ADOPTS WITHOUT AMENDMENTS:

International Energy Conservation Code 2021 (IECC 2021)

IECC—COMMERCIAL Provisions

IECC—RESIDENTIAL Provisions

Heads up: There are no amended sections in this chapter.

User note:

About this chapter: Chapter 4 presents the paths and options for compliance with the energy efficiency provisions. Chapter 4 contains energy efficiency provisions for the building envelope, mechanical and water heating systems, lighting and additional efficiency requirements. A performance alternative is also provided to allow for energy code compliance other than by the prescriptive method.

The provisions in this chapter are applicable to commercial buildings and their building sites.
Commercial buildings shall comply with one of the following:
  1. Prescriptive Compliance. The Prescriptive Compliance option requires compliance with Sections C402 through C406 and Section C408Dwelling units and sleeping units in Group R-2 buildings without systems serving multiple units shall be deemed to be in compliance with this chapter, provided that they comply with Section R406.
  2. Total Building Performance. The Total Building Performance option requires compliance with Section C407.
Exception: Additions, alterations, repairs and changes of occupancy to existing buildings complying with Chapter 5.
Commercial buildings shall comply with the requirements of ANSI/ASHRAE/IESNA 90.1.
A permanent thermal envelope certificate shall be completed by an approved party. Such certificate shall be posted on a wall in the space where the space conditioning equipment is located, a utility room or other approved location. If located on an electrical panel, the certificate shall not cover or obstruct the visibility of the circuit directory label, service disconnect label or other required labels. A copy of the certificate shall also be included in the construction files for the project. The certificate shall include the following:
  1. R-values of insulation installed in or on ceilings, roofs, walls, foundations and slabs, basement walls, crawl space walls and floors and ducts outside conditioned spaces.
  2. U-factors and solar heat gain coefficients (SHGC) of fenestrations.
  3. Results from any building envelope air leakage testing performed on the building.
Where there is more than one value for any component of the building envelope, the certificate shall indicate the area-weighted average value where available. If the area-weighted average is not available, the certificate shall list each value that applies to 10 percent or more of the total component area.

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 1 of Section C401.2.1 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 building envelope assemblies shall comply with Section C402.4.
  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 Item 2 of Section C401.2.1 or Section C401.2.2.

Walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers shall comply with Section C403.11.

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

  1. Those with a peak design rate of energy usage less than 3.4 Btu/h × ft2 (10.7 W/m2) or 1.0 watt per square foot (10.7 W/m2) of floor area for space conditioning purposes.
  2. Those that do not contain conditioned space.
Greenhouse structures or areas that are mechanically heated or cooled and that comply with all of the following shall be exempt from the building envelope requirements of this code:
  1. Exterior opaque envelope assemblies comply with Sections C402.2 and C402.4.5.

    Exception: Low energy greenhouses that comply with Section C402.1.1.

  2. Interior partition building thermal envelope assemblies that separate the greenhouse from conditioned space comply with Sections C402.2, C402.4.3 and C402.4.5.
  3. Fenestration assemblies that comply with the thermal envelope requirements in Table C402.1.1.1. The U-factor for a roof shall be for the roof assembly or a roof that includes the assembly and an internal curtain system.

    Exception: Unconditioned greenhouses.

TABLE C402.1.1.1

FENESTRATION THERMAL ENVELOPE MAXIMUM REQUIREMENTS

COMPONENT U-FACTOR (BTU/h × ft2 × °F)
Skylight 0.5
Vertical fenestration 0.7

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

  1. Are separate buildings with floor area not more than 1,200 square feet (110 m2).
  2. Are intended to house electric equipment with installed equipment power totaling not less than 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 setpoint 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.
Building thermal envelope opaque assemblies shall comply with 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 cavity insulation and continuous insulation shall be not less than that specified in Table C402.1.3. Where cavity insulation is installed in multiple layers, the cavity insulation R-values shall be summed to determine compliance with the cavity insulation R-value requirements. Where continuous insulation is installed in multiple layers, the continuous insulation R-values shall be summed to determine compliance with the continuous insulation R-value requirements. Cavity insulation R-values shall not be used to determine compliance with the continuous insulation R-value requirements in Table C402.1.3. 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.

TABLE C402.1.3

OPAQUE THERMAL ENVELOPE INSULATION COMPONENT MINIMUM REQUIREMENTS, R-VALUE METHODa

CLIMATE ZONE 0 AND 1 2 3 4 EXCEPT MARINE 5 AND MARINE 4 6 7 8
All other Group R All other Group R All other Group R All other Group R All other Group R All other Group R All other Group R All other Group R
Roofs
Insulation entirely
above roof deck
R-20ci R-25ci R-25ci R-25ci R-25ci R-25ci R-30ci R-30ci R-30ci R-30ci R-30ci R-30ci R-35ci R-35ci R-35ci R-35ci
Metal buildingsb R-19 +
R-11 LS
R-19 +
R-11 LS
R-19 +
R11 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-30 + R-11 LS R-30 +
R-11 LS
R-30 +
R-11 LS
R-25 + R-11 + R-11 LS R-25 + R-11 + R-11 LS
Attic and other R-38 R-38 R-38 R-38 R-38 R-38 R-49 R-49 R-49 R-49 R-49 R-49 R-60 R-60 R-60 R-60
Walls, above grade
Massf R-5.7cic R-5.7cic R-5.7cic R-7.6ci R-7.6ci R-9.5ci R-9.5ci R-11.4ci R-11.4ci R-13.3ci R-13.3ci R-15.2ci R-15.2ci R-15.2ci R-25ci R-25ci
Metal building R-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-14ci R-13 + R-14ci R-13 + R-14ci R-13 + R-14ci R-13 + R-14ci R-13 + R-17ci R-13+
R-19.5ci
R-13 + R-19.5ci R-13+
R-19.5ci
Metal framed R-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-10ci R-13 + R-10ci R-13 + R-12.5ci R-13 + R-12.5ci R-13 + R-12.5ci R-13 +
R-15.6ci
R-13 + R-18.8ci R-13 + R-18.8ci
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-7.5ci or R20 + R3.8ci
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
R-13 +
R-7.5ci or
R-20 +
R-3.8ci
R-13 + R-18.8ci R-13 + R-18.8ci
Walls, below grade
Below-grade walld NR NR NR NR NR NR R-7.5ci R-10ci R-7.5ci R-10ci R-10ci R-15ci R-15ci R-15ci R-15ci R-15ci
Floors
Masse NR NR R-6.3ci R-8.3ci R-10ci R-10ci R-14.6ci R-16.7ci R-14.6ci R-16.7ci R-16.7ci R-16.7ci R-20.9ci R-20.9ci R-23ci R-23ci
Joist/framing R-13 R-13 R-30 R-30 R-30 R-30 R-30 R-30 R-30 R-30 R-38 R-38 R-38 R-38 R-38 R-38
Slab-on-grade floors
Unheated slabs NR NR NR NR NR R-10 for 24" below

R-15 for 24" below

R-15 for 24" below
R-15 for 24" below
R-20 for 24" below
R-20 for 24" below
R-20 for 48" below
R-20 for 24" below
R-20 for 48" below
R-20 for 48" below
R-25 for 48" below
Heated slabsg R-7.5 for
12" below
+ R-5 full slab
R-7.5 for
12" below
+ R-5 full slab
R-7.5 for
12" below
+ R-5 full slab
R-7.5 for
12" below
+ R-5 full slab
R-10 for
24" below
+ R-5 full slab
R-10 for
24" below
+ R-5 full slab
R-15 for
24" below
+ R-5 full slab
R-15 for
24" below
+ R-5 full slab
R-15 for
36" below
+ R-5 full slab
R-15 for
36" below
+ R-5 full slab
R-15 for
36" below
+ R-5 full slab
R-20 for
48" below
+ R-5 full slab
R-20 for
48" below
+ R-5 full slab
R-20 for
48" below
+ R-5 full slab
R-20 for
48" below
+ R-5 full slab
R-20 for
48" below
+ R-5 full slab

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 90.1 Appendix A.
  2. Where using R-value compliance method, a thermal spacer block 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 C90, 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.
  4. Where heated slabs are below grade, below-grade walls shall comply with the exterior insulation requirements for heated slabs.
  5. "Mass floors" shall be in accordance with Section C402.2.3.
  6. "Mass walls" shall be in accordance with Section C402.2.2.
  7. The first value is for perimeter insulation and the second value is for full, under-slab insulation. Perimeter insulation is not required to extend below the bottom of the slab.
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. 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

TABLE C402.1.4

OPAQUE THERMAL ENVELOPE ASSEMBLY MAXIMUM REQUIREMENTS, U-FACTOR METHODa, b

CLIMATE ZONE 0 AND 1 2 3 4 EXCEPT MARINE 5 AND MARINE 4 6 7 8
All other Group R All other Group R All other Group R All other Group R All other Group R All other Group R All other Group R All other Group 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-0.032 U-0.032 U-0.032 U-0.028 U-0.028 U-0.028 U-0.028
Metal buildings 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-0.035 U-0.035 U-0.031 U-0.029 U-0.029 U-0.029 U-0.026 U-0.026
Attic and other 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-0.017 U-0.017 U-0.017 U-0.017
Walls, above grade
Massg 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-0.080 U-0.080 U-0.071 U-0.071 U-0.071 U-0.037 U-0.037
Metal building U-0.079 U-0.079 U-0.079 U-0.079 U-0.079 U-0.052 U-0.052 U-0.050 U-0.050 U-0.050 U-0.050 U-0.050 U-0.044 U-0.039 U-0.039 U-0.039
Metal 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-0.055 U-0.055 U-0.049 U-0.049 U-0.049 U-0.042 U-0.037 U-0.037
Wood framed and otherc 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-0.051 U-0.051 U-0.051 U-0.051 U-0.051 U-0.051 U-0.032 U-0.032
Walls, below grade
Below-grade wallc C-1.140e C-1.140e C-1.140e C-1.140e C-1.140e C-1.140e C-0.119 C-0.092 C-0.119 C-0.092 C-0.092 C-0.063 C-0.063 C-0.063 C-0.063 C-0.063
Floors
Massd U-0.322e U-0.322e U-0.107 U-0.087 U-0.074 U-0.074 U-0.057 U-0.051 U-0.057 U-0.051 U-0.051 U-0.051 U-0.042 U-0.042 U-0.038 U-0.038
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-0.033 U-0.027 U-0.027 U-0.027 U-0.027 U-0.027 U-0.027
Slab-on-grade floors
Unheated slabs F-0.73e F-0.73e F-0.73e F-0.73e F-0.73e F-0.54 F-0.52 F-0.52 F-0.52 F-0.51 F-0.51 F-0.434 F-0.51 F-0.434 F-0.434 F-0.424
Heated slabs F-0.69 F-0.69 F-0.69 F-0.69 F-0.66 F-0.66 F-0.62 F-0.62 F-0.62 F-0.62 F-0.62 F-0.602 F-0.602 F-0.602 F-0.602 F-0.602
Opaque doors
Nonswinging door U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31
Swinging doorh U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37 U-0.37
Garage door < 14% glazingi U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31 U-0.31

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.

  • a. Where assembly U-factors, C-factors and F-factors are established in ANSI/ASHRAE/IESNA 90.1 Appendix A, such opaque assemblies shall be a compliance alternative where those values meet the criteria of this table, and provided that the construction, excluding the cladding system on walls, complies with the appropriate construction details from ANSI/ASHRAE/ISNEA 90.1 Appendix A.
  • b. Where U-factors have been established by testing in accordance with ASTM C1363, such opaque assemblies shall be a compliance alternative where those values meet the criteria of this table. The R-value of continuous insulation shall be permitted to be added to or subtracted from the original tested design.
  • c. Where heated slabs are below grade, below-grade walls shall comply with the U-factor requirements for above-grade mass walls.
  • d. "Mass floors" shall be in accordance with Section C402.2.3.
  • e. These C-, F- and U-factors are based on assemblies that are not required to contain insulation.
  • g. "Mass walls" shall be in accordance with Section C402.2.2.
  • h. Swinging door U-factors shall be determined in accordance with NFRC-100.
  • i. Garage doors having a single row of fenestration shall have an assembly U-factor less than or equal to 0.44 in Climate Zones 0 through 6 and less than or equal to 0.36 in Climate Zones 7 and 8, provided that the fenestration area is not less than 14 percent and not more than 25 percent of the total door area.
The maximum roof/ceiling assembly U-factor shall not exceed that specified in Table C402.1.4 based on construction materials used in the roof/ceiling assembly.
Where used as a component of a maximum roof/ceiling assembly U-factor calculation, the sloped roof insulation R-value contribution to that calculation shall use the average thickness in inches (mm) along with the material R-value-per-inch (per-mm) solely for U-factor compliance as prescribed in Section C402.1.4.
Insulation installed on suspended ceilings having removable ceiling tiles shall not be considered part of the assembly U-factor of the roof/ceiling construction.
Continuous insulation board shall be installed in not less than two layers, and the edge joints between each layer of insulation shall be staggered, except where insulation tapers to the roof deck at a gutter edge, roof drain or scupper.

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 as specified in Table C402.1.4.2.


TABLE C402.1.4.2

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)
31/2 16 13 0.46 5.98
15 0.43 6.45
31/2 24 13 0.55 7.15
15 0.52 7.80
6 16 19 0.37 7.03
21 0.35 7.35
6 24 19 0.45 8.55
21 0.43
9.03
8 16 25 0.31 7.75
24 25 0.38 9.50

For SI: 1 inch = 25.4 mm.

Building envelope values and fenestration areas determined in accordance with Equation 4-2 shall be an alternative to compliance with the U-, F- and C-factors in Tables C402.1.4 and C402.4 and the maximum allowable fenestration areas in Section C402.4.1. Fenestration shall meet the applicable SHGC requirements of Section C402.4.3.

(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 × Area.

UA Table = (U-factor from Table C402.1.3, C402.1.4 or C402.4) × 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 × Perimeter length.

FL Table  = (F-factor specified in Table C402.1.4) × 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.

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

D  = (DA × UV) — (DA × U Wall), but not less than zero.

DA  = (Proposed Vertical Glazing Area) — (Vertical Glazing Area allowed by Section C402.4.1).

UA Wall = Sum of the (UA Proposed) values for each opaque assembly of the exterior wall.

U Wall  = Area-weighted average U-value of all above-grade wall assemblies.

UAV = Sum of the (UA Proposed) values for each vertical glazing assembly.

UV = UAV/total vertical glazing area.

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

E = (EA × US) — (EA × U Roof), but not less than zero.

EA = (Proposed Skylight Area) — (Allowable Skylight Area as specified in Section C402.4.1).

U Roof = Area-weighted average U-value of all roof assemblies.

UAS = Sum of the (UA Proposed) values for each skylight assembly.

US  = UAS/total skylight area.

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.
Where used as a component of a roof/ceiling assembly R-value calculation, the sloped roof insulation R-value contribution to that calculation shall use the average thickness in inches (mm) along with the material R-value-per-inch (per-mm) solely for R-value compliance as prescribed in Section 402.1.3.
The minimum thickness of above-deck roof insulation at its lowest point, gutter edge, roof drain or scupper, shall be not less than 1 inch (25 mm).
Insulation installed on suspended ceilings having removable ceiling tiles shall not be considered part of the minimum thermal resistance (R-value) of roof insulation in roof/ceiling construction.
Continuous insulation board shall be installed in not less than two layers and the edge joints between each layer of insulation shall be staggered, except where insulation tapers to the roof deck at a gutter edge, roof drain or scupper.

Skylight curbs shall be insulated to the level of roofs with insulation entirely above the deck or R-5, whichever is less.

Exception: 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.

The minimum thermal resistance (R-value) of materials installed in the wall cavity between 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 shall not be used in determining compliance with Table C402.1.3 except as otherwise noted in the table. In determining compliance with Table C402.1.4, the use of the U-factor of concrete masonry units with integral insulation shall be permitted.

"Mass walls" where used as a component in the thermal envelope of a building shall comply with one of the following:

  1. Weigh not less than 35 pounds per square foot (171 kg/m2) of wall surface area.
  2. Weigh not less than 25 pounds per square foot (122 kg/m2) of wall surface area where the material weight is not more than 120 pcf (1900 kg/m3).
  3. Have a heat capacity exceeding 7 Btu/ft2× °F (144 kJ/m2× K).
  4. Have a heat capacity exceeding 5 Btu/ft2× °F (103 kJ/m2× K), where the material weight is not more than 120 pcf (1900 kg/m3).

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.

"Mass floors" where used as a component of the thermal envelope of a building shall provide one of the following weights:

  1. 35 pounds per square foot (171 kg/m2) of floor surface area.
  2. 25 pounds per square foot (122 kg/m2) of floor surface area where the material weight is not more than 120 pounds per cubic foot (1923 kg/m3).

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.
The minimum thermal resistance (R-value) of the insulation for 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.
Where installed, the perimeter insulation shall be placed on the outside of the foundation or on the inside of the foundation wall. The perimeter insulation shall extend downward from the top of the slab for the minimum distance shown in the table or to the top of the footing, whichever is less, or downward to not less than 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 10 inches (254 mm) of soil. Where installed, full slab insulation shall be continuous under the entire area of the slab-on-grade floor, except at structural column locations and service penetrations. Insulation required at the heated slab perimeter shall not be required to extend below the bottom of the heated slab and shall be continuous with the full slab insulation.

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

The C-factor for the below-grade exterior walls shall be in accordance with Table C402.1.4. The R-value of the insulating material installed continuously within or on the below-grade exterior walls of the building envelope shall be in accordance with Table C402.1.3. The C-factor or R-value required 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.

Radiant heating system panels, and their associated components that are installed in interior or exterior assemblies, shall be insulated to an R-value of not less than R-3.5 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 C402.2.4.

Where the R-value of an airspace is used for compliance in accordance with Section C402.1, the airspace shall be enclosed in an unventilated cavity constructed to minimize airflow into and out of the enclosed airspace. Airflow shall be deemed minimized where the enclosed airspace is located on the interior side of the continuous air barrier and is bounded on all sides by building components.

Exception: The thermal resistance of airspaces located on the exterior side of the continuous air barrier and adjacent to and behind the exterior wall-covering material shall be determined in accordance with ASTM C1363 modified with an airflow entering the bottom and exiting the top of the airspace at an air movement rate of not less than 70 mm/second.

Low-sloped roofs directly above cooled conditioned spaces in Climate Zones 0 through 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.  Photovoltaic systems or components.

    1.2.  Solar air or water-heating systems or components.

    1.3.  Vegetative roofs or landscaped roofs.

    1.4.  Above-roof decks or walkways.

    1.5.  Skylights.

    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 C1549, ASTM E903 or ASTM E1918 or CRRC-S100.
  3. Aged thermal emittance tested in accordance with ASTM C1371 or ASTM E408 or CRRC-S100.
  4. Solar reflectance index (SRI) shall be determined in accordance with ASTM E1980 using a convection coefficient of 2.1 Btu/h × ft2× °F (12 W/m2× K). Calculation of aged SRI shall be based on aged tested values of solar reflectance and thermal emittance.

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-S100.

Fenestration shall comply with Sections C402.4.1 through C402.4.5 and Table C402.4. Daylight responsive controls shall comply with this section and Section C405.2.4.

TABLE C402.4

BUILDING ENVELOPE FENESTRATION MAXIMUM U-FACTOR AND SHGC REQUIREMENTS

CLIMATE ZONE 0 AND 1 2 3 4 EXCEPT MARINE 5 AND MARINE 4 6 7 8

Vertical fenestration

U-factor

Fixed fenestration 0.50 0.45 0.42 0.36 0.36 0.34 0.29 0.26
Operable fenestration 0.62 0.60 0.54 0.45 0.45 0.42 0.36 0.32
Entrance doors 0.83 0.77 0.68 0.63 0.63 0.63 0.63 0.63

SHGC

 

Fixed

Operable

Fixed

Operable

Fixed

Operable

Fixed

Operable

Fixed

Operable

Fixed

Operable

Fixed

Operable

Fixed

Operable

PF < 0.2 0.23 0.21 0.25 0.23 0.25 0.23 0.36 0.33 0.38 0.33 0.38 0.34 0.40 0.36 0.40 0.36
0.2 ≤ PF < 0.5 0.28 0.25 0.30 0.28 0.30 0.28 0.43 0.40 0.46 0.40 0.46 0.41 0.48 0.43 0.48 0.43
PF ≥ 0.5 0.37 0.34 0.40 0.37 0.40 0.37 0.58 0.53 0.61 0.53 0.61 0.54 0.64 0.58 0.64 0.58
Skylights
U-factor 0.70 0.65 0.55 0.50 0.50 0.50 0.44 0.41
SHGC 0.30 0.30 0.30 0.40 0.40 0.40 NR NR

NR = No Requirement, PF = Projection Factor.

The vertical fenestration area, not including opaque doors and opaque spandrel panels, shall be not greater than 30 percent of the gross above-grade wall area. The skylight area shall be not greater than 3 percent of the gross roof area.

In Climate Zones 0 through 6, not more than 40 percent of the gross above-grade wall area shall be vertical fenestration, provided that 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 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 are installed in daylight zones.
  4. Visible transmittance (VT) of vertical fenestration is not less than 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.

The skylight area shall be not more than 6 percent of the roof area provided that daylight responsive controls are installed in toplitdaylight zones.

Skylights shall be provided in enclosed spaces 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 height 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 toplit daylight zone shall be not less than half the floor area and shall comply with one of the following:

  1.   A minimum skylight area to toplit daylight zone of not less than 3 percent where all skylights have a VT of not less than 0.40, or VTannual of not less than 0.26, as determined in accordance with Section C303.1.3.
  2. A minimum skylight effective aperture, determined in accordance with Equation 4-4, of:

    2.1.  Not less than 1 percent, using a skylight's VT rating; or

    2.2.  Not less than 0.66 percent using a Tubular Daylighting Device's VTannual rating.

(Equation 4-4)
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, or 1.0 for Tubular Daylighting Devices with VTannual ratings.

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.
  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 not less than 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 area minus the area of sidelit daylight zones is less than 2,500 square feet (232 m2), and where the lighting is controlled in accordance with Section C405.2.3.
  6. Spaces designed as storm shelters complying with ICC 500.

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 D1003.

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

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 4-5.

(Equation 4-5)

where:

PF = Projection factor (decimal).

A = Distance measured horizontally from the farthest 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.

In Climate Zones 0 through 6, skylights shall be permitted a maximum SHGC of 0.60 where located above daylight zones provided with daylight responsive controls.
Where skylights are installed above daylight zones provided with daylight responsive controls, a maximum U-factor of 0.9 shall be permitted in Climate Zones 0 through 3 and a maximum U-factor of 0.75 shall be permitted in Climate Zones 4 through 8.

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.

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.
Daylight zones referenced in Sections C402.4.1.1 through C402.4.3.2 shall comply with Sections C405.2.4.2 and C405.2.4.3, as applicable. Daylight zones shall include toplit daylight zones and sidelit daylight zones.
Opaque swinging doors shall comply with Table C402.1.4. Opaque nonswinging doors shall comply with Table C402.1.4. Opaque doors shall be considered as part of the gross area of above-grade walls that are part of the building thermal envelope. Opaque doors shall comply with Section C402.4.5.1 or C402.4.5.2. Other doors shall comply with the provisions of Section C402.4.3 for vertical fenestration.
Opaque swinging doors shall comply with Table C402.1.4.
Opaque nonswinging doors that are horizontally hinged sectional doors with a single row of fenestration shall have an assembly U-factor less than or equal to 0.440 in Climate Zones 0 through 6 and less than or equal to 0.360 in Climate Zones 7 and 8, provided that the fenestration area is not less than 14 percent and not more than 25 percent of the total door area.
Exception: Other doors shall comply with the provisions of Section C402.4.3 for vertical fenestration.
The building thermal envelope shall comply with Sections C402.5.1 through Section C402.5.11.1, or the building thermal envelope shall be tested in accordance with Section C402.5.2 or C402.5.3.  Where compliance is based on such testing, the building shall also comply with Sections C402.5.7, C402.5.8 and C402.5.9.

A continuous air barrier shall be provided throughout the building thermal envelope. The continuous air barriers shall be located on the inside or outside of the building thermal envelope, located within the assemblies composing the building thermal 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.

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. Sealing shall allow for expansion, contraction and mechanical vibration. Joints and seams associated with penetrations shall be sealed in the same manner or taped. Sealing materials shall be securely installed around the penetration 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 C402.5.10. Where similar objects are installed that penetrate the air barrier, provisions shall be made to maintain the integrity of the air barrier.

A continuous air barrier for the opaque building envelope shall comply with the following:

  1. Buildings or portions of buildings, including Group R and I occupancies, shall meet the provisions of Section C402.5.2.

    Exception: Buildings in Climate Zones 2B, 3C and 5C.

  2. Buildings or portions of buildings other than Group R and I occupancies shall meet the provisions of Section C402.5.3.

    Exceptions:

    1. Buildings in Climate Zones 2B, 3B, 3C and 5C.
    2. Buildings larger than 5,000 square feet (464.5 m2) floor area in Climate Zones 0B, 1, 2A, 4B and 4C.
    3. Buildings between 5,000 square feet (464.5 m2) and 50,000 square feet  (4645 m2) floor area in Climate Zones 0A, 3A and 5B.
  3. Buildings or portions of buildings that do not complete air barrier testing shall meet the provisions of Section C402.5.1.3 or C402.5.1.4 in addition to Section C402.5.1.5.

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 E2178 shall comply with this section. Materials in Items 1 through 16 shall be deemed to comply with this section, provided that 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 having a minimum density of 1.5 pcf (2.4 kg/m3) and 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. 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.

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 E2357, ASTM E1677 , ASTM D8052 or ASTM E283 shall comply with this section. Assemblies listed in Items 1 through 3 shall be deemed to comply, provided that 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.
The installation of the continuous air barrier shall be verified by the code official, a registered design professional or approved agency in accordance with the following:
  1. A review of the construction documents and other supporting data shall be conducted to assess compliance with the requirements in Section C402.5.1.
  2. Inspection of continuous air barrier components and assemblies shall be conducted during construction while the air barrier is still accessible for inspection and repair to verify compliance with the requirements of Sections C402.5.1.3 and C402.5.1.4.
  3. A final commissioning report shall be provided for inspections completed by the registered design professional or approved agency. The commissioning report shall be provided to the building owner or owner's authorized agent and the code official. The report shall identify deficiencies found during the review of the construction documents and inspection and details of corrective measures taken.
The building thermal envelope shall be tested in accordance with ASTM E779, ANSI/RESNET/ICC 380, ASTM E1827 or an equivalent method approved by the code official. The measured air leakage shall not exceed 0.30 cfm/ft2 (1.5 L/s m2) of the testing unit enclosure area at a pressure differential of 0.2 inch water gauge (50 Pa). Where multiple dwelling units or sleeping units or other occupiable conditioned spaces are contained within one building thermal envelope, each unit shall be considered an individual testing unit, and the building air leakage shall be the weighted average of all testing unit results, weighted by each testing unit's enclosure area. Units shall be tested separately with an unguarded blower door test as follows:
  1. Where buildings have fewer than eight testing units, each testing unit shall be tested.
  2. For buildings with eight or more testing units, the greater of seven units or 20 percent of the testing units in the building shall be tested, including a top floor unit, a ground floor unit and a unit with the largest testing unit enclosure area. For each tested unit that exceeds the maximum air leakage rate, an additional two units shall be tested, including a mixture of testing unit types and locations.
The building thermal envelope shall be tested in accordance with ASTM E779, ANSI/RESNET/ICC 380, ASTM E3158 or ASTM E1827 or an equivalent method approved by the code official. The measured air leakage shall not exceed 0.40 cfm/ft2 (2.0 L/s × m2) of the building thermal envelope area at a pressure differential of 0.3 inch water gauge (75 Pa). Alternatively, portions of the building shall be tested and the measured air leakages shall be area weighted by the surface areas of the building envelope in each portion. The weighted average test results shall not exceed the whole building leakage limit. In the alternative approach, the following portions of the building shall be tested:
  1. The entire envelope area of all stories that have any spaces directly under a roof.
  2. The entire envelope area of all stories that have a building entrance, exposed floor, or loading dock, or are below grade.
  3. Representative above-grade sections of the building totaling at least 25 percent of the wall area enclosing the remaining conditioned space.

Exception: Where the measured air leakage rate exceeds 0.40 cfm/ft2 (2.0 L/s × m2) but does not exceed 0.60 cfm/ft2 (3.0 L/s × m2), a diagnostic evaluation using smoke tracer or infrared imaging shall be conducted while the building is pressurized along with a visual inspection of the air barrier. Any leaks noted shall be sealed where such sealing can be made without destruction of existing building components. An additional report identifying the corrective actions taken to seal leaks shall be submitted to the code official and the building owner, and shall be deemed to comply with the requirements of this section.

The air leakage of fenestration assemblies shall meet the provisions of Table C402.5.4. Testing shall be in accordance with the applicable reference test standard in Table C402.5.4 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 C402.5.4.

TABLE C402.5.4

MAXIMUM AIR LEAKAGE RATE FOR FENESTRATION ASSEMBLIES

FENESTRATION ASSEMBLY MAXIMUM RATE (CFM/FT2) TEST PROCEDURE
Windows 0.20a AAMA/WDMA/CSA101/I.S.2/A440 or NFRC 400
Sliding doors 0.20a
Swinging doors 0.20a
Skylights—with condensation weepage openings 0.30
Skylights—all other 0.20a
Curtain walls 0.06 NFRC 400 or ASTM E283 at 1.57 psf (75 Pa)
Storefront glazing 0.06
Commercial glazed swinging entrance doors 1.00
Power-operated sliding doors and power operated folding doors 1.00
Revolving doors 1.00
Garage doors 0.40 ANSI/DASMA 105, NFRC 400, or ASTM E283 at 1.57 psf (75 Pa)
Rolling doors 1.00
High-speed doors 1.30

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).

In Climate Zones 3 through 8, where combustion air is supplied through openings in an exterior wall to a room or space containing a space-conditioning fuel-burning appliance, one of the following shall apply:

  1. The room or space containing the appliance shall be located outside of the building thermal envelope.
  2. The room or space containing the appliance shall be enclosed and isolated from conditioned spaces inside the building thermal envelope. Such rooms shall comply with all of the following:

    2.1.  The walls, floors and ceilings that separate the enclosed room or space from conditioned spaces shall be insulated to be not less than equivalent to the insulation requirement of below-grade walls as specified in Table C402.1.3 or Table C402.1.4.

    2.2.  The walls, floors and ceilings that separate the enclosed room or space from conditioned spaces shall be sealed in accordance with Section C402.5.1.1.

    2.3.  The doors into the enclosed room or space shall be fully gasketed.

    2.4.  Water lines and ducts in the enclosed room or space shall be insulated in accordance with Section C403.

    2.5.  Where an air duct supplying combustion air to the enclosed room or space passes through conditioned space, the duct shall be insulated to an R-value of not less than R-8.

Exception: Fireplaces and stoves complying with Sections 901 through 905 of the International Mechanical Code, and Section 2111.14 of the International Building Code.

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 C402.5.4 shall be gasketed, weather-stripped or sealed.

Exceptions:

  1. Door openings required to comply with Section 716 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 C403.7.7.
Cargo door openings and loading door openings shall be equipped with weather seals that restrict infiltration and provide direct contact along the top and sides of vehicles that are parked in the doorway.

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.

Exceptions: Vestibules are not required for the following:

  1. Buildings in Climate Zones 0 through 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.
  3. Doors opening directly from a sleeping unit or dwelling unit.
  4. Doors that open directly from a space less than 3,000 square feet (298 m2) in area.
  5. Revolving doors.
  6. Doors used primarily to facilitate vehicular movement or material handling and adjacent personnel doors.
  7. 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.

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 2.0 cfm (0.944 L/s) when tested in accordance with ASTM E283 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.
Where occupancies utilize operable openings to the outdoors that are larger than 40 square feet (3.7 m2) in area, such openings shall be interlocked with the heating and cooling system so as to raise the cooling setpoint to 90°F (32°C) and lower the heating setpoint to 55°F (13°C) whenever the operable opening is open. The change in heating and cooling setpoints shall occur within 10 minutes of opening the operable opening.

Exceptions:

  1. Separately zoned areas associated with the preparation of food that contain appliances that contribute to the HVAC loads of a restaurant or similar type of occupancy.
  2. Warehouses that utilize overhead doors for the function of the occupancy, where approved by the code official.
  3. The first entrance doors where located in the exterior wall and are part of a vestibule system.
Controls shall comply with Section C403.14.

Mechanical systems and equipment serving the building heating, cooling, ventilating or refrigerating needs shall comply with this section.

Exception: Data center systems are exempt from the requirements of Sections C403.4 and C403.5.

Design loads associated with heating, ventilating and air conditioning of the building shall be determined in accordance with ANSI/ASHRAE/ACCA Standard 183 or by an approved 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.
Data center systems shall comply with Sections 6 and 8 of ASHRAE 90.4 with the following changes:
  1. Replace design mechanical load component (MLC) values specified in Table 6.2.1.1 of the ASHRAE 90.4 with the values in Table C403.1.2(1) as applicable in each climate zone.
  2. Replace annualized MLC values specified in Table 6.2.1.2 of the ASHRAE 90.4 with the values in Table C403.1.2(2) as applicable in each climate zone.

TABLE C403.1.2(1)

MAXIMUM DESIGN MECHANICAL LOAD COMPONENT (DESIGN MLC)

CLIMATE ZONE DESIGN MLC AT 100% AND AT 50% ITE LOAD
0A 0.24
OB 0.26
1A 0.23
2A 0.24
3A 0.23
4A 0.23
5A 0.22
6A 0.22
1B 0.28
2B 0.27
3B 0.26
4B 0.23
5B 0.23
6B 0.21
3C 0.19
4C 0.21
5C 0.19
7 0.20
8 0.19

 

TABLE C403.1.2(2)

MAXIMUM ANNUALIZED MECHANICAL LOAD COMPONENT (ANNUALIZED MLC)

CLIMATE ZONE HVAC MAXIMUM ANNUALIZED MLC AT 100% AND AT 50% ITE LOAD
0A 0.19
0B 0.20
1A 0.18
2A 0.19
3A 0.18
4A 0.17
5A 0.17
6A 0.17
1B 0.16
2B 0.18
3B 0.18
4B 0.18
5B 0.16
6B 0.17
3C 0.16
4C 0.16
5C 0.16
7 0.16
8 0.16
Mechanical systems shall be designed to comply with Sections C403.2.1 through C403.2.3. Where elements of a building's mechanical systems are addressed in Sections C403.3 through C403.14, such elements shall comply with the applicable provisions of those sections.

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 C403.4.2.2. 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.
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 provide the capability to reduce the outdoor air supply to the minimum required by Chapter 4 of the International Mechanical Code.
New buildings with an HVAC system serving a gross conditioned floor area of 100,000 square feet (9290 m2) or larger shall include a fault detection and diagnostics (FDD) system to monitor the HVAC system's performance and automatically identify faults. The FDD system shall:
  1. Include permanently installed sensors and devices to monitor the HVAC system's performance.
  2. Sample the HVAC system's performance at least once every 15 minutes.
  3. Automatically identify and report HVAC system faults.
  4. Automatically notify authorized personnel of identified HVAC system faults.
  5. Automatically provide prioritized recommendations for repair of identified faults based on analysis of data collected from the sampling of HVAC system performance.
  6. Be capable of transmitting the prioritized fault repair recommendations to remotely located authorized personnel.

Exception: R-1 and R-2 occupancies.

Heating and cooling equipment installed in mechanical systems shall be sized in accordance with Section C403.3.1 and shall be not less efficient in the use of energy than as specified in Section C403.3.2.

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 C403.1.1. 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 are configured to sequence the operation of each unit based on load.
Equipment shall meet the minimum efficiency requirements of Tables C403.3.2(1) through C403.3.2(16) when tested and rated in accordance with the applicable test procedure. Plate-type liquid-to-liquid heat exchangers shall meet the minimum requirements of AHRI 400. The efficiency shall be verified through certification under an approved certification program or, where a certification program does not exist, 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.

TABLE C403.3.2(1)

ELECTRICALLY OPERATED UNITARY AIR CONDITIONERS AND CONDENSING UNITS—MINIMUM EFFICIENCY REQUIREMENTSc, d

EQUIPMENT
TYPE
SIZE CATEGORY HEADING SECTION TYPE SUBCATEGORY OR RATING CONDITION MINIMUM
EFFICIENCY
TEST PROCEDUREa
Air conditioners, air cooled < 65,000 Btu/hb All Split system, three phase and applications outside US single phaseb 13.0 SEER

before 1/1/2023

13.4 SEER2

after 1/1/2023
AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Single-package, three phase and applications outside US single phaseb 14.0 SEER

before 1/1/2023

13.4 SEER2

after 1/1/2023
Space constrained, air cooled ≤ 30,000 Btu/hb All Split system, three phase and applications outside US single phaseb 12.0 SEER

before 1/1/2023

11.7 SEER2

after 1/1/2023
AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Single package, three phase and applications outside US single phaseb 12.0 SEER

before 1/1/2023

11.7 SEER2

after 1/1/2023
Small duct, high velocity, air cooled < 65,000 Btu/hb All Split system, three phase and applications outside US single phaseb 12.0 SEER

before 1/1/2023

12.1 SEER2

after 1/1/2023
AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Air conditioners, air cooled ≥ 65,000 Btu/h and

< 135,000 Btu/h
Electric resistance

(or none)
Split systemand single package 11.2 EER

12.9 IEER

before 1/1/2023

14.8 IEER

after 1/1/2023
AHRI 340/360
All other 11.0 EER

12.7 IEER

before 1/1/2023

14.6 IEER

after 1/1/2023
≥ 135,000 Btu/h and

< 240,000 Btu/h
Electric resistance

(or none)
11.0 EER

12.4 IEER

before 1/1/2023

14.2 IEER

after 1/1/2023

All other 10.8 EER

12.2 IEER

before 1/1/2023

14.0 IEER

after 1/1/2023
≥ 240,000 Btu/h and

< 760,000 Btu/h
Electric resistance

(or none)
Split system and

single package
10.0 EER

11.6 IEER

before 1/1/2023

13.2 IEER

after 1/1/2023
AHRI 340/360
All other 9.8 EER

11.4 IEER

before 1/1/2023

13.0 IEER

after 1/1/2023
≥ 760,000 Btu/h Electric resistance

(or none)
9.7 EER

11.2 IEER before

1/1/2023

12.5 IEERafter 1/1/2023
All other 9.5 EER

11.0 IEER

before 1/1/2023

12.3 IEER

after 1/1/2023
Air conditioners,

water cooled
< 65,000 Btu/h All Split systemand

single package
12.1 EER

12.3 IEER
AHRI 210/240
≥ 65,000 Btu/h and

< 135,000 Btu/h
Electric resistance

(or none)
12.1 EER

13.9 IEER
AHRI 340/360
All other 11.9 EER

13.7 IEER
≥ 135,000 Btu/h and

< 240,000 Btu/h
Electric resistance

(or none)
12.5 EER

13.9 IEER
All other 12.3 EER

13.7 IEER
≥ 240,000 Btu/h and

< 760,000 Btu/h
Electric resistance

(or none)
12.4 EER

13.6 IEER
All other 12.2 EER

13.4 IEER
≥ 760,000 Btu/h Electric resistance

(or none)
12.2 EER

13.5 IEER
All other 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
AHRI 210/240
≥ 65,000 Btu/h and

< 135,000 Btu/h
Electric resistance

(or none)
12.1 EER

12.3 IEER
AHRI 340/360
All other 11.9 EER

12.1 IEER
≥ 135,000 Btu/h and

< 240,000 Btu/h
Electric resistance

(or none)
12.0 EER

12.2 IEER
All other 11.8 EER

12.0 IEER
≥ 240,000 Btu/h and

< 760,000 Btu/h
Electric resistance

(or none)
11.9 EER

12.1 IEER
All other 11.7 EER

11.9 IEER
≥ 760,000 Btu/h Electric resistance

(or none)
11.7 EER

11.9 IEER
All other 11.5 EER

11.7 IEER
Condensing units, air cooled ≥ 135,000 Btu/h 10.5 EER

11.8 IEER
AHRI 365
Condensing units, water cooled ≥ 135,000 Btu/h 13.5 EER

14.0 IEER
AHRI 365
Condensing units, evaporatively

cooled
≥ 135,000 Btu/h 13.5 EER

14.0 IEER
AHRI 365

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

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. Single-phase, US air-cooled air conditioners less than 65,000 Btu/h are regulated as consumer products by the US Department of Energy Code of Federal Regulations DOE 10 CFR 430. SEER and SEER2 values for single-phase products are set by the US Department of Energy.
  3. DOE 10 CFR 430 Subpart B Appendix M1 includes the test procedure updates effective 1/1/2023 that will be incorporated in AHRI 210/240—2023.
  4. This table is a replica of ASHRAE 90.1 Table 6.8.1-1 Electrically Operated Unitary Air Conditioners and Condensing Units—Minimum Efficiency Requirements.

TABLE C403.3.2(2)

ELECTRICALLY OPERATED AIR-COOLED UNITARY HEAT PUMPS—MINIMUM EFFICIENCY REQUIREMENTSc, d

EQUIPMENT TYPE SIZE CATEGORY HEADING SECTION TYPE SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
Air cooled (cooling mode) < 66,000 Btu/h All Split system, three phase and applications outside US single phaseb 14.0 SEER before 1/1/2023 14.3 SEER2 after 1/1/2023 AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Single package, three phase and applications outside US single phaseb 14.0 SEER before 1/1/2023 13.4 SEER2 after 1/1/2023
Space constrained, air cooled (cooling mode) ≤ 30,000 Btu/h All Split system, three phase and applications outside US single phaseb 12.0 SEER before 1/1/2023 11.7 SEER2 after 1/1/2023 AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Single package, three phase and applications outside US single phaseb 12.0 SEER before 1/1/2023 11.7 SEER2 after 1/1/2023
Single duct, high velocity, air cooled (cooling mode) < 65,000 All Split system, three phase and applications outside US single phaseb 12.0 SEER before 1/1/2023 12.0 SEER2 after 1/1/2023 AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
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 12.2 IEER before 1/1/2023 14.1 IEER after 1/1/2023 AHRI 340/360
All other 10.8 EER 12.0 IEER before 1/1/2023 13.9 IEER after 1/1/2023
≥ 135,000 Btu/h and < 240,000 Btu/h Electric resistance (or none) 10.6 EER 11.6 IEER before 1/1/2023 13.5 IEER after 1/1/2023
All other 10.4 EER 11.4 IEER before 1/1/2023 13.3 IEER after 1/1/2023
≥ 240,000 Btu/h Electric resistance (or none) 9.5 EER 10.6 IEER before 1/1/2023 12.5 IEER after 1/1/2023
All other 9.3 EER 10.4 IEER before 1/1/2023 12.3 IEER after 1/1/2023
Air cooled (heating mode) < 65,000 Btu/h All Split system, three phase and applications outside US single phaseb 8.2 HSPF

before 1/1/2023

7.5 HSPF2

after 1/1/2023
AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Single package, three phase and applications outside US single phaseb 8.0 HSPF

before 1/1/2023

6.7 HSPF2

after 1/1/2023
Space constrained, air cooled

(heating mode)
≤ 30,000 Btu/h All Split system, three phase and applications outside US single phaseb 7.4 HSPF

before 1/1/2023

6.3 HSPF2

after 1/1/2023
AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Single package, three phase and applications outside US single phaseb 7.4 HSPF

before 1/1/2023

6.3 HSPF2

after 1/1/2023
Small duct, high velocity, air cooled (heating mode) < 65,000 Btu/h All Split system, three phase and applications outside US single phaseb 7.2 HSPF

before 1/1/2023

6.1 HSPF2

after 1/1/2023
AHRI 210/240—2017

before 1/1/2023

AHRI 210/240—2023

after 1/1/2023
Air cooled (heating mode) ≥ 65,000 Btu/h and

< 135,000 Btu/h (cooling capacity)
All 47°F db/43°F wb
outdoor air
3.30 COPH
before 1/1/2023

3.40 COPH
after 1/1/2023
AHRI 340/360
17°F db/15°F wb
outdoor air
2.25 COPH

≥ 135,000 Btu/h and

< 240,000 Btu/h (cooling capacity)
47°F db/43°F wb
outdoor air
3.20 COPH
before 1/1/2023

3.30 SOPH
after 1/1/2023
17°F db/15°F wb
outdoor air
2.05 COPH
≥ 240,000 Btu/h (cooling capacity) 47°F db/43°F wb
outdoor air
3.20 COPH
17°F db/15°F wb
outdoor air
2.05 COPH

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

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. Single-phase, US air-cooled heat pumps less than 65,000 Btu/h are regulated as consumer products by the US Department of Energy Code of Federal Regulations DOE 10 CFR 430. SEER, SEER2 and HSPF values for single-phase products are set by the US Department of Energy.
  3. DOE 10 CFR 430 Subpart B Appendix M1 includes the test procedure updates effective 1/1/2023 that will be incorporated in AHRI 210/240—2023.
  4. This table is a replica of ASHRAE 90.1 Table 6.8.1-2 Electrically Operated Air-Cooled Unitary Heat Pumps—Minimum Efficiency Requirements.

TABLE C403.3.2(3)

WATER-CHILLING PACKAGES—MINIMUM EFFICIENCY REQUIREMENTSa, b, e, f

EQUIPMENT
TYPE
SIZE CATEGORY UNITS PATH A PATH B TEST PROCEDUREc
Air cooled chillers < 150 tons EER (Btu/Wh) ≥ 10.100 FL ≥ 9.700 FL AHRI 550/590
≥ 13.700 IPLV.IP ≥ 15.800 IPLV.IP
≥ 150 tons ≥ 10.100 FL ≥ 9.700FL
≥ 14.000 IPLV.IP ≥ 16.100 IPLV.IP
Air cooled without condenser, electrically operated All capacities EER (Btu/Wh) Air-cooled chillers without condenser must be rated with matching condensers and comply with air-cooled chiller efficiency requirements AHRI 550/590
Water cooled, electrically operated positive displacement < 75 tons kW/ton ≤ 0.750 FL ≤ 0.780 FL AHRI 550/590
≤ 0.600 IPLV.IP ≤ 0.500 IPLV.IP
≥ 75 tons and < 150 tons ≤ 0.720 FL ≤ 0.750 FL
≤ 0.560 IPLV.IP ≤ 0.490 IPLV.IP
≥ 150 tons and < 300 tons ≤ 0.660 FL ≤ 0.680 FL
≤ 0.540 IPLV.IP ≤ 0.440 IPLV.IP
≥ 300 tons and < 600 tons ≤ 0.610 FL ≤ 0.625 FL
≤ 0.520 IPLV.IP ≤ 0.410 IPLV.IP
≥ 600 tons ≤ 0.560 FL ≤ 0.585 FL
≤ 0.500 IPLV.IP ≤ 0.380 IPLV.IP
Water cooled, electrically operated centrifugal < 150 tons kW/ton ≤ 0.610 FL ≤ 0.695 FL AHRI 550/590
≤ 0.550 IPLV.IP ≤ 0.440 IPLV.IP
  ≤ 0.610 FL ≤ 0.635 FL
≤ 0.550 IPLV.IP ≤ 0.400 IPLV.IP
≥ 300 tons and

< 400 tons
≤ 0.560 FL ≤ 0.595 FL
≤ 0.520 IPLV.IP ≤ 0.390 IPLV.IP
≥ 400 tons and

< 600 tons
≤ 0.560 FL ≤ 0.585 FL
≤ 0.500 IPLV.IP ≤ 0.380 IPLV.IP
≥ 600 tons ≤ 0.560 FL ≤ 0.585 FL
≤ 0.500 IPLV.IP ≤ 0.380 IPLV.IP
Air cooled absorption, single effect All capacities COP (W/W) ≥ 0.600 FL NAd AHRI 560
Water cooled absorption, single effect All capacities COP (W/W) ≥ 0.700 FL NAd AHRI 560
Absorption double effect, indirect fired All capacities COP (W/W) ≥ 1.000 FL NAd AHRI 560
≥ 0.150 IPLV.IP
Absorption double effect, direct fired All capacities COP (W/W) ≥ 1.000 FL NAd AHRI 560
≥ 1.000 IPLV
  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. The requirements for centrifugal chillers shall be adjusted for nonstandard rating conditions per Section C403.3.2.1 and are applicable only for the range of conditions listed there. The requirements for air-cooled, water-cooled positive displacement and absorption chillers are at standard rating conditions defined in the reference test procedure.
  3. Both the full-load and IPLV.IP requirements must be met or exceeded to comply with this standard. When there is a Path B, compliance can be with either Path A or Path B for any application.
  4. NA means the requirements are not applicable for Path B, and only Path A can be used for compliance.
  5. FL is the full-load performance requirements, and IPLV.IP is for the part-load performance requirements.
  6. This table is a replica of ASHRAE 90.1 Table 6.8.1-3 Water-Chilling Packages—Minimum Efficiency Requirements.

TABLE C403.3.2(4)

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—MINIMUM EFFICIENCY REQUIREMENTSe

EQUIPMENT TYPE SIZE CATEGORY (INPUT) SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCYd TEST PROCEDUREa
PTAC (cooling mode)

standard size
< 7,000 Btu/h 95°F db/75°F wb

outdoor airc
11.9 EER AHRI 310/380
≥ 7,000 Btu/h and

≤ 15,000 Btu/h
14.0 — (0.300 × Cap/1,000) EERd
> 15,000 Btu/h 9.5 EER
PTAC (cooling mode)

nonstandard sizea
< 7,000 Btu/h 95°F db/75°F wb

outdoor airc
9.4 EER AHRI 310/380
≥ 7,000 Btu/h and

≤ 15,000 Btu/h
10.9 — (0.213 × Cap/1,000) EERd
> 15,000 Btu/h 7.7 EER
PTHP (cooling mode)

standard size
< 7,000 Btu/h 95°F db/75°F wb

outdoor airc
11.9 EER AHRI 310/380
≥ 7,000 Btu/h and

≤ 15,000 Btu/h
14.0 — (0.300 × Cap/1,000) EERd
> 15,000 Btu/h 9.5 EER
PTHP (cooling mode)

nonstandard sizeb
< 7,000 Btu/h 95°F db/75°F wb

outdoor airc
9.3 EER AHRI 310/380
≥ 7,000 Btu/h and

≤ 15,000 Btu/h
10.8 — (0.213 × Cap/1,000) EERd
> 15,000 Btu/h 7.6 EER
PTHP (heating mode)

standard size
< 7,000 Btu/h 47°F db/43°F wb

outdoor air
3.3 COPH AHRI 310/380
≥ 7,000 Btu/h and

≤ 15,000 Btu/h
3.7 — (0.052 × Cap/1,000) COPHd
> 15,000 Btu/h 2.90 COPH
PTHP (heating mode)

nonstandard sizeb
< 7,000 Btu/h 47°F db/43°F wb

outdoor air
2.7 COPH AHRI 310/380
≥ 7,000 Btu/h and

≤ 15,000 Btu/h
2.9 — (0.026 × Cap/1000) COPHd
> 15,000 Btu/h 2.5 COPH
SPVAC (cooling mode)

single and three phase
< 65,000 Btu/h 95°F db/75°F wb

outdoor airc
11.0 EER AHRI 390
≥ 65,000 Btu/h and

≤ 135,000 Btu/h
10.0 EER
≥ 135,000 Btu/h and

≤ 240,000 Btu/h
10.0 EER
SPVHP (cooling mode) < 65,000 Btu/h 95°F db/75°F wb

outdoor airc
11.0 EER AHRI 390
≥ 65,000 Btu/h and

≤ 135,000 Btu/h
10.0 EER
≥ 135,000 Btu/h and

≤ 240,000 Btu/h
10.1 EER
SPVHP(heating mode) < 65,000 Btu/h 47°F db/43°F wb

outdoor air
3.3 COPH AHRI 390
≥ 65,000 Btu/h and

≤ 135,000 Btu/h
3.0 COPH
≥ 135,000 Btu/h and

≤ 240,000 Btu/h
3.0 COPH
Room air conditioners without reverse cycle with louvered sides for applications outside US < 6,000 Btu/h 11.0 CEER ANSI/AHAM RAC-1
≥ 6,000 Btu/h and < 8,000 Btu/h 11.0 CEER
≥ 8,000 Btu/h and

< 14,000 Btu/h
10.9 CEER
≥ 14,000 Btu/h and

< 20,000 Btu/h
10.7 CEER
≥ 20,000 Btu/h and

< 28,000 Btu/h
9.4 CEER
≥ 28,000 Btu/h 9.0 CEER
Room air conditioners without louvered sides < 6,000 Btu/h 10.0 CEER ANSI/AHAM RAC-1
≥ 6,000 Btu/h and < 8,000 Btu/h 10.0 CEER
≥ 8,000 Btu/h and

< 11,000 Btu/h
9.6 CEER
≥ 11,000 Btu/h and

< 14,000 Btu/h
9.5 CEER
≥ 14,000 Btu/h and

< 20,000 Btu/h
9.3 CEER
≥ 20,000 Btu/h 9.4 CEER
Room air conditioners with reverse cycle, with louvered sides for applications outside US < 20,000 Btu/h   9.8 CEER ANSI/AHAM RAC-1
≥ 20,000 Btu/h 9.3 CEER
Room air conditioners with reverse cycle without louvered sides for applications outside US < 14,000 Btu/h 9.3 CEER ANSI/AHAM RAC-1
≥ 14,000 Btu/h 8.7 CEER
Room air conditioners, casement only for applications outside US All 9.5 CEER ANSI/AHAM RAC-1
Room air conditioners, casement slider for applications outside US All 10.4 CEER ANSI/AHAM RAC-1

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 in Btu/h. Where the unit's capacity is less than 7,000 Btu/h, use 7,000 Btu/h in the calculation. Where the unit's capacity is greater than 15,000 Btu/h, use 15,000 Btu/h in the calculations.

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. Nonstandard size units must be factory labeled as follows: "MANUFACTURED FOR NONSTANDARD SIZE APPLICATIONS ONLY; NOT TO BE INSTALLED IN NEW STANDARD PROJECTS." Nonstandard size efficiencies apply only to units being installed in existing sleeves having an external wall opening of less than 16 inches (406 mm) high or less than 42 inches (1067 mm) wide and having a cross-sectional area less than 670 square inches (0.43 m2).
  3. The cooling-mode wet bulb temperature requirement only applies for units that reject condensate to the condenser coil.
  4. "Cap" in EER and COPH equations for PTACs and PTHPs means cooling capacity in Btu/h at 95°F outdoor dry-bulb temperature.
  5. This table is a replica of ASHRAE 90.1 Table 6.8.1-4 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—Minimum Efficiency Requirements.

TABLE C403.3.2(5)

WARM-AIR FURNACES AND COMBINATION WARM-AIR FURNACES/AIR-CONDITIONING UNITS, WARM-AIR DUCT FURNACES AND UNIT HEATERS—MINIMUM EFFICIENCY REQUIREMENTSg

EQUIPMENT TYPE SIZE CATEGORY (INPUT) SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
Warm-air furnace, gas fired for application outside the US < 225,000 Btu/h Maximum capacityc 80% AFUE

(nonweatherized) or 81% AFUE

(weatherized) or 80% Etb, d
DOE 10 CFR 430 Appendix N or

Section 2.39, Thermal

Efficiency, ANSI Z21.47
Warm-air furnace, gas fired < 225,000 Btu/h Maximum capacityc 80% Etb, d

before 1/1/2023 81% Etd

after 1/1/2023
Section 2.39, Thermal

Efficiency, ANSI Z21.47
Warm-air furnace, oil fired for application outside the US < 225,000 Btu/h Maximum capacityc 83% AFUE

(nonweatherized) or 78% AFUE

(weatherized) or 80% Etb, d
DOE 10 CFR 430 Appendix N or

Section 42, Combustion, UL 727
Warm-air furnace, oil fired < 225,000 Btu/h Maximum capacityc 80% Et

before 1/1/2023 82% Etd after 1/1/2023
Section 42, Combustion, UL 727
Electric furnaces for applications outside the US < 225,000 Btu/h All 96% AFUE DOE 10 CFR 430 Appendix N
Warm-air duct furnaces, gas fired All capacities Maximum capacityc 80% Ece Section 2.10, Efficiency, ANSI Z83.8
Warm-air unit heaters, gas fired All capacities Maximum capacityc 80% Ece, f Section 2.10, Efficiency, ANSI Z83.8
Warm-air unit heaters, oil fired All capacities Maximum capacityc 80% Ece, f Section 40, Combustion, UL 731

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

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. Combination units (i.e., furnaces contained within the same cabinet as an air conditioner) not covered by DOE 10 CFR 430 (i.e., three-phase power or with cooling capacity greater than or equal to 65,000 Btu/h) may comply with either rating. All other units greater than 225,000 Btu/h sold in the US must meet the AFUE standards for consumer products and test using USDOE's AFUE test procedure at DOE 10 CFR 430, Subpart B, Appendix N.
  3. Compliance of multiple firing rate units shall be at the maximum firing rate.
  4. Et = thermal efficiency. Units must also include an interrupted or intermittent ignition device (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.
  5. Ec = combustion efficiency (100 percent less flue losses). See test procedure for detailed discussion.
  6. Units must also include an interrupted or intermittent ignition device (IID) and have either power venting or an automatic flue damper.
  7. This table is a replica of ASHRAE 90.1 Table 6.8.1-5 Warm-Air Furnaces and Combination Warm-Air Furnaces/Air-Conditioning Units, Warm-Air Duct Furnaces, and Unit Heaters—Minimum Efficiency Requirements.

TABLE C403.3.2(6)

GAS- AND OIL-FIRED BOILERS—MINIMUM EFFICIENCY REQUIREMENTSi

EQUIPMENT TYPEb SUBCATEGORY OR RATING CONDITION SIZE CATEGORY (INPUT) MINIMUM EFFICIENCY EFFICIENCY AS OF

3/2/2022
TEST PROCEDUREa
Boilers, hot water Gas fired < 300,000 Btu/hg, h for applications outside

US
82% AFUE 82% AFUE DOE 10 CFR 430 Appendix N
≥ 300,000 Btu/h and

≤ 2,500,000 Btu/he
80% Etd 80% Etd DOE 10 CFR 431.86
> 2,500,000 Btu/hb 82% Ecc 82% Ecc
Oil firedf < 300,000 Btu/hg,h for applications outside

US
84% AFUE 84% AFUE DOE 10 CFR 430 Appendix N
≥ 300,000 Btu/h and

≤ 2,500,000 Btu/he
82% Etd 82% Etd DOE 10 CFR 431.86
> 2,500,000 Btu/hb 84% Ecc 84% Ecc
Boilers, steam Gas fired < 300,000 Btu/hg for applications outside

US
80% AFUE 80% AFUE DOE 10 CFR 430 Appendix N
Gas fired—all, except natural draft ≥ 300,000 Btu/h and

≤ 2,500,000 Btu/he
79% Etd 79% Etd DOE 10 CFR 431.86
> 2,500,000 Btu/hb 79% Etd 79% Etd
Gas fired—natural draft ≥ 300,000 Btu/h and

≤ 2,500,000 Btu/he
77% Etd 79% Etd
> 2,500,000 Btu/hb 77% Etd 79% Etd
Oil firedf < 300,000 Btu/hg for applications outside

US
82% AFUE 82% AFUE DOE 10 CFR 430 Appendix N
≥ 300,000 Btu/h and

≤ 2,500,000 Btu/he
81% Etd 81% Etd DOE 10 CFR 431.86
> 2,500,000 Btu/hb 81% Etd 81% Etd

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

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. 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.
  3. Ec = Combustion efficiency (100 percent less flue losses). 
  4. Et = Thermal efficiency. 
  5. Maximum capacity—minimum and maximum ratings as provided for and allowed by the unit's controls.
  6. Includes oil-fired (residual).
  7. Boilers shall not be equipped with a constant burning pilot light.
  8. A boiler not equipped with a tankless domestic water-heating coil shall be equipped with an automatic means for adjusting the temperature of the water such that an incremental change in inferred heat load produces a corresponding incremental change in the temperature of the water supplied.
  9. This table is a replica of ASHRAE 90.1 Table 6.8.1-6 Gas- and Oil-Fired Boilers—Minimum Efficiency Requirements.

TABLE C403.3.2(7)

PERFORMANCE REQUIREMENTS FOR HEAT REJECTION EQUIPMENT—MINIMUM EFFICIENCY REQUIREMENTSi

EQUIPMENT TYPE TOTAL SYSTEM HEAT-REJECTION CAPACITY AT RATED CONDITIONS SUBCATEGORY OR RATING CONDITIONh PERFORMANCE REQUIREDb, c, d, f, g TEST PROCEDUREa, e
Propeller or axial fan open-circuit cooling towers All 95°F entering water

85°F leaving water

75°F entering wb
≥ 40.2 gpm/hp CTI ATC-105 and CTI STD-201 RS
Centrifugal fan open-circuit cooling towers All 95°F entering water

85°F leaving water

75°F entering wb
≥ 20.0 gpm/hp CTI ATC-105 and CTI STD-201 RS
Propeller or axial fan closed-circuit cooling towers All 102°F entering water

90°F leaving water

75°F entering wb
≥ 16.1 gpm/hp CTI ATC-105S and CTI STD-201 RS
Centrifugal fan closed-circuit cooling towers All 102°F entering water

90°F leaving water

75°F entering wb
≥ 7.0 gpm/hp CTI ATC-105S and CTI STD-201 RS
Propeller or axial fan dry coolers (air-cooled fluid coolers) All 115°F entering water

105°F leaving water

95°F entering wb
≥ 4.5 gpm/hp CTI ATC-105DS
Propeller or axial fan evaporative condensers All R-448A test fluid

165°F entering gas temperature

105°F condensing temperature

75°F entering wb
≥ 160,000 Btu/h × hp CTI ATC-106
Propeller or axial fan evaporative condensers All Ammonia test fluid

140°F entering gas temperature

96.3°F condensing temperature

75°F entering wb
≥ 134,000 Btu/h × hp CTI ATC-106
Centrifugal fan evaporative condensers All R-448A test fluid

165°F entering gas temperature

105°F condensing temperature

75°F entering wb
≥ 137,000 Btu/h × hp CTI ATC-106
Centrifugal fan evaporative condensers All Ammonia test fluid

140°F entering gas temperature

96.3°F condensing temperature

75°F entering wb
≥ 110,000 Btu/h × hp CTI ATC-106
Air-cooled condensers All 125°F condensing temperature

190°F entering gas temperature

15°F subcooling

95°F entering db
≥ 176,000 Btu/h × hp AHRI 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, wb = wet bulb temperature.

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  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 the table divided by the fan motor nameplate power.
  3. For purposes of this table, closed-circuit cooling tower performance is defined as the process water-flow rating of the tower at the thermal rating condition listed in the table divided by the sum of the fan motor nameplate power and the integral spray pump motor nameplate power.
  4. For purposes of this table, dry-cooler performance is defined as the process water-flow rating of the unit at the thermal rating condition listed in the table divided by the total fan motor nameplate power of the unit, and air-cooled condenser performance is defined as the heat rejected from the refrigerant divided by the total fan motor nameplate power of the unit.
  5. 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 separate wet and dry heat exchange sections. The certification requirements do not apply to field-erected cooling towers.
  6. All 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.
  7. 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.
  8. Requirements for evaporative condensers are listed with ammonia (R-717) and R-448A as test fluids in the table. Evaporative condensers intended for use with halocarbon refrigerants other than R-448A must meet the minimum efficiency requirements listed with R-448A as the test fluid. For ammonia, the condensing temperature is defined as the saturation temperature corresponding to the refrigerant pressure at the condenser entrance. For R-448A, which is a zeotropic refrigerant, the condensing temperature is defined as the arithmetic average of the dew point and the bubble point temperatures corresponding to the refrigerant pressure at the condenser entrance.
  9. This table is a replica of ASHRAE 90.1 Table 6.8.1-7 Performance Requirements for Heat Rejection Equipment—Minimum Efficiency Requirements.

TABLE C403.3.2(8)

ELECTRICALLY OPERATED VARIABLE-REFRIGERANT-FLOW AIR CONDITIONERS—MINIMUM EFFICIENCY REQUIREMENTSb

EQUIPMENT TYPE SIZE CATEGORY HEATING SECTION TYPE SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
VRFair conditioners, air cooled < 65,000 Btu/h All VRF multisplit

system
13.0 SEER AHRI 1230
≥ 65,000 Btu/h and

< 135,000 Btu/h
Electric resistance

(or none)
VRF multisplit

system
11.2 EER

13.1 IEER

15.5 IEER
≥ 135,000 Btu/h and

< 240,000 Btu/h
Electric resistance

(or none)
VRF multisplit

system
11.0 EER

12.9 IEER

14.9 IEER
≥ 240,000 Btu/h Electric resistance

(or none)
VRF multisplit

system
10.0 EER

11.6 IEER

13.9 IEER

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

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. This table is a replica of ASHRAE 90.1 Table 6.8.1-8 Electrically Operated Variable-Refrigerant-Flow Air Conditioners—Minimum Efficiency Requirements.

TABLE C403.3.2(9)

ELECTRICALLY OPERATED VARIABLE-REFRIGERANT-FLOW AND APPLIED HEAT PUMPS—MINIMUM EFFICIENCY REQUIREMENTSb

EQUIPMENT TYPE SIZE CATEGORY HEATING SECTION TYPE SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
VRFair cooled (cooling mode) < 65,000 Btu/h All VRF multisplit system 13.0 SEER AHRI 1230
≥ 65,000 Btu/h and

< 135,000 Btu/h
Electric resistance

(or none)
11.0 EER

12.9 IEER

14.6 IEER
VRF multisplit system

with heat recovery
10.8 EER

12.7 IEER

14.4 IEER
≥ 135,000 Btu/h and

< 240,000 Btu/h
VRF multisplit system 10.6 EER

12.3 IEER

13.9 IEER
VRF multisplit system

with heat recovery
10.4 EER

12.1 IEER

13.7 IEER
≥ 240,000 Btu/h VRF multisplit system 9.5 EER

11.0 IEER

12.7 IEER
VRF multisplit system

with heat recovery
9.3 EER

10.8 IEER

12.5 IEER
VRF water source (cooling mode) < 65,000 Btu/h All VRF multisplit systems

86°F entering water
12.0 EER

16.0 IEER
AHRI 1230
VRF multisplit systems

with heat recovery

86°F entering water
11.8 EER

15.8 IEER
≥ 65,000 Btu/h and

< 135,000 Btu/h
VRF multisplit system

86°F entering water
12.0 EER

16.0 IEER
VRF multisplit system

with heat recovery

86°F entering water
11.8 EER

15.8 IEER
≥ 135,000 Btu/h and

< 240,000 Btu/h
VRF multisplit system

86°F entering water
10.0 EER

14.0 IEER
VRF multisplit system

with heat recovery

86°F entering water
9.8 EER

13.8 IEER
≥ 240,000 Btu/h VRF multisplit system

86°F entering water
10.0 EER

12.0 IEER
VRF multisplit system

with heat recovery

86°F entering water
9.8 EER

11.8 IEER
VRFgroundwater source (cooling mode) < 135,000 Btu/h All VRF multisplit system

59°F entering water
16.2 EER AHRI 1230
VRF multisplit system

with heat recovery

59°F entering water
16.0 EER
≥ 135,000 Btu/h VRF multisplit system

59°F entering water
13.8 EER
VRF multisplit system

with heat recovery

59°F entering water
13.6 EER
VRFground source (cooling mode) < 135,000 Btu/h All VRF multisplit system

77°F entering water
13.4 EER AHRI 1230
VRF multisplit system

with heat recovery

77°F entering water
13.2 EER
≥ 135,000 Btu/h VRF multisplit system

77°F entering water
11.0 EER
VRF multisplit system

with heat recovery

77°F entering water
10.8 EER
VRFair cooled (heating mode) < 65,000 Btu/h

(cooling capacity)
VRF multisplit system 7.7 HSPF AHRI 1230
≥ 65,000 Btu/h and

< 135,000 Btu/h

(cooling capacity)
VRF multisplit system

47°F db/43°F wb

outdoor air
3.3 COPH
17°F db/15°F wb

outdoor air
2.25 COPH
≥ 135,000 Btu/h

(cooling capacity)
VRF multisplit system

47°F db/43°F wb

outdoor air
3.2 COPH
17°F db/15°F wb

outdoor air
2.05 COPH
VRFwater source (heating mode) < 65,000 Btu/h

(cooling capacity)
VRF multisplit system

68°F entering water
4.2 COPH

4.3 COPH
AHRI 1230
≥ 65,000 Btu/h and

< 135,000 Btu/h

(cooling capacity)
VRF multisplit system

68°F entering water
4.2 COPH

4.3 COPH
≥ 135,000 Btu/h and

< 240,000 Btu/h

(cooling capacity)
VRF multisplit system

68°F entering water
3.9 COPH

4.0 COPH
≥ 240,000 Btu/h

(cooling capacity)
VRF multisplit system

68°F entering water
3.9 COPH
VRF groundwater source (heating mode) < 135,000 Btu/h

(cooling capacity)
VRF multisplit system

50°F entering water
3.6 COPH AHRI 1230
≥ 135,000 Btu/h

(cooling capacity)
VRF multisplit system

50°F entering water
3.3 COPH
VRF ground source (heating mode) < 135,000 Btu/h

(cooling capacity)
VRF multisplit system

32°F entering water
3.1 COPH AHRI 1230
≥ 135,000 Btu/h

(cooling capacity)
VRF multisplit system

32°F entering water
2.8 COPH

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

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. This table is a replica of ASHRAE 90.1 Table 6.8.1-9 Electrically Operated Variable-Refrigerant-Flow and Applied Heat Pumps—Minimum Efficiency Requirements.

TABLE C403.3.2(10)

FLOOR-MOUNTED AIR CONDITIONERS AND CONDENSING UNITS SERVING COMPUTER ROOMS—MINIMUM EFFICIENCY REQUIREMENTSb

EQUIPMENT TYPE STANDARD MODEL NET SENSIBLE COOLING CAPACITY MINIMUM NET SENSIBLE COP RATING CONDITIONS RETURN AIR

(dry bulb/dew point)
TEST PROCEDUREa
Air cooled Downflow < 80,000 Btu/h 2.70 85°F/52°F (Class 2) AHRI 1360
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.58
≥ 295,000 Btu/h 2.36
Upflow—ducted < 80,000 Btu/h 2.67
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.55
≥ 295,000 Btu/h 2.33
Upflow—nonducted < 65,000 Btu/h 2.16 75°F/52°F (Class 1)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.04
≥ 240,000 Btu/h 1.89
Horizontal < 65,000 Btu/h 2.65 95°F/52°F (Class 3)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.55
≥ 240,000 Btu/h 2.47
Air cooled with fluid economizer Downflow < 80,000 Btu/h 2.70 85°F/52°F (Class 1) AHRI 1360
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.58
≥ 295,000 Btu/h 2.36
Upflow—ducted < 80,000 Btu/h 2.67
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.55
≥ 295,000 Btu/h 2.33
Upflow—nonducted < 65,000 Btu/h 2.09 75°F/52°F (Class 1)
≥ 65,000 Btu/h and

< 240,000 Btu/h
1.99
≥ 240,000 Btu/h 1.81
Horizontal < 65,000 Btu/h 2.65 95°F/52°F (Class 3)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.55
≥ 240,000 Btu/h 2.47
Water cooled Downflow < 80,000 Btu/h 2.82 85°F/52°F (Class 1) AHRI 1360
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.73
≥ 295,000 Btu/h 2.67
Upflow—ducted < 80,000 Btu/h 2.79
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.70
≥ 295,000 Btu/h 2.64
Upflow—nonducted < 65,000 Btu/h 2.43 75°F/52°F (Class 1)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.32
≥ 240,000 Btu/h 2.20
Horizontal < 65,000 Btu/h 2.79 95°F/52°F (Class 3)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.68
≥ 240,000 Btu/h 2.60
Water cooled with fluid economizer Downflow < 80,000 Btu/h 2.77 85°F/52°F (Class 1) AHRI 1360
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.68
≥ 295,000 Btu/h 2.61
Upflow—ducted < 80,000 Btu/h 2.74
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.65
≥ 295,000 Btu/h 2.58
Upflow—nonducted < 65,000 Btu/h 2.35 75°F/52°F (Class 1)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.24
≥ 240,000 Btu/h 2.12
Horizontal < 65,000 Btu/h 2.71 95°F/52°F (Class 3)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.60
≥ 240,000 Btu/h 2.54
Glycol cooled Downflow < 80,000 Btu/h 2.56 85°F/52°F (Class 1) AHRI 1360
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.24
≥ 295,000 Btu/h 2.21
Upflow—ducted < 80,000 Btu/h 2.53
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.21
≥ 295,000 Btu/h 2.18
Upflow,

nonducted
< 65,000 Btu/h 2.08 75°F/52°F (Class 1)
≥ 65,000 Btu/h and

< 240,000 Btu/h
1.90
≥ 240,000 Btu/h 1.81
Horizontal < 65,000 Btu/h 2.48 95°F/52°F (Class 3)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.18
≥ 240,000 Btu/h 2.18
Glycol cooled with fluid economizer Downflow < 80,000 Btu/h 2.51 85°F/52°F (Class 1) AHRI 1360
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.19
≥ 295,000 Btu/h 2.15
Upflow—ducted < 80,000 Btu/h 2.48
≥ 80,000 Btu/h and

< 295,000 Btu/h
2.16
≥ 295,000 Btu/h 2.12
Upflow—nonducted < 65,000 Btu/h 2.00 75°F/52°F (Class 1)
≥ 65,000 Btu/h and

< 240,000 Btu/h
1.82
≥ 240,000 Btu/h 1.73
Horizontal < 65,000 Btu/h 2.44 95°F/52°F (Class 3)
≥ 65,000 Btu/h and

< 240,000 Btu/h
2.10
≥ 240,000 Btu/h 2.10

For SI: 1 British thermal unit per hour = 0.2931 W, °C = [(°F) — 32]/1.8, COP = (Btu/h × hp)/(2,550.7).

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. This table is a replica of ASHRAE 90.1 Table 6.8.1-10 Floor-Mounted Air Conditioners and Condensing Units Serving Computer Rooms—Minimum Efficiency Requirements.

TABLE C403.3.2(11)

VAPOR-COMPRESSION-BASED INDOOR POOL DEHUMIDIFIERS—MINIMUM EFFICIENCY REQUIREMENTSb

EQUIPMENT TYPE SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
Single package indoor (with or without economizer) Rating Conditions: A or C 3.5 MRE AHRI 910
Single package indoor water cooled (with or without economizer) Rating Conditions: A, B or C 3.5 MRE
Single package indoor air cooled (with or without economizer) Rating Conditions: A, B or C 3.5 MRE
Split systemindoor air cooled (with or without economizer) Rating Conditions: A, B or C 3.5 MRE
  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. This table is a replica of ASHRAE 90.1 Table 6.8.1-12 Vapor-Compression-Based Indoor Pool Dehumidifiers—Minimum Efficiency Requirements.

TABLE C403.3.2(12)

ELECTRICALLY OPERATED DX-DOAS UNITS, SINGLE-PACKAGE AND REMOTE CONDENSER, WITHOUT ENERGY RECOVERY—MINIMUM EFFICIENCY REQUIREMENTSb

EQUIPMENT TYPE SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
Air cooled (dehumidification mode) 4.0 ISMRE AHRI 920
Air-source heat pumps (dehumidification mode) 4.0 ISMRE AHRI 920
Water cooled (dehumidification mode) Cooling tower condenser water 4.9 ISMRE AHRI 920
Chilled water 6.0 ISMRE
Air-source heat pump (heating mode) 2.7 ISCOP AHRI 920
Water-source heat pump (dehumidification mode) Ground source, closed loop 4.8 ISMRE AHRI 920
Ground-water source 5.0 ISMRE
Water source 4.0 ISMRE
Water-source heat pump (heating mode) Ground source, closed loop 2.0 ISCOP AHRI 920
Ground-water source 3.2 ISCOP
Water source 3.5 ISCOP
  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. This table is a replica of ASHRAE 90.1 Table 6.8.1-13 Electrically Operated DX-DOAS Units, Single-Package and Remote Condenser, without Energy Recovery—Minimum Efficiency Requirements.

TABLE C403.3.2(13)

ELECTRICALLY OPERATED DX-DOAS UNITS, SINGLE-PACKAGE AND REMOTE CONDENSER,
WITH ENERGY RECOVERY—MINIMUM EFFICIENCY REQUIREMENTSb

EQUIPMENT TYPE SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
Air cooled (dehumidification mode) 5.2 ISMRE AHRI 920
Air-source heat pumps (dehumidification mode) 5.2 ISMRE AHRI 920
Water cooled (dehumidification mode) Cooling tower condenser water 5.3 ISMRE AHRI 920
Chilled water 6.6 ISMRE
Air-source heat pump (heating mode) 3.3 ISCOP AHRI 920
Water-source heat pump (dehumidification mode) Ground source, closed loop 5.2 ISMRE AHRI 920
Ground-water source 5.8 ISMRE
Water source 4.8 ISMRE
Water-source heat pump (heating mode) Ground source, closed loop 3.8 ISCOP AHRI 920
Ground-water source 4.0 ISCOP
Water source 4.8 ISCOP
  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. This table is a replica of ASHRAE 90.1 Table 6.8.1-14 Electrically Operated DX-DOAS Units, Single-Package and Remote Condenser, with Energy Recovery—Minimum Efficiency Requirements.

TABLE C403.3.2(14)

ELECTRICALLY OPERATED WATER-SOURCE HEAT PUMPS—MINIMUM EFFICIENCY REQUIREMENTSc

EQUIPMENT TYPE SIZE CATEGORYb HEATING SECTION TYPE SUBCATEGORY OR RATING CONDITION MINIMUM EFFICIENCY TEST PROCEDUREa
Water-to-air, water loop (cooling mode) < 17,000 Btu/h All 86°F entering water 12.2 EER ISO 13256-1
≥ 17,000 Btu/h and

< 65,000 Btu/h
13.0 EER
≥ 65,000 Btu/h and

< 135,000 Btu/h
13.0 EER
Water-to-air, ground water (cooling mode) < 135,000 Btu/h All 59°F entering water 18.0 EER ISO 13256-1
Brine-to-air, ground loop (cooling mode) < 135,000 Btu/h All 77°F entering water 14.1 EER ISO 13256-1
Water-to-water, water loop (cooling mode) < 135,000 Btu/h All 86°F entering water 10.6 EER ISO 13256-2
Water-to-water, ground water (cooling mode) < 135,000 Btu/h All 59°F entering water 16.3 EER ISO 13256-2
Brine-to-water, ground loop (cooling mode) < 135,000 Btu/h All 77°F entering water 12.1 EER ISO 13256-2
Water-to-water, water loop (heating mode) < 135,000 Btu/h

(cooling capacity)
68°F entering water 4.3 COPH ISO 13256-1
Water-to-air, ground water (heating mode) < 135,000 Btu/h

(cooling capacity)
50°F entering water 3.7 COPH ISO 13256-1
Brine-to-air, ground loop (heating mode) < 135,000 Btu/h

(cooling capacity)
32°F entering water 3.2 COPH ISO 13256-1
Water-to-water, water loop (heating mode) < 135,000 Btu/h

(cooling capacity)
68°F entering water 3.7 COPH ISO 13256-1
Water-to-water, ground water (heating mode) < 135,000 Btu/h

(cooling capacity)
50°F entering water 3.1 COPH ISO 13256-2
Brine-to-water, ground loop (heating mode) < 135,000 Btu/h

(cooling capacity)
32°F entering water 2.5 COPH ISO 13256-2

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

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. Single-phase, US air-cooled heat pumps less than 19 kW are regulated as consumer products by DOE 10 CFR 430. SCOPC, SCOP2C, SCOPH and SCOP2H values for single-phase products are set by the USDOE.
  3. This table is a replica of ASHRAE 90.1 Table 6.8.1-15 Electrically Operated Water-Source Heat Pumps—Minimum Efficiency Requirements.

TABLE C403.3.2(15)

HEAT-PUMP AND HEAT RECOVERY CHILLER PACKAGES—MINIMUM EFFICIENCY REQUIREMENTSg

HEATING OPERATION
EQUIPMENT TYPE SIZE CATEGORY, tonR COOLING-ONLY OPERATION COOLING EFFICIENCYc
AIR-SOURCE EER (FL/IPLV), Btu/W × h
WATER-SOURCE POWER INPUT PER CAPACITY (FL/IPLV), kW/tonR
HEATING
SOURCE CONDITIONS (entering/ leaving water) OR OAT (db/wb), °F
HEAT-PUMP HEATING FULL-LOAD EFFICIENCY
(COPH)b, W/W
HEAT RECOVERY CHILLER FULL-LOAD EFFICIENCY (COPHR)c,d, W/W
SIMULTANEOUS COOLING AND HEATING FULL-LOAD
EFFICIENCY (COPSHC)c, W/W
Test Procedurea
Leaving Heating Water Temperature Leaving Heating Water Temperature
Low Medium High Boost Low Medium High Boost
Path A Path B 105°F 120°F 140°F 140°F 105°F 120°F 140°F 140°F
Air source All sizes ≥ 9.595 FL

≥ 13.02 IPLV.IP
≥ 9.215 FL

≥ 15.01 IPLV.IP
47 db

43 wbe
≥ 3.290 ≥ 2.770 ≥ 2.310 NA NA NA NA NA AHRI 550/590
≥ 9.595 FL

≥ 13.30 IPLV.IP
≥ 9.215 FL

≥ 15.30 IPLV.IP
17 db

15 wbe
≥ 2.230 ≥ 1.950 ≥ 1.630 NA NA NA NA NA
Water-source electrically operated positive

displacement
< 75 ≤ 0.7885 FL

≤ 0.6316 IPLV.IP
≤ 0.7875 FL

≤ 0.5145 IPLV.IP
54/44f ≥ 4.640 ≥ 3.680 ≥ 2.680 NA ≥ 8.330 ≥ 6.410 ≥ 4.420 NA AHRI 550/590
75/65f NA NA NA ≥ 3.550 NA NA NA 6.150
≥ 75 and

< 150
≤ 0.7579 FL

≤ 0.5895 IPLV.IP
≤ 0.7140 FL

≤ 0.4620 IPLV.IP
54/44f ≥ 4.640 ≥ 3.680 ≥ 2.680 NA ≥ 8.330 ≥ 6.410 ≥ 4.420 NA
75/65f NA NA NA ≥ 3.550 NA NA NA 6.150
≥ 150 and

< 300
≤ 0.6947 FL

≤ 0.5684 IPLV.IP
≤ 0.7140 FL

≤ 0.4620 IPLV.IP
54/44f ≥ 4.640 ≥ 3.680 ≥ 2.680 NA ≥ 8.330 ≥ 6.410 ≥ 4.420 NA
75/65f NA NA NA ≥ 3.550 NA NA NA 6.150
≥ 300 and

< 600
≤ 0.6421 FL

≤ 0.5474 IPLV.IP
≤ 0.6563 FL

≤ 0.4305 IPLV.IP
54/44f ≥ 4.930 ≥ 3.960 ≥ 2.970 NA ≥ 8.900 ≥ 6.980 ≥ 5.000 NA
75/65f NA NA NA ≥ 3.900 NA NA NA 6.850
≥ 600 ≤ 0.5895 FL

≤ 0.5263 IPLV.IP
≤ 0.6143 FL

≤ 0.3990 IPLV.IP
54/44f ≥ 4.930 ≥ 3.960 ≥ 2.970 NA ≥ 8.900 ≥ 6.980 ≥ 5.000 NA
75/65f NA NA NA ≥ 3.900 NA NA NA 6.850
Water-source electrically operated centrifugal < 75 ≤ 0.6421 FL

≤ 0.5789 IPLV.IP
≤ 0.7316 FL

≤ 0.4632 IPLV.IP
54/44f ≥ 4.640 ≥ 3.680 ≥ 2.680 NA ≥ 8.330 ≥ 6.410 ≥ 4.420 NA AHRI 550/590
75/65f NA NA NA ≥ 3.550 NA NA NA ≥ 6.150
≥ 75 and

< 150
≤ 0.5895 FL

≤ 0.5474 IPLV.IP
≤ 0.6684 FL

≤ 0.4211 IPLV.IP
54/44f ≥ 4.640 ≥ 3.680 ≥ 2.680 NA ≥ 8.330 ≥ 6.410 ≥ 4.420 NA
75/65f NA NA NA ≥ 3.550 NA NA NA ≥ 6.150
≥ 150 and

< 300
≤ 0.5895 FL

≤ 0.5263 IPLV.IP
≤ 0.6263 FL

≤ 0.4105 IPLV.IP
54/44f ≥ 4.640 ≥ 3.680 ≥ 2.680 NA ≥ 8.330 ≥ 6.410 ≥ 4.420 NA
75/65f NA NA NA ≥ 3.550 NA NA NA ≥ 6.150
≥ 300 and

< 600
≤ 0.5895 FL

≤ 0.5263 IPLV.IP
≤ 0.6158 FL

≤ 0.4000 IPLV.IP
54/44f ≥ 4.930 ≥ 3.960 ≥ 2.970 NA ≥ 8.900 ≥ 6.980 ≥ 5.000 NA
75/65f NA NA NA ≥ 3.900 NA NA NA ≥ 6.850
≥ 600 ≤ 0.5895 FL

≤ 0.5263 IPLV.IP
≤ 0.6158 FL

≤ 0.4000 IPLV.IP
54/44f ≥ 4.930 ≥ 3.960 ≥ 2.970 NA ≥ 8.900 ≥ 6.980 ≥ 5.000 NA
75/65f NA NA NA ≥ 3.900 NA NA NA ≥ 6.850

For SI: °C = [(°F) — 32]/1.8.

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. Cooling-only rating conditions are standard rating conditions defined in AHRI 550/590, Table 1.
  3. Heating full-load rating conditions are at rating conditions defined in AHRI 550/590, Table 1.
  4. For water-cooled heat recovery chillers that have capabilities for heat rejection to a heat recovery condenser and a tower condenser, the COPHR applies to operation at full load with 100 percent heat recovery (no tower rejection). Units that only have capabilities for partial heat recovery shall meet the requirements of Table C403.3.2(3).
  5. Outdoor air entering dry-bulb (db) temperature and wet-bulb (wb) temperature.
  6. Source-water entering and leaving water temperature.
  7. This table is a replica of ASHRAE 90.1 Table 6.8.1-16 Heat-Pump and Heat Recovery Chiller Packages—Minimum Efficiency Requirements.

TABLE C403.3.2(16)

CEILING-MOUNTED COMPUTER-ROOM AIR CONDITIONERS—MINIMUM EFFICIENCY REQUIREMENTSb

EQUIPMENT TYPE STANDARD MODEL NET SENSIBLE COOLING CAPACITY MINIMUM NET SENSIBLE COP RATING CONDITIONS RETURN AIR

(dry bulb/dew point)
TEST PROCEDUREa
Air cooled with free air discharge condenser Ducted < 29,000 Btu/h 2.05 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
2.02
≥ 65,000 Btu/h 1.92
Nonducted < 29,000 Btu/h 2.08
≥ 29,000 Btu/h and

< 65,000 Btu/h
2.05
≥ 65,000 Btu/h 1.94
Air cooled with free air discharge condenser with fluid economizer Ducted < 29,000 Btu/h 2.01 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.97
≥ 65,000 Btu/h 1.87
Nonducted < 29,000 Btu/h 2.04
≥ 29,000 Btu/h and

< 65,000 Btu/h
2.00
≥ 65,000 Btu/h 1.89
Air cooled with ducted condenser Ducted < 29,000 Btu/h 1.86 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.83
≥ 65,000 Btu/h 1.73
Nonducted < 29,000 Btu/h 1.89
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.86
≥ 65,000 Btu/h 1.75
Air cooled with fluid economizer and ducted condenser Ducted < 29,000 Btu/h 1.82 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.78
≥ 65,000 Btu/h 1.68
Nonducted < 29,000 Btu/h 1.85
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.81
≥ 65,000 Btu/h 1.70
Water cooled Ducted < 29,000 Btu/h 2.38 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
2.28
≥ 65,000 Btu/h 2.18
Nonducted < 29,000 Btu/h 2.41
≥ 29,000 Btu/h and

< 65,000 Btu/h
2.31
≥ 65,000 Btu/h 2.20
Water cooled with fluid economizer Ducted < 29,000 Btu/h 2.33 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
2.23
≥ 65,000 Btu/h 2.13
Nonducted < 29,000 Btu/h 2.36
≥ 29,000 Btu/h and

< 65,000 Btu/h
2.26
≥ 65,000 Btu/h 2.16
Glycol cooled Ducted < 29,000 Btu/h 1.97 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.93
≥ 65,000 Btu/h 1.78
Nonducted < 29,000 Btu/h 2.00
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.98
≥ 65,000 Btu/h 1.81
Glycol cooled with fluid economizer Ducted < 29,000 Btu/h 1.92 75°F/52°F (Class 1) AHRI 1360
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.88
≥ 65,000 Btu/h 1.73
Nonducted < 29,000 Btu/h 1.95
≥ 29,000 Btu/h and

< 65,000 Btu/h
1.93
≥ 65,000 Btu/h 1.76

For SI: 1 British thermal unit per hour = 0.2931 W, °C = [(°F) — 32]/1.8, COP = (Btu/h × hp)/(2,550.7).

  1. Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
  2. This is a replica of ASHRAE 90.1 Table 6.8.1-17 Ceiling-Mounted Computer-Room Air Conditioners—Minimum Efficiency Requirements.
Equipment not designed for operation at AHRI Standard 550/590 test conditions of 44.00°F leaving and 54.00°F  entering chilled-fluid temperatures, and with 85.00°F  entering and 94.30°F leaving condenser-fluid temperatures, shall have maximum full-load kW/ton (FL) and part-load rating requirements adjusted using the following equations:

(Equation 4-6)

(Equation 4-7)

where:
  1. Kadj = A × B
  2. FL = Full-load kW/ton value from Table C403.3.2(3)
  3. FLadj = Maximum full-load kW/ton rating, adjusted for nonstandard conditions.
  4. IPLV.IP = IPLV.IP value from Table C403.3.2(3)
  5. PLVadj = Maximum NPLV rating, adjusted for nonstandard conditions.
  6. A = 0.00000014592 × (LIFT)4— 0.0000346496 × (LIFT)3+ 0.00314196 × (LIFT)2— 0.147199 × (LIFT) + 3.93073
  7. B = 0.0015 × LvgEvap + 0.934
  8. LIFT = LvgCondLvgEvap
  9. LvgCond = Full-load condenser leaving fluid temperature (°F).
  10. LvgEvap = Full-load evaporator leaving temperature (°F).
 
The FLadj and PLVadj values are applicable only for centrifugal chillers meeting all of the following full-load design ranges:
  • 36.00°F ≤ LvgEvap ≤ 60.00°F 
  • LvgCond ≤ 115.00°F 
  • 20.00°F  ≤ LIFT ≤ 80.00°F 
Manufacturers shall calculate the FLadj and PLVadj before determining whether to label the chiller. Centrifugal chillers designed to operate outside of these ranges are not covered by this code.
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 the tables in Section C403.3.2 when tested or certified with water at standard rating conditions, in accordance with the referenced test procedure.
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 C403.3.3, as limited by Section C403.5.1.

TABLE C403.3.3

MAXIMUM HOT GAS BYPASS CAPACITY

RATED CAPACITY MAXIMUM HOT GAS BYPASS CAPACITY (% of total capacity)
≤ 240,000 Btu/h 50
> 240,000 Btu/h 25

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

Boiler systems with design input of greater than 1,000,000 Btu/h (293 kW) shall comply with the turndown ratio specified in Table C403.3.4.

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 C403.3.4

BOILER TURNDOWN

BOILER SYSTEM DESIGN INPUT (Btu/h) MINIMUM TURNDOWN RATIO
≥ 1,000,000 and ≤ 5,000,000 3 to 1
> 5,000,000 and ≤ 10,000,000 4 to 1
> 10,000,000 5 to 1

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

Each heating and cooling system shall be provided with controls in accordance with Sections C403.4.1 through C403.4.5.

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. Where humidification or dehumidification or both is provided, not fewer than one humidity control device shall be provided for each humidity control system.

Exception: Independent perimeter systems that are designed to offset only building envelope heat losses, gains or both serving one or more perimeter zones also served by an interior system provided that both of the following conditions are met:

  1. The perimeter system includes not fewer than 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).
  2. The perimeter system heating and cooling supply is controlled by thermostats located within the zones served by the system.

Heat pumps having supplementary electric resistance heat shall have controls that limit supplemental heat operation to only those times when one of the following applies:

  1. The vapor compression cycle cannot provide the necessary heating energy to satisfy the thermostat setting.
  2. The heat pump is operating in defrost mode.
  3. The vapor compression cycle malfunctions.
  4. The thermostat malfunctions.

Where used to control both heating and cooling, zone thermostatic controls shall be configured to provide a temperature range or deadband of not less than 5°F (2.8°C) within which the supply of heating and cooling energy to the zone is 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.
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 configured to prevent the heating setpoint from exceeding the cooling setpoint and to maintain a deadband in accordance with Section C403.4.1.2.

The heating system for heated vestibules and air curtains with integral heating shall be provided with controls configured to shut off the source of heating when the outdoor air temperature is greater than 45°F (7°C). Vestibule heating and cooling systems shall be controlled by a thermostat located in the vestibule configured to limit heating to a temperature not greater than 60°F (16°C) and cooling to a temperature not less than 85°F (29°C).

Exception: Control of heating or cooling provided by site-recovered energy or transfer air that would otherwise be exhausted.

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.

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 manual shutoff switch located with ready access.
Thermostatic setback controls shall 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).
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 not fewer than 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 configured to operate the system for up to 2 hours; or an occupancy sensor.
Automatic start and stop controls shall be provided for each HVAC system. The automatic start controls shall be configured to automatically adjust the daily start time of the HVAC system in order to bring each space to the desired occupied temperature immediately prior to scheduled occupancy. Automatic stop controls shall be provided for each HVAC system with direct digital control of individual zones. The automatic stop controls shall be configured to reduce the HVAC system's heating temperature setpoint and increase the cooling temperature setpoint by not less than 2°F (-16.6°C) before scheduled unoccupied periods based on the thermal lag and acceptable drift in space temperature that is within comfort limits.
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 C403.4.3.1 through C403.4.3.3. 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 configured to sequence operation of the boilers. Hydronic heating systems composed of a single boiler and greater than 500,000 Btu/h (146.5 kW) input design capacity shall include either a multistaged or modulating burner.
Hydronic systems that use a common return system for both hot water and chilled water are prohibited.
Systems that use a common distribution system to supply both heated and chilled water shall be designed to allow a deadband between changeover from one mode to the other of not less than 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 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.
Hydronic heat pump systems shall comply with Sections C403.4.3.3.1 through C403.4.3.3.3.

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 configured to provide a heat pump water supply temperature deadband of not less than 20°F (11°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, deadbands of less than 20°F (11°C) shall be permitted.

The following shall apply to hydronic water loop heat pump systems in Climate Zones 3 through 8:

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

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

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 automatic valve interlocked to shut off the water flow when the compressor is off.

Hydronic systems greater than or equal to 300,000 Btu/h (87.9 kW) in design output capacity supplying heated or chilled water to comfort conditioning systems shall include controls that are configured to do all of the following:

  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 air temperature. The temperature shall be reset by not less than 25 percent of the design supply-to-return water temperature difference.
  2. Automatically vary fluid flow for hydronic systems with a combined pump motor capacity of 2 hp (1.5 kW) or larger with three or more control valves or other devices by reducing the system design flow rate by not less than 50 percent or the maximum reduction allowed by the equipment manufacturer for proper operation of equipment by 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 heating-water systems, chilled-water systems and heat rejection loops serving water-cooled unitary air conditioners as follows:

    3.1.  Where pumps operate continuously or operate based on a time schedule, pumps with nominal output motor power of 2 hp or more shall have a variable speed drive.

    3.2.  Where pumps have automatic direct digital control configured to operate pumps only when zone heating or cooling is required, a variable speed drive shall be provided for pumps with motors having the same or greater nominal output power indicated in Table C403.4.4 based on the climate zone and system served.

  4. Where a variable speed drive is required by Item 3 of this section, pump motor power input shall be not more than 30 percent of design wattage at 50 percent of the design water flow. 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 is not required for chilled-water systems supplied by off-site district chilled water or chilled water from ice storage systems.
  2. Variable pump flow is not required on dedicated coil circulation pumps where needed for freeze protection.
  3. Variable pump flow is not required 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.
  4. Variable speed drives are not required on heating water pumps where more than 50 percent of annual heat is generated by an electric boiler.

TABLE C403.4.4

VARIABLE SPEED DRIVE (VSD) REQUIREMENTS FOR DEMAND-CONTROLLED PUMPS

CHILLED WATER AND HEAT REJECTION LOOP PUMPS IN THESE CLIMATE ZONES HEATING WATER PUMPS IN THESE CLIMATE ZONES VSD REQUIRED FOR MOTORS WITH RATED OUTPUT OF:
0A, 0B, 1A, 1B, 2B ≥ 2 hp
2A, 3B ≥ 3 hp
3A, 3C, 4A, 4B 7, 8 ≥ 5 hp
4C, 5A, 5B, 5C, 6A, 6B 3C, 5A, 5C, 6A, 6B ≥ 7.5 hp
4A, 4C, 5B ≥ 10 hp
7, 8 4B ≥ 15 hp
2A, 2B, 3A, 3B ≥ 25 hp
0B, 1B ≥ 100 hp
0A, 1A ≥ 200 hp

For SI: 1 hp = 0.746 kW.

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

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

Economizers shall comply with Sections C403.5.1 through C403.5.5.

An air or water economizer shall be provided for the following cooling systems:

  1. Chilled water systems with a total cooling capacity, less cooling capacity provided with air economizers, as specified in Table C403.5(1).
  2. Individual fan systems with cooling capacity greater than or equal to 54,000 Btu/h (15.8 kW) in buildings having other than a Group R occupancy,

    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. Individual fan systems with cooling capacity greater than or equal to 270,000 Btu/h (79.1 kW) in buildings having a Group R occupancy.

    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 1,500,000 Btu/h (440 kW), whichever is greater.

Exceptions: Economizers are not required for the following systems.

  1. Individual fan systems not served by chilled water for buildings located in Climate Zones0A, 0B, 1A and 1B.
  2. 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.
  3. Systems expected to operate less than 20 hours per week.
  4. Systems serving supermarket areas with open refrigerated casework.
  5. Where the cooling efficiency is greater than or equal to the efficiency requirements in Table C403.5(2).
  6. Systems that include a heat recovery system in accordance with Section C403.10.5.
  7. VRF systems installed with a dedicated outdoor air system.

TABLE C403.5(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 systems Air-cooled chilled-water systems or district chilled-water systems
0A, 1A Economizer not required Economizer not required
0B, 1B, 2A, 2B 960,000 Btu/h 1,250,000 Btu/h
3A, 3B, 3C, 4A, 4B, 4C 720,000 Btu/h 940,000 Btu/h
5A, 5B, 5C, 6A, 6B, 7, 8 1,320,000 Btu/h 1,720,000 Btu/h

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


TABLE C403.5(2)

EQUIPMENT EFFICIENCY PERFORMANCE EXCEPTION FOR ECONOMIZERS

CLIMATE ZONES COOLING EQUIPMENT PERFORMANCE IMPROVEMENT (EER OR IPLV)
2A, 2B 10% efficiency improvement
3A, 3B 15% efficiency improvement
4A, 4B 20% efficiency improvement

Economizer systems shall be integrated with the mechanical cooling system and be 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) or greater of rated capacity of the capacity of the mechanical cooling directly based on occupied space temperature shall have not fewer than two stages of mechanical cooling capacity.
  3. Other DX units, including those that control space temperature by modulating the airflow to the space, shall be in accordance with Table C403.5.1.

TABLE C403.5.1

DX COOLING STAGE REQUIREMENTS FOR MODULATING AIRFLOW UNITS

RATING CAPACITY MINIMUM 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/h 4 stages ≤ 25% 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.

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 because of a reduction in supply air temperature.

Where economizers are required by Section C403.5, air economizers shall comply with Sections C403.5.3.1 through C403.5.3.5.
Air economizer systems shall be 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.

Economizer controls and dampers shall be configured to sequence the dampers with the mechanical cooling equipment and shall not be controlled by only mixed-air temperature.

Exception: The use of mixed-air temperature limit control shall be permitted for systems controlled from space temperature (such as single-zone systems).

Air economizers shall be configured to automatically reduce outdoor air intake to the design minimum outdoor air quantity when outdoor air intake will not reduce cooling energy usage. High-limit shutoff control types for specific climates shall be chosen from Table C403.5.3.3. High-limit shutoff control settings for these control types shall be those specified in Table C403.5.3.3.

TABLE C403.5.3.3

HIGH-LIMIT SHUTOFF CONTROL SETTING FOR AIR ECONOMIZERSb

DEVICE TYPE CLIMATE ZONE REQUIRED HIGH LIMIT (ECONOMIZER OFF WHEN):
Equation Description
Fixed dry bulb 0B, 1B, 2B, 3B, 3C, 4B, 4C, 5B, 5C, 6B, 7, 8 TOA> 75°F Outdoor air temperature exceeds 75°F
5A, 6A TOA> 70°F Outdoor air temperature exceeds 70°F
0A, 1A, 2A, 3A, 4A TOA> 65°F Outdoor air temperature exceeds 65°F
Differential dry bulb 0B, 1B, 2B, 3B, 3C, 4B, 4C, 5A, 5B, 5C, 6A, 6B, 7, 8 TOA > TRA Outdoor air temperature exceeds return air temperature
Fixed enthalpy with fixed dry-bulb temperatures All hOA > 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 temperature All hOA > hRA or TOA > 75°F Outdoor air enthalpy exceeds return air enthalpy or

Outdoor air temperature exceeds 75°F

For SI: °C = (°F — 32)/1.8, 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.
Systems shall be capable of relieving excess outdoor air during air economizer operation to prevent overpressurizing 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 C403.7.7.
Where economizers are required by Section C403.5, water-side economizers shall comply with Sections C403.5.4.1 and C403.5.4.2.

Water economizer systems shall be configured to cool 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 that 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.
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 kPa) 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.

Air-cooled unitary direct-expansion units listed in the tables in Section C403.3.2 and variable refrigerant flow (VRF) units that are equipped with an economizer in accordance with Sections C403.5 through C403.5.4 shall include a fault detection and diagnostics system complying with the following:

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

    1.1.  Outside air.

    1.2.  Supply air.

    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 configured to provide system status by indicating the following:

    4.1.  Free cooling available.

    4.2.  Economizer enabled.

    4.3.  Compressor enabled.

    4.4.  Heating enabled.

    4.5.  Mixed air low limit cycle active.

    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 configured to report faults to a fault management application available for access by day-to-day operating or service personnel, or annunciated locally on zone thermostats.
  7. The fault detection and diagnostics system shall be configured to detect the following faults:

    7.1.  Air temperature sensor failure/fault.

    7.2.  Not economizing when the unit should be economizing.

    7.3.  Economizing when the unit should not be economizing.

    7.4.  Damper not modulating.

    7.5.  Excess outdoor air.

Sections C403.6.1 through C403.6.9 shall apply to mechanical systems serving multiple zones.

Supply air systems serving multiple zones shall be variable air volume (VAV) systems that have zone controls configured to reduce the volume of air that is reheated, recooled or mixed in each zone to one of the following:

  1. Twenty percent of the zone design peak supply for systems with direct digital control (DDC) and 30 percent for other systems.
  2. Systems with DDC where all of the following apply:

    2.1.  The airflow rate in the deadband between heating and cooling does not exceed 20 percent of the zone design peak supply rate or higher allowed rates under Items 3, 4 and 5 of this section.

    2.2.  The first stage of heating modulates the zone supply air temperature setpoint up to a maximum setpoint while the airflow is maintained at the deadband flow rate.

    2.3.  The second stage of heating modulates the airflow rate from the deadband flow rate up to the heating maximum flow rate that is less than 50 percent of the zone design peak supply rate.

  3. The outdoor airflow rate required to meet 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 individual zones or entire air distribution systems are exempted from the requirement for VAV control:

  1. Zones or supply air systems where not less than 75 percent of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered, including condenser heat, or site-solar energy source.
  2. Systems that 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.
Single-duct VAV systems shall use terminal devices capable of and configured to reduce the supply of primary supply air before reheating or recooling takes place.
Systems that have one warm air duct and one cool air duct shall use terminal devices that are configured to reduce the flow from one duct to a minimum before mixing of air from the other duct takes place.
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.

Multiple-zone HVAC systems shall include controls that are capable of and configured to automatically reset the supply-air temperature in response to representative building loads, or to outdoor air temperature. The controls shall be configured to reset the supply air temperature not less than 25 percent of the difference between the design supply-air temperature and the design room air temperature. Controls that adjust the reset based on zone humidity are allowed in Climate Zones 0B, 1B, 2B, 3B, 3C and 4 through 8. HVAC zones that are expected to experience relatively constant loads shall have maximum airflow designed to accommodate the fully reset supply-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. Systems in Climate Zones 0A, 1A and 3A with less than 3,000 cfm (1500 L/s) of design outside air.
  4. Systems in Climate Zone 2A with less than 10,000 cfm (5000 L/s) of design outside air.
  5. Systems in Climate Zones 0A, 1A, 2A and 3A with not less than 80 percent outside air and employing exhaust air energy recovery complying with Section C403.7.4.
In Climate Zones 0A, 1A, 2A and 3A, the system design shall allow supply-air temperature reset while dehumidification is provided. When dehumidification control is active, air economizers shall be locked out.

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 where total design exhaust airflow is more than 70 percent of total design outdoor air intake flow requirements.

Parallel-flow fan-powered VAV air terminals shall have automatic controls configured to:

  1. Turn off the terminal fan except when space heating is required or where required for ventilation.
  2. Turn on the terminal fan as the first stage of heating before the heating coil is activated.
  3. During heating for warmup or setback temperature control, either:

    3.1.  Operate the terminal fan and heating coil without primary air.

    3.2.  Reverse the terminal damper logic and provide heating from the central air handler by primary air.

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 case, the setpoint 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. Automatic detection of any zone that excessively drives the reset logic.
  2. Generation of an alarm to the system operational location.
  3. Allowance for an operator to readily remove one or more zones from the reset algorithm.
Static pressure sensors used to control VAV fans shall be located such that the controller setpoint 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.
In addition to other requirements of Section C403 applicable to the provision of ventilation air or the exhaust of air, ventilation and exhaust systems shall be in accordance with Sections C403.7.1 through C403.7.7.

Demand control ventilation (DCV) shall be provided for all single-zone systems required to comply with Sections C403.5 through C403.5.3 and spaces larger than 500 square feet (46.5 m2) and with an average occupant load of 15 people or greater 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).

Exceptions:

  1. Systems with energy recovery complying with Section C403.7.4.2.
  2. Multiple-zone systems without direct digital control of individual zones communicating with a central control panel.
  3. Multiple-zone systems with a design outdoor airflow less than 750 cfm (354 L/s).
  4. Spaces where more than 75 percent of the space design outdoor airflow is required for makeup air that is exhausted from the space or transfer air that is required for makeup air that is exhausted from other spaces.  
  5. Spaces with one of the following occupancy classifications as defined in Table 403.3.1.1 of the International Mechanical Code: correctional cells, education laboratories, barber, beauty and nail salons, and bowling alley seating areas.

Enclosed parking garages used for storing or handling automobiles operating under their own power shall employ carbon monoxide detectors applied in conjunction with nitrogen dioxide detectors 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 8,000 cfm (3,755 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 1,125 cfm/hp (710 L/s/kW) and do not utilize heating or mechanical cooling.
Units that provide ventilation air to multiple zones and operate in conjunction with zone heating and cooling systems shall not use heating or heat recovery to warm supply air to a temperature greater than 60°F (16°C) when representative building loads or outdoor air temperatures indicate that the majority of zones require cooling.
Energy recovery ventilation systems shall be provided as specified in either Section C403.7.4.1 or C403.7.4.2, as applicable.
Nontransient dwelling units shall be provided with outdoor air energy recovery ventilation systems with an enthalpy recovery ratio of not less than 50 percent at cooling design condition and not less than 60 percent at heating design condition.

Exceptions:

  1. Nontransient dwelling units in Climate Zone 3C.
  2. Nontransient dwelling units with not more than 500 square feet (46 m2) of conditioned floor area in Climate Zones 0, 1, 2, 3, 4C and 5C.
  3. Enthalpy recovery ratio requirements at heating design condition in Climate Zones 0, 1 and 2.
  4. Enthalpy recovery ratio requirements at cooling design condition in Climate Zones 4, 5, 6, 7 and 8.

Where the supply airflow rate of a fan system serving a space other than a nontransient dwelling unit exceeds the values specified in Tables C403.7.4.2(1) and C403.7.4.2(2), the system shall include an energy recovery system. The energy recovery system shall provide an enthalpy recovery ratio of not less than 50 percent at design conditions. Where an air economizer is required, the energy recovery system shall include a bypass or controls that permit operation of the economizer as required by Section C403.5.

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 not fewer than one of the following features:

    2.1.  Variable-air-volume hood exhaust and room supply systems configured to reduce exhaust and makeup air volume to 50 percent or less of design values.

    2.2.  Direct makeup (auxiliary) air supply equal to or greater than 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, with 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 that are not cooled.
  4. Where more than 60 percent of the outdoor heating energy is provided from site-recovered or site-solar energy.
  5. Enthalpy recovery ratio requirements at heating design condition in Climate Zones 0, 1 and 2.
  6. Enthalpy recovery ratio requirements at cooling design condition 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 C403.7.4.2(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 C403.7.4.2(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)
3B, 3C, 4B, 4C, 5B NR NR NR NR NR NR NR NR
0B, 1B, 2B, 5C NR NR NR NR ≥ 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
0A, 1A, 2A, 3A, 4A, 5A, 6A ≥ 26,000 ≥ 16,000 ≥ 5,500 ≥ 4,500 ≥ 3,500 ≥ 2,000 ≥ 1,000 > 120
7, 8 ≥ 4,500 ≥ 4,000 ≥ 2,500 ≥ 1,000 > 140 > 120 > 100 > 80

For SI: 1 cfm = 0.4719 L/s.

NR = Not Required.

TABLE C403.7.4.2(2)

ENERGY RECOVERY REQUIREMENT (Ventilation systems operating not 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)
3C NR NR NR NR NR NR NR NR
0B, 1B, 2B, 3B, 4C, 5C NR ≥ 19,500 ≥ 9,000 ≥ 5,000 ≥ 4,000 ≥ 3,000 ≥ 1,500 ≥ 120
0A, 1A, 2A, 3A, 4B, 5B ≥ 2,500 ≥ 2,000 ≥ 1,000 ≥ 500 ≥ 140 ≥ 120 ≥ 100 ≥ 80
4A, 5A, 6A, 6B, 7, 8 ≥ 200 ≥ 130 ≥ 100 ≥ 80 ≥ 70 ≥ 60 ≥ 50 ≥ 40

For SI: 1 cfm = 0.4719 L/s.

NR = Not Required.

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 to be 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 C403.7.5 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.

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

TABLE C403.7.5

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 = 304.8 mm.

NA = Not Allowed.

In Group R-1 buildings containing more than 50 guestrooms, each guestroom shall be provided with controls complying with the provisions of Sections C403.7.6.1 and C403.7.6.2. Card key controls comply with these requirements.

Controls shall be provided on each HVAC system that are capable of and configured with three modes of temperature control.

  1. When the guestroom is rented but unoccupied, the controls shall automatically raise the cooling setpoint and lower the heating setpoint by not less than 4°F (2°C) from the occupant setpoint within 30 minutes after the occupants have left the guestroom.
  2. When the guestroom is unrented and unoccupied, the controls shall automatically raise the cooling setpoint to not lower than 80°F (27°C) and lower the heating setpoint to not higher than 60°F (16°C). Unrented and unoccupied guestroom mode shall be initiated within 16 hours of the guestroom being continuously occupied or where a networked guestroom control system indicates that the guestroom is  unrented and the guestroom is unoccupied for more than 20 minutes. A networked guestroom control system that is capable of returning the thermostat setpoints to default occupied setpoints 60 minutes prior to the time a guestroom is scheduled to be occupied is not precluded by this section. Cooling that is capable of limiting relative humidity with a setpoint not lower than 65-percent relative humidity during unoccupied periods is not precluded by this section.
  3. When the guestroom is occupied, HVAC setpoints shall return to their occupied setpoints once occupancy is sensed.

Controls shall be provided on each HVAC system that are capable of and configured to automatically turn off the ventilation and exhaust fans within 20 minutes of the occupants leaving the guestroom, or isolation devices shall be provided to each guestroom that are capable of automatically shutting off the supply of outdoor air to and exhaust air from the guestroom.

Exception: Guestroom ventilation systems are not precluded from having an automatic daily pre-occupancy purge cycle that provides daily outdoor air ventilation during unrented periods at the design ventilation rate for 60 minutes, or at a rate and duration equivalent to one air change.

Outdoor air intake and exhaust openings and stairway and shaft vents shall be provided with Class I motorized dampers. The dampers shall have an air leakage rate not greater than 4 cfm/ft2(20.3 L/s × m2) of damper surface area at 1.0 inch water gauge (249 Pa) and shall be labeled by an approved agency when tested in accordance with AMCA 500D for such purpose.

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.

Exception: Nonmotorized gravity dampers shall be an alternative to motorized dampers for exhaust and relief openings as follows:

  1. In buildings less than three stories in height above grade plane.
  2. In buildings of any height located in Climate Zones 0, 1, 2 or 3.
  3. Where the design exhaust capacity is not greater than 300 cfm (142 L/s).

Nonmotorized gravity dampers shall have an air leakage rate not greater than 20 cfm/ft2 (101.6 L/s × m2) where not less than 24 inches (610 mm) in either dimension and 40 cfm/ft2 (203.2 L/s × 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 (249 Pa) when tested in accordance with AMCA 500D for such purpose. The dampers shall be labeled by an approved agency.

Fans in HVAC systems shall comply with Sections C403.8.1 through C403.8.6.1.

Each HVAC system having a total fan system motor nameplate horsepower exceeding 5 hp (3.7 kW) at fan system design conditions shall not exceed the allowable fan system motor nameplate hp (Option 1) or fan system bhp (Option 2) shown in Table C403.8.1(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 C403.8.1(1)

FAN POWER LIMITATION

LIMIT CONSTANT VOLUME VARIABLE VOLUME
Option 1: Fan system motor nameplate hp Allowable nameplate motor hp hp ≤ CFMS × 0.0011 hp ≤ CFMS × 0.0015
Option 2: Fan system bhp Allowable fan system bhp bhp ≤ CFMS × 0.00094 + A bhp ≤ 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.

= Sum of [PD × CFMD / 4131].

where:

PD  = Each applicable pressure drop adjustment from Table C403.8.1(2) in. w.c.

CFMD  = The design airflow through each applicable device from Table C403.8.1(2) in cubic feet per minute.

TABLE C403.8.1(2)

FAN POWER LIMITATION PRESSURE DROP ADJUSTMENT

DEVICE ADJUSTMENT
Credits
Return air or exhaust systems required by code or accreditation standards to be fully ducted, or systems required to maintain air pressure differentials between adjacent rooms 0.5 inch w.c. (2.15 inches w.c. for laboratory and vivarium systems)
Return and exhaust airflow control devices 0.5 inch w.c.
Exhaust filters, scrubbers or other exhaust treatment The pressure drop of device calculated at fan system design condition
Particulate filtration credit: MERV 9 thru 12 0.5 inch w.c.
Particulate filtration credit: MERV 13 thru 15 0.9 inch w.c.
Particulate filtration credit: MERV 16 and greater and electronically enhanced filters Pressure drop calculated at 2 times the clean filter pressure drop at fan system design condition.
Carbon and other gas-phase air cleaners Clean filter pressure drop at fan system design condition.
Biosafety cabinet Pressure drop of device at fan system design condition.
Energy recovery device, other than coil runaround loop For each airstream, (2.2 × energy recovery effectiveness - 0.5) inch w.c.
Coil runaround loop 0.6 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 hoods 0.35 inch w.c.
Laboratory and vivarium exhaust systems in high-rise buildings 0.25 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 heat - 0.2 inch w.c.

For SI: 1 inch w.c. = 249 Pa, 1 inch = 25.4 mm, 1 foot = 304.8 mm.

w.c. = Water Column, NC = Noise Criterion.

For each fan, the fan brake horsepower (bhp) 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 (4476 W), 1.5 times the fan brake horsepower.
  2. For fans 6 bhp (4476 W) and larger, 1.3 times the fan brake horsepower.

Exceptions:

  1. Fans equipped with electronic speed control devices to vary the fan airflow as a function of load.
  2. Fans with a fan nameplate electrical input power of less than 0.89 kW.
  3. Systems complying with Section C403.8.1 fan system motor nameplate hp (Option 1).
  4. Fans with motor nameplate horsepower less than 1 hp (746 W).

Each fan and fan array shall have a fan energy index (FEI) of not less than 1.00 at the design point of operation, as determined in accordance with AMCA 208 by an approved independent testing laboratory and labeled by the manufacturer. Each fan and fan array used for a variable-air-volume system shall have an FEI of not less than 0.95 at the design point of operation, as determined in accordance with AMCA 208 by an approved independent testing laboratory and labeled by the manufacturer. The FEI for fan arrays shall be calculated in accordance with AMCA 208 Annex C.

Exceptions: The following fans are not required to have a fan energy index:

  1. Fans that are not embedded fans with motor nameplate horsepower of less than 1.0 hp (0.75 kW) or with a nameplate electrical input power of less than 0.89 kW.
  2. Embedded fans that have a motor nameplate horsepower of 5 hp (3.7 kW) or less, or with a fan system electrical input power of 4.1 kW or less.
  3. Multiple fans operated in series or parallel as the functional equivalent of a single fan that have a combined motor nameplate horsepower of 5 hp (3.7 kW) or less or with a fan system electrical input power of 4.1 kW or less.
  4. Fans that are part of equipment covered in Section C403.3.2.
  5. Fans included in an equipment package certified by an approved agency for air or energy performance.
  6. Ceiling fans, which are defined as nonportable devices suspended from a ceiling or overhead structure for circulating air via the rotation of the blades.
  7. Fans used for moving gases at temperatures above 425°F (250°C).
  8. Fans used for operation in explosive atmospheres.
  9. Reversible fans used for tunnel ventilation.
  10. Fans that are intended to operate only during emergency conditions.
  11. Fans outside the scope of AMCA 208.

Motors for fans that are not less than 1/12 hp (0.062 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 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 C403.3.2 or Sections C403.8.1. through C403.8.3.
  3. Motors that comply with Section C405.8.
Mechanical ventilation system fans with motors less than 1/12 hp (0.062 kW) in capacity shall meet the efficacy requirements of Table C403.8.5 at one or more rating points.

Exceptions:

  1. Where ventilation fans are a component of a listed heating or cooling appliance.
  2. Dryer exhaust duct power ventilators, domestic range hoods and domestic range booster fans that operate intermittently.

TABLE C403.8.5

LOW-CAPACITY VENTILATION FAN EFFICACYa

FAN LOCATION AIRFLOW RATE MINIMUM (CFM) MINIMUM EFFICACY (CFM/WATT) AIRFLOW RATE MAXIMUM (CFM)
HRV or ERV Any 1.2 cfm/watt Any
In-line fan Any 3.8 cfm/watt Any
Bathroom, utility room 10 2.8 cfm/watt < 90
Bathroom, utility room 90 3.5 cfm/watt Any

For SI: 1 cfm/ft = 47.82 W.

  1.  Airflow shall be tested in accordance with HVI 916 and listed. Efficacy shall be listed or shall be derived from listed power and airflow. Fan efficacy for fully ducted HRV, ERV, balanced and in-line fans shall be determined at a static pressure not less than 0.2 inch w.c. Fan efficacy for ducted range hoods, bathroom and utility room fans shall be determined at a static pressure not less than 0.1 inch w.c.
Controls shall be provided for fans in accordance with Section C403.8.6.1 and as required for specific systems provided in Section C403.

Each cooling system listed in Table C403.8.6.1 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 air-side economizer in accordance with Section C403.5 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 C403.8.6, the minimum speed shall be selected to provide the required ventilation air.

TABLE C403.8.6.1

COOLING SYSTEMS

COOLING SYSTEM TYPE FAN MOTOR SIZE MECHANICAL COOLING CAPACITY
DX cooling Any ≥ 65,000 Btu/h
Chilled water and evaporative cooling 1/4 hp Any

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

Where provided, large-diameter ceiling fans shall be tested and labeled in accordance with AMCA 230.

Heat rejection equipment, including air-cooled condensers, dry coolers, open-circuit cooling towers, closed-circuit cooling towers and evaporative condensers, shall comply with this section.

Exception: Heat rejection devices where energy usage is included in the equipment efficiency ratings listed in Tables C403.3.2(6) and C403.3.2(7).

Each fan system powered by an individual motor or array of motors with connected power, including the motor service factor, totaling 5 hp (3.7 kW) or more shall have controls and devices configured to automatically modulate the fan speed to control the leaving fluid temperature or condensing temperature and pressure of the heat rejection device. Fan motor power input shall be not more than 30 percent of design wattage at 50 percent of the design airflow.

Exceptions:

  1. Fans serving multiple refrigerant or fluid cooling circuits.
  2. Condenser fans serving flooded condensers.
Multiple-cell heat rejection equipment with variable speed fan drives shall be controlled to operate the maximum number of fans allowed that comply with the manufacturer's requirements for all system components and so that all fans operate at the same fan speed required for the instantaneous cooling duty, as opposed to staged on and off operation. The minimum fan speed shall be the minimum allowable speed of the fan drive system in accordance with the manufacturer's recommendations.

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 C403.3.2(8).

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

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.

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 (1758 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.
Where heating water is used for space heating, a condenser heat recovery system shall be installed provided all of the following are true:
  1. The building is a Group I-2 Condition 2 occupancy
  2. The total design chilled water capacity for the Group I-2 Condition 2 occupancy, either air cooled or water cooled, required at cooling design conditions exceeds 3,600,000 Btu/h (1,100 kw) of cooling.
  3. Simultaneous heating and cooling occurs above 60°F (16°C) outdoor air temperature.
The required heat recovery system shall have a cooling capacity that is not less than 7 percent of the total design chilled water capacity of the Group I-2 Condition 2 occupancy at peak design conditions.
Exceptions:
  1. Buildings that provide 60 percent or more of their reheat energy from on-site renewable energy or site-recovered energy
  2. Buildings in Climate Zones 5C, 6B, 7 and 8.

Refrigeration equipment performance shall be determined in accordance with Sections C403.11.1 and C403.11.2 for commercial refrigerators, freezers, refrigerator-freezers, walk-in coolers, walk-in freezers and refrigeration equipment.  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.

Exception: Walk-in coolers and walk-in freezers regulated under federal law in accordance with Subpart R of DOE 10 CFR 431.

Refrigeration equipment, defined in DOE 10 CFR Part 431.62, shall have an energy use in kWh/day not greater than the values of Table C403.11.1 when tested and rated in accordance with AHRI Standard 1200.

TABLE C403.11.1

MINIMUM EFFICIENCY REQUIREMENTS: COMMERCIAL REFRIGERATORS AND FREEZERS AND REFRIGERATION

EQUIPMENT CATEGORY CONDENSING UNIT CONFIGURATION EQUIPMENT FAMILY RATING TEMP., °F OPERATING TEMP., °F EQUIPMENT CLASSIFICATIONa, c MAXIMUM DAILY ENERGY CONSUMPTION,

kWh/dayd, e
TEST STANDARD
Remote condensing commercial refrigerators and commercial freezers Remote (RC) Vertical open (VOP) 38 (M) ≥ 32 VOP.RC.M 0.64 × TDA + 4.07 AHRI 1200
0 (L) < 32 VOP.RC.L 2.20 × TDA + 6.85
Semivertical open (SVO) 38 (M) ≥ 32 SVO.RC.M 0.66 × TDA + 3.18
0 (L) < 32 SVO.RC.L 2.20 × TDA + 6.85
Horizontal open (HZO) 38 (M) ≥ 32 HZO.RC.M 0.35 × TDA + 2.88
0 (L) < 32 HZO.RC.L 0.55 × TDA + 6.88
Vertical closed transparent (VCT) 38 (M) ≥ 32 VCT.RC.M 0.15 × TDA + 1.95
0 (L) < 32 VCT.RC.L 0.49 × TDA + 2.61
Horizontal closed transparent (HCT) 38 (M) ≥ 32 HCT.RC.M 0.16 × TDA + 0.13
0 (L) < 32 HCT.RC.L 0.34 × TDA + 0.26
Vertical closed solid (VCS) 38 (M) ≥ 32 VCS.RC.M 0.10 × V + 0.26
0 (L) < 32 VCS.RC.L 0.21 × V + 0.54
Horizontal closed solid (HCS) 38 (M) ≥ 32 HCS.RC.M 0.10 × V + 0.26
0 (L) < 32 HCS.RC.L 0.21 × V + 0.54
Service over counter (SOC) 38 (M) ≥ 32 SOC.RC.M 0.44 × TDA + 0.11
0 (L) < 32 SOC.RC.L 0.93 × TDA + 0.22
Self-contained commercial refrigerators and commercial freezers with and without doors Self-contained

(SC)
Vertical open (VOP) 38 (M) ≥ 32 VOP.SC.M 1.69 × TDA + 4.71 AHRI 1200
0 (L) < 32 VOP.SC.L 4.25 × TDA + 11.82
Semivertical open (SVO) 38 (M) ≥ 32 SVO.SC.M 1.70 × TDA + 4.59
0 (L) < 32 SVO.SC.L 4.26 × TDA + 11.51
Horizontal open (HZO) 38 (M) ≥ 32 HZO.SC.M 0.72 × TDA + 5.55
0 (L) < 32 HZO.RC.L 1.90 × TDA + 7.08
Vertical closed transparent (VCT) 38 (M) ≥ 32 VCT.SC.M 0.10 × V + 0.86
0 (L) < 32 VCT.SC.L 0.29 × V + 2.95
Vertical closed solid (VCS) 38 (M) ≥ 32 VCS.SC.M 0.05 × V + 1.36
0 (L) < 32 VCS.SC.L 0.22 × V + 1.38
Horizontal closed transparent (HCT) 38 (M) ≥ 32 HCT.SC.M 0.06 × V + 0.37
0 (L) < 32 HCT.SC.L 0.08 × V + 1.23
Horizontal closed solid (HCS) 38 (M) ≥ 32 HCS.SC.M 0.05 × V + 0.91
0 (L) < 32 HCS.SC.L 0.06 × V + 1.12
Service over counter (SOC) 38 (M) ≥ 32 SOC.SC.M 0.52 × TDA + 1.00
0 (L) < 32 SOC.SC.L 1.10 × TDA + 2.10
Self-contained commercial refrigerators with transparent doors for pull-down temperature applications Self-contained

(SC)
Pull-down (PD) 38 (M) ≥ 32 PD.SC.M 0.11 × V + 0.81 AHRI 1200
Commercial ice cream freezers Remote (RC) Vertical open (VOP) -15 (I) ≤ -5b VOP.RC.I 2.79 × TDA + 8.70 AHRI 1200
Semivertical open (SVO) SVO.RC.I 2.79 × TDA + 8.70
Horizontal open (HZO) HZO.RC.I 0.70 × TDA + 8.74
Vertical closed transparent (VCT) VCT.RC.I 0.58 × TDA + 3.05
Horizontal closed transparent (HCT) HCT.RC.I 0.40 × TDA + 0.31
Vertical closed solid (VCS) VCS.RC.I 0.25 × V + 0.63
Horizontal closed solid (HCS) HCS.RC.I 0.25 × V + 0.63
Service over counter (SOC) SOC.RC.I 1.09 × TDA + 0.26
Self-contained

(SC)
Vertical open (VOP) VOP.SC.I 5.40 × TDA + 15.02 AHRI 1200
Semivertical open (SVO) SVO.SC.I 5.41 × TDA + 14.63
Horizontal open (HZO) HZO.SC.I 2.42 × TDA + 9.00
Vertical closed transparent (VCT) VCT.SC.I 0.62 × TDA + 3.29
Horizontal closed transparent (HCT) HCT.SC.I 0.56 × TDA + 0.43
Vertical closed solid (VCS) VCS.SC.I 0.34 × V + 0.88
Horizontal closed solid (HCS) HCS.SC.I 0.34 × V + 0.88
Service over counter (SOC) SOC.SC.I 1.53 × TDA + 0.36

For SI: 1 square foot = 0.0929 m2, 1 cubic foot = 0.02832 m3, °C = (°F — 32)/1.8.

  1. The meaning of the letters in this column is indicated in the columns to the left.
  2. Ice cream freezer is defined in DOE 10 CFR 431.62 as a commercial freezer that is designed to operate at or below -5 °F and that the manufacturer designs, markets or intends for the storing, displaying or dispensing of ice cream.
  3. Equipment class designations consist of a combination [in sequential order separated by periods (AAA).(BB).(C)] of the following:

    1. •  (AAA)—An equipment family code (VOP = vertical open, SVO = semivertical open, HZO = horizontal open, VCT = vertical closed transparent doors, VCS = vertical closed solid doors, HCT = horizontal closed transparent doors, HCS = horizontal closed solid doors, and SOC = service over counter); 
    2. •  (BB)—An operating mode code (RC = remote condensing and SC = self-contained); and
    3. •  (C)—A rating temperature code [M = medium temperature (38°F), L = low temperature (0°F), or I = ice cream temperature (-15°F)]. 
    4. •  For example, "VOP.RC.M" refers to the "vertical open, remote condensing, medium temperature" equipment class.
  4. V is the volume of the case (ft3) as measured in AHRI 1200, Appendix C.
  5. TDA is the total display area of the case (ft2) as measured in AHRI 1200, Appendix D.
Walk-in cooler and walk-in freezer refrigeration systems, except for walk-in process cooling refrigeration systems as defined in DOE 10 CFR 431.302, shall meet the requirements of Tables C403.11.2.1(1), C403.11.2.1(2) and C403.11.2.1(3).
Walk-in coolers and walk-in freezers shall meet the requirements of Tables C403.11.2.1(1), C403.11.2.1(2) and C403.11.2.1(3).

TABLE C403.11.2.1(1)

WALK-IN COOLER AND FREEZER DISPLAY DOOR EFFICIENCY REQUIREMENTSa

CLASS DESCRIPTOR CLASS MAXIMUM ENERGY CONSUMPTION (kWh/day)a
Display door, medium temperature DD, M 0.04 × Add + 0.41
Display door, low temperature DD, L 0.15 × Add + 0.29
  1. Add is the surface area of the display door.

TABLE C403.11.2.1(2)

WALK-IN COOLER AND FREEZER NONDISPLAY DOOR EFFICIENCY REQUIREMENTSa

CLASS DESCRIPTOR CLASS MAXIMUM ENERGY CONSUMPTION (kWh/day)a
Passage door, medium temperature PD, M 0.05 × And + 1.7
Passage door, low temperature PD, L 0.14 × And + 4.8
Freight door, medium temperature FD, M 0.04 × And + 1.9
Freight door, low temperature FD, L 0.12 × And + 5.6
  1. And is the surface area of the nondisplay door.

TABLE C403.11.2.1(3)

WALK-IN COOLER AND FREEZER REFRIGERATION SYSTEM EFFICIENCY REQUIREMENTS

CLASS DESCRIPTOR CLASS MINIMUM ANNUAL WALK-IN ENERGY FACTOR AWEF (Btu/W-h)a TEST PROCEDURE
Dedicated condensing, medium temperature, indoor system DC.M.I 5.61 AHRI 1250
Dedicated condensing, medium temperature, outdoor system DC.M.O 7.60
Dedicated condensing, low temperature, indoor system, net capacity (qnet) < 6,500 Btu/h DC.L.I, < 6,500 9.091 × 10-5 × qnet + 1.81
Dedicated condensing, low temperature, indoor system, net capacity (qnet) ≥ 6,500 Btu/h DC.L.I, ≥ 6,500 2.40
Dedicated condensing, low temperature, outdoor system, net capacity (qnet) < 6,500 Btu/h DC.L.O, < 6,500 6.522 × 10-5 × qnet + 2.73
Dedicated condensing, low temperature, outdoor system, net capacity (qnet) ≥ 6,500 Btu/h DC.L.O, ≥ 6,500 3.15
Unit cooler, medium UC.M 9.00
Unit cooler, low temperature, net capacity (qnet) < 15,500 Btu/h UC.L, < 15,500 1.575 × 10-5 × qnet + 3.91
Unit cooler, low temperature, net capacity (qnet) ≥ 15,500 Btu/h UC.L, ≥ 15,500 4.15

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

  1. qnet is net capacity (Btu/h) as determined in accordance with AHRI 1250.

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 C403.11.3.1 and C403.11.3.2.

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

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:

    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.

    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).

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 (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.

    2.1.  Insulation for liquid lines with a fluid operating temperature less than 60°F (15.6°C) shall comply with Table C403.11.3.

  3. Compressors that incorporate internal or external crankcase heaters shall provide a means to cycle the heaters off during compressor operation.
Ducts, plenums, piping and other elements that are part of an HVAC system shall be constructed and insulated in accordance with Sections C403.12.1 through C403.12.3.1.

Supply and return air ducts and plenums shall be insulated with not less than R-6 insulation where located in unconditioned spaces and where located outside the building with not less than R-8 insulation in Climate Zones 0 through 4 and not less than R-12 insulation in Climate Zones 5 through 8. Ducts located underground beneath buildings shall be insulated as required in this section or have an equivalent thermal distribution efficiency. Underground ducts utilizing the thermal distribution efficiency method shall be listed and labeled to indicate the R-value equivalency. Where located within a building envelope assembly, the duct or plenum shall be separated from the building exterior or unconditioned or exempt spaces by not less than R-8 insulation in Climate Zones 0 through 4 and not less than 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.

Ductwork shall be constructed and erected in accordance with the International Mechanical Code.

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), mas-tic-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.

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 C403.12.1. Pressure classifications specific to the duct system shall be clearly indicated on the construction documents in accordance with the International Mechanical Code.

Ducts and plenums designed to operate at static pressures equal to or greater than 3 inches water gauge (747 Pa) shall be insulated and sealed in accordance with Section C403.12.1. 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 (9.3 m2) of duct surface.

= The static pressure of the test.

Documentation shall be furnished demonstrating that representative sections totaling not less than 25 percent of the duct area have been tested and that all tested sections comply with the requirements of this section.

Piping serving as part of a heating or cooling system shall be thermally insulated in accordance with Table C403.12.3.

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).
  7. In radiant heating systems, sections of piping intended by design to radiate heat.

TABLE C403.12.3

MINIMUM PIPE INSULATION THICKNESS (in inches)a, c

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 < 11/2 11/2 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 50 0.5 1.0 1.0 1.0 1.5

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 Note 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:

    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).       
    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 Note b but not to thicknesses less than 1 inch.
Piping insulation exposed to the weather shall be protected from damage, including that caused by 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.
Mechanical systems providing heat outside of the thermal envelope of a building shall comply with Sections C403.13.1 through C403.13.3.

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 de-energized when occupants are not present.

Snow- and ice-melting systems shall include automatic controls configured to shut off the system when the pavement temperature is above 50°F (10°C) and precipitation is not falling, and an automatic or manual control that is configured to shut off when the outdoor temperature is above 40°F (4°C).
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.
The heating and cooling systems shall have controls that will interlock these mechanical systems to the set temperatures of 90°F (32°C) for cooling and 55°F (12.7°C) for heating when the conditions of Section C402.5.8 exist. The controls shall configure to shut off the systems entirely when the outdoor temperatures are below 90°F (32°C) or above 55°F (12.7°C).
This section covers the minimum efficiency of, and controls for, service water-heating equipment and insulation of service hot water piping.
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 under an approved certification program. Water-heating equipment 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 Tabletope, ≥ 20 gallons and ≤ 120 gallons 0.93 — 0.00132V, EF DOE 10 CFR Part 430
Resistance ≥ 20 gallons and ≤ 55 gallons 0.960 — 0.0003V, EF
Grid-enabledf > 75 gallons and ≤ 120 gallons 1.061 — 0.00168V, EF
> 12 kW Resistance (0.3 + 27/Vm), %/h ANSI Z21.10.3
≤ 24 amps and ≤ 250 volts Heat pump > 55 gallons and ≤ 120 gallons 2.057 — 0.00113V, EF DOE 10 CFR Part 430
Storage water heaters, gas ≤ 75,000 Btu/h ≥ 20 gallons and > 55 gallons 0.675 — 0.0015V, EF DOE 10 CFR Part 430
> 55 gallons and ≤ 100 gallons 0.8012 — 0.00078V, EF
> 75,000 Btu/h and ≤ 155,000 Btu/h < 4,000 Btu/h/gal 80% Et

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 0.82 — 0.00 19V, EF DOE 10 CFR Part 430
≥ 200,000 Btu/h ≥ 4,000 Btu/h/gal and < 10 gal 80% Et 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 and ≤ 50 gallons 0.68 — 0.0019V, EF DOE 10 CFR Part 430
≥ 105,000 Btu/h < 4,000 Btu/h/gal 80% Et

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 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 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% Et ASHRAE 146
Heat pump pool heaters All 4.0 COP AHRI 1160
Unfired storage tanks All Minimum insulation requirement R-12.5 (h × ft2 × °F)/Btu (none)

For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, °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 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 shall comply with these requirements where the water heater is designed to heat water to temperatures 180°F or higher.
  4. Electric water heaters with an input rating of 12 kW (40,950 Btu/h) 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).
  5. A tabletop water heater is a water heater that is enclosed in a rectangular cabinet with a flat top surface not more than 3 feet in height.
  6. A grid-enabled water heater is an electric-resistance water heater that meets all of the following:

    1. Has a rated storage tank volume of more than 75 gallons.
    2. Was manufactured on or after April 16, 2015.
    3. Is equipped at the point of manufacture with an activation lock.
    4. Bears a permanent label applied by the manufacturer that complies with all of the following:

      4.1.  Is made of material not adversely affected by water.

      4.2.  Is attached by means of nonwater-soluble adhesive.

      4.3.  Advises purchasers and end users of the intended and appropriate use of the product with the following notice printed in 16.5 point Arial Narrow Bold font: "IMPORTANT INFORMATION: This water heater is intended only for use as part of an electric thermal storage or demand response program. It will not provide adequate hot water unless enrolled in such a program and activated by your utility company or another program operator. Confirm the availability of a program in your local area before purchasing or installing this product."

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 92 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 less than 90 percent.

Exceptions:

  1. Where not less than 25 percent of the annual service water-heating requirement is provided by on-site renewable energy 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 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.
Storage tank-type water heaters and hot water storage tanks that have vertical water pipes connecting to the inlet and outlet of the tank shall be provided with integral heat traps at those inlets and outlets or shall have pipe-configured heat traps in the piping connected to those inlets and outlets. Tank inlets and outlets associated with solar water heating system circulation loops shall not be required to have heat traps.

Piping from a water heater to the termination of the heated water fixture supply pipe shall be insulated in accordance with Table C403.12.3. 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 C403.12.3 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.

Heated water supply piping shall be in accordance with Section C404.5.1 or C404.5.2. 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).

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 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

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

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 to be 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).
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 or from Table C404.5.2.1. 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.

TABLE C404.5.2.1

INTERNAL VOLUME OF VARIOUS WATER DISTRIBUTION TUBING

OUNCES OF WATER PER FOOT OF TUBE
Nominal Size (inches) Copper Type M Copper Type L Copper Type K CPVC CTS SDR 11 CPVC SCH 40 CPVC SCH 80 PE-RT SDR 9 Composite ASTM F1281 PEX CTS SDR 9
3/8 1.06 0.97 0.84 N/A 1.17 0.64 0.63 0.64
1/2 1.69 1.55 1.45 1.25 1.89 1.46 1.18 1.31 1.18
3/4 3.43 3.22 2.90 2.67 3.38 2.74</