.
    2. 1.2. Multiple fans in series or parallel that have a combined motor nameplate horsepower of 5 hp (3.7 kW) or less and are operated as the functional equivalent of a single fan.
  2. Fans that are part of equipment covered under Section C403.2.3.
  3. Fans included in an equipment package certified by an approved agency for air or energy performance.
  4. Powered wall/roof ventilators.
  5. Fans outside the scope of AMCA 205.
  6. Fans that are intended to operate only during emergency conditions.

C403.2.13 Heating outside a building

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Systems installed to provide heat outside a building shall be radiant systems.

Such heating systems shall be controlled by an occupancy sensing device or a timer switch, so that the system is automatically deenergized when no occupants are present.

C403.2.13 Variable flow capacity

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For fan and pump motors 7.5 hp and greater including motors in or serving custom and packaged air handlers serving variable air volume fan systems, constant volume fans, heating and cooling hydronic pumping systems, pool and service water pumping systems, domestic water pressure boosting systems, cooling tower fan, and other pump or fan motors where variable flows are required, there shall be:

  1. Variable speed drives; or
  2. Other controls and devices that will result in fan and pump motor demand of no more than 30 percent of design wattage at 50 percent of design air volume for fans when static pressure set point equals 1/3 the total design static pressure, and 50 percent of design water flow for pumps, based on manufacturer's certified test data. Variable inlet vanes, throttling valves (dampers), scroll dampers or bypass circuits shall not be allowed.
Exception: Variable speed devices are not required for motors that serve:
  1. Fans or pumps in packaged equipment where variable speed drives are not available as a factory option from the equipment manufacturer.
  2. Fans or pumps that are required to operate only for emergency fire-life-safety events (e.g., stairwell pressurization fans, elevator pressurization fans, fire pumps, etc.).

C403.2.13.1 Heat rejection equipment

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The requirements of this section apply to heat rejection equipment used in comfort cooling systems such as air-cooled condensers, open cooling towers, closed-circuit cooling towers, and evaporative condensers.

Exception: Heat rejection devices included as an integral part of equipment listed in Tables C403.2.3(1) through C403.2.3(3).

Heat rejection equipment shall have a minimum efficiency performance not less than values specified in Table C403.2.3(8). These requirements apply to all propeller, axial fan and centrifugal fan cooling towers. Table C403.2.3(8) specifies requirements for air-cooled condensers that are within rating conditions specified within the table.

C403.2.13.1.1 Variable flow controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Cooling tower fans 7.5 hp and greater shall have control devices that vary flow by controlling the leaving fluid temperature or condenser temperature/pressure of the heat rejection device.

C403.2.13.1.2 Limitation on centrifugal fan cooling towers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Open cooling towers with a combined rated capacity of 1,100 gpm and greater at 95°F condenser water return, 85°F condenser water supply and 75°F outdoor wet-bulb temperature shall meet the energy efficiency requirement for axial fan open circuit cooling towers.

C403.2.14 Refrigeration equipment performance

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Refrigeration equipment shall have an energy use in kWh/day not greater than the values of Tables C403.2.14(1) and C403.2.14(2) when tested and rated in accordance with AHRI Standard 1200. The energy use shall be verified through certification under an approved certification program or, where a certification program does not exist, the energy use shall be supported by data furnished by the equipment manufacturer.

TABLE C403.2.14(1)

MINIMUM EFFICIENCY REQUIREMENTS: COMMERCIAL REFRIGERATION

EQUIPMENT TYPEAPPLICATIONENERGY USE LIMITS
(kWh per day)a
TEST PROCEDURE
Refrigerator with solid doorsHolding Temperature0.10 V + 2.04AHRI 1200
Refrigerator with transparent doors0.12 V + 3.34
Freezers with solid doors0.40 V + 1.38
Freezers with transparent doors0.75 V + 4.10
Refrigerators/freezers with solid doorsthe greater of 0.12 V + 3.34 or 0.70
Commercial refrigeratorsPulldown0.126 V + 3.51
  1. V = volume of the chiller or frozen compartment as defined in AHAM-HRF-1.

TABLE C403.2.14(2)

MINIMUM EFFICIENCY REQUIREMENTS: COMMERCIAL REFRIGERATORS AND FREEZERS

EQUIPMENT TYPEENERGY USE LIMITS
(kWh/day)a, b
TEST
PROCEDURE
Equipment ClasscFamily CodeOperating ModeRating Temperature
VOP.RC.MVertical openRemote condensingMedium0.82 TDA + 4.07AHRI 1200
SVO.RC.MSemivertical openRemote condensingMedium0.83 TDA + 3.18
HZO.RC.MHorizontal openRemote condensingMedium0.35 TDA + 2.88
VOP.RC.LVertical openRemote condensingLow2.27 TDA + 6.85
HZO.RC.LHorizontal openRemote condensingLow0.57 TDA + 6.88
VCT.RC.MVertical
transparent door
Remote condensingMedium0.22 TDA + 1.95
VCT.RC.LVertical
transparent door
Remote condensingLow0.56 TDA + 2.61
SOC.RC.MService over counterRemote condensingMedium0.51 TDA + 0.11
VOP.SC.MVertical openSelf-containedMedium1.74 TDA + 4.71
SVO.SC.MSemivertical openSelf-containedMedium1.73 TDA + 4.59
HZO.SC.MHorizontal openSelf-containedMedium0.77 TDA + 5.55
HZO.SC.LHorizontal openSelf-containedLow1.92 TDA + 7.08
VCT.SC.IVertical
transparent door
Self-containedIce cream0.67 TDA + 3.29
VCS.SC.IVertical solid doorSelf-containedIce cream0.38 V + 0.88
HCT.SC.IHorizontal
transparent door
Self-containedIce cream0.56 TDA + 0.43
SVO.RC.LSemivertical openRemote condensingLow2.27 TDA + 6.85
VOP.RC.IVertical openRemote condensingIce cream2.89 TDA + 8.7
SVO.RC.ISemivertical openRemote condensingIce cream2.89 TDA + 8.7
HZO.RC.IHorizontal openRemote condensingIce cream0.72 TDA + 8.74
VCT.RC.IVertical
transparent door
Remote condensingIce cream0.66 TDA + 3.05
HCT.RC.MHorizontal
transparent door
Remote condensingMedium0.16 TDA + 0.13
HCT.RC.LHorizontal
transparent door
Remote condensingLow0.34 TDA + 0.26
HCT.RC.IHorizontal
transparent door
Remote condensingIce cream0.4 TDA + 0.31
VCS.RC.MVertical solid doorRemote condensingMedium0.11 V + 0.26
VCS.RC.LVertical solid doorRemote condensingLow0.23 V + 0.54
VCS.RC.IVertical solid doorRemote condensingIce cream0.27 V + 0.63
HCS.RC.MHorizontal solid doorRemote condensingMedium0.11 V + 0.26
HCS.RC.LHorizontal solid doorRemote condensingLow0.23 V + 0.54
HCS.RC.IHorizontal solid doorRemote condensingIce cream0.27 V + 0.63
HCS.RC.IHorizontal solid doorRemote condensingIce cream0.27 V + 0.63
SOC.RC.LService over counterRemote condensingLow1.08 TDA + 0.22
SOC.RC.IService over counterRemote condensingIce cream1.26 TDA + 0.26
VOP.SC.LVertical openSelf-containedLow4.37 TDA + 11.82
VOP.SC.IVertical openSelf-containedIce cream5.55 TDA + 15.02
SVO.SC.LSemivertical openSelf-containedLow4.34 TDA + 11.51
SVO.SC.ISemivertical openSelf-containedIce cream5.52 TDA + 14.63
HZO.SC.IHorizontal openSelf-containedIce cream2.44 TDA + 9.0
SOC.SC.IService over counterSelf-containedIce cream1.76 TDA + 0.36
HCS.SC.IHorizontal solid doorSelf-containedIce cream0.38 V + 0.88
  1. V = Volume of the case, as measured in accordance with Appendix C of AHRI 1200.
  2. TDA = Total display area of the case, as measured in accordance with Appendix D of AHRI 1200.
  3. Equipment class designations consist of a combination [(in sequential order separated by periods (AAA).(BB).(C))] of:

    (AAA)An equipment family code where:
    VOP=vertical open
    SVO=semivertical open
    HZO=horizontal open
    VCT=vertical transparent doors
    VCS=vertical solid doors
    HCT=horizontal transparent doors
    HCS=horizontal solid doors
    SOC=service over counter
    (BB)An operating mode code:
    RC=remote condensing
    SC=self-contained
    (C)A rating temperature code:
    M=medium temperature (38°F)
    L=low temperature (0°F)
    I=ice-cream temperature (15°F)

    For example, “VOP.RC.M” refers to the “vertical-open, remote-condensing, medium-temperature” equipment class.

C403.2.14 Electric motor efficiency

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Electric motors, including fractional hp motors, shall comply with the provisions of Section C405.8.

C403.2.15 Walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Refrigerated warehouse coolers and refrigerated warehouse freezers shall comply with this section. Walk-in coolers and walk-in freezers that are not either site assembled or site constructed shall comply with the following:

1. Be equipped with automatic door-closers that firmly close walk-in doors that have been closed to within 1 inch (25 mm) of full closure.

Exception: Automatic closers are not required for doors more than 45 inches (1143 mm) in width or more than 7 feet (2134 mm) in height.

2. Doorways shall have strip doors, curtains, spring-hinged doors or other method of minimizing infiltration when doors are open.

3. Walk-in coolers and refrigerated warehouse coolers shall contain wall, ceiling, and door insulation of not less than R-25 and walk-in freezers and refrigerated warehouse freezers shall contain wall, ceiling and door insulation of not less than R-32.

Exception: Glazed portions of doors or structural members need not be insulated.

4. Walk-in freezers shall contain floor insulation of not less than R-28.

5. Transparent reach-in doors for walk-in freezers and windows in walk-in freezer doors shall be of triple-pane glass, either filled with inert gas or with heat-reflective treated glass.

6. Windows and transparent reach-in doors for walk-in coolers doors shall be of double-pane or triple-pane, inert gas-filled, heat-reflective treated glass.

7. Evaporator fan motors that are less than 1 hp

(0.746 kW) and less than 460 volts shall use electronically commutated motors, brushless direct-current motors, or 3-phase motors.

8. Condenser fan motors that are less than 1 hp

(0.746 kW) shall use electronically commutated motors, permanent split capacitor-type motors or 3-phase motors.

9. Where antisweat heaters without antisweat heater controls are provided, they shall have a total door rail, glass and frame heater power draw of not more than 7.1 W/ft2 (76 W/m2) of door opening for walk-in freezers and 3.0 W/ft2 (32 W/m2) of door opening for walk-in coolers.

10. Where antisweat heater controls are provided, they shall reduce the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.

11. Lights in walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers shall either use light sources with an efficacy of not less than 40 lumens per watt, including ballast losses, or shall use light sources with an efficacy of not less than 40 lumens per watt, including ballast losses, in conjunction with a device that turns off the lights within 15 minutes when the space is not occupied.

C403.2.16 Walk-in coolers and walk-in freezers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Site-assembled or site-constructed walk-in coolers and walk-in freezers shall comply with the following:

1. Automatic door closers shall be provided that fully close walk-in doors that have been closed to within 1 inch (25 mm) of full closure.

Exception: Closers are not required for doors more than 45 inches (1143 mm) in width or more than 7 feet (2134 mm) in height.

2. Doorways shall be provided with strip doors, curtains, spring-hinged doors or other method of minimizing infiltration when the doors are open.

3. Walls shall be provided with insulation having a thermal resistance of not less than R-25, ceilings shall be provided with insulation having a thermal resistance of not less than R-25 and doors of walk-in coolers and walk-in freezers shall be provided with insulation having a thermal resistance of not less than R-32.

Exception: Insulation is not required for glazed portions of doors or at structural members associated with the walls, ceiling or door frame.

4. The floor of walk-in freezers shall be provided with insulation having a thermal resistance of not less than R-28.

5. Transparent reach-in doors for and windows in opaque walk-in freezer doors shall be provided with triple-pane glass having the interstitial spaces filled with inert gas or provided with heat-reflective treated glass.

6. Transparent reach-in doors for and windows in opaque walk-in cooler doors shall be double-pane heat-reflective treated glass having the interstitial space gas filled.

7. Evaporator fan motors that are less than 1 hp

(0.746 kW) and less than 460 volts shall be electronically commutated motors or 3-phase motors.

8. Condenser fan motors that are less than 1 hp

(0.746 kW) in capacity shall be of the electronically commutated or permanent split capacitor-type or shall be 3-phase motors.

Exception: Fan motors in walk-in coolers and walk-in freezers combined in a single enclosure greater than 3,000 square feet (279 m2) in floor area are exempt.

9. Antisweat heaters that are not provided with anti-sweat heater controls shall have a total door rail, glass and frame heater power draw not greater than 7.1 W/ft2 (76 W/m2) of door opening for walk-in freezers, and not greater than 3.0 W/ft2 (32 W/m2) of door opening for walk-in coolers.

10. Antisweat heater controls shall be capable of reducing the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.

11. Light sources shall have an efficacy of not less than 40 lumens per Watt, including any ballast losses, or shall be provided with a device that automatically turns off the lights within 15 minutes of when the walk-in cooler or walk-in freezer was last occupied.

C403.2.17 Refrigerated display cases

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Site-assembled or site-constructed refrigerated display cases shall comply with the following:

  1. Lighting and glass doors in refrigerated display cases shall be controlled by one of the following:

    1. 1.1. Time switch controls to turn off lights during nonbusiness hours. Timed overrides for display cases shall turn the lights on for up to 1 hour and shall automatically time out to turn the lights off.
    2. 1.2. Motion sensor controls on each display case section that reduce lighting power by at least 50 percent within 3 minutes after the area within the sensor range is vacated.
  2. Low-temperature display cases shall incorporate temperature-based defrost termination control with a time-limit default. The defrost cycle shall terminate first on an upper temperature limit breach and second upon a time limit breach.
  3. Antisweat heater controls shall reduce the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.

C403.3 Economizers (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Each cooling system shall include either an air or water economizer complying with Sections C403.3.1 through C403.3.4.

Exceptions: Economizers are not required for the systems listed below.

  1. In cooling systems for buildings located in Climate Zones 1A and 1B.
  2. In climate zones other than 1A and 1B, where individual fan cooling units have a capacity of less than 54,000 Btu/h (15.8 kW) and meet one of the following:

    1. 2.1. Have direct expansion cooling coils.
    2. 2.2. The total chilled water system capacity less the capacity of fan units with air economizers is less than the minimum specified in Table C403.3(1).

    The total supply capacity of all fan-cooling units not provided with economizers shall not exceed 20 percent of the total supply capacity of all fan-cooling units in the building or 300,000 Btu/h (88 kW), whichever is greater.

  3. Where more than 25 percent of the air designed to be supplied by the system is to spaces that are designed to be humidified above 35°F (1.7°C) dew-point temperature to satisfy process needs.
  4. Systems that serve residential spaces where the system capacity is less than five times the requirement listed in Table C403.3(1).
  5. Systems expected to operate less than 20 hours per week.
  6. Where the use of outdoor air for cooling will affect supermarket open refrigerated casework systems.
  7. Where the cooling efficiency meets or exceeds the efficiency requirements in Table C403.3(2).
  8. Chilled-water cooling systems that are passive (without a fan) or use induction where the total chilled water system capacity less the capacity of fan units with air economizers is less than the minimum specified in Table C403.3(1).
  9. Systems that include a heat recovery system in accordance with Section C403.4.5.

TABLE C403.3(1)

MINIMUM CHILLED-WATER SYSTEM COOLING CAPACITY FOR DETERMINING ECONOMIZER COOLING REQUIREMENTS

CLIMATE ZONES
(COOLING)
TOTAL CHILLED-WATER SYSTEM CAPACITY LESS CAPACITY OF COOLING UNITS WITH AIR ECONOMIZERS
Local Water-cooled Chilled-water SystemsAir-cooled Chilled-water Systems or District Chilled-Water Systems
1aNo economizer requirementNo economizer requirement
1b, 2a, 2b960,000 Btu/h1,250,000 Btu/h
3a, 3b, 3c, 4a, 4b, 4c720,000 Btu/h940,000 Btu/h
5a, 5b, 5c, 6a, 6b, 7, 81,320,000 Btu/h1,720,000 Btu/h

For SI: 1 British thermal unit per hour = 0.2931 W.

TABLE C403.3(2)

EQUIPMENT EFFICIENCY PERFORMANCE EXCEPTION FOR ECONOMIZERS

CLIMATE
ZONES
COOLING EQUIPMENT PERFORMANCE
IMPROVEMENT (EER OR IPLV)
2B10% efficiency improvement
3B15% efficiency improvement
4B20% efficiency improvement
Air economizers shall be provided on all new systems including those serving computer server rooms, electronic equipment, radio equipment, and telephone switchgear. Economizers shall comply with Sections C403.3.1 through C403.3. 4.

Exception: Economizers are not required for the systems listed below:
  1. Systems complying with Section C403.6 Dedicated outdoor air systems (DOAS) with year-round cooling loads from lights and equipment of less than 5 watts per square foot.
  2. Unitary or packaged systems serving one zone with dehumidification that affect other systems so as to increase the overall building energy consumption. New humidification equipment shall comply with Section C403.2.3.4
  3. Unitary or packaged systems serving one zone where the cooling efficiency meets or exceeds the efficiency requirements in Table C403.3.
  4. Water-cooled refrigeration equipment serving chilled beams and chilled ceiling space cooling systems only which are provided with a water economizer meeting the requirements of Section C403.3.4.
  5. Systems complying with all of the following criteria:

    1. Consist of multiple water source heat pumps connected to a common water loop.
    2. Have a minimum of 60 percent air economizer.
    3. Have water source heat pumps with an EER at least 15 percent higher for cooling and a COP of at least 15 percent higher for heating than that specified in Section C403.2.3.
    4. Where provided, have a central boiler or furnace efficiency of 90 percent minimum for units up to 199,000 Btu/h.
    5. Provide heat recovery with a minimum 50 percent heat recovery effectiveness as defined in Section C403.5 to preheat the outside air supply.
  6. For Group R occupancies, cooling units installed outdoors or in a mechanical room adjacent to outdoors with a total cooling capacity less than 20,000 Btu/h and other cooling units with a total cooling capacity less than 54,000 Btu/h provided that these are high-efficiency cooling equipment with IEER, SEER, and EER values more than 15 percent higher than minimum efficiencies listed in Tables C403.2.3 (1) through (3), in the appropriate size category, using the same test procedures. Equipment shall be listed in the appropriate certification program to qualify for this exception. For split systems, compliance is based on the cooling capacity of individual fan coil units.
  7. Variable refrigerant flow (VRF) systems, multiple-zone split-system heat pumps, consisting of multiple, individually metered indoor units with multi-speed fan motors, served on a single common refrigeration circuit with an exterior reverse-cycle heat pump with variable speed compressor(s) and variable speed condenser fan(s). These systems shall also be capable of providing simultaneous heating and cooling operation, where recovered energy from the indoor units operating in one mode can be transferred to one or more perimeter zones (as determined by conditioned floor area) and the outdoor unit shall be at least 65,000 Btu/h in total capacity. Systems utilizing this exception shall have 50 percent heat recovery effectiveness as defined by Section C403.5 on the outside air. For the purposes of this exception, dedicated server rooms, electronic equipment rooms or telecom switch rooms are not considered perimeter zones.
  8. Equipment used to cool Controlled Plant Growth Environments provided these are high-efficiency cooling equipment with SEER, EER and IEER values a minimum of 20 percent greater than the values listed in Tables C403.2.3(1), (3) and (7).
  9. Equipment used to cool any spaces with year-round cooling loads from lights and equipment of greater than 5 watts per square foot, where it can be demonstrated through calculations, to the satisfaction of the code official, that the heat rejection load of the equipment will be recovered and used for on-site space heating or service water heating demands such that the energy use of the building is decreased in comparison to a baseline of the same equipment provided with an air economizer complying with Section C403.3.
  10. Equipment used to cool any dedicated server room, electronic equipment room or telecom switch room provided the system complies with Option a, b or c in the table below. The total capacity of all systems without economizers shall not exceed 240,000 Btu/h per building or 10 percent of its air economizer capacity, whichever is greater. This exception shall not be used for Total Building Performance.


Equipment Type Higher Equipment Efficiency Part-Load Control Economizer
Option a Tables C403.2.3(1) and C403.2.3(2)a +15%b Required over 85,000 Btu/hc None Required
Option b Tables C403.2.3(1) and C403.2.3(2)a +5%d Required over 85,000 Btu/hc Waterside Economizer
Option c ASHRAE Standard 127f +0%g Required over 85,000 Btu/hc Waterside Economizer


Notes for Exception 10:
  1. For a system where all of the cooling equipment is subject to the AHRI standards listed in Tables C403.2.3(1) and C403.2.3(2), the system shall comply with all of the following (note that if the system contains any cooling equipment that exceeds the capacity limits in Table C403.2.3(1) or C403.2.3(2), or if the system contains any cooling equipment that is not included in Table C403.2.3(1) or C403.2.3(2), then the system is not allowed to use this option).
  2. The cooling equipment shall have an EER value and an IPLV value that is a minimum of 15 percent greater than the value listed in Tables C403.2.3(1) and C403.2.3(2).
  3. For units with a total cooling capacity over 85,000 Btu/h, the system shall utilize part-load capacity control schemes that are able to modulate to a part-load capacity of 50 percent of the load or less that results in the compressor operating at the same or higher EER at part loads than at full load (e.g., minimum of two-stages of compressor unloading such as cylinder unloading, two-stage scrolls, dual tandem scrolls, but hot gas bypass is not credited as a compressor unloading system).
  4. The cooling equipment shall have an EER value and an IPLV value that is a minimum of 5 percent greater than the value listed in Tables C403.2.3(1) and C403.2.3(2).
  5. The system shall include a water economizer in lieu of air economizer. Water economizers shall meet the requirements of Sections C403.3.1 and C403.3.2 and be capable of providing the total concurrent cooling load served by the connected terminal equipment lacking airside economizer, at outside air temperatures of 50°F dry-bulb/45°F wet-bulb and below. For this calculation, all factors including solar and internal load shall be the same as those used for peak load calculations, except for the outside temperatures. The equipment shall be served by a dedicated condenser water system unless a nondedicated condenser water system exists that can provide appropriate water temperatures during hours when waterside economizer cooling is available.
  6. For a system where all cooling equipment is subject to ASHRAE Standard 127.
  7. The cooling equipment subject to ASHRAE Standard 127 shall have an EER value and an IPLV value that is equal or greater than the value listed in Tables C403.2.3(1) and C403.2.3(2) when determined in accordance with the rating conditions in ASHRAE Standard 127 (i.e., not the rating conditions in AHRI Standard 210/240 or 340/360). This information shall be provided by an independent third party.

TABLE C403.3
EQUIPMENT EFFICIENCY PERFORMANCE
EXCEPTION FOR ECONOMIZERS


Climate Zone Efficiency Improvementa
4C 64%
5B 59%

a. If a unit is rated with an IPLV, IEER or SEER then to eliminate the required air or water economizer, the minimum cooling efficiency of the HVAC unit must be increased by the percentage shown. If the HVAC unit is only rated with a full load metric like EER or COP cooling, then these must be increased by the percentage shown.

C403.3.1 Integrated economizer control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Economizer systems shall be integrated with the mechanical cooling system and be capable of providing configured to provide partial cooling even where additional mechanical cooling is required to provide the remainder of the cooling load. Controls shall not be capable of creating a false load in the mechanical cooling systems by limiting or disabling the economizer or any other means, such as hot gas bypass, except at the lowest stage of mechanical cooling.

Units that include an air economizer shall comply with the following:

  1. Unit controls shall have the mechanical cooling capacity control interlocked with the air economizer controls such that the outdoor air damper is at the 100- percent open position when mechanical cooling is on and the outdoor air damper does not begin to close to prevent coil freezing due to minimum compressor run time until the leaving air temperature is less than 45°F (7°C).
  2. Direct expansion (DX) units that control 75,000 Btu/h (22 kW) with cooling capacity 65,000 Btu/H (19 kW) or greater of rated capacity shall comply with the following:

    1. DX units that controlof the capacity of the mechanical cooling directly based on occupied space temperature shall have not fewer than two stages of mechanical cooling capacity
    2. Other DX units, including those that control space temperature by modulating the airflow to the space, shall be in accordance with Table C403.3.1.

TABLE C403.3.1
DX COOLING STAGE REQUIREMENTS FOR MODULATING AIRFLOW UNITS

RATING CAPACITYMINIMUM NUMBER
OF MECHANICAL COOLING STAGES
MINIMUM
COMPRESSOR DISPLACEMENTa
≥ 65,000 Btu/h and
< 240,000 Btu/h
3 stages≤ 35% of full load
≥ 240,000 Btu/h4 stages≤ 25% of full load

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. For mechanical cooling stage control that does not use variable compressor displacement, the percent displacement shall be equivalent to the mechanical cooling capacity reduction evaluated at the full load rating conditions for the compressor.

C403.3.2 Economizer heating system impact

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

HVAC system design and economizer controls shall be such that economizer operation does not increase building heating energy use during normal operation.

Exception: Economizers on variable air volume (VAV) systems that cause zone level heating to increase due to a reduction in supply air temperature.

Air economizers shall comply with Sections C403.3.3.1 through C403.3.3.5.

C403.3.3.1 Design capacity

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Air economizer systems shall be capable of modulating configured to modulate outdoor air and return air dampers to provide up to 100 percent of the design supply air quantity as outdoor air for cooling.

C403.3.3.2 Control signal

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Economizer controls and dampers shall be capable of beingconfigured to sequenced the dampers with the mechanical cooling equipment and shall not be controlled by only mixed- air temperature. Air economizers on systems with cooling capacity greater than 65,000 Btu/h shall be configured to provide partial cooling even when additional mechanical cooling is required to meet the remainder of the cooling load.

Exception: The use of mixed- air temperature limit control shall be permitted for systems that are both controlled from space temperature (such as single- zone systems) and having cooling capacity less than 65,000 Btu/h.

C403.3.3.3 High-limit shutoff

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Air economizers shall be capable ofconfigured to automatically reducing reduce outdoor air intake to the design minimum outdoor air quantity when outdoor air intake will no longer reduce cooling energy usage. High-limit shutoff control types for specific climates shall be chosen from Table C403.3.3.3. High-limit shutoff control settings for these control types shall be those specified in Table C403.3.3.3.

TABLE C403.3.3.3
HIGH-LIMIT SHUTOFF CONTROL SETTING FOR AIR ECONOMIZERSb

DEVICE TYPECLIMATE ZONEREQUIRED HIGH LIMIT
(ECONOMIZER OFF WHEN):
EquationDescription
Fixed dry bulb1B, 2B, 3B, 3C, 4B, 4C,
5B, 5C, 6B, 7, 8
4C, 5B
TOA > 75°FOutdoor air temperature exceeds 75°F
5A, 6ATOA > 70°FOutdoor air temperature exceeds 70°F
1A, 2A, 3A, 4ATOA > 65°FOutdoor air temperature exceeds 65°F
Differential dry bulb1B, 2B, 3B, 3C, 4B, 4C, 5A,
5B, 5C, 6A, 6B, 7, 8
4C, 5B
TOA > TRAOutdoor air temperature exceeds
return air temperature
Fixed enthalpy with fixed
dry-bulb temperatures
AllhOA > 28 Btu/lba or
TOA > 75°F
Outdoor air enthalpy exceeds
28 Btu/lb of dry aira or
outdoor air temperature exceeds 75°F
Differential enthalpy with
fixed dry-bulb temperatures
AllhOA > Hra or
TOA > 75°F
Outdoor air enthalpy exceeds
return air enthalpy or
outdoor air temperature exceeds 75°F

For SI: 1 foot = 305 mm, °C = (°F - 32)/1.8, 1 Btu/lb = 2.33 kJ/kg.For SI: °C = (°F - 32) × 5/9, 1 Btu/lb = 2.33 kJ/kg.

  1. At altitudes substantially different than sea level, the Fixed Enthalpy limit shall be set to the enthalpy value at 75°F and 50-percent relative humidity. As an example, at approximately 6,000 feet elevation, the fixed enthalpy limit is approximately 30.7 Btu/lb.
  2. Devices with selectable setpoints shall be capable of being set to within 2°F and 2 Btu/lb of the setpoint listed.

C403.3.3.4 Relief of excess outdoor air

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Systems shall be capable of relieving excessoutdoor air during air economizer operation to prevent over-pressurizing the building. The relief air outlet shall be located to avoid recirculation into the building.
Return, exhaust/relief and outdoor air dampers used in economizers shall comply with Section C403.2.4.3.
Water-side economizers shall comply with Sections C403.3.4.1 and C403.3.4.2.

C403.3.4.1 Water-side economizers Design capacity

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Water economizer systems shall be capable of cooling supply air by indirect evaporation and providing up to 100 percent of the expected system cooling load at outdoor air temperatures of not greater than 50°F (10°C) dry bulb/45°F (7°C) wet bulb.

Exceptions:

  1. Systems primarily serving computer rooms in which 100 percent of the expected system cooling load at 40°F (4°C) dry bulb/35°F (1.7°C) wet bulb is met with evaporative water economizers.
  2. Systems primarily serving computer rooms with dry cooler water economizers which satisfy 100 percent of the expected system cooling load at 35°F (1.7°C) dry bulb.
  3. Systems where dehumidification requirements cannot be met using outdoor air temperatures of 50°F (10°C) dry bulb/45°F (7°C) wet bulb and where 100 percent of the expected system cooling load at 45°F (7°C) dry bulb/40°F (4°C) wet bulb is met with evaporative water economizers.
Water economizer systems shall be configured to supply air by indirect evaporation and providing up to 100 percent of the expected system cooling load at outdoor air temperatures of not greater than 50°F dry-bulb (10°C dry-bulb)/45°F wet-bulb (7.2°C wet-bulb).

Exception: Systems in which a water economizer is used and where dehumidification requirements cannot be met using outdoor air temperatures of 50°F dry-bulb (10°C dry-bulb)/45°F wet-bulb (7.2°C wet-bulb) shall satisfy 100 percent of the expected system cooling load at 45°F dry-bulb (7.2°C dry-bulb)/40°F wet-bulb (4.5°C wet-bulb).

C403.3.4.2 Maximum pressure drop

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Precooling coils and water-to-water heat exchangers used as part of a water economizer system shall either have a water-side pressure drop of less than 15 feet (45 kPa4572 mm) of water or a secondary loop shall be created so that the coil or heat exchanger pressure drop is not seen by the circulating pumps when the system is in the normal cooling (noneconomizer) mode.

C403.4 Hydronic and multiple-zone HVAC systems controls and equipment. (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Hydronic and multiple-zone HVAC system controls and equipment shall comply with this section.

For buildings with a total equipment cooling capacity of 300 tons and above, the equipment shall comply with one of the following:
  1. No one unit shall have a cooling capacity of more than 2/3 of the total installed cooling equipment capacity.
  2. The equipment shall have a variable speed drive.
  3. The equipment shall have multiple compressors.

C403.4.1 Multiple-zone system fan control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Controls shall be provided for fans in accordance with Sections C403.4.1.1 through C403.4.1.3 C403.4.1.2.

C403.4.1.1 Fan airflow control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Each cooling system listed in Table C403.4.1.1 shall be designed to vary the indoor fan airflow as a function of load and shall comply with the following requirements:

  1. Direct expansion (DX) and chilled water cooling units that control the capacity of the mechanical cooling directly based on space temperature shall have not fewer than two stages of fan control. Low or minimum speed shall not be greater than 66 percent of full speed. At low or minimum speed, the fan system shall draw not more than 40 percent of the fan power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  2. Other units including DX cooling units and chilled water units that control the space temperature by modulating the airflow to the space shall have modulating fan control. Minimum speed shall be not greater than 50 percent of full speed. At minimum speed the fan system shall draw not more than 30 percent of the power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  3. Units that include an airside economizer in accordance with Section C403.3 shall have not fewer than two speeds of fan control during economizer operation

Exceptions:

  1. Modulating fan control is not required for chilled water and evaporative cooling units with fan motors of less than 1 hp (0.746 kW) where the units are not used to provide ventilation air and the indoor fan cycles with the load.
  2. Where the volume of outdoor air required to comply with the ventilation requirements of the International Mechanical Code at low speed exceeds the air that would be delivered at the speed defined in Section C403.4.1, the minimum speed shall be selected to provide the required ventilation air.

TABLE C403.4.1.1

EFFECTIVE DATES FOR FAN CONTROL

COOLING
SYSTEM TYPE
FAN
MOTOR SIZE
MECHANICAL
COOLING CAPACITY
DX coolingAny≥ 75,000 Btu/h
(before 1/1/2016)
≥ 65,000 Btu/h
(after 1/1/2016)
Chilled water and
evaporative cooling
≥ 5 hpAny
1/4 hpAny

For SI: 1 British thermal unit per hour = 0.2931 W; 1 hp = 0.746 kW.

C403.4.1.1 Static pressure sensor location

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Static pressure sensors used to control VAV fans shall be located such that the controller setpoint is no greater than 1.2 inches w.c. (2099 Pa). Where this results in one or more sensors being located downstream of major duct splits, not less than one sensor shall be located on each major branch to ensure that static pressure can be maintained in each branch.

Exception: Systems complying with Section C403.4.1.2.

C403.4.1.2 Static pressure sensor location

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Static pressure sensors used to control VAV fans shall be located such that the controller set point is not greater than 1.2 inches w.c. (299 Pa). Where this results in one or more sensors being located downstream of major duct splits, not less than one sensor shall be located on each major branch to ensure that static pressure can be maintained in each branch.

C403.4.1.2 Set points for direct digital control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For systems with direct digital control of individual zones reporting to the central control panel, the static pressure setpoint shall be reset based on the zone requiring the most pressure. In such cases, the set point is reset lower until one zone damper is nearly wide open. The direct digital controls shall be capable of monitoring zone damper positions or shall have an alternative method of indicating the need for static pressure that is configured to provide all of the following:
  1. Automatically detecting any zone that excessively drives the reset logic.
  2. Generating an alarm to the system operational location.
  3. Allowing an operator to readily remove one or more zones from the reset algorithm.

C403.4.1.3 Set points for direct digital control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

For systems with direct digital control of individual zones reporting to the central control panel, the static pressure set point shall be reset based on the zone requiring the most pressure. In such case, the set point is reset lower until one zone damper is nearly wide open. The direct digital controls shall be capable of monitoring zone damper positions or shall have an alternative method of indicating the need for static pressure that is capable of all of the following:

  1. Automatically detecting any zone that excessively drives the reset logic.
  2. Generating an alarm to the system operational location.
  3. Allowing an operator to readily remove one or more zones from the reset algorithm.

C403.4.2 Hydronic systems controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The heating of fluids that have been previously mechanically cooled and the cooling of fluids that have been previously mechanically heated shall be limited in accordance with Sections C403.4.2.1 through C403.4.2.3. Hydronic heating systems comprised of multiple-packaged boilers and designed to deliver conditioned water or steam into a common distribution system shall include automatic controls capable of sequencing configured to sequence operation of the boilers. Hydronic heating systems comprised of a single boiler and greater than 500,000 Btu/h (146.5 k146,550 W) input design capacity shall include either a multi-staged or modulating burner.
Hydronic systems that use a common return system for both hot water and chilled water are prohibited.

C403.4.2.2 Two-pipe changeover system

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Systems that use a common distribution system to supply both heated and chilled water shall be designed to allow a dead band between changeover from one mode to the other of not less than at least 15°F (8.3°C) outside air temperatures; be designed to and provided with controls that will allow operation in one mode for not less than at least 4 hours before changing over to the other mode; and be provided with controls that allow heating and cooling supply temperatures at the changeover point to be not more than 30°F (16.7°C) apart.

C403.4.2.3 Hydronic (water loop) heat pump systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Hydronic heat pump systems shall comply with Sections C403.4.2.3.1 through C403.4.2.3.2 C403.4.2.3.3.

C403.4.2.3.1 Temperature dead band

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Hydronic heat pumps connected to a common heat pump water loop with central devices for heat rejection and heat addition shall have controls that are capable of providingconfigured to provide a heat pump water supply temperature dead band of not less thanat least 20°F (11.1°C) between initiation of heat rejection and heat addition by the central devices.

Exception: Where a system loop temperature optimization controller is installed and can determine the most efficient operating temperature based on real time conditions of demand and capacity, dead bands of less than 20°F (11°C) shall be permitted.

Heat rejection equipment shall comply with Sections C403.4.2.3.2.1 and C403.4.2.3.2.2.

Exception: Where it can be demonstrated that a heat pump system will be required to reject heat throughout the year.

C403.4.2.3.2.1 Climate Zones 3 and 4

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

For Climate Zones 3 and 4:

  1. Where If a closed-circuit cooling tower is used directly in the heat pump loop, either an automatic valve shall be installed to bypass all but a minimal flow of water around the tower, or lower leakage positive closure dampers shall be provided.
  2. Where If an open-circuit tower is used directly in the heat pump loop, an automatic valve shall be installed to bypass all heat pump water flow around the tower.
  3. Where If an open- or closed-circuit cooling tower is used in conjunction with a separate heat exchanger to isolate the cooling tower from the heat pump loop, then heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop.

C403.4.2.3.2.2 Climate Zones 5 through 8

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For Climate Zones 5 through 8, where if an open- or closed-circuit cooling tower is used, then a separate heat exchanger shall be provided to isolate the cooling tower from the heat pump loop, and heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop and providing an automatic valve to stop the flow of fluid.

C403.4.2.3.3 Two-position valve

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each hydronic heat pump on the hydronic system having a total pump system power exceeding 10 hp (7.5 kW) shall have a two-position valve.

C403.4.2.3.3 Isolation valve

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each hydronic heat pump on the hydronic system having a total pump system power exceeding 10 horsepower (hp) (7.5 kW) shall have a two-way (but not three-way) valve. For the purposes of this section, pump system power is the sum of the nominal power demand (i.e., nameplate horsepower at nominal motor efficiency) of motors of all pumps that are required to operate at design conditions to supply fluid from the heating or cooling source to all heat transfer devices (e.g., coils, heat exchanger) and return it to the source. This converts the system into a variable flow system and, as such, the primary circulation pumps shall comply with the variable flow requirements in Section C403.4.2.6.

C403.4.2.4 Part-load controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Hydronic systems greater than or equal to 500,000 300,000 Btu/h (146.588 kW) in design output capacity supplying heated or chilled water to comfort conditioning systems shall include controls that have the capability to do all of the following are configured to:

  1. Automatically reset the supply-water temperatures in response to varying building heating and cooling demand using coil valve position, zone-return water temperature, building-return water temperature or outside outdoor air temperature. The temperature shall be capable of being reset by not less than 25 percent of the design supply-to-return water temperature difference.

    Exception: Hydronic systems serving hydronic heat pumps.
  2. Automatically vary fluid flow for hydronic systems with a combined motor capacity of 10 hp (7.5 kW) 3 hp or larger with three or more control valves or other devices by reducing the system design flow rate by not less than 50 percent by designed valves that modulate or step open and close, or pumps that modulate or turn on and off as a function of load.
  3. Automatically vary pump flow on chilled-water systems and heat rejection loops serving water-cooled unitary air conditioners with a combined motor capacity of 10 hp (7.5 kW)3 hp or larger by reducing pump design flow by not less than 50 percent, utilizing adjustable speed drives on pumps, or multiple-staged pumps where not less than one-half of the total pump horsepower is capable of being automatically turned off. Pump flow shall be controlled to maintain one control valve nearly wide open or to satisfy the minimum differential pressure.

Exceptions:

  1. Supply-water temperature reset for chilled-water systems supplied by off-site district chilled water or chilled water from ice storage systems.
  2. Minimum flow rates other than 50 percent as required by the equipment manufacturer for proper operation of equipment where using flow bypass or end-of-line 3-way valves.
  3. Variable pump flow on dedicated equipment circulation pumps where configured in primary/secondary design to provide the minimum flow requirements of the equipment manufacturer for proper operation of equipment.

Boiler systems with design input of greater than 1,000,000 Btu/h (293 kW) shall comply with the turndown ratio specified in Table C403.4.2.5.

The system turndown requirement shall be met through the use of multiple single input boilers, one or more modulating boilers or a combination of single input and modulating boilers.

TABLE C403.4.2.5

BOILER TURNDOWN

BOILER SYSTEM DESIGN INPUT (Btu/h)MINIMUM
TURNDOWN
RATIO
≥ 1,000,000 and less than or equal to 5,000,0003 to 1
> 5,000,000 and less than or equal to 10,000,0004 to 1
> 10,000,0005 to 1

For SI: 1 British thermal unit per hour = 0.2931 W.

C403.4.2.6 Pump isolation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Chilled water plants including more than one chiller shall have the capabilitybe capable of and configured to reduce flow automatically through the chiller plant when a chiller is shut down and automatically shut off flow to chillers that are shut down. Chillers piped in series for the purpose of increased temperature differential shall be considered as one chiller.

Exception: Chillers that are piped in series for the purpose of increased temperature differential.

Boiler plants including more than one boiler shall have the capability be capable of and configured to reduce flow automatically through the boiler plant when a boiler is shut down.

C403.4.2.7 Variable flow controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Individual pumps required by this code to have variable speed control shall be controlled in one of the following manners:
  1. For systems having a combined pump motor horsepower less than or equal to 20 hp (15 kW) and without direct digital control of individual coils, pump speed shall be a function of either:
    1. Required differential pressure; or
    2. Reset directly based on zone hydronic demand, or other zone load indicators; or
    3. Reset directly based on pump power and pump differential pressure.
  2. For systems having a combined pump motor horsepower that exceeds 20 hp (15 kW) or smaller systems with direct digital control, pump speed shall be a function of either:
    1. The static pressure set point as reset based on the valve requiring the most pressure; or
    2. Directly controlled based on zone hydronic demand.

C403.4.3 Heat rejection equipment

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Each fan powered by a motor of 7.5 hp (5.6 kW) or larger shall have the capability to operate that fan at two-thirds of full speed or less, and shall have controls that automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device.

Exception: Factory-installed heat rejection devices within HVAC equipment tested and rated in accordance with Tables C403.2.3(6) and C403.2.3(7).

C403.4.3 Heat rejection equipment

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heat rejection equipment such as air-cooled condensers, dry coolers, open-circuit cooling towers, closed-circuit cooling towers and evaporative condensers used for comfort cooling applications shall comply with this section.

Exception: Heat rejection devices where energy use is included in the equipment efficiency ratings listed in Tables C403.2.3(1)A, C403.2.3(1)B, C403.2.3(1)C, C403.2.3(2), C403.2.3(3), C403.2.3(7) and C403.2.3(9).

C403.4.3.1 General

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Heat rejection equipment such as air-cooled condensers, dry coolers, open-circuit cooling towers, closed-circuit cooling towers and evaporative condensers used for comfort cooling applications shall comply with this section.

Exception: Heat rejection devices where energy usage is included in the equipment efficiency ratings listed in Tables C403.2.3(6) and C403.2.3(7).

C403.4.3.1 Fan speed control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The fan speed shall be controlled as provided in Sections C403.4.3.1.1 and C403.4.3.1.2.

C403.4.3.1.1 Fan motors not less than 7.5 hp

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Each fan powered by a motor of 7.5 hp (5.6 kW) or larger shall have controls that automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device.

C403.4.3.1.2 Multiple-cell heat rejection equipment

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Multiple-cell heat rejection equipment with variable speed fan drives shall be controlled in both of the following manners:

  1. To operate the maximum number of fans allowed that comply with the manufacturer's requirements for all system components.
  2. So all fans can operate at the same fan speed required for the instantaneous cooling duty, as opposed to staged (on/off) operation. Minimum fan speed shall be the minimum allowable speed of the fan drive system in accordance with the manufacturer's recommendations.

C403.4.3.2 Fan speed control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The fan speed shall be controlled as provided in Sections C403.4.3.2.1 and C403.4.3.2.2.

C403.4.3.2 Limitation on centrifugal fan open-circuit cooling towers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Centrifugal fan open-circuit cooling towers with a combined rated capacity of 1,100 gpm (4164 L/m) or greater at 95°F (35°C) condenser water return, 85°F (29°C) condenser water supply, and 75°F (24°C) outdoor air wet-bulb temperature shall meet the energy efficiency requirement for axial fan open-circuit cooling towers listed in Table C403.2.3(8).

Exception: Centrifugal open-circuit cooling towers that are designed with inlet or discharge ducts or require external sound attenuation.

C403.4.3.2.1 Fan motors not less than 7.5 hp

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Each fan powered by a motor of 7.5 hp (5.6 kW) or larger shall have the capability to operate that fan at two-thirds of full speed or less, and shall have controls that automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device.

Exception: The following fan motors over 7.5 hp (5.6 kW) are exempt:

  1. Condenser fans serving multiple refrigerant circuits.
  2. Condenser fans serving flooded condensers.
  3. Installations located in Climate Zones 1 and 2.

C403.4.3.2.2 Multiple-cell heat rejection equipment

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Multiple-cell heat rejection equipment with variable speed fan drives shall be controlled in both of the following manners:

  1. To operate the maximum number of fans allowed that comply with the manufacturer’s requirements for all system components.
  2. So all fans can operate at the same fan speed required for the instantaneous cooling duty, as opposed to staged (on/off) operation.

Minimum fan speed shall be the minimum allowable speed of the fan drive system in accordance with the manufacturer’s recommendations.

C403.4.3.3 Limitation on centrifugal fan open-circuit cooling towers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Centrifugal fan open-circuit cooling towers with a combined rated capacity of 1,100 gpm (4164 L/m) or greater at 95°F (35°C) condenser water return, 85°F (29°C) condenser water supply, and 75°F (24°C) outdoor air wet-bulb temperature shall meet the energy efficiency requirement for axial fan open-circuit cooling towers listed in Table C403.2.3(8).

Exception: Centrifugal open-circuit cooling towers that are designed with inlet or discharge ducts or require external sound attenuation.

C403.4.3.3 Tower flow turndown

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Open-circuit cooling towers used on water-cooled chiller systems that are configured with multiple- or variable-speed condenser water pumps shall be designed so that all open circuit cooling tower cells can be run in parallel with the larger of the flow that is produced by the smallest pump at its minimum expected flow rate or at 50 percent of the design flow for the cell.

C403.4.3.4 Tower flow turndown

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Open-circuit cooling towers used on water-cooled chiller systems that are configured with multiple- or variable-speed condenser water pumps shall be designed so that all open-circuit cooling tower cells can be run in parallel with the larger of the flow that is produced by the smallest pump at its minimum expected flow rate or at 50 percent of the design flow for the cell.

C403.4.4 Requirements for complex mechanical systems serving multiple zones

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Sections C403.4.4.1 through C403.4.6.4 C403.4.4.4 shall apply to complex mechanical systems serving multiple zones. Supply air systems serving multiple zones shall be variable air volume (VAV) systems thatwhich, during periods of occupancy, are designed and capable of being controlled configured to reduce primary air supply to each zone to one of the following before reheating, recooling or mixing takes place:

  1. Thirty percent of the maximum supply air to each zone.
  2. Three hundred cfm (142 L/s) or less where the maximum flow rate is less than 10 percent of the total fan system supply airflow rate.
  3. The minimum ventilation requirements of Chapter 4 of the International Mechanical Code.
  4. Any higher rate that can be demonstrated to reduce overall system annual energy use by offsetting reheat/recool energy losses through a reduction in outdoor air intake for the system, as approved by the code official.
  5. The airflow rate required to comply with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates.

Exception: The following define where individual zones or where entire air distribution systems are exempted from the requirement for VAV control:

  1. Zones or supply air systems where not less thanat least 75 percent of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered or site-solar energy source.
  2. Zones where special humidity levels are required to satisfy process needs.
  3. Zones with a peak supply air quantity of 300 cfm (142 L/s) or less and where the flow rate is less than 10 percent of the total fan system supply airflow rate.
  4. Zoneswhere the volume of air to be reheated, recooled or mixed is not greater than the volume of outside air required to provide the minimum ventilation requirements of Chapter 4 of the International Mechanical Code. Zones without DDC for which the volume of air that is reheated, recooled or remixed is less than the larger of the following:
    1. 30 percent of the zone design peak supply rate.
    2. The outdoor airflow rate required to meet the ventilation requirements of Chapter 4 of the International Mechanical Code for the zone.
    3. Any higher rate that can be demonstrated, to the satisfaction of the code official, to reduce overall system annual energy usage by offsetting reheat/recool energy losses through a reduction in outdoor air intake for the system.
    4. The airflow rate required to comply with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates.
  5. Zones or supply air systems with thermostatic and humidistatic controls capable of operating in sequence the supply of heating and cooling energy to the zones and which are capable of preventing reheating, recooling, mixing or simultaneous supply of air that has been previously cooled, either mechanically or through the use of economizer systems, and air that has been previously mechanically heated. Zones with DDC that comply with all of the following:
    1. The airflow rate in dead band between heating and cooling does not exceed the larger of the following:
      1. 20 percent of the zone design peak supply rate.
      2. The outdoor airflow rate required to meet the ventilation requirements of Chapter 4 of the International Mechanical Code for the zone.
      3. Any higher rate that can be demonstrated, to the satisfaction of the code official, to reduce overall system annual energy usage by offsetting reheat/recool energy losses through a reduction in outdoor air intake for the system.
      4. The airflow rate required to comply with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates.
    2. The airflow rate that is reheated, recooled or mixed shall be less than 50 percent of the zone design peak supply rate.
    3. The first stage of heating consists of modulating the zone supply air temperature setpoint up to a maximum setpoint while the airflow is maintained at the dead band flow rate.
    4. The second stage of heating consists of modulating the airflow rate from the dead band flow rate up to the heating maximum flow rate.
  6. Zones or supply air systems with thermostatic and humidistatic controls capable of operating in sequence the supply of heating and cooling energy to the zones and which are configured to prevent reheating, recooling, mixing or simultaneous supply of air that has been previously cooled, either mechanically or through the use of economizer systems, and air that has been previously mechanically heated.

C403.4.4.1 Single- duct variable air volume (VAV) systems, terminal devices

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Single- duct VAV systems shall use terminal devices capable of reducing capable of and configured to reduce the supply of primary supply air before reheating or recooling takes place.

C403.4.4.2 Dual- duct and mixing VAV systems, terminal devices

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Systems that have one warm air duct and one cool air duct shall use terminal devices thatwhich are capable of reducing and configured to reduce the flow from one duct to a minimum before mixing of air from the other duct takes place.

C403.4.4.3 Single-fan dual-duct and mixing VAV systems, economizers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Individual dual-duct or mixing heating and cooling systems with a single fan and with total capacities greater than 90,000 Btu/h [(26.4 kW) 7.5 tons] shall not be equipped with air economizers.

C403.4.4.3 Multiple-zone VAV system ventilation optimization controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Multiple-zone VAV systems with direct digital control of individual zone boxes reporting to a central control panel shall have automatic controls configured to reduce outdoor air intake flow below design rates in response to changes in system ventilation efficiency (Ev) as defined by the International Mechanical Code.

Exceptions:
  1. VAV systems with zonal transfer fans that recirculate air from other zones without directly mixing it with outdoor air, dual-duct dual-fan VAV systems, and VAV systems with fan-powered terminal units.
  2. Systems having exhaust air energy recovery complying with Section C403.5.
  3. Systems where total design exhaust airflow is more than 70 percent of total design outdoor air intake flow requirements.

C403.4.4.4 Fractional hp fan motors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Motors for fans that are not less than 1/12 hp (0.082 kW) and less than 1 hp (0.746 kW) shall be electronically commutated motors or shall have a minimum motor efficiency of 70 percent, rated in accordance with DOE 10 CFR 431. These motors shall also have the means to adjust motor speed for either balancing or remote control. The use of belt-driven fans to sheave adjustments for airflow balancing instead of a varying motor speed shall be permitted.

Exceptions: The following motors are not required to comply with this section:

  1. Motors in the airstream within fan coils and terminal units that only provide heating to the space served.
  2. Motors in space-conditioning equipment that comply with Section 403.2.3 or C403.2.12.
  3. Motors that comply with Section C405.8.

C403.4.4.4 Supply-air temperature reset controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Multiple zone HVAC systems shall include controls that automatically reset the supply-air temperature in response to representative building loads, or to outdoor air temperature. The controls shall be capable of resetting the supply air temperature at least 25 percent of the difference between the design supply-air temperature and the design room air temperature.

Exceptions:
  1. Systems that prevent reheating, recooling or mixing of heated and cooled supply air.
  2. Seventy-five percent of the energy for reheating is from site-recovered or site solar energy sources.
  3. Zones with peak supply air quantities of 300 cfm (142 L/s) or less.

C403.4.4.5 Supply-air temperature reset controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Multiple-zone HVAC systems shall include controls that automatically reset the supply-air temperature in response to representative building loads, or to outdoor air temperature. The controls shall be capable of resetting the supply air temperature not less than 25 percent of the difference between the design supply-air temperature and the design room air temperature.

Exceptions:

  1. Systems that prevent reheating, recooling or mixing of heated and cooled supply air.
  2. Seventy-five percent of the energy for reheating is from site-recovered or site-solar energy sources.
  3. Zones with peak supply air quantities of 300 cfm (142 L/s) or less.

C403.4.4.6 Multiple-zone VAV system ventilation optimization control

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Multiple-zone VAV systems with direct digital control of individual zone boxes reporting to a central control panel shall have automatic controls configured to reduce outdoor air intake flow below design rates in response to changes in system ventilation efficiency (Ev) as defined by the International Mechanical Code.

Exceptions:

  1. VAV systems with zonal transfer fans that recirculate air from other zones without directly mixing it with outdoor air, dual-duct dual-fan VAV systems, and VAV systems with fan-powered terminal units.
  2. Systems having exhaust air energy recovery complying with Section C403.2.7.
  3. Systems where total design exhaust airflow is more than 70 percent of total design outdoor air intake flow requirements.

C403.4.5 Heat recovery for service water heating

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Condenser heat recovery shall be installed for heating or reheating of service hot water provided that the facility operates 24 hours a day, the total installed heat capacity of water-cooled systems exceeds 6,000,000 Btu/hr (1 758 kW) of heat rejection, and the design service water heating load exceeds 1,000,000 Btu/h (293 kW).

The required heat recovery system shall have the capacity to provide the smaller of the following:

  1. Sixty percent of the peak heat rejection load at design conditions.
  2. The preheating required to raise the peak service hot water draw to 85°F (29°C).

Exceptions:

  1. Facilities that employ condenser heat recovery for space heating or reheat purposes with a heat recovery design exceeding 30 percent of the peak water-cooled condenser load at design conditions.
  2. Facilities that provide 60 percent of their service water heating from site solar or site recovered energy or from other sources.

C403.4.5 Reserved

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
(See C403.5.4 for Heat recovery for service water heating.)

Cooling systems shall not use hot gas bypass or other evaporator pressure control systems unless the system is designed with multiple steps of unloading or continuous capacity modulation. The capacity of the hot gas bypass shall be limited as indicated in Table C403.4.6, as limited by Section C403.3.1.

TABLE C403.4.6

MAXIMUM HOT GAS BYPASS CAPACITY

RATED CAPACITYMAXIMUM HOT GAS BYPASS CAPACITY
(% of total capacity)
≤ 240,000 Btu/h50
> 240,000 Btu/h25

For SI: 1 British thermal unit per hour = 0.2931 W.

C403.5 Refrigeration systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Refrigerated display cases, walk-in coolers or walk-in freezers that are served by remote compressors and remote condensers not located in a condensing unit, shall comply with Sections C403.5.1 and C403.5.2.

Exception: Systems where the working fluid in the refrigeration cycle goes through both subcritical and supercritical states (transcritical) or that use ammonia refrigerant are exempt.

C403.5 Energy recovery

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

C403.5.1 Condensers serving refrigeration systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Fan-powered condensers shall comply with the following:

  1. The design saturated condensing temperatures for air-cooled condensers shall not exceed the design dry-bulb temperature plus 10°F (5.6°C) for low-temperature refrigeration systems, and the design dry-bulb temperature plus 15°F (8°C) for medium temperature refrigeration systems where the saturated condensing temperature for blend refrigerants shall be determined using the average of liquid and vapor temperatures as converted from the condenser drain pressure.
  2. Condenser fan motors that are less than 1 hp (0.75 kW) shall use electronically commutated motors, permanent split-capacitor-type motors or 3-phase motors.
  3. Condenser fans for air-cooled condensers, evaporatively cooled condensers, air- or water-cooled fluid coolers or cooling towers shall reduce fan motor demand to not more than 30 percent of design wattage at 50 percent of design air volume, and incorporate one of the following continuous variable speed fan control approaches:

    1. 3.1. Refrigeration system condenser control for air-cooled condensers shall use variable setpoint control logic to reset the condensing temperature setpoint in response to ambient dry-bulb temperature.
    2. 3.2. Refrigeration system condenser control for evaporatively cooled condensers shall use variable setpoint control logic to reset the condensing temperature setpoint in response to ambient wet-bulb temperature.
  4. Multiple fan condensers shall be controlled in unison.
  5. The minimum condensing temperature setpoint shall be not greater than 70°F (21°C).

C403.5.1 Energy recovery ventilation systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Any system with minimum outside air requirements at design conditions greater than 5,000 cfm or any system where the system’s supply airflow rate exceeds the value listed in Tables C403.5.1(1) and C403.5.1(2)m based on the climate zone and percentage of outdoor airflow rate at design conditions, shall include an energy recovery system. Table C403.5.1(1) shall be used for all ventilation systems that operate less than 8,000 hours per year, and Table C403.5.1(2) shall be used for all ventilation systems that operate 8,000 hours or more per year. The energy recovery system shall have the capability to provide a change in the enthalpy of the outdoor air supply of not less than 50 percent of the difference between the outdoor air and return air enthalpies, at design conditions. Where an air economizer is required, the energy recovery system shall include a bypass or controls which permit operation of the economizer as required by Section C403.3. Where a single room or space is supplied by multiple units, the aggregate ventilation (cfm) of those units shall be used in applying this requirement. The return/exhaust air stream temperature for heat recovery device selection shall be 70°F (21°C) at 30 percent relative humidity, or as calculated by the registered design professional.

Exception: An energy recovery ventilation system shall not be required in any of the following conditions:
  1. Where energy recovery systems are restricted per Section 514 of the International Mechanical Code to sensible energy, recovery shall comply with one of the following:

    1. Kitchen exhaust systems where they comply with Section C403.2.7.1.
    2. Laboratory fume hood systems where they comply with Exception 2 of Section C403.5.1.
    3. Other sensible energy recovery systems with the capability to provide a change in dry bulb temperature of the outdoor air supply of not less than 50 percent of the difference between the outdoor air and the return air dry bulb temperatures, at design conditions.
  2. Laboratory fume hood systems that include at least one of the following features and also comply with Section C403.2.7.2:

    1. Variable-air-volume hood exhaust and room supply systems capable of reducing exhaust and makeup air volume to 50 percent or less of design values.
    2. Direct makeup (auxiliary) air supply equal to at least 75 percent of the exhaust rate, heated no warmer than 2°F (1.1°C) above room setpoint, cooled to no cooler than 3°F (1.7°C) below room setpoint, no humidification added, and no simultaneous heating and cooling used for dehumidification control.
  3. Systems serving spaces that are heated to less than 60°F (15.5°C) and are not cooled.
  4. Where more than 60 percent of the outdoor heating energy is provided from site-recovered or site solar energy.
  5. Systems exhausting toxic, flammable, paint or corrosive fumes or dust.
  6. Cooling energy recovery in Climate Zones 3C, 4C, 5B, 5C, 6B, 7 and 8.
  7. Systems requiring dehumidification that employ energy recovery in series with the cooling coil.
  8. Multi-zone systems where the supply airflow rate is less than the values specified in Tables C403.5.1(1) and C403.5.1(2) for the corresponding percent of outdoor air. Where a value of NR is listed, energy recovery shall not be required.
  9. Systems serving Group R dwelling or sleeping units where the largest source of air exhausted at a single location at the building exterior is less than 25 percent of the design outdoor air flow rate.
TABLE C403.5.1(1)
ENERGY RECOVERY REQUIREMENT
(VENTILATION SYSTEMS OPERATING LESS THAN 8,000 HOURS PER YEAR)

CLIMATE ZONE PERCENT (%) OUTDOOR AIR AT FULL DESIGN AIRFLOW RATE
≥ 10% and < 20% ≥ 20% and < 30% ≥ 30% and < 40% ≥ 40% and < 50% ≥ 50% and < 60% ≥ 60% and < 70% ≥70% and < 80% ≥ 80%
DESIGN SUPPLY FAN AIRFLOW RATE (cfm)
4C, 5B NR NR NR NR NR NR ≥5000 ≥ 5000

NR = not required

TABLE C403.5.1(2)
ENERGY RECOVERY REQUIREMENT
(VENTILATION SYSTEMS OPERATING NOT LESS 8,000 HOURS PER YEAR)

CLIMATE ZONE PERCENT (%) OUTDOOR AIR AT FULL DESIGN AIRFLOW RATE
≥ 10% and < 20% ≥ 20% and < 30% ≥ 30% and < 40% ≥ 40% and < 50% ≥ 50% and < 60% ≥ 60% and < 70% ≥70% and < 80% ≥ 80%
DESIGN SUPPLY FAN AIRFLOW RATE (cfm)
4C NR ≥ 19500 ≥ 9000 ≥ 5000 ≥ 4000 ≥ 3000 ≥ 1500 ≥ 0
5B ≥ 2500 ≥ 2000 ≥ 1000 ≥ 500 ≥ 0 ≥ 0 ≥ 0 ≥ 0

NR = not required

C403.5.2 Compressor systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Refrigeration compressor systems shall comply with the following:

  1. Compressors and multiple-compressor system suction groups shall include control systems that use floating suction pressure control logic to reset the target suction pressure temperature based on the temperature requirements of the attached refrigeration display cases or walk-ins.

    Exception: Controls are not required for the following:

    1. Single-compressor systems that do not have variable capacity capability.
    2. Suction groups that have a design saturated suction temperature of 30°F (-1.1°C) or higher, suction groups that comprise the high stage of a two-stage or cascade system, or suction groups that primarily serve chillers for secondary cooling fluids.
  2. Liquid subcooling shall be provided for all low-temperature compressor systems with a design cooling capacity equal to or greater than 100,000 Btu/hr (29.3 kW) with a design-saturated suction temperature of -10°F (-23°C) or lower. The sub-cooled liquid temperature shall be controlled at a maximum temperature setpoint of 50°F (10°C) at the exit of the subcooler using either compressor economizer (interstage) ports or a separate compressor suction group operating at a saturated suction temperature of 18°F (-7.8°C) or higher.

    1. 2.1. Insulation for liquid lines with a fluid operating temperature less than 60°F (15.6°C) shall comply with Table C403.2.10.
  3. Compressors that incorporate internal or external crankcase heaters shall provide a means to cycle the heaters off during compressor operation.

C403.5.2 Condensate systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
On-site steam heating systems shall have condensate water heat recovery. On-site includes a system that is located within or adjacent to one or more buildings within the boundary of a contiguous area or campus under one ownership and which serves one or more of those buildings.

Buildings using steam generated off-site with steam heating systems which do not have condensate water recovery shall have condensate water recovery.

C403.5.3 Condenser heat recovery

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Facilities having food service, meat or deli departments and having 500,000 Btu/h or greater of remote refrigeration condensers shall have condenser waste heat recovery from freezers and coolers and shall use the waste heat for service water heating, space heating or for dehumidification reheat. Facilities having a gross conditioned floor area of 40,000 ft2 or greater and 1,000,000 Btu/h or greater of remote refrigeration shall have condenser waste heat recovery from freezers and coolers and shall use the waste heat for service water heating, and either for space heating or for dehumidification reheat for maintaining low space humidity.

C403.5.4 Heat recovery for service water heating

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Condenser heat recovery shall be installed for heating or reheating of service hot water provided the facility operates 24 hours a day, the total installed heat capacity of water cooled systems exceeds 1,500,000 Btu/hr of heat rejection, and the design service water heating load exceeds 250,000 Btu/hr. The required heat recovery system shall have the capacity to provide the smaller of:

  1. Sixty percent of the peak heat rejection load at design conditions; or
  2. The preheating required to raise the peak service hot water draw to 85°F (29°C).

    Exceptions:

    1. Facilities that employ condenser heat recovery for space heating or reheat purposes with a heat recovery design exceeding 30 percent of the peak water-cooled condenser load at design conditions.
    2. Facilities that provide 60 percent of their service water heating from site solar or site recovered energy or from other sources.

C403.6 Dedicated outdoor air systems (DOAS). (This section is Optional through 6/30/2017; it becomes Prescriptive as of 7/1/2017)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For office, retail, education, libraries and fire stations, outdoor air shall be provided to each occupied space by a dedicated outdoor air system (DOAS) which delivers 100 percent outdoor air without requiring operation of the heating and cooling system fans for ventilation air delivery.

Exceptions:
  1. Occupied spaces that are not ventilated by a mechanical ventilation system and are only ventilated by a natural ventilation system per Section 402 of the International Mechanical Code.
  2. High efficiency variable air volume (VAV) systems complying with Section C403.7. This exception shall not be used as a substitution for a DOAS per Section C406.6 or as a modification to the requirements for the Standard Reference Design per Section C407

C403.6.1 Energy recovery ventilation with DOAS

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The DOAS shall include energy recovery ventilation that complies with the minimum energy recovery efficiency and energy recovery bypass requirements, where applicable, of Section C403.5.1.

Exceptions:
  1. Occupied spaces under the threshold of Section C403.5 with an average occupant load greater than 25 people per 1000 square feet (93 m2) of floor area (as established in Table 403.3.1.1 of the International Mechanical Code) that include demand control ventilation configured to reduce outdoor air by at least 50% below design minimum ventilation rates when the actual occupancy of the space served by the system is less than the design occupancy.
  2. Systems installed for the sole purpose of providing makeup air for systems exhausting toxic, flammable, paint, or corrosive fumes or dust, dryer exhaust, or commercial kitchen hoods used for collecting and removing grease vapors and smoke.

C403.6.2 Heating/cooling system fan controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heating and cooling equipment fans, heating and cooling circulation pumps, and terminal unit fans shall cycle off and terminal unit primary cooling air shall be shut off when there is no call for heating or cooling in the zone.

Exception: Fans used for heating and cooling using less than 0.12 watts per cfm may operate when space temperatures are within the setpoint deadband (Section C403.2.4.1.2) to provide destratification and air mixing in the space.

C403.6.3 Impracticality

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where the code official determines full compliance with all of the requirements of Section C403.6.1 and C403.6.2 would be impractical, it is permissible to provide an approved alternate means of compliance that achieves a comparable level of energy efficiency. For the purposes of this section, impractical means that an HVAC system complying with Section C403.6 cannot effectively be utilized due to an unusual use or configuration of the building.

C403.7 High efficiency variable air volume (VAV) systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For HVAC systems subject to the requirements of Section C403.6 but utilizing Exception 2 of that section, a high efficiency VAV system may be provided without a separate parallel DOAS when the system is designed, installed, and configured to comply with all of the following criteria (this exception shall not be used as a substitution for a DOAS per Section C406.6 or as a modification to the requirements for the Standard Reference Design per Section C407):

  1. The VAV systems are provided with airside economizer per Section 403.3 without exceptions.
  2. A direct-digital control (DDC) system is provided to control the VAV air handling units and associated terminal units per Section C403.2.4.12 regardless of sizing thresholds of Table C403.2.4.12.1.
  3. Multiple-zone VAV systems with a minimum outdoor air requirement of 2,500 cfm (1180 L/s) or greater shall be equipped with a device capable of measuring outdoor airflow intake under all load conditions. The system shall be capable of increasing or reducing the outdoor airflow intake based on feedback from the VAV terminal units as required by Section C403.4.4.3, without exceptions, and Section C403.2.6.2 demand controlled ventilation.
  4. Multiple-zone VAV systems with a minimum outdoor air requirement of 2,500 cfm (1180 L/s) or greater shall be equipped with a device capable of measuring supply airflow to the VAV terminal units under all load conditions.
  5. In addition to meeting the zone isolation requirements of C403.2.4.4 a single VAV air handling unit shall not serve more than 50,000 square feet (2323 m2) unless a single floor is greater than 50,000 square feet (2323 m2) in which case the air handler is permitted to serve the entire floor.
  6. The primary maximum cooling air for the VAV terminal units serving interior cooling load driven zones shall be sized for a supply air temperature that is a minimum of 5°F greater than the supply air temperature for the exterior zones in cooling.
  7. Air terminal units with a minimum primary airflow setpoint of 50% or greater of the maximum primary airflow setpoint shall be sized with an inlet velocity of no greater than 900 feet per minute.
  8. DDC systems be designed and configured per the guidelines set by High Performance Sequences of Operation for HVAC Systems (ASHRAE GPC 36, RP-1455).
  9. Allowable fan motor horsepower shall not exceed 90% of the allowable HVAC fan system bhp (Option 2) as defined by Section C403.2.11.1.
  10. All fan powered VAV terminal units (series or parallel) shall be provided with electronically commutated motors. The DDC system shall be configured to vary the speed of the motor as a function of the heating and cooling load in the space. Minimum speed shall not be greater than 66 percent of design airflow required for the greater of heating or cooling operation. Minimum speed shall be used during periods of low heating and cooling operation and ventilation-only operation.

    Exception: For series fan powered terminal units where the volume of primary air required to deliver the ventilation requirements at minimum speed exceeds the air that would be delivered at the speed defined above, the minimum speed setpoint shall be configured to exceed the value required to provide the required ventilation air.
  11. Fan-powered VAV terminal units shall only be permitted at perimeter zones with an envelope heating load requirement. All other VAV terminal units shall be single duct terminal units.
  12. When in occupied heating or in occupied deadband between heating and cooling all fan powered VAV terminal units shall be configured to reset the primary air supply setpoint, based on the VAV air handling unit outdoor air vent fraction, to the minimum ventilation airflow required per International Mechanical Code without utilizing exceptions 2, 3, or 4 of Section C403.4.4.
  13. Spaces that are larger than 150 square feet (14 m2) and with an occupant load greater than or equal to 25 people per 1000 square feet (93 m2) of floor area (as established in Table 403.3.1.1 of the International Mechanical Code) shall be provided with all of the following features:

    1. A dedicated VAV terminal unit capable of controlling the space temperature and minimum ventilation shall be provided.
    2. Demand control ventilation (DCV) shall be provided that utilizes a carbon dioxide sensor to reset the ventilation setpoint of the VAV terminal unit from the design minimum to design maximum ventilation rate as required by Chapter 4 of the International Mechanical Code.
    3. Occupancy sensors shall be provided that are configured to reduce the minimum ventilation rate to zero and setback room temperature setpoints by a minimum of 5°F, for both cooling and heating, when the space is unoccupied.
  14. Dedicated server rooms, electronic equipment rooms, telecom rooms, or other similar spaces with cooling loads greater than 5 watts/ft2 shall be provided with separate, independent HVAC systems to allow the VAV air handlers to turn off during unoccupied hours in the office space and to allow the supply air temperature reset to occur.

    Exception: The VAV air handling unit and VAV terminal units may be used for secondary backup cooling when there is a failure of the primary HVAC system.

    Additionally, server rooms, electronic equipment rooms, telecom rooms, or other similar spaces shall be provided with airside economizer per Section 403.3 without using the exceptions to Section C403.3.

    Exception: Heat recovery per exception 9 of Section 403.3 may be in lieu of airside economizer for the separate, independent HVAC system.
  15. HVAC system central heating or cooling plant will include a minimum of one of the following options:

    1. VAV terminal units with hydronic heating coils connected to systems with hot water generation equipment limited to the following types of equipment: gas-fired hydronic boilers with a thermal efficiency, Et, of not less than 90 percent, air-to-water heat pumps or heat recovery chillers.
    2. Chilled water VAV air handing units connected to systems with chilled water generation equipment with IPLV values more than 25 percent higher than the minimum part load efficiencies listed in Table C403.2.3(7), in the appropriate size category, using the same test procedures. Equipment shall be listed in the appropriate certification program to qualify. The smallest chiller or compressor in the central plant shall not exceed 20% of the total central plant cooling capacity or the chilled water system shall include thermal storage sized for a minimum of 20% of the total central cooling plant capacity.
  16. The DDC system shall include a fault detection and diagnostics (FDD) system complying with the following:

    1. The following temperature sensors shall be permanently installed to monitor system operation:

      1. Outside air.
      2. Supply air.
      3. Return air.
    2. Temperature sensors shall have an accuracy of ±2°F (1.1°C) over the range of 40°F to 80°F (4°C to 26.7°C).
    3. The VAV air handling unit controller shall be configured to provide system status by indicating the following:

      1. Free cooling available.
      2. Economizer enabled.
      3. Compressor enabled.
      4. Heating enabled.
      5. Mixed air low limit cycle active.
      6. The current value of each sensor.
    4. The VAV air handling unit controller shall be capable of manually initiating each operating mode so that the operation of compressors, economizers, fans and the heating system can be independently tested and verified.
    5. The VAV air handling unit shall be configured to report faults to a fault management application accessible by day-to-day operating or service personnel or annunciated locally on zone thermostats.
    6. The VAV terminal unit shall be configured to report if the VAV inlet valve has failed by performing the following diagnostic check at a maximum interval of once a month:

      1. Command VAV terminal unit primary air inlet valve closed and verify that primary airflow goes to zero.
      2. Command VAV thermal unit primary air inlet valve to design airflow and verify that unit is controlling to with 10% of design airflow.
    7. The VAV terminal unit shall be configured to report and trend when the zone is driving the following VAV air handling unit reset sequences. The building operator shall have the capability to exclude zones used in the reset sequences from the DDC control system graphical user interface:

      1. Supply air temperature setpoint reset to lowest supply air temperature setpoint for cooling operation.
      2. Supply air duct static pressure setpoint reset for the highest duct static pressure setpoint allowable.
    8. The FDD system shall be configured to detect the following faults:

      1. Air temperature sensor failure/fault.
      2. Not economizing when the unit should be economizing.
      3. Economizing when the unit should not be economizing.
      4. Outdoor air or return air damper not modulating.
      5. Excess outdoor air.
      6. VAV terminal unit primary air valve failure.
This section covers the minimum efficiency of, and controls for, service water-heating equipment and insulation of service hot water piping.

C404.2 Service water-heating equipment performance efficiency

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Water-heating equipment and hot water storage tanks shall meet the requirements of Table C404.2. The efficiency shall be verified through data furnished by the manufacturer of the equipment or through certification and listed under an approved certification program, or if no certification program exists, the equipment efficiency ratings shall be supported by data furnished by the manufacturer. Water-heating equipment also intended to be used to provide space heating shall meet the applicable provisions of Table C404.2.

TABLE C404.2
MINIMUM PERFORMANCE OF WATER-HEATING EQUIPMENT

EQUIPMENT TYPE SIZE CATEGORY
(input)
SUBCATEGORY OR
RATING CONDITION
PERFORMANCE
REQUIREDa, b
TEST
PROCEDURE
Water heaters,
electric
≤ 12 kWd Resistance ≥20 gal 0.97 - 0.00 132V, EF DOE 10 CFR Part 430
> 12 kW Resistance ≥20 gal (0.3 + 27/Vm), %/h Section G.2 of ANSI Z21.10.3
≤ 24 amps and
≤ 250 volts
Heat pump 0.93 - 0.00 132V, EF DOE 10 CFR Part 430
 Instantaneous water heaters, electric  All  Resistance  0.97 - 0.00 132V, EF DOE 10 CFR Part 430
Storage water heaters,
gas
≤ 75,000 Btu/h ≥ 20 gal 0.67 - 0.0019V, EF DOE 10 CFR Part 430
> 75,000 Btu/h and
≤ 155,000 Btu/h
< 4,000 Btu/h/gal 80% Et
Section G.1 and G.2 of ANSI Z21.10.3
> 155,000 Btu/h < 4,000 Btu/h/gal 80% Et
Instantaneous
water heaters, gas
> 50,000 Btu/h and
< 200,000 Btu/hc
≥ 4,000 (Btu/h)/gal
and < 2 gal
0.62 - 0.00 19V, EF DOE 10 CFR Part 430
≥ 200,000 Btu/hc ≥ 4,000 Btu/h/gal
and < 10 gal
80% Et Section G.1 and G.2 of ANSI Z21.10.3
≥ 200,000 Btu/h ≥ 4,000 Btu/h/gal
and ≥ 10 gal
80% Et
Storage water heaters,
oil
≤ 105,000 Btu/h ≥ 20 gal 0.59 - 0.0019V, EF DOE 10 CFR Part 430
> 105,000 Btu/h < 4,000 Btu/h/gal 80% Et
Section G.1 and  G.2 of ANSI Z21.10.3
Instantaneous
water heaters, oil
≤ 210,000 Btu/h ≥ 4,000 Btu/h/gal and
< 2 gal
0.59 - 0.0019V, EF DOE 10 CFR Part 430
> 210,000 Btu/h ≥ 4,000 Btu/h/gal and
< 10 gal
80% Et Section G.1 and G.2 of ANSI Z21.10.3
> 210,000 Btu/h ≥ 4,000 Btu/h/gal and
≥ 10 gal
78% Et
Hot water supply boilers,
gas and oil
≥ 300,000 Btu/h and
< 12,500,000 Btu/h
≥ 4,000 Btu/h/gal and
< 10 gal
80% Et Section G.1 and G.2 of ANSI Z21.10.3
Hot water supply boilers,
gas
≥ 300,000 Btu/h and
< 12,500,000 Btu/h
≥ 4,000 Btu/h/gal and
≥ 10 gal
80% Et
Hot water supply boilers,
oil
> ≥ 300,000 Btu/h and
< 12,500,000 Btu/h
> ≥ 4,000 Btu/h/gal and
> 10 gal
78% Et
Pool heaters, gas and oil All 82% 78% Et ASHRAE 146
Heat pump pool heaters All 4.0 COP AHRI 1160
Unfired storage tanks All Minimum insulation
requirement R-12.5
(h x ft2 x °F)/Btu
(none)
For SI: °C = [(°F) - 32]/1.8, 1 British thermal unit per hour = 0.2931 W, 1 gallon = 3.785 L, 1 British thermal unit per hour per gallon = 0.078 W/L.
  1. Energy factor (EF) and thermal efficiency (Et) are minimum requirements. In the EF equation, V is the rated volume in gallons.
  2. Standby loss (SL) is the maximum Btu/h based on a nominal 70°F temperature difference between stored water and ambient requirements. In the SL equation, Q is the nameplate input rate in Btu/h. In the SL equations for electric water heaters, V is the rated volume in gallons and Vm is the measured volume in gallons. In the SL equation for oil and gas water heaters and boilers, V is the rated volume in gallons.
  3. Instantaneous water heaters with input rates below 200,000 Btu/h shallmust comply with these requirements where if the water heater is designed to heat water to temperatures 180°F or higher.
  4. Electric water heaters with an input rating of 12kW (40,950 Btu/hr) or less that are designed to heat water to temperatures of 180°F or greater shall comply with the requirements for electric water heaters that have an input rating greater than 12 kW (40,950 Btu/h).

C404.2.1 High input-rated service water-heating systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Gas-fired water-heating equipment installed in new buildings shall be in compliance with this section. Where a singular piece of water-heating equipment serves the entire building and the input rating of the equipment is 1,000,000 Btu/h (293 kW) or greater, such equipment shall have a thermal efficiency, Et, of not less than 90 percent. Where multiple pieces of water-heating equipment serve the building and the combined input rating of the water-heating equipment is 1,000,000 Btu/h (293 kW) or greater, the combined input-capacity-weighted-average thermal efficiency, Et, shall be not be less than 90 percent.


Exceptions:

  1. Where 25 percent of the annual service water-heating requirement is provided by site-solar or site-recovered energy, the minimum thermal efficiency requirements of this section shall not apply.
  2. The input rating of water heaters installed in individual dwelling units shall not be required to be included in the total input rating of the service water-heating equipment for a building.
  3. The input rating of water heaters with an input rating of not greater than 100,000 Btu/h (29.3 kW) shall not be required to be included in the total input rating of service water-heating equipment for a building.

C404.3 Heat traps

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Water-heating equipment not supplied with integral heat traps and serving noncirculating systems shall be provided with heat traps on the supply and discharge piping associated with the equipment.

C404.3 Efficient heated water supply piping

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heated water supply piping shall be in accordance with Section C404.3.1 or C404.3.2. The flow rate through 1/4-inch (6.4 mm) piping shall be not greater than 0.5 gpm (1.9 L/m). The flow rate through 5/16-inch (7.9 mm) piping shall be not greater than 1 gpm (3.8 L/m). The flow rate through 3/8-inch (9.5 mm) piping shall be not greater than 1.5 gpm (5.7 L/m). Water heaters, circulating water systems and heat trace temperature maintenance systems shall be considered sources of heated water.

C404.3.1 Maximum allowable pipe length method

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The maximum allowable piping length from the nearest source of heater water to the termination of the fixture supply pipe shall be in accordance with the following. Where the piping contains more than one size of pipe, the largest size of pipe within the piping shall be used for determining the maximum allowable length of the piping in Table C404.3.1.

  1. For a public lavatory faucet, use the "Public lavatory faucets" column in Table C404.3.1.
  2. For all other plumbing fixtures and plumbing appliances, use the "Other fixtures and appliances" column in Table C404.3.1.

TABLE C404.3.1
PIPING VOLUME AND MAXIMUM PIPING LENGTHS

NOMINAL PIPE SIZE
(inches)
VOLUME
(liquid ounces per foot length)
MAXIMUM PIPING LENGTH
(feet)
Public lavatory faucets Other fixtures and appliances
1/4 0.33 6 50
5/16 0.5 4 50
3/8 0.75 3 50
1/2 1.5 2 43
5/8 2 1 32
3/4 3 0.5 21
7/8 4 0.5 16
1 5 0.5 13
11/4 8 0.5 8
11/2 11 0.5 6
2 or larger 18 0.5 4

C404.3.2 Maximum allowable pipe volume method

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The water volume in the piping shall be calculated in accordance with Section C404.3.2.1. The volume from the nearest source of heated water to the termination of the fixture supply pipe shall be as follows:

  1. For a public lavatory faucet: Not more than 2 ounces (0.06 L).
  2. For other plumbing fixtures or plumbing appliances; not more than 0.5 gallon (1.89 L).

C404.3.2.1 Water volume determination

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The volume shall be the sum of the internal volumes of pipe, fittings, valves, meters and manifolds between the nearest source of heated water and the termination of the fixture supply pipe. The volume in the piping shall be determined from the "Volume" column in Table C404.3.1. The volume contained within fixture shutoff valves, within flexible water supply connectors to a fixture fitting and within a fixture fitting shall not be included in the water volume determination. Where heated water is supplied by a recirculating system or heat-traced piping, the volume shall include the portion of the fitting on the branch pipe that supplies water to the fixture.

C404.4 Insulation of piping

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Piping from a water heater to the termination of the heated water fixture supply pipe shall be insulated in accordance with Table C403.2.10. On both the inlet and outlet piping of a storage water heater or heated water storage tank, the piping to a heat trap or the first 8 feet (2438 mm) of piping, whichever is less, shall be insulated. Piping that is heat traced shall be insulated in accordance with Table C403.2.10 or the heat trace manufacturer’s instructions. Tubular pipe insulation shall be installed in accordance with the insulation manufacturer’s instructions. Pipe insulation shall be continuous except where the piping passes through a framing member. The minimum insulation thickness requirements of this section shall not supersede any greater insulation thickness requirements necessary for the protection of piping from freezing temperatures or the protection of personnel against external surface temperatures on the insulation.

Exception: Tubular pipe insulation shall not be required on the following:

  1. The tubing from the connection at the termination of the fixture supply piping to a plumbing fixture or plumbing appliance.
  2. Valves, pumps, strainers and threaded unions in piping that is 1 inch (25 mm) or less in nominal diameter.
  3. Piping from user-controlled shower and bath mixing valves to the water outlets.
  4. Cold-water piping of a demand recirculation water system.
  5. Tubing from a hot drinking-water heating unit to the water outlet.
  6. Piping at locations where a vertical support of the piping is installed.
  7. Piping surrounded by building insulation with a thermal resistance (R-value) of not less than R-3.

C404.4 Heat traps

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Water-heating equipment not supplied with integral heat traps and serving noncirculating systems shall be provided with heat traps on the supply and discharge piping associated with the equipment.

C404.5 Efficient heated water supply piping

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heated water supply piping shall be in accordance with Section C404.5.1 or C404.5.2. The flow rate through1 / 4 -inch (6.4 mm) piping shall be not greater than 0.5 gpm (1.9 L/m). The flow rate through 5 / 16 -inch (7.9 mm) piping shall be not greater than 1 gpm (3.8 L/m). The flow rate through 3 / 8 -inch (9.5 mm) piping shall be not greater than 1.5 gpm (5.7 L/m).

C404.5 Water heater installation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Electric water heaters in unconditioned spaces or on concrete floors shall be placed on an incompressible, insulated surface with a minimum thermal resistance of R-10.

C404.5.1 Maximum allowable pipe length method

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The maximum allowable piping length from the nearest source of heated water to the termination of the fixture supply pipe shall be in accordance with the following. Where the piping contains more than one size of pipe, the largest size of pipe within the piping shall be used for determining the maximum allowable length of the piping in Table C404.5.1.

  1. For a public lavatory faucet, use the “Public lavatory faucets” column in Table C404.5.1.
  2. For all other plumbing fixtures and plumbing appliances, use the “Other fixtures and appliances” column in Table C404.5.1.

TABLE C404.5.1

PIPING VOLUME AND MAXIMUM PIPING LENGTHS

NOMINAL PIPE SIZE
(inches)
VOLUME
(liquid ounces per foot length)
MAXIMUM PIPING LENGTH
(feet)
Public lavatory faucetsOther fixtures and appliances
1/40.33650
5/160.5450
3/80.75350
1/21.5243
5/82132
3/430.521
7/840.516
150.513
11/480.58
11/2110.56
2 or larger180.54

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 liquid ounce = 0.030 L, 1 gallon = 128 ounces.

C404.5.2 Maximum allowable pipe volume method

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

The water volume in the piping shall be calculated in accordance with Section C404.5.2.1. Water heaters, circulating water systems and heat trace temperature maintenance systems shall be considered sources of heated water.

The volume from the nearest source of heated water to the termination of the fixture supply pipe shall be as follows:

1. For a public lavatory faucet: not more than 2 ounces

(0.06 L).

2. For other plumbing fixtures or plumbing appliances; not more than 0.5 gallon (1.89 L).

C404.5.2.1 Water volume determination

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The volume shall be the sum of the internal volumes of pipe, fittings, valves, meters and manifolds between the nearest source of heated water and the termination of the fixture supply pipe. The volume in the piping shall be determined from the “Volume” column in Table C404.5.1. The volume contained within fixture shutoff valves, within flexible water supply connectors to a fixture fitting and within a fixture fitting shall not be included in the water volume determination. Where heated water is supplied by a recirculating system or heat-traced piping, the volume shall include the portion of the fitting on the branch pipe that supplies water to the fixture.

C404.6 Heated-water circulating and temperature maintenance systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heated-water circulation systems shall be in accordance with Section C404.6.1. Heat trace temperature maintenance systems shall be in accordance with Section C404.6.2. Controls for hot water storage shall be in accordance with Section C404.6.3. Automatic controls, temperature sensors and pumps shall beaccessible . Manual controls shall be readily accessible .

C404.6 Insulation of piping

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Piping from a water heater to the termination of the heated water fixture supply pipe shall be insulated in accordance with Table C403.2.9. On both the inlet and outlet piping of a storage hot water heater or heated water storage tank, the piping to a heat trap or the first 8 feet (2438 mm) of piping, whichever is less, shall be insulated. Piping that is heat traced shall be insulated in accordance with Table C403.2.9 or the heat trace manufacturer’s instructions. Tubular pipe insulation shall be installed in accordance with the insulation manufacturer’s instructions. Pipe insulation shall be continuous except where the piping passes through a framing member. The minimum insulation thickness requirements of this section shall not supersede any greater insulation thickness requirements necessary for the protection of piping from freezing temperatures or the protection of personnel against external surface temperatures on the insulation.

Exception: Tubular pipe insulation shall not be required on the following:
  1. The tubing from the connection at the termination of the fixture supply piping to a plumbing fixture or plumbing appliance.
  2. Valves, pumps, strainers and threaded unions in piping that is 1 inch (25 mm) or less in nominal diameter.
  3. Piping from user-controlled shower and bath mixing valves to the water outlets.
  4. Cold-water piping of a demand recirculation water system.
  5. Tubing from a hot drinking-water heating unit to the water outlet.
  6. Piping at locations where a vertical support of the piping is installed.
  7. Piping surrounded by building insulation with a thermal resistance (R-value) of not less than R-3.
  8. Hot water piping that is part of the final pipe run to the plumbing fixture and is not part of the heated-water circulation system circulation path is not required to meet the minimum insulation requirements of C404.6.

C404.6.1 Circulation systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heated-water circulation systems shall be provided with a circulation pump. The system return pipe shall be a dedicated return pipe or a cold water supply pipe. Gravity and thermo-syphon circulation systems shall be prohibited. Controls for circulating hot water system pumps shall start the pump based on the identification of a demand for hot water within the occupancy. The controls shall automatically turn off the pump when the water in the circulation loop is at the desired temperature and when there is no demand for hot water.

C404.6.2 Heat trace systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Electric heat trace systems shall comply with IEEE 515.1. Controls for such systems shall be able to automatically adjust the energy input to the heat tracing to maintain the desired water temperature in the piping in accordance with the times when heated water is used in the occupancy. Heat trace shall be arranged to be turned off automatically when there is no hot water demand.

C404.6.3 Controls for hot water storage

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The controls on pumps that circulate water between a water heater and a heated-water storage tank shall limit operation of the pump from heating cycle startup to not greater than 5 minutes after the end of the cycle.

C404.7 Demand recirculation controls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

A water distribution system having one or more recirculation pumps that pump water from a heated-water supply pipe back to the heated-water source through a cold-water supply pipe shall be a demand recirculation water system. Pumps shall have controls that comply with both of the following:

  1. The control shall start the pump upon receiving a signal from the action of a user of a fixture or appliance, sensing the presence of a user of a fixture or sensing the flow of hot or tempered water to a fixture fitting or appliance.
  2. The control shall limit the temperature of the water entering the cold-water piping to 104°F (40°C).

C404.7 Heated-water circulating and temperature maintenance systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heated-water circulation systems shall be in accordance with Section C404.7.1. Heat trace temperature maintenance systems shall be in accordance with Section C404.7.2. Controls for ho