ADOPTS WITH AMENDMENTS:

International Energy Conservation Code 2009 (IECC 2009)

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

501.1 Scope

AMENDMENT
This section has been amended at the state or city level.
The requirements contained in this chapter are applicable to commercial buildings, or portions of commercial buildings. These commercial buildings shall either:
  1. Meet the requirements contained in this chapter, or
  2. Meet the requirements of ANSI/ASHRAE/IESNA Standard 90.1—2010.
North Carolina specific COMcheck shall be permitted to demonstrate compliance with this code.

501.2 Application

AMENDMENT
This section has been amended at the state or city level.
The commercial building project shall comply with the requirements in Sections 502 (Building envelope requirements), 503 (Building mechanical systems), 504 (Service water heating), 505 (Electrical power and lighting systems) and 506 (Additional prescriptive options). Compliance with section 506 requires complying with one (1) of the following prescriptive options:
  1. 506.2.1 More Efficient Mechanical Equipment,
  2. 506.2.2 Reduced Lighting Power Density,
  3. 506.2.3 Energy Recovery Ventilation Systems,
  4. 506.2.4 Higher Efficiency Service Water Heating,
  5. 506.2.5 On-Site Supply of Renewable Energy, or
  6. 506.2.6 Automatic Daylighting Control System.
At the time of plan submittal, the building jurisdiction shall be provided, by the submittal authority, documentation designating the intent to comply with Section 506.2.1, 506.2.2, 506.2.3, 506.2.4, 506.2.5 or 506.2.6 in their entirety.
Exception: Buildings conforming to Section 507, provided Sections 502.4, 503.2, 504, 505.2, 505.3, 505.4, 505.6 and 505.7 are each satisfied.

502.1.1 Insulation and Fenestration Criteria

AMENDMENT
This section has been amended at the state or city level.
The building thermal envelope shall meet the requirements of Tables 502.2(1) and 502.3 based on the climate zone specified in Chapter 3. Commercial buildings or portions of commercial buildings enclosing Group R occupancies shall use the R-values from the "Group R" column of Table 502.2(1). 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 502.2(1).

502.1.2 U-factor Alternative

AMENDMENT
This section has been amended at the state or city level.
An assembly with a U-factor, C-factor, or F-factor equal or less than that specified in Table 502.1.2 shall be permitted as an alternative to the R-value in Table 502.2(1). Commercial buildings or portions of commercial buildings enclosing Group R occupancies shall use the U-factor, C-factor, or F-factor from the "Group R" column of Table 502.1.2.

Commercial buildings or portions of commercial buildings enclosing occupancies other than Group R shall use the U-factor, C-factor or F-factor from the "All other" column of Table 502.1.2.
TABLE 502.1.2
BUILDING ENVELOPE REQUIREMENTS OPAQUE ELEMENT, MAXIMUM U-FACTORS
CLIMATE ZONE 3 4 5
All Other Group R All Other Group R All Other Group R
Roofs
Insulation entirely above
deck
U-0.039 U-0.039 U-0.032 U-0.032 U-0.032 U-0.032
Metal buildings U-0.041 U-0.041 U-0.037 U-0.037 U-0.037 U-0.037
Attic and other —
wood framing
Attic and other —
steel framing
U-0.027

U-0.035
U-0.027

U-0.035
U-0.024

U-0.029
U-0.024

U-0.029
U-0.024

U-0.029
U-0.024

U-0.029
Walls, Above Grade
Mass U-0.123 U-0.104 U-0.104 U-0.090 U-0.090 U-0.071
Metal building U-0.094 U-0.072 U-0.060 U-0.050 U-0.050 U-0.050
Metal framed U-0.064 U-0.064 U-0.064 U-0.064 U-0.064 U-0.055
Wood framed and other U-0.064 U-0.064 U-0.064 U-0.0464 U-0.064 U-0.051
Walls, Below Grade
Below-grade walla C-1.119 C-0.119 C-0.119 C-0.092 C-0.119 C-0.092
Floors
Mass U-0.064 U-0.064 U-0.057 U-0.051 U-0.057 U-0.051
Joist/Framing — wood
Joist/Framing — steel
U-0.033
U-0.032
U-0.033
U-0.032
U-0.026
U-0.032
U-0.026
U-0.032
U-0.026
U-0.032
U-0.026
U-0.032
Slab-on-Grade Floors
Unheated slabs F-0.730 F-0.540 F-0.520 F-0.520 F-0.520 F-0.510
Heated slabs F-0.860 F-0.860 F-0.843 F-0.688 F-0.688 F-0.688

a. When heated slabs are placed below-grade, below grade walls must meet the F-factor requirements for perimeter insulation according to the heated slab-on-grade construction.

502.2 Specific Insulation Requirements (Prescriptive)

AMENDMENT
This section has been amended at the state or city level.
Opaque assemblies shall comply with Table 502.2(1).
TABLE 502.2(1)
BUILDING ENVELOPE REQUIREMENTS - OPAQUE ASSEMBLIES
CLIMATE ZONE 3 4
5
All other Group R All other Group R All other Group R
Roofs
Insulation entirely above deck
R-25ci R-25ci R-30ci R-30ci R-30ci R-30ci
Metal buildings a, b
R-10 + R-19 FC R-10 + R-19 FC R-19 + R-11 Ls or
R-25 + R-8 LS
R-19 + R-11 Ls or
R-25 + R-8 LS
R-19 + R-11 Ls or
R-25 + R-8 LS
R-19 + R-11 Ls or
R-25 + R-8 LS
Attic and other — wood framingf
R-38 R-38 R-42 R-42 R-42 R-342
Attic and other — steel framingf
R-38 R-38 R-49 R-49 R-49 R-49
Walls, Above Grade
Mass R-7.6ci R-9.5ci R-9.5ci  R-11.4ci R-11.4ci R-15ci
Metal buildingb R-0 +R-9.8ci R-0 +R-13ci R-0 +R-15.8ci R-0 +R-19ci R-0 +R-19ci R-0 +R-19ci
Metal framed R-13 + R-7.5ci R-13 + R-7.5ci R-13 +
R-7.5ci
R-13 + R-7.5ci R-13 +
R-7.5 ci
R-13 + R-10ci
Wood framed and other R-13 + R-3.8ci  or R-20 R-13 + R-3.8  or R-20 R-13 + R-3.8ci  or R-20 R-13+ R-3.8ci  or R-20 R-13 + R-3.8ci  or R-20 R-13 +
R-7.5ci  or R-20
Walls, Below Grade
Below grade wallc R-7.5ci R-7.5ci R-7.5ci R-10ci R-7.5ci R-10ci
Floors
Mass R-12.5ci R-12.5ci R-12.5ci R-14.6ci R-16.7ci R-14.6ci R-16.7ci
Joist/Framing
R-30e R-30e R-38 R-38 R-38 R-38
Slab-on-Grade Floors
Unheated slabs NR R-10 for 24 in. R-15 for 24 in. R-15 for 24 in. R-15 for 24 in. R-15 for 24 in.
Heated slabs R-15 for 24 in. R-15 for 24 in. R-20 for 24 in. R-20 for 48 in. R-20 for 48 in. R-20 for 48 in.
Opaque doors
Swinging U — 0.70 U — 0.50 U —0.50 U — 0.50 U — 0.50 U — 0.50
Roll-up or sliding U — 0.50 U — 0.50 U — 0.50 U — 0.50 U — 0.50 U — 0.50
For SI: 1 inch = 25.4 mm.
ci = Continuous insulation. FC = Filled Cavity. LS = Linear System. NR = No requirement.
LS = Liner System — Liner systems shall have a minimum R-3.5 thermal spacer block between the purlins and the metal roof panels as required, unless compliance is shown by the overall assembly U-factor.
FC = Filled Cavity — Filled cavity assemblies shall have a minimum R-5 thermal spacer block between the purlins and the metal roof panels as required, unless compliance is shown by the overall assembly U-factor.
  1. When using R-value compliance method, a thermal spacer block is required, otherwise use the U-factor compliance method. [see Tables 502.1.2 and 502.2(2)].
  2. Assembly descriptions can be found in Table 502.2(2).
  3. R-5.7 ci is allowed to be substituted with concrete block walls complying with ASTM C 90, ungrouted or partially grouted at 32 inches or less on center vertically and 48 inches or less on center horizontally, with ungrouted cores filled with material having a maximum thermal conductivity of 0.44 Btu-in./hr • ft2 • °F.
  4. When heated slabs are placed below grade, below-grade walls must meet the exterior insulation requirements for perimeter insulation according to the heated slab-on-grade construction.
  5. Steel floor joist systems shall to be R-38.
  6. R-30 shall be deemed to satisfy the requirement for R-38 wherever the full height of uncompressed R-30 insulation extends over the wall top plate at the eaves. Similarly, R-38 shall be deemed to satisfy the requirement for R-42 or R-49 wherever the full height of uncompressed R-38 insulation extends over the wall top plate at the eaves.
TABLE 502.2(2)
BUILDING ENVELOPE REQUIREMENTS—OPAQUE ASSEMBLIES
ROOFS
DESCRIPTION
R-10 + R-19 FC Filled cavity fiberglass insulation.

A continuous vapor barrier is installed below the purlins and uninterrupted by framing members. Both layers of uncompressed, unfaced fiberglass insulation rest on top of the vapor barrier and are installed parallel, between the purlins. A minimum R-5 thermal spacer block is placed above the purlin/batt, and the roof deck is secured to the purlins. Drawings of typical details are shown in Appendix 2.2.
WALLS  
R-0 + R-13 ci
R-0 + R-19 ci
The second rated R-value is for continuous rigid insulation installed between the metal wall panel and steel framing, or on the interior of the steel framing. Drawings of typical details are shown in Appendix 2.2.
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 502.2(1), based on construction materials used in the roof assembly.
Exception:Continuously insulated roof assemblies where the thickness of insulation varies 1 inch (25 mm) or less and where the area-weighted U-factor is equivalent to the same assembly with the R-value specified in Table 502.2(1).

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

Walls associated with the building envelope shall be classified in accordance with Section 502.2.2.1 or 502.2.2.2.
Above-grade walls are those walls covered by Section 502.2.3 on the exterior of the building and completely above grade or walls that are more than 15 percent above grade.
Below-grade walls covered by Section 502.2.4 are basement or first-story walls associated with the exterior of the building that are at least 85 percent below grade.
The minimum thermal resistance (R-value) of the insulating material(s) installed in the wall cavity between the framing members and continuously on the walls shall be as specified in Table 502.2(1), based on framing type and construction materials used in the wall assembly. The R-value of integral insulation installed in concrete masonry units (CMU) shall not be used in determining compliance with Table 502.2(1). "Mass walls" shall include walls weighing at least (1) 35 pounds per square foot (170 kg/m2) of wall surface area or (2) 25 pounds per square foot (120 kg/m2) of wall surface area if the material weight is not more than 120 pounds per cubic foot (1900 kg/m3).
The minimum thermal resistance (R-value) of the insulating material installed in, or continuously on, the below-grade walls shall be as specified in Table 502.2(1), and shall extend to a depth of 10 feet (3048 mm) below the outside finished ground level, or to the level of the floor, whichever is less.

The minimum thermal resistance (R-value) of the insulating material installed either between the floor framing or continuously on the floor assembly shall be as specified in Table 502.2(1), based on construction materials used in the floor assembly.

"Mass floors" shall include floors weighing at least (1) 35 pounds per square foot (170 kg/m2) of floor surface area or (2) 25 pounds per square foot (120 kg/m2) of floor surface area if the material weight is not more than 120 pounds per cubic foot (1,900 kg/m3).

The minimum thermal resistance (R-value) of the insulation around the perimeter of unheated or heated slab-on-grade floors shall be as specified in Table 502.2(1). The insulation shall be placed on the outside of the foundation or on the inside of a foundation wall. The insulation shall extend downward from the top of the slab for a minimum distance as shown in the table or to the top of the footing, whichever is less, or downward to at least the bottom of the slab and then horizontally to the interior or exterior for the total distance shown in the table.
Opaque doors (doors having less than 50 percent glass area) shall meet the applicable requirements for doors as specified in Table 502.2(1) and be considered as part of the gross area of above-grade walls that are part of the building envelope.

502.3 Fenestration (Prescriptive)

AMENDMENT
This section has been amended at the state or city level.
Fenestration shall comply with Table 502.3.
TABLE 502.3
BUILDING ENVELOPE REQUIREMENTS: FENESTRATION
CLIMATE ZONE 3 4 5
Vertical fenestration (30% maximum of above-grade wall)
U-factor
Framing materials other than metal with or without metal reinforcement or cladding
U-factor 0.32 0.32 0.30
Metal framing with or without thermal break
Curtain wall/storefront U-factor 0.45 0.45 0.38
Entrance door U-factor 0.77 0.77 0.77
All other U-factora 0.45 0.45 0.45
SHGC-all frame types
SHGC: PF < 0.25 0.25 0.25 0.40
SHGC: 0.25 ≤ PF < 0.5 0.33 0.33 NR
SHGC: PF ≥ 0.5 0.40 0.40 NR
Skylights (3% maximum, 5% if using automatic daylighting controls)
U-factor 0.60 0.60 0.60
SHGC 0.35 0.35 0.40
SHGC = Solar Heat Gain Coefficient. (approximately equal to 0.87 times the Shading Coefficient).

NR = No requirement.

PF = Projection factor (see Section 502.3.2).

  1. All others includes operable windows, fixed windows and nonentrance doors.
The vertical fenestration area (not including opaque doors) shall not exceed the percentage of the gross wall area specified in Table 502.3. The skylight area shall not exceed the percentage of the gross roof area specified in Table 502.3.

For vertical fenestration, the maximum U-factor and solar heat gain coefficient (SHGC) shall be as specified in Table 502.3, based on the window projection factor. For skylights, the maximum U-factor and solar heat gain coefficient (SHGC) shall be as specified in Table 502.3.

The window projection factor shall be determined in accordance with Equation 5-1.

PF = A/B (Equation 5-1)

where:

PF = Projection factor (decimal).

A = Distance measured horizontally from the furthest continuous extremity of any overhang, eave, or permanently attached shading device to the vertical surface of the glazing.

B = Distance measured vertically from the bottom of the glazing to the underside of the overhang, eave, or permanently attached shading device.

Where different windows or glass doors have different PF values, they shall each be evaluated separately, or an area-weighted PF value shall be calculated and used for all windows and glass doors.

502.4 Air Leakage Control (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.

502.4.1 Window and Door Assemblies

AMENDMENT
This section has been amended at the state or city level.
The air leakage of window and sliding or swinging door assemblies that are part of the building envelope shall be determined in accordance with AAMA/WDMA/CSA 101/I.S.2/A440, or NFRC 400 by an accredited (by a body such as IAS or NFRC), independent laboratory, and labeled and certified by the manufacturer and shall not exceed the values in Section 402.4.4.
Exception: Site-constructed windows and doors that are weatherstripped or sealed in accordance with Section 502.4.3.
Curtain wall, storefront glazing and commercial-glazed swinging entrance doors and revolving doors shall be tested for air leakage at 1.57 pounds per square foot (psf) (75 Pa) in accordance with ASTM E 283. For curtain walls and storefront glazing, the maximum air leakage rate shall be 0.3 cubic foot per minute per square foot (cfm/ft2) (5.5 m3/h × m2) of fenestration area. For commercial glazed swinging entrance doors and revolving doors, the maximum air leakage rate shall be 1.00 cfm/ft2 (18.3 m3/h × m2) of door area when tested in accordance with ASTM E 283.

502.4.3 Sealing of the Building Envelope

AMENDMENT
This section has been amended at the state or city level.
Openings and penetrations in the building envelope shall be sealed with caulking materials or closed with gasketing systems compatible with the construction materials and location. Joints and seams of the air barrier system shall be sealed in the same manner or taped or covered with a moisture vapor-permeable wrapping material. Sealing materials spanning joints between construction materials shall allow for expansion and contraction of the construction materials. See construction details in Appendix 2.1.

The following connections shall be air sealed:
  1. Joints around fenestration and door frames
  2. Junctions between walls and foundations, between walls at building corners, between walls and structural floors or roofs, and between walls and roof or wall panels
  3. Openings at penetrations of utility services through roofs, walls, and floors including but not limited to electrical, plumbing, mechanical, security, and communications
  4. Site-built fenestration and doors
  5. Joints, seams, and penetrations of the air barrier system
  6. Other openings in the building envelope

502.4.5 Outdoor Air Intakes and Exhaust Openings

AMENDMENT
This section has been amended at the state or city level.

502.4.5 Stair and Elevator Vents

AMENDMENT
This section has been amended at the state or city level.
Shaft vents serving stairs and elevators integral to the building thermal envelope shall be equipped with not less than a Class I motorized, leakage- rated damper with a maximum leakage rate of 4 cfm per square foot (6.8 L/s • Cm2) at 1.0 inch water gauge (w.g.) (125 Pa) when tested in accordance with AMCA 500D.

Exceptions:
  1. Buildings without fire alarm systems.
  2. Stairway vents open to the exterior.
Cargo doors and loading dock doors shall be equipped with weatherseals to restrict infiltration when vehicles are parked in the doorway.

502.4.7 Vestibules

AMENDMENT
This section has been amended at the state or city level.
A door that separates conditioned space from the exterior 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.
Exceptions:
  1. Doors not intended to be used as a building entrance door, such as doors to mechanical or electrical equipment rooms.
  2. Doors opening directly from a sleeping unit or dwelling unit.
  3. Doors that open directly from a space less than 3,000 square feet (298 m2) in area.
  4. Revolving doors.
  5. Doors used primarily to facilitate vehicular movement or material handling and adjacent personnel doors.
  6. Building entrances in buildings that are less than four stories above grade and less than 10,000 square feet in area.

502.4.8 Recessed Lighting

AMENDMENT
This section has been amended at the state or city level.
Recessed luminaires installed in the building thermal envelope shall be IC-rated and labeled as meeting ASTM E 283 when tested at 1.57 psf (75 Pa) pressure differential with no more than 2.0 cfm (0.944 L/s) of air movement from the conditioned space to the ceiling cavity. Such recessed luminaires shall be sealed with a gasket or caulk between the housing and interior wall or ceiling covering.

Mechanical systems and equipment serving the building heating, cooling or ventilating needs shall comply with Section 503.2 (referred to as the mandatory provisions) and either:

  1. Section 503.3 (Simple systems), or
  2. Section 503.4 (Complex systems).

503.2 Provisions Applicable to All Mechanical Systems (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.
Design loads shall be determined in accordance with the procedures described in the ASHRAE/ACCA Standard 183. Heating and cooling loads shall be adjusted to account for load reductions that are achieved when energy recovery systems are utilized in the HVAC system in accordance with the ASHRAE HVAC Systems and Equipment Handbook. Alternatively, design loads shall be determined by an approved equivalent computation procedure, using the design parameters specified in Chapter 3.

503.2.2 Equipment and System Sizing

AMENDMENT
This section has been amended at the state or city level.
Heating and cooling equipment and systems capacity shall not exceed the loads calculated in accordance with Section 503.2.1, within available equipment options. A single piece of equipment providing both heating and cooling must satisfy this provision for one function with the capacity for the other function as small as possible.
Exceptions:
  1. Required standby equipment and systems provided with controls and devices that allow such systems or equipment to operate automatically only when the primary equipment is not operating.
  2. Multiple units of the same equipment type with combined capacities exceeding the design load and provided with controls that have the capability to sequence the operation of each unit based on load.
  3. When the equipment selected is the smallest size needed to meet the load within available options of the desired equipment line.

503.2.3 HVAC Equipment Performance Requirements

AMENDMENT
This section has been amended at the state or city level.
Equipment shall meet the minimum efficiency requirements of Tables 503.2.3(1), 503.2.3(2), 503.2.3(3), 503.2.3(4), 503.2.3(5), 503.2.3(6), 503.2.3(7) and 503.2.3(8) when tested and rated in accordance with the applicable test procedure. The efficiency shall be verified through certification under an approved certification program or, if no certification program exists, the equipment efficiency ratings shall be supported by data furnished by the manufacturer. Where multiple rating conditions or performance requirements are provided, the equipment shall satisfy all stated requirements. Where components, such as indoor or outdoor coils, from different manufacturers are used, calculations and supporting data shall be furnished by the designer that demonstrates that the combined efficiency of the specified components meets the requirements herein.
Exception: Water-cooled centrifugal water-chilling packages listed in Table 503.2.3(7) not designed for operation at ARHI Standard 550/590 test conditions of 44°F (7°C) leaving chilled water temperature and 85°F (29°C) entering condenser water temperature with 3 gpm/ton (0.054 I/s.kW) condenser water flow shall have maximum full load and NPLV ratings adjusted using the following equations:
Adjusted maximum full load kW/ton rating = [full load kW/ton from Table 503.2.3(7)]/Kadj

Adjusted maximum NPLV rating = [IPLV from Table 503.2.3(7)]/Kadj

where:
Kadj = 6.174722 - 0.303668(X) + 0.00629466(X)2 - 0.000045780(X)3

X = DTstd + LIFT

DTstd = {24+[full load kW/ton from Table 503.2.3(7)] × 6.83}/Flow

Flow = Condenser water flow (GPM)/Cooling Full Load Capacity (tons)

LIFT = CEWT — CLWT (°F)

CEWT = Full Load Condenser Entering Water Temperature (°F)

CLWT = Full Load Leaving Chilled Water Temperature (°F)

The adjusted full load and NPLV values are only applicable over the following full-load design ranges:

Minimum Leaving Chilled Water Temperature: 38°F (3.3°C)

Maximum Condenser Entering Water Temperature: 102°F (38.9°C)

Condensing Water Flow: 1 to 6 gpm/ton 0.018 to 0.1076 1/s × kW) and X ≥ 39 and ≤ 60

Chillers designed to operate outside of these ranges or applications utilizing fluids or solutions with secondary coolants (e.g., glycol solutions or brines) with a freeze point of 27°F (-2.8°C) or lower for freeze protection are not covered by this code.

TABLE 503.2.3(1)
UNITARY AIR CONDITIONERS AND CONDENSING UNITS, ELECTRICALLY OPERATED, MINIMUM EFFICIENCY REQUIREMENTS
EQUIPMENT TYPE SIZE CATEGORYe SUBCATEGORY OR
RATING CONDITION
MINIMUM EFFICIENCYb TEST PROCEDUREa
Air conditioners,
Air cooled
< 65,000 Btu/hd Split system 13.0 SEER AHRI 210/240
Single package 13.0 SEER
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Split system and
single package
11.2 EERc
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Split system and
single package
11.0 EERc AHRI 340/360
≥ 240,000 Btu/h
and
< 760,000 Btu/h
Split system and
single package
10.0 EERc
9.7 IPLVg
≥ 760,000 Btu/h Split system and
single package
9.7 EERc
9.4 IPLVc
Through-the-wall,
Air cooled
< 30,000 Btu/hd Split system 12.0 SEER AHRI 210/240
Single package 12.0 SEER
Air conditioners, Water
and evaporatively cooled
< 65,000 Btu/h Split system and
single package
12.1 EER AHRI 210/240
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Split system and
single package
11.5 EERc
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Split system and
single package
11.0 EERc AHRI 340/360
≥ 240,000 Btu/h Split system and
single package
11.5 EERc

For SI: 1 British thermal unit per hour = 0.2931 W.
  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. IPLVs are only applicable to equipment with capacity modulation.
  3. Deduct 0.2 from the required EERs and IPLVs for units with a heating section other than electric resistance heat.
  4. Single-phase air-cooled air conditioners < 65,000 Btu/h are regulated by the National Appliance Energy Conservation Act of 1987 (NAECA); SEER values are those set by NAECA.
  5. Size category is based on nominal equipment sizes, e.g. < 65,000 Btu/h indicates ≤ 5 tons, < 135,000 Btu/h indicates ≤ 10 tons, < 240,000 Btu/h indicates < 20 tons, ≥ 760,000 Btu/h indicates > 60 tons.
TABLE 503.2.3(2)
UNITARY AIR CONDITIONERS AND CONDENSING UNITS, ELECTRICALLY OPERATED, MINIMUM EFFICIENCY REQUIREMENTS
EQUIPMENT TYPE SIZE CATEGORYe SUBCATEGORY OR
RATING CONDITION
MINIMUM EFFICIENCYb TEST PROCEDUREa
Air cooled,
(Cooling mode)
< 65,000 Btu/hd Split system 13.0 SEER AHRI 210/240
Single package 13.0 SEER
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Split system and
single package
11.0 EERc
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Split system and
single package
10.6 EERc AHRI 340/360
≥ 240,000 Btu/h Split system and
single package
9.5 EERc
9.2 IPLVc
Through-the-Wall
(Air cooled, cooling mode)
< 30,000 Btu/hd Split system 12.0 SEER AHRI 210/240
Single package 12.0 SEER
Water Source
(Cooling mode)
< 17,000 Btu/h 86°F entering water 11.2 EER AHRI/ASHRAE 13256-1
≥ 17,000 Btu/h
and
< 135,000 Btu/h
86°F entering water 12.0 EER AHRIASHRAE 13256-1
Groundwater Source
(Cooling mode)
< 135,000 Btu/h 59°F entering water 16.2 EER AHRI/ASHRAE 13256-1
Ground source
(Cooling mode)
< 135,000 Btu/h 77°F entering water 13.4 EER AHRI/ASHRAE 13256-1
Air cooled
(Heating mode)
< 65,000 Btu/hd
(Cooling capacity)
Split system 7.7 HSPF AHRI 210/240
Single package 7.7 HSPF
≥ 65,000 Btu/h
and
< 135,000 Btu/h
(Cooling capacity)
47°F db/43°F wb Outdoor air 3.3 COP
≥ 135,000 Btu/h
(Cooling capacity)
47°F db/43°F wb Outdoor air 3.2 COP AHRI 340/360
Through-the-wall
(Air cooled, heating mode)
< 30,000 Btu/h Split System 7.4 HSPF AHRI 210/240
Single package 7.4 HSPF
Water source
(Heating mode)
< 135,000 Btu/h
(Cooling capacity)
68°F entering water 4.2 COP AHRI/ASHRAE 13256-1
Groundwater source
(Heating mode)
< 135,000 Btu/h
(Cooling capacity)
50°F entering water 3.6 COP AHRI/ASHRAE 13256-1
Ground source
(Heating mode)
< 135,000 Btu/h
(Cooling capacity)
32°F entering water 3.1 COP AHRI/ASHRAE 13256-1

For SI: °C = [(°F) - 32]/1.8, 1 British thermal unit per hour = 0.2931 W. db = dry-bulb temperature, °F; wb = wet-bulb temperature, °F.
  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. IPLVs and Part load rating conditions are only applicable to equipment with capacity modulation.
  3. Deduct 0.2 from the required EERs and IPLVs for units with a heating section other than electric resistance heat.
  4. Single-phase air-cooled heat pumps < 65,000 Btu/h are regulated by the National Appliance Energy Conservation Act of 1987 (NAECA), SEER and HSPF values are those set by NAECA.
  5. Size category is based on nominal equipment sizes, e.g. < 65,000 Btu/h indicates ≤ 5 tons, < 135,000 Btu/h indicates ≤ 10 tons, < 240,000 Btu/h indicates < 20 tons, ≥ 760,000 Btu/h indicates > 60 tons.

TABLE 503.2.3(3)
PACKAGED TERMINAL AIR CONDITIONERS AND PACKAGED TERMINAL HEAT PUMPS
EQUIPMENT TYPE SIZE CATEGORY
(INPUT)
SUBCATEGORY OR
RATING CONDITION
MINIMUM EFFICIENCYb TEST PROCEDUREa
PTAC (Cooling mode)
New construction
All capacities 95°F db outdoor air 12.5 - (0.213 × Cap/1000) EER AHRI 310/380
PTAC (Cooling mode)
Replacementsc
All capacities 95°F db outdoor air 10.9 - (0.213 × Cap/1000) EER
PTHP (Cooling mode)
New construction
All capacities 95°F db outdoor air 12.3 - (0.213 × Cap/1000) EER
PTHP (Cooling mode)
Replacementsc
All capacities 95°F db outdoor air 10.8 - (0.213 × Cap/1000) EER
PTHP (Heating mode)
New construction
All capacities 3.2 - (0.026 × Cap/1000) COP
PTHP (Heating mode)
Replacementsc
All capacities 2.9 - (0.026 × Cap/1000) COP

For SI: °C - [(°F) - 32]/1.8, 1 British thermal unit per hour - 0.2931 W.
db = dry-bulb temperature, °F.
wb = wet-bulb temperature, °F.
  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. Cap means the rated cooling capacity of the product in Btu/h. If the unit's capacity is less than 7,000 Btu/h, use 7,000 Btu/h in the calculation. If the unit's capacity is greater than 15,000 Btu/h, use 15,000 Btu/h in the calculation.
  3. Replacement units must be factory labeled as follows: "MANUFACTURED FOR REPLACEMENT APPLICATIONS ONLY: NOT TO BE INSTALLED IN NEW CONSTRUCTION PROJECTS." Replacement efficiencies apply only to units with existing sleeves less than 16 inches (406 mm) high and less than 42 inches (1067 mm) wide.

TABLE 503.2.3(4)
WARM AIR FURNACES AND COMBINATION WARM AIR FURNACES/AIR-CONDITIONING UNITS,
WARM AIR DUCT FURNACES AND UNIT HEATERS, MINIMUM EFFICIENCY REQUIREMENTS
EQUIPMENT TYPE SIZE CATEGORY
(INPUT)h
SUBCATEGORY OR
RATING CONDITION
MINIMUM
EFFICIENCY
d, e
TEST PROCEDUREa
Warm air furnaces,
gas fired
< 225,000 Btu/h 78% AFUE
or
80% Etc
DOE 10 CFR Part 430
or ANSI Z21.47
≥ 225,000 Btu/h Maximum capacityc 80% Etf ANSI Z21.47
Warm air furnaces,
oil fired
< 225,000 Btu/h 78% AFUE
or
80% Etc
DOE 10 CFR Part 430
or UL 727
≥ 225,000 Btu/h Maximum capacityb 81% Etg UL 727
Warm air duct furnaces,
gas fired
All capacities Maximum capacityb 80% Ec ANSI Z83.8
Warm air unit heaters,
gas fired
All capacities Maximum capacityb 80% Ec ANSI Z83.8
Warm air unit heaters,
oil fired
All capacities Maximum capacityb 80% Ec UL 731

For SI: 1 British thermal unit per hour = 0.2931 W.
  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. Minimum and maximum ratings as provided for and allowed by the unit's controls.
  3. Combination units not covered by the National Appliance Energy Conservation Act of 1987 (NAECA) (3-phase power or cooling capacity greater than or equal to 65,000 Btu/h [19 kW]) shall comply with either rating.
  4. Et = Thermal efficiency. See test procedure for detailed discussion.
  5. Ec = Combustion efficiency (100% less flue losses). See test procedure for detailed discussion.
  6. Ec = Combustion efficiency. Units must also include an IID, have jackets not exceeding 0.75 percent of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.
  7. Et = Thermal efficiency. Units must also include an IID, have jacket losses not exceeding 0.75 percent of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.
  8. Size category is based on nominal equipment sizes, e.g. < 65,000 Btu/h indicates ≤ 5 tons, < 135,000 Btu/h indicates ≤ 10 tons, < 240,000 Btu/h indicates < 20 tons, ≥ 760,000 Btu/h indicates > 60 tons.
TABLE 503.2.3(5)
BOILERS, GAS- AND OIL-FIRED, MINIMUM EFFICIENCY REQUIREMENTS
EQUIPMENT TYPEf SIZE CATEGORY
(input)g
SUBCATEGORY OR RATING
CONDITION
MINIMUM EFFICIENCYc, d, e TEST PROCEDUREa
Boilers, Gas-fired < 300,000 Btu/h Hot water 80% AFUE DOE 10 CFR
Part 430
Steam 75% AFUE
≥ 300,000 Btu/h
and
≤ 2,500,000 Btu/h
Minimum capacityb 75% Et and 80% Ec
(See Note c, d)
DOE 10 CFR
Part 431
> 2,500,000 Btu/hf Hot water 80% Ec
(See Note c, d)
Steam 80% Ec
(See Note c, d)
Boilers, Oil-fired < 300,000 Btu/h 80% AFUE DOE 10 CFR
Part 430
≥ 300,000 Btu/h
and
≤ 2,500,000 Btu/h
Minimum capacityb 78% Et and 83% Ec
(See Note c, d)
DOE 10 CFR
Part 431
> 2,500,000 Btu/hf Hot water 83% Ec
(See Note c, d)
Steam 83% Ec
(See Note c, d)
Boilers, Oil-fired
(Residual)
≥ 300,000 Btu/h
and
≤ 2,500,000 Btu/h
Minimum capacityb 78% Et and 83% Ec
(See Note c, d)
DOE 10 CFR
Part 431
> 2,500,000 Btu/hf Hot water 83% Ec
(See Note c, d)
Steam 83% Ec
(See Note c, d)

For SI: 1 British thermal unit per hour = 0.2931 W.
  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. Minimum ratings as provided for and allowed by the unit's controls.
  3. Ec = Combustion efficiency (100 percent less flue losses). See reference document for detailed information.
  4. Et = Thermal efficiency. See reference document for detailed information.
  5. Alternative test procedures used at the manufacturer's option are ASME PTC-4.1 for units greater than 5,000,000 Btu/h input, or ANSI Z21.13 for units greater than or equal to 300,000 Btu/h and less than or equal to 2,500,000 Btu/h input.
  6. 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.
  7. Size category is based on nominal equipment sizes, e.g. < 65,000 Btu/h indicates ≤ 5 tons, < 135,000 Btu/h indicates ≤ 10 tons, < 240,000 Btu/h indicates < 20 tons, ≥ 760,000 Btu/h indicates > 60 tons.
TABLE 503.2.3(6)
CONDENSING UNITS, ELECTRICALLY OPERATED, MINIMUM EFFICIENCY REQUIREMENTS
EQUIPMENT TYPE SIZE CATEGORY MINIMUM EFFICIENCYb TEST PROCEDUREa
Condensing units,
air cooled
≥ 135,000 Btu/h 10.1 EER
11.2 IPLV
AHRI 365
Condensing units,
water or evaporatively cooled
≥ 135,000 Btu/h 13.1 EER
13.1 IPLV

For SI: 1 British thermal unit per hour = 0.2931 W.
  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. IPLVs are only applicable to equipment with capacity modulation.
TABLE 503.2.3(7)
WATER CHILLING PACKAGES, EFFICIENCY REQUIREMENTSa
EQUIPMENT TYPE SIZE
CATEGORY
UNITS BEFORE 1/1/2010 AS OF 1/1/2010c TEST
PROCEDUREb
    PATH A PATH B
FULL LOAD IPLV FULL LOAD IPLV FULL LOAD IPLV
Air-cooled chillers < 150 tons EER ≥ 9.562 ≥ 10.416 ≥ 9.562 ≥ 12.500 NAd NAd AHRI 550/590
≥ 150 tons EER ≥ 9.562 ≥ 12.750 NAd NAd
Air cooled without
condenser, electrical
operated
All capacities EER ≥ 10.586 ≥ 11.782 Air-cooled chillers without condensers must
be rated with matching condensers and
comply with the air-cooled chiller efficiency
requirements
Water cooled,
electrically operated,
reciprocating
All capacities kW/ton ≤ 0.837 ≤ 0.696 Reciprocating units must comply with water
cooled positive displacement efficiency
requirements
Water cooled,
electrically operated,
positive displacement
< 75 tons kW/ton ≤ 0.790 ≤ 0.676 ≤ 0.780 ≤ 0.630 ≤ 0.800 ≤ 0.600
≥ 75 tons
and
< 150 tons
kW/ton ≤ 0.775 ≤ 0.615 ≤ 0.790 ≤ 0.586
≥ 150 tons
and
< 300 tons
kW/ton ≤ 0.717 ≤ 0.627 ≤ 0.680 ≤ 0.580 ≤ 0.718 ≤ 0.540
≥ 300 tons kW/ton ≤ 0.639 ≤ 0.571 ≤ 0.620 ≤ 0.540 ≤ 0.639 ≤ 0.490
Water cooled,
electrically operated,
centrifugal
< 150 tons kW/ton ≤ 0.703 ≤ 0.669 ≤ 0.634 ≤ 0.596 ≤ 0.639 ≤ 0.450
≥ 150 tons
and
< 300 tons
kW/ton ≤ 0.634 ≤ 0.596
≥ 300 tons
and
< 600 tons
kW/ton ≤ 0.576 ≤ 0.549 ≤ 0.576 ≤ 0.549 ≤ 0.600 ≤ 0.400
≥ 600 tons kW/ton ≤ 0.576 ≤ 0.549 ≤ 0.570 ≤ 0.539 ≤ 0.590 ≤ 0.400
Air cooled, absorption
single effect
All capacities COP ≥ 0.600 NRe ≥ 0.600 NRe NAd NAd AHRI 560
Water-cooled,
absorption single
effect
All capacities COP ≥ 0.700 NRe ≥ 0.700 NRe NAd NAd
Absorption double
effect, indirect-fired
All capacities COP ≥ 1.000 ≥ 1.050 ≥ 1.000 ≥ 1.050 NAd NAd
Absorption double
effect, direct fired
All capacities COP ≥ 1.000 ≥ 1.000 ≥ 1.000 ≥ 1.000 NAd NAd

For SI: 1 ton = 3517 W, 1 British thermal unit per hour = 0.2931 W.
  1. The chiller equipment requirements do not apply for chillers used in low-temperature applications where the design leaving fluid temperature is < 40°F.
  2. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  3. Compliance with this standard can be obtained by meeting the minimum requirements of Path A or B. However, both the full load and IPLV must be met to fulfill the requirements of Path A or B.
  4. NA means that this requirement is not applicable and cannot be used for compliance.
  5. NR means that there are no minimum requirements for this category.
Each heating and cooling system shall be provided with thermostatic controls as required in Section 503.2.4.1, 503.2.4.2, 503.2.4.3, 503.2.4.4, 503.4.1, 503.4.2, 503.4.3 or 503.4.4.

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, at least 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 or gains or both serving one or more perimeter zones also served by an interior system provided:

  1. The perimeter system includes at least one thermostatic control zone for each building exposure having exterior walls facing only one orientation (within +/- 45 degrees) (0.8 rad) for more than 50 contiguous feet (15.2 m); and
  2. The perimeter system heating and cooling supply is controlled by a thermostat(s) located within the zone(s) served by the system.

503.2.4.1.1 Heat Pump Supplementary Heat

AMENDMENT
This section has been amended at the state or city level.
Heat pumps having supplementary electric resistance heat shall have controls that, except during defrost, prevent supplementary heat operation when the heat pump can meet the heating load.

In systems with a cooling capacity of less than 65,000 Btuh, a heat strip outdoor temperature lockout shall be provided to prevent supplemental heat operation in response to the thermostat being changed to a warmer setting. The lockout shall be set no lower than 35°F and no higher than 40°F.

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

Exception: Thermostats requiring manual changeover between heating and cooling modes.

503.2.4.3 Off-Hour Controls

AMENDMENT
This section has been amended at the state or city level.

Each zone shall be provided with thermostatic setback controls that are controlled by either an automatic time clock or programmable control system.

Exceptions:
  1. Zones that will be operated continuously.
  2. Zones with a full HVAC load demand not exceeding 6,800 Btu/h (2 kW) and having a readily accessible manual shutoff switch.
  3. HVAC systems serving hotel/motel guestrooms or other residential units complying with Section 503.2.2 requirements.
  4. Packaged terminal air conditioners, packaged terminal heat pumps, and room air conditioner systems.
Thermostatic setback controls shall have the capability 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 at least 10 hours. Additionally, the controls shall have a manual override that allows temporary operation of the system for up to 2 hours; a manually operated timer capable of being adjusted to operate the system for up to 2 hours; or an occupancy sensor.

503.2.4.4 Shutoff Damper Controls

AMENDMENT
This section has been amended at the state or city level.

Outdoor air supply and exhaust ducts, fans or openings in the building thermal envelope shall be equipped with motorized dampers that will automatically shut when the systems or spaces served are not in use.

Exceptions:
  1. Gravity dampers shall be permitted in buildings less than three stories in height.
  2. Gravity dampers shall be permitted for outside air intake or exhaust airflows of 300 cfm (0.14m3/s) or less.
Snow- and ice-melting systems, supplied through energy service to the building, shall include automatic controls capable of shutting off the system when the pavement temperature is above 50°F (10°C) and no precipitation is falling and an automatic or manual control that will allow shutoff when the outdoor temperature is above 40°F (4°C) so that the potential for snow or ice accumulation is negligible.
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.

503.2.5.1 Demand Controlled Ventilation

AMENDMENT
This section has been amended at the state or city level.
Ventilation systems in buildings over 10,000 square feet of conditioned area shall have demand controls. In all buildings, spaces larger than 500 square feet (50 m2) with a maximum occupant load of 40 or more people per 1,000 square feet (93 m2) of floor area (as established in Table 403.3 of the North Carolina Mechanical Code), ventilation supply air flow shall be controlled by monitoring indoor air quality conditions, such as with CO2 sensors or thermostats. Demand controlled ventilation systems shall be capable of reducing outside supply air to at least 50 percent below design ventilation rates.
Exceptions:
  1. Systems with energy recovery that provide a change in the enthalpy of the outdoor air supply of 50 percent or more of the difference between the outdoor air and return air at design conditions.
  2. Building spaces where the primary ventilation needs are for process loads, including laboratories and hospital.
  3. Individual units with less than 65,000 Btu/h of cooling capacity.
Individual fan systems that have both a design supply air capacity of 5,000 cfm (2.36 m3/s) or greater and a minimum outside air supply of 70 percent or greater of the design supply air quantity shall have an energy recovery system that provides a change in the enthalpy of the outdoor air supply of 50 percent or more of the difference between the outdoor air and return air at design conditions. Provision shall be made to bypass or control the energy recovery system to permit cooling with outdoor air where cooling with outdoor air is required.
Exception: An energy recovery ventilation system shall not be required in any of the following conditions:
  1. Where energy recovery systems are prohibited by the International Mechanical Code.
  2. Laboratory fume hood systems that include at least one of the following features:
    1. Variable-air-volume hood exhaust and room supply systems capable of reducing exhaust and makeup air volume to 50 percent or less of design values.
    2. Direct makeup (auxiliary) air supply equal to at least 75 percent of the exhaust rate, heated no warmer than 2°F (1.1°C) below room setpoint, cooled to no cooler than 3°F (1.7°C) above room setpoint, no humidification added, and no simultaneous heating and cooling used for dehumidification control.
  3. Systems serving spaces that are not cooled and are heated to less than 60°F (15.5°C).
  4. Where more than 60 percent of the outdoor heating energy is provided from site-recovered or site solar energy.
  5. Heating systems in climates with less than 3,600 HDD.
  6. Cooling systems in climates with a 1-percent cooling design wet-bulb temperature less than 64°F (18°C).
  7. Systems requiring dehumidification that employ series-style energy recovery coils wrapped around the cooling coil.

All supply and return air ducts and plenums shall be insulated with a minimum of R-5 insulation when located in unconditioned spaces and a minimum of R-8 insulation when located outside the building. When located within a building envelope assembly, the duct or plenum shall be separated from the building exterior or unconditioned or exempt spaces by a minimum of R-8 insulation.

Exceptions:

  1. When located within equipment.
  2. When the design temperature difference between the interior and exterior of the duct or plenum does not exceed 15°F (8°C).

All 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.

503.2.7.1.1 Low-Pressure Duct Systems

AMENDMENT
This section has been amended at the state or city level.

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


Exceptions:
  1. Continuously welded and locking-type longitudinal joints and seams on ducts operating at static pressures less than 2 inches w.g. (500 Pa) pressure classification.
  2. Ducts exposed within the conditioned space they serve shall not be required to be sealed.

503.2.7.1.2 Medium-Pressure Duct Systems

AMENDMENT
This section has been amended at the state or city level.
All ducts and plenums designed to operate at a static pressure greater than 2 inches w.g. (500 Pa) but less than 3 inches w.g. (750 Pa) shall be insulated and sealed in accordance with Section 503.2.7. Pressure classifications specific to the duct system shall be indicated on the construction documents in accordance with the International Mechanical Code.

Ducts designed to operate at static pressures in excess of 3 inches w.g. (746 Pa) shall be insulated and sealed in accordance with Section 503.2.7. In addition, ducts and plenums shall be leak-tested in accordance with the SMACNA HVAC Air Duct Leakage Test Manual with the rate of air leakage (CL) less than or equal to 6.0 as determined in accordance with Equation 5-2.

CL = F × P 0.65 (Equation 5-2)

where:

F = The measured leakage rate in cfm per 100 square feet of duct surface.

P = The static pressure of the test.

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

503.2.8 Piping Insulation

AMENDMENT
This section has been amended at the state or city level.
All piping serving as part of a heating or cooling system shall be thermally insulated in accordance with Table 503.2.8.
Exceptions:
  1. Factory-installed piping within HVAC equipment tested and rated in accordance with a test procedure referenced by this code.
  2. Factory-installed piping within room fan-coils and unit ventilators tested and rated according to AHRI 440 (except that the sampling and variation provisions of Section 6.5 shall not apply) and 840, respectively.
  3. Piping that conveys fluids that have a design operating temperature range between 55°F (13°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. Runout piping not exceeding 4 feet (1219 mm) in length and 1 inch (25 mm) in diameter between the control valve and HVAC coil.
  6. Refrigerant suction piping located in conditioned space is not required to be insulated other than as may be necessary for preventing the formation of condensation.
TABLE 503.2.8
MINIMUM PIPE INSULATION
(thickness in inches)
FLUID NOMINAL PIPE DIAMETER
≤ 1.5" > 1.5"
Steam 11/2 3
Hot water 11/2 2
Chilled water, brine or refrigerant 11/2 11/2

For SI: 1 inch = 25.4 mm.
  1. Based on insulation having a conductivity (k) not exceeding 0.27 Btu per inch/h • ft2 • °F.
  2. For insulation with a thermal conductivity not equal to 0.27 Btu • inch/h • ft2 • °F at a mean temperature of 75°F, the minimum required pipe thickness is adjusted using the following equation;
    T = r[(1+t/r)K/k-1]
    where:
    T = Adjusted insulation thickness (in).
    r = Actual pipe radius (in).
    t = Insulation thickness from applicable cell in table (in).
    K = New thermal conductivity at 75°F (Btu • in/hr • ft2 • °F).
    k = 0.27 Btu • in/hr • ft2 • °F.

503.2.9 HVAC System Completion

AMENDMENT
This section has been amended at the state or city level.
Prior to the issuance of a certificate of occupancy, the following shall be completed.

Exception: A temporary certificate of occupancy shall be allowed to be issued when requested prior to the completion of this section.

503.2.9.1 Air System Balancing

AMENDMENT
This section has been amended at the state or city level.
All HVAC systems shall be balanced by contractor. Test and balance activities shall include the following items:

503.2.9.1.1 Air Systems Balancing

AMENDMENT
This section has been amended at the state or city level.
Each supply air outlet and zone terminal device shall be equipped with means for air balancing in accordance with the requirements of Chapter 6 of the North Carolina Mechanical Code. Discharge dampers are prohibited on constant volume fans and variable volume fans with motors 10 hp (7.5 kW) and larger.

Exception: Fan with fan motors of 1 hp or less.

503.2.9.1.2 Hydronic Systems Balancing

AMENDMENT
This section has been amended at the state or city level.
Individual hydronic heating and cooling coils shall be equipped with means for balancing and pressure test connections. Hydronic systems shall be balanced in a manner to first minimize throttling losses, then the pump impeller shall be trimmed or pump speed shall be adjusted to meet design flow conditions. Each hydronic system shall have either the ability to measure pressure across the pump, or test ports at each side of each pump.

Exceptions:
  1. Pumps with pump motors of 5 hp or less.
  2. When throttling of an individual pump results in no greater than 5% of the nameplate horsepower draw above that required if the impeller were trimmed.

503.2.9.2 Hydronic System Balancing

AMENDMENT
This section has been amended at the state or city level.

503.2.9.3 503.2.9.2 Manuals

AMENDMENT
This section has been amended at the state or city level.
An operating and maintenance manual shall be provided to the building owner by the contractor. The manual shall include the following:
  1. Submittal data stating equipment model number and capacity (input and output) and selected options for each piece of equipment.
  2. Manufacturer's operation manuals and maintenance manuals for each piece of equipment requiring maintenance, except equipment not furnished as part of the project. Required routine maintenance actions shall be identified.
  3. Name and address of at least one service agency.
  4. HVAC controls system maintenance and calibration information, including wiring diagrams, schematics, and control sequence descriptions. Desired or field-determined set points shall be permanently recorded on control drawings at control devices or, for digital control systems, in programming comments.
  5. A complete narrative of how each system is intended to operate.
  6. Names and addresses of designers of record, contractors, subcontractors and equipment suppliers.

503.2.9.3 System Installation Statement

AMENDMENT
This section has been amended at the state or city level.
A North Carolina licensed design professional shall prepare and sign the Statement of Compliance — HVAC System Installation (Appendix 5). This statement shall be submitted to the code official and the facility owner.

Exception: The HVAC contractor will be allowed to prepare the Statement of Compliance when a building permit is issued for a project without the seal of a licensed design professional as allowed by an exception under NC State Building Administrative Code and Policies: Section 204.3.5.

503.2.9.3.1 Equipment

AMENDMENT
This section has been amended at the state or city level.
Equipment installation and operation shall be verified, to the extent feasible, to be in accordance with approved plans and specifications. Verification shall include demonstration of operation of components, systems and system-to-system interfacing relationships.

503.2.9.3.2 Controls

AMENDMENT
This section has been amended at the state or city level.
Controls installation and operation shall be verified, to the extent feasible, to be in accordance with approved plans and specifications. Verification shall include demonstration of operation of control devices, systems and system-to-system interfacing relationships. Control sequences shall be functionally verified, to the extent feasible, to demonstrate operation in accordance with the intent of the approval plans and specifications.
Each HVAC system having a total fan system motor nameplate horsepower (hp) exceeding 5 horsepower (hp) shall meet the provisions of Sections 503.2.10.1 through 503.2.10.2.

503.2.10.1 Allowable Fan Floor Horsepower

AMENDMENT
This section has been amended at the state or city level.
Each HVAC system at fan system design conditions shall not exceed the allowable fan system motor nameplate hp (Option 1) or fan system bhp (Option 2) as shown in Table 503.2.10.1(1). This includes supply fans, return/relief fans, and fan-powered terminal units associated with systems providing heating or cooling capability.
Exceptions:
  1. Hospital 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 or less.
  3. Fans exhausting air from fume hoods. (Note: If this exception is taken, no related exhaust side credits shall be taken from Table 503.2.10.1(2) and the Fume Exhaust Exception Deduction must be taken from Table 503.2.10.1(2).
TABLE 503.2.10.1(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

where:

CFMS = The maximum design supply airflow rate to conditioned spaces served by the system in cubic feet per minute.

hp = The maximum combined motor nameplate horsepower.

Bhp = The maximum combined fan brake horsepower.

A = Sum of [PD × CFMD / 4131].

where:

PD = Each applicable pressure drop adjustment from Table 503.2.10.1(2) in. w.c.

CFMD = The design airflow through each applicable device from Table 503.2.10.1(2) in cubic feet per minute.


TABLE 503.2.10.1(2)
FAN POWER LIMITATION PRESSURE DROP ADJUSTMENT

DEVICE

ADJUSTMENT

Credits

Fully ducted return and/or exhaust air systems with capacity ≤ 20,000 cfm

0.5 in w.c.

Fully ducted return and/or exhaust air systems with capacity > 20,000 cfm

2.0 in w.c.

Return and/or exhaust airflow control devices

0.5 in 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 in w.c.

Particulate filtration credit: MERV 13 thru 15

0.9 in w.c.

Particulate filtration credit: MERV 16 and greater and electronically
enhanced filters

Pressure drop calculated at 2x clean filter pressure drop at fan system
design condition.

Carbon and other gas-phase air cleaners

Clean filter pressure drop at fan system design condition.

Heat recovery device

Pressure drop of device at fan system design condition.

Evaporative humidifier/cooler in series with another cooling coil

Pressure drop of device at fan system design conditions

Sound attenuation section

0.15 in w.c.

Deductions

Fume hood exhaust exception
(required if Section 503.2.10.1.1, Exception 3, is taken)

-1.0 in w.c.

For each fan, the selected fan motor shall be no larger than the first available motor size greater than the brake horsepower (bhp). The fan brake horsepower (bhp) shall be indicated on the design documents to allow for compliance verification by the code official.

Exceptions:

  1. For fans less than 6 bhp, where the first available motor larger than the brake horsepower has a nameplate rating within 50 percent of the bhp, selection of the next larger nameplate motor size is allowed.
  2. For fans 6 bhp and larger, where the first available motor larger than the bhp has a nameplate rating within 30 percent of the bhp, selection of the next larger nameplate motor size is allowed.
Systems installed to provide heat outside a building shall be radiant systems. Such heating systems shall be controlled by an occupancy sensing device or a timer switch, so that the system is automatically deenergized when no occupants are present.

This section applies to buildings served by unitary or packaged HVAC equipment listed in Tables 503.2.3(1) through 503.2.3(5), each serving one zone and controlled by a single thermostat in the zone served. It also applies to two-pipe heating systems serving one or more zones, where no cooling system is installed.

This section does not apply to fan systems serving multiple zones, nonunitary or nonpackaged HVAC equipment and systems or hydronic or steam heating and hydronic cooling equipment and distribution systems that provide cooling or cooling and heating which are covered by Section 503.4.

503.3.1 Economizers

AMENDMENT
This section has been amended at the state or city level.

Supply air economizers shall be provided on each cooling system as shown in Table 503.3.1(1).

Economizers shall be capable of providing 100-percent outdoor air, even if additional mechanical cooling is required to meet the cooling load of the building. Systems shall provide a means to relieve excess outdoor air during economizer operation to prevent overpressurizing the building. The relief air outlet shall be located to avoid recirculation into the building. Where a single room or space is supplied by multiple air systems, the aggregate capacity of those systems shall be used in applying this requirement.

Exceptions:
  1. Where the cooling equipment is covered by the minimum efficiency requirements of Table 503.2.3(1) or 503.2.3(2) and meets or exceeds the minimum cooling efficiency requirement (EER) by the percentages shown in Table 503.3.1(2).
  2. Systems with air or evaporatively cooled condensors and which serve spaces with open case refrigeration or that require filtration equipment in order to meet the minimum ventilation requirements of Chapter 4 of the International Mechanical Code.
TABLE 503.3.1(1)
ECONOMIZER REQUIREMENTS

CLIMATE ZONES

ECONOMIZER REQUIREMENT

1A, 1B, 2A, 7, 8

No requirement

2B, 3A, 3B, 3C, 4A, 4B, 4C, 5A, 5B, 5C, 6A, 6B

Economizers on all cooling systems
65,000 Btu/ha

For SI: 1 British thermal unit per hour = 0.293 W.

  1.  The total capacity of all systems without economizers shall not exceed 480,000 Btu/h per building, or 20 percent of its air economizer capacity, whichever is greater.
TABLE 503.3.1(2)
EQUIPMENT EFFICIENCY PERFORMANCE EXCEPTION FOR ECONOMIZERS

CLIMATE ZONES

COOLING EQUIPMENT PERFORMANCE IMPROVEMENT
(EER OR IPLV)

3B

15% Efficiency Improvement

4B

20% Efficiency Improvement

Hydronic systems of at least 300,000 Btu/h (87,930 W) design output capacity supplying heated and chilled water to comfort conditioning systems shall include controls that meet the requirements of Section 503.4.3.
This section applies to buildings served by HVAC equipment and systems not covered in Section 503.3.

Supply air economizers shall be provided on each cooling system according to Table 503.3.1(1). Economizers shall be capable of operating at 100 percent outside air, even if additional mechanical cooling is required to meet the cooling load of the building.

Exceptions:

  1. Systems utilizing water economizers that are capable of cooling supply air by direct or indirect evaporation or both and providing 100 percent of the expected system cooling load at outside air temperatures of 50°F (10°C) dry bulb/45°F (7°C) wet bulb and below.
  2. Where the cooling equipment is covered by the minimum efficiency requirements of Table 503.2.3(1), 503.2.3(2), or 503.2.3(6) and meets or exceeds the minimum EER by the percentages shown in Table 503.3.1(2)
  3. Where the cooling equipment is covered by the minimum efficiency requirements of Table 503.2.3(7) and meets or exceeds the minimum integrated part load value (IPLV) by the percentages shown in Table 503.3.1(2).

Individual VAV fans with motors of 10 horsepower (7.5 kW) or greater shall be:

  1. Driven by a mechanical or electrical variable speed drive; or
  2. The fan motor shall have controls or devices that will result in fan motor demand of no more than 30 percent of their design wattage at 50 percent of design airflow when static pressure set point equals one-third of the total design static pressure, based on manufacturer's certified fan data.

For systems with direct digital control of individual zone boxes reporting to the central control panel, the static pressure set point shall be reset based on the zone requiring the most pressure, i.e., the set point is reset lower until one zone damper is nearly wide open.

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 503.4.3.1 through 503.4.3.3. 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 capable of sequencing operation of the boilers. Hydronic heating systems comprised of a single boiler and greater than 500,000 Btu/h 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 dead band between changeover from one mode to the other of at least 15°F (8.3°C) outside air temperatures; be designed to and provided with controls that will allow operation in one mode for at least 4 hours before changing over to the other mode; and be provided with controls that allow heating and cooling supply temperatures at the changeover point to be no more than 30°F (16.7°C) apart.
Hydronic heat pump systems shall comply with Sections 503.4.3.3.1 through 503.4.3.3.3.

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 capable of providing a heat pump water supply temperature dead band of at least 20°F (11.1°C) between initiation of heat rejection and heat addition by the central devices.

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

Heat rejection equipment shall comply with Sections 503.4.3.3.2.1 and 503.4.3.3.2.2.

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

For Climate Zones 3 and 4 as indicated in Figure 301.1 and Table 301.1:

  1. If a closed-circuit cooling tower is used directly in the heat pump loop, either an automatic valve shall be installed to bypass all but a minimal flow of water around the tower, or lower leakage positive closure dampers shall be provided.
  2. If an open-circuit tower is used directly in the heat pump loop, an automatic valve shall be installed to bypass all heat pump water flow around the tower.
  3. If an open- or closed-circuit cooling tower is used in conjunction with a separate heat exchanger to isolate the cooling tower from the heat pump loop, then heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop.
For climate Zones 5 through 8 as indicated in Figure 301.1 and Table 301.1, if an open- or closed-circuit cooling tower is used, then a separate heat exchanger shall be required to isolate the cooling tower from the heat pump loop, and heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop and providing an automatic valve to stop the flow of fluid.
Each hydronic heat pump on the hydronic system having a total pump system power exceeding 10 horsepower (hp) (7.5 kW) shall have a two-position valve.

503.4.3.4 Part Load Controls

AMENDMENT
This section has been amended at the state or city level.

Hydronic heating systems greater than or equal to 300,000 Btu/h (87,930 W) in design output capacity supplying heated or chilled water to comfort conditioning systems shall include controls that have the capability to:

  1. Automatically reset the supply hot water temperatures using zone-return water temperature, building-return water temperature, or outside air temperature as an indicator of building heating or cooling demand. The temperature shall be capable of being reset by at least 25 percent of the design supply-to-return water temperature difference; or
  2. Reduce system pump flow by at least 50 percent of design flow rate utilizing adjustable speed drive(s) on pump(s), or multiple-staged pumps where at least one-half of the total pump horsepower is capable of being automatically turned off or control valves designed to modulate or step down, and close, as a function of load, or other approved means.

Chilled water plants including more than one chiller shall have the capability 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 plants including more than one boiler shall have the capability to reduce flow automatically through the boiler plant when a boiler is shut down.

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

Exception: Factory-installed heat rejection devices within HVAC equipment tested and rated in accordance with Tables 503.2.3(6) and 503.2.3(7).

Sections 503.4.5.1 through 503.4.5.4 shall apply to complex mechanical systems serving multiple zones. Supply air systems serving multiple zones shall be VAV systems which, during periods of occupancy, are designed and capable of being controlled to reduce primary air supply to each zone to one of the following before reheating, recooling or mixing takes place:

  1. Thirty percent of the maximum supply air to each zone.
  2. Three hundred cfm (142 L/s) or less where the maximum flow rate is less than 10 percent of the total fan system supply airflow rate.
  3. The minimum ventilation requirements of Chapter 4 of the International Mechanical Code.

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

  1. Zones where special pressurization relationships or cross-contamination requirements are such that VAV systems are impractical.
  2. Zones or supply air systems where at least 75 percent of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered or site-solar energy source.
  3. Zones where special humidity levels are required to satisfy process needs.
  4. Zones with a peak supply air quantity of 300 cfm (142 L/s) or less and where the flow rate is less than 10 percent of the total fan system supply airflow rate.
  5. Zones where the volume of air to be reheated, recooled or mixed is no greater than the volume of outside air required to meet the minimum ventilation requirements of Chapter 4 of the International Mechanical Code.
  6. Zones or supply air systems with thermostatic and humidistatic controls capable of operating in sequence the supply of heating and cooling energy to the zone(s) and which are capable of preventing reheating, recooling, mixing or simultaneous supply of air that has been previously cooled, either mechanically or through the use of economizer systems, and air that has been previously mechanically heated.
Single duct VAV systems shall use terminal devices capable of reducing 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 which are capable of reducing 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 [(26 375 W) 7.5 tons] shall not be equipped with air economizers.

Multiple zone HVAC systems shall include controls that automatically reset the supply-air temperature in response to representative building loads, or to outdoor air temperature. The controls shall be capable of resetting the supply air temperature at least 25 percent of the difference between the design supply-air temperature and the design room air temperature.

Exceptions:

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

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

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

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

Exceptions:

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

503.4.7 Hot Gas Bypass Limitation

AMENDMENT
This section has been amended at the state or city level.
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 503.4.7.
Exception: Unitary packaged systems with nominal cooling capacities of 7.5 tons or less (approximately 90 kBtu/h or 26.4 kW).

TABLE 503.4.7
MAXIMUM HOT GAS BYPASS CAPACITY
RATED CAPACITY MAXIMUM HOT GAS BYPASS CAPACITY
(% of total capacity)
20 nominal tons (240 kBtu/h) 50%
20 nominal tons (240 kBtu/h)  25%
For SI: 1 Btu/h = 0.29 watts.

Section 504 Service Water Heating (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.
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 504.2. The efficiency shall be verified through data furnished by the manufacturer or through certification under an approved certification program.

 

TABLE 504.2
MINIMUM PERFORMANCE OF WATER-HEATING EQUIPMENT

EQUIPMENT TYPE

SIZE CATEGORY
(input)

SUBCATEGORY OR
RATING CONDITION

PERFORMANCE
REQUIREDa, b

TEST
PROCEDURE

Water heaters,
Electric

≤ 12 kW

Resistance

0.97 - 0.00132V, EF

DOE 10 CFR Part 430

> 12 kW

Resistance

1.73V + 155 SL, Btu/h

ANSI Z21.10.3

≤ 24 amps and
≤ 250 volts

Heat pump

0.93 - 0.00132V, EF

DOE 10 CFR Part 430

Storage water heaters,
Gas

≤ 75,000 Btu/h

≥ 20 gal

0.67 - 0.0019V, EF

DOE 10 CFR Part 430

> 75,000 Btu/h and
≤ 155,000 Btu/h

< 4,000 Btu/h/gal

80% Et

ANSI Z21.10.3

> 155,000 Btu/h

< 4,000 Btu/h/gal

80% Et

Instantaneous water heaters, Gas

> 50,000 Btu/h and
< 200,000 Btu/hc

≥ 4,000 (Btu/h)/gal
and < 2 gal

0.62 - 0.0019V, 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

0.59 - 0.0019V, EF

DOE 10 CFR Part 430

> 105,000 Btu/h

< 4,000 Btu/h/gal

78% 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

78% Et

ASHRAE 146

Heat pump pool heaters

All

4.0 COP

AHRI 1160

Unfired storage tanks

All

Minimum insulation requirement R-12.5
(h • ft2 • °F)/Btu

(none)

For SI: °C = [(°F) - 32]/1.8, 1 British thermal unit per hour = 0.2931 W, 1 gallon = 3.785 L, 1 British thermal unit per hour per gallon = 0.078 W/L.

  1. Energy factor (EF) and thermal efficiency (Et) are minimum requirements. In the EF equation, V is the rated volume in gallons.
  2. Standby loss (SL) is the maximum Btu/h based on a nominal 70°F temperature difference between stored water and ambient requirements. In the SL equation, Q is the nameplate input rate in Btu/h. In the SL equation for electric water heaters, V is the rated 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 must comply with these requirements if the water heater is designed to heat water to temperatures 180°F or higher.
Service water-heating equipment shall be provided with controls to allow a setpoint of 110°F (43°C) for equipment serving dwelling units and 90°F (32°C) for equipment serving other occupancies. The outlet temperature of lavatories in public facility rest rooms shall be limited to 110°F (43°C).
Water-heating equipment not supplied with integral heat traps and serving noncirculating systems shall be provided with heat traps on the supply and discharge piping associated with the equipment.
For automatic-circulating hot water systems, piping shall be insulated with 1 inch (25 mm) of insulation having a conductivity not exceeding 0.27 Btu per inch/h × ft2 × °F (1.53 W per 25 mm/m2 × K). The first 8 feet (2438 mm) of piping in noncirculating systems served by equipment without integral heat traps shall be insulated with 0.5 inch (12.7 mm) of material having a conductivity not exceeding 0.27 Btu per inch/h × ft2 × °F (1.53 W per 25 mm/m2 × K).
Automatic-circulating hot water system pumps or heat trace shall be arranged to be conveniently turned off automatically or manually when the hot water system is not in operation.

504.7 Pools and Inground Permanently Installed Spas (Mandatory)

AMENDMENT
This section has been amended at the state or city level.
Pools and inground permanently installed spas shall comply with Sections 504.7.1 through 504.7.3.

504.7.1 Pool Heaters

AMENDMENT
This section has been amended at the state or city level.
All heaters shall be equipped with a readily accessible on-off switch that is mounted outside of the heater to allow shutting off the heater without adjusting the thermostat setting. Gas-fired heaters shall not be equipped with constant burning pilot lights.

504.7.2 Time Switches

AMENDMENT
This section has been amended at the state or city level.
Time switches or other control method that can automatically turn off and on heaters and pumps according to a preset schedule shall be installed on all heaters and pumps. Heaters, pumps and motors that have built-in timers shall be deemed in compliance with this requirement.
Exceptions:
  1. Where public health standards require 24-hour pump operation.
  2. Where pumps are required to operate solar- and waste-heat-recovery pool heating systems.

504.7.3 Pool Covers

AMENDMENT
This section has been amended at the state or city level.

Heated pools and inground permanently installed spas shall be provided with a vapor-retardant cover.


Exception: Pools deriving over 70 percent of the energy for heating from site-recovered energy, such as a heat pump or solar energy source computed over an operating season.

Section 505 Electrical Power and Lighting Systems (Mandatory)

AMENDMENT
This section has been amended at the state or city level.

505.1 General (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.
This section covers lighting system controls, the connection of ballasts, the maximum lighting power for interior applications, and minimum acceptable lighting equipment for exterior applications.
Exception: Lighting within dwelling units where 75 percent or more of the permanently installed interior light fixtures are fitted with high-efficacy lamps.

505.2 Lighting Controls (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.
Lighting systems shall be provided with controls as required in Sections 505.2.1, 505.2.2, 505.2.3 and 505.2.4.

Each area enclosed by walls or floor-to-ceiling partitions shall have at least one manual control for the lighting serving that area. The required controls shall be located within the area served by the controls or be a remote switch that identifies the lights served and indicates their status.

Exceptions:

  1. Areas designated as security or emergency areas that must be continuously lighted.
  2. Lighting in stairways or corridors that are elements of the means of egress.
Each area that is required to have a manual control shall have additional controls that meet the requirements of Sections 505.2.2.1 and 505.2.2.2.

Each area that is required to have a manual control shall also allow the occupant to reduce the connected lighting load in a reasonably uniform illumination pattern by at least 50 percent. Lighting reduction shall be achieved by one of the following or other approved method:

  1. Controlling all lamps or luminaires;
  2. Dual switching of alternate rows of luminaires, alternate luminaires or alternate lamps;
  3. Switching the middle lamp luminaires independently of the outer lamps; or
  4. Switching each luminaire or each lamp.

Exceptions:

  1. Areas that have only one luminaire.
  2. Areas that are controlled by an occupant-sensing device.
  3. Corridors, storerooms, restrooms or public lobbies.
  4. Sleeping unit (see Section 505.2.3).
  5. Spaces that use less than 0.6 watts per square foot (6.5 W/m2).

505.2.2.2 Automatic Lighting Shutoff

AMENDMENT
This section has been amended at the state or city level.

505.2.2.2.1 Occupant Override

AMENDMENT
This section has been amended at the state or city level.

505.2.2.2.1 Building Automatic Lighting Controls

AMENDMENT
This section has been amended at the state or city level.
Buildings larger than 5,000 square feet (465 m2) shall be equipped with an automatic control device to shut off lighting. This automatic control requirement shall be achieved by one or a combination of the following:
  1. A scheduled basis, using time-of-day, with an independent program schedule that controls the interior lighting in areas that do not exceed 25,000 square feet (2,323 m2) and are not more than one floor;
  2. A signal from another control or alarm system that indicates the area is unoccupied; or
  3. An occupancy sensor that automatically turns lighting off within 30 minutes of an occupant leaving a space.

    Exception: The following shall not require an automatic control device:
    1. Sleeping unit (see Section 505.2.3).
    2. Lighting in spaces where patient care is directly provided.
    3. Spaces where an automatic shutoff would endanger occupant safety or security.
    4. Spaces with daylight control zones that have automatic daylighting controls using either continuous or stepped control systems.
    5. Lighting intended for 24-hour operation.
    6. Tenant spaces less than 2,000 square feet complying with Section 505.2.2.2.2.

505.2.2.2.2 Holiday Scheduling

AMENDMENT
This section has been amended at the state or city level.

505.2.2.2.2 Occupancy Sensors

AMENDMENT
This section has been amended at the state or city level.
All buildings shall have occupancy sensors in all of the following spaces:
  1. Classrooms;
  2. Conference/meeting rooms;
  3. Employee lunch and break rooms;
  4. Private offices;
  5. Storage rooms over 100 square feet; and
  6. Computer rooms over 100 square feet.

505.2.2.2.3 Occupant Override

AMENDMENT
This section has been amended at the state or city level.
Where an automatic time switch control device is installed to comply with Section 505.2.2.2.1, Item 1, it shall incorporate an override switching device that:
  1. Is readily accessible.
  2. Is located so that a person using the device can see the lights or the area controlled by that switch, or so that the area being lit is annunciated.
  3. Is manually operated.
  4. Allows the lighting to remain on for no more than 2 hours when an override is initiated.
  5. Controls an area not exceeding 5,000 square feet (465 m2).

    Exceptions:
    1. In malls and arcades, auditoriums, single-tenant retail spaces, industrial facilities and arenas, where captivekey override is utilized, override time shall be permitted to exceed 2 hours.
    2. In malls and arcades, auditoriums, single-tenant retail spaces, industrial facilities and arenas, the area controlled shall not exceed 20,000 square feet (1860 m2).

505.2.2.2.4 Holiday Scheduling

AMENDMENT
This section has been amended at the state or city level.
If an automatic time switch control device is installed in accordance with Section 505.2.2.2, Item 1, it shall incorporate an automatic holiday scheduling feature that turns off all loads for at least 24 hours, then resumes the normally scheduled operation.

Exception: Retail stores and associated malls, restaurants, grocery stores, places of religious worship and theaters.

505.2.2.3 Daylight Zone Control

AMENDMENT
This section has been amended at the state or city level.
Sleeping units in hotels, motels, boarding houses or similar buildings shall have at least one master switch at the main entry door that controls all permanently wired luminaires and switched receptacles, except those in the bathroom(s). Suites shall have a control meeting these requirements at the entry to each room or at the primary entry to the suite.
Lighting not designated for dusk-to-dawn operation shall be controlled by either a combination of a photosensor and a time switch, or an astronomical time switch. Lighting designated for dusk-to-dawn operation shall be controlled by an astronomical time switch or photosensor. All time switches shall be capable of retaining programming and the time setting during loss of power for a period of at least 10 hours.

505.2.5 Additional Miscellaneous Lighting Control

AMENDMENT
This section has been amended at the state or city level.

505.2.5.1 Separate Lighting Controls

AMENDMENT
This section has been amended at the state or city level.
Separate lighting controls shall be required for:
  1. Display/Accent Lighting;
  2. Case Lighting;
  3. Nonvisual Lighting—lighting for nonvisual applications, such as plant growth and food warming; and
  4. Demonstration Lighting—lighting equipment that is for sale or for demonstrations in lighting education.

505.2.5.2 Hotel and Motel Guest Room Lighting

AMENDMENT
This section has been amended at the state or city level.
Hotel and motel guest rooms and guest suites shall have a master control device at the main room entry that controls all permanently installed luminaires and switched receptacles.

505.2.5.3 Task Lighting

AMENDMENT
This section has been amended at the state or city level.
Supplemental task lighting, including permanently installed undershelf or undercabinet lighting, shall have a control device integral to the luminaires or be controlled by a wall-mounted control device provided the control device is readily accessible and located so that the occupant can see the controlled lighting.

505.2.6 Lighting Controls Functional Performance Testing Requirements

AMENDMENT
This section has been amended at the state or city level.
For lighting controls which include daylight or occupant sensing automatic controls, automatic shut-off controls, occupancy sensors, or automatic time switches, the lighting control shall be tested to ensure that control devices, components, equipment, and systems are calibrated, adjusted and operate in accordance with approved plans and specifications. Sequences of operation shall be functionally tested to ensure they operate in accordance with approved plans and specifications.

505.3 Tandem Wiring (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.
The following luminaires located within the same area shall be tandem wired:
  1. Fluorescent luminaires equipped with one, three or odd-numbered lamp configurations, that are recess- mounted within 10 feet (3048 mm) center-to-center of each other.
  2. Fluorescent luminaires equipped with one, three or any odd-numbered lamp configuration, that are pendant- or surface-mounted within 1 foot (305 mm) edge- to-edge of each other.
Exceptions:
  1. Where electronic high-frequency ballasts are used.
  2. Luminaires on emergency circuits.
  3. Luminaires with no available pair in the same area.

505.4 Exit Signs (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.
Internally illuminated exit signs shall not exceed 5 watts per side.
A building complies with this section if its total connected lighting power calculated under Section 505.5.1 is no greater than the interior lighting power calculated under Section 505.5.2.

505.5.1 Total Connected Interior Lighting Power

AMENDMENT
This section has been amended at the state or city level.

The total connected interior lighting power (watts) shall be the sum of the watts of all interior lighting equipment as determined in accordance with Sections 505.5.1.1 through 505.5.1.4.

Exceptions:
  1. The connected power associated with the following lighting equipment is not included in calculating total connected lighting power.
    1. Professional sports arena playing field lighting.
    2. Sleeping unit lighting in hotels, motels, boarding houses or similar buildings.
    3. Emergency lighting automatically off during normal building operation.
    4. Lighting in spaces designed for use by occupants with special lighting needs including the visually impaired visual impairment and other medical and age-related issues.
    5. Lighting in interior spaces that have been designated as a registered interior historic landmark.
    6. Casino gaming areas.
  2. Lighting equipment used for the following shall be exempt provided that it is in addition to general lighting and is controlled by an independent control device:
    1. Task lighting for medical and dental purposes.
    2. Display lighting for exhibits in galleries, museums and monuments.
  3. Lighting for theatrical purposes, including performance, stage, film production and video production.
  4. Lighting for photographic processes.
  5. Lighting integral to equipment or instrumentation and is installed by the manufacturer.
  6. Task lighting for plant growth or maintenance.
  7. Advertising signage or directional signage.
  8. In restaurant buildings and areas, lighting for food warming or integral to food preparation equipment.
  9. Lighting equipment that is for sale.
  10. Lighting demonstration equipment in lighting education facilities.
  11. Lighting approved because of safety or emergency considerations, inclusive of exit lights.
  12. Lighting integral to both open and glass enclosed refrigerator and freezer cases.
  13. Lighting in retail display windows, provided the display area is enclosed by ceiling-height partitions.
  14. Furniture mounted supplemental task lighting that is controlled by automatic shutoff.
The wattage shall be the maximum labeled wattage of the luminaire.
The wattage shall be the specified wattage of the transformer supplying the system.
The wattage of all other lighting equipment shall be the wattage of the lighting equipment verified through data furnished by the manufacturer or other approved sources.

The wattage shall be:

  1. The specified wattage of the luminaires included in the system with a minimum of 30 W/lin ft. (98 W/lin. m);
  2. The wattage limit of the system's circuit breaker; or
  3. The wattage limit of other permanent current limiting device(s) on the system.

505.5.2 Interior Lighting Power

AMENDMENT
This section has been amended at the state or city level.
Interior lighting power allowance shall be calculated using one of the following two methods:
  1. Building area method:
    1. Determine the appropriate building area type from Table 505.5.2 and the allowed lighting power density (watts per unit area) from the building area method column. For building area types not listed, selection of a reasonably equivalent type shall be permitted.
    2. Determine the gross lighted floor area (square feet) of the building area type.
    3. Multiply the gross lighted floor areas of the building area type(s) times the lighting power density.
    4. The interior lighting power allowance for the building is the sum of the lighting power allowances of all building area types. Tradeo-ffs among building area types are permitted provided that the total installed interior lighting power does not exceed the interior lighting power allowance.
  2. Space-by-space method:
    1. Determine the appropriate building type from Table 505.5.2. For building types not listed, selection of a reasonably equivalent type shall be permitted.
    2. For each space enclosed by partitions 80 percent or greater than ceiling height, determine the gross interior floor area by measuring to the center of the partition wall. Include the floor area of balconies or other projections. Retail spaces do not have to comply with the 80 percent partition height requirements.
    3. Determine the interior lighting power allowance by using the columns designated space-by-space method in Table 505.5.2. Multiply the floor area(s) of the space(s) times the allowed lighting power density for the space type that most closely represents the proposed use of the space(s). The product is the lighting power allowance for the space(s). For space types not listed, selection of a reasonably equivalent category shall be permitted.
    4. The interior lighting power allowance is the sum of lighting power allowances of all spaces. Trade-offs among spaces are permitted provided that the total installed interior lighting power does not exceed the interior lighting power allowance.
TABLE 505.5.2
INTERIOR LIGHTING POWER ALLOWANCES
LIGHTING POWER DENSITY
  Whole Building Space by Space
Building Area Typea (W/ft2)
Common Space Types    
Active Storage
  0.63
Atrium - First Three Floors
  0.63
Atrium - Each Additional Floor
  0.16
Automotive Facility
  0.91
Bank/Office, Bank Activity Area
  1.38
Classroom/Lecture/Training
  1.25
Conference/Meeting/Multipurpose
  1.29
Corridor/Transition
  0.65
Education Laboratory
  1.28
Electrical/Mechanical
  0.95
Food Preparation
  0.99
Lobby
  0.60
Locker Room
  0.78
Medical/Industrial Research
Laboratory
  1.62
Parking Garage - Garage Area
  0.21
Restroom
  0.84
Stairway
  0.69
Convention Center 1.05  
Exhibit Space
  1.58
Audience/Seating Area
  0.80
Court House 1.07  
Audience/Seating Area
  0.80
Courtroom
  1.91
Confinement Cells
  1.10
Judges Chambers
  1.17
Dressing/Locker/Fitting Room
  0.78
Dining: Bar/Lounge/Leisure 1.01  
Lounge/Leisure Dining
  1.40
Dining: Cafeteria/Fast Food 0.93  
Dining: Family 0.94  
Dining
  0.99
Dormitory 0.58  
Living Quarters
  0.32
Bedroom
  0.50
Study Hall
  1.30
Exercise Center 0.89  
Dressing/Locker/Fitting Room
  0.78
Audience/Seating Area
  0.30
Exercise Area/Gymnasium
  0.72
Gymnasium 0.70  
Dressing/Locker/Fitting Room
  0.78
Audience/Seating Area
  0.40
Playing Area
  1.35
Exercise Area
  0.72
Healthcare Clinic/Hospital 1.06  
Corridors w/patient waiting, exam
  0.94
Exam/Treatment
  1.66
Emergency
  2.35
Public & Staff Lounge
  0.79
Hospital/Medical Supplies
  1.27
Hospital - Nursery
  0.60
Nurse Station
  0.87
Physical Therapy
  0.91
Patient Room
  0.62
Pharmacy
  1.14
Hospital/Radiology
  1.34
Operating Room
  1.89
Recovery
  1.15
Active Storage
  0.63
Laundry — Washing
  0.60
Hotel 1.01  
Dining Area
  0.85
Guest quarters
  1.11
Reception/Waiting
  2.30
Lobby
  1.05
Library 0.96  
Library - Audio Visual
  0.60
Stacks
  1.42
Card File & Cataloguing
  0.72
Reading Area
  0.93
Manufacturing Facility 0.98  
Low Bay (< 25 ft Floor to Ceiling)
  1.19
High Bay (> 25 ft Floor to Ceiling)
  1.34
Detailed Manufacturing
  1.29
Equipment Room
  0.95
Corridor/Transition
  0.41
Motel 1.05  
Dining Area
  1.05
Living Quarters
  0.75
Reception/Waiting
  1.90
Motion Picture Theater 0.86  
Audience/Seating Area
  0.53
Lobby
  1.13
Multi-Family 0.53  
Museum 1.05  
Active Storage
  0.63
General Exhibition
  1.05
Restoration
  1.02
Office 0.89  
Enclosed
  1.11
Open Plan
  0.98
Parking Garage 0.22  
Penitentiary 0.94  
Performing Arts Theater 1.35  
Audience/Seating Area
  2.30
Lobby
  2.34
Dressing/Locker/Fitting Room
  1.14
Police/Fire Station 0.94  
Fire Station Engine Room
  0.56
Sleeping Quarters
  0.25
Post Office/SF 0.84  
Sorting Area
  0.94
Lobby
  1.00
Religious Buildings 1.14  
Lobby/Fellowship Hall
  0.64
Worship/Pulpit/Choir
  1.95
Retailc 1.41  
Department Store Sales Area
  1.30
Dressing/Fitting Room
  0.96
Fine Merchandise Sales Area
  2.60
Mall Concourse
  1.06
Mass Merchandising Sales Area
  1.30
Personal Services Sales Area
  1.30
Specialty Store Sales Area
  1.60
Supermarket Sales Area
  1.30
School/University 0.98  
Classroom
  1.30
Audience
  0.70
Dining Area
  1.00
Office
  1.00
Corridor
  0.50
Storage
  0.50
Laboratory
  1.28
Sports Arena 0.71  
Ring Sports Arena
  2.68
Court Sports Arena
  1.80
Town Hall 0.89  
Transportation 0.76  
Dining Area
  1.90
Baggage Area
  0.76
Airport - Concourse
  0.39
Terminal - Ticket Counter
  1.12
Reception/Waiting
  0.50
Warehouse 0.56  
Fine Material
  0.95
Medium Bulky Material
  0.63
Workshop 1.59  

For SI: 1 foot = 304.8 mm, 1 watt per square foot = W/0.0929 m2.
  1. In cases where both a general building area type and a more specific building area type are listed, the more specific building area type shall apply.
  2. The lighting power densities contained in this table include allowances for video-display terminals, decorative lighting and display lighting Additional lighting power is not allowed for these uses. Task lighting is not included in these connected LPD limits.
  3. Where lighting equipment is specified to be installed to highlight specific merchandise in addition to lighting equipment specified for general lighting and is switched or dimmed on circuits different from the circuits for general lighting, the smaller of the actual wattage of the lighting equipment installed specifically for merchandise, or additional lighting power as determined below shall be added to the interior lighting power determined in accordance with this line item.

    Calculate the additional lighting power as follows:

    Additional Interior Lighting Power Allowance = (Retail Area 1 × 0.4 W/ft2) + (Retail Area 2 × 0.6 W/ft2) + (Retail Area 3 × 0.9 W/ft2) + (Retail Area 4 × 1.5 W/ft2).

    where:

    Retail Area 1 = The floor area for all products not listed in Retail Area 2, 3 or 4.

    Retail Area 2 = The floor area used for the sale of vehicles, sporting goods and small electronics.

    Retail Area 3 = The floor area used for the sale of furniture, clothing, cosmetics and artwork.

    Retail Area 4 = The floor area used for the sale of jewelry, crystal and china.
    Exception: Other merchandise categories are permitted to be included in Retail Areas 2 through 4 above, provided that justification documenting the need for additional lighting power based on visual inspection, contrast, or other critical display is approved by the authority having jurisdiction.

505.6 Exterior Lighting. (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.
When the power for exterior lighting is supplied through the energy service to the building, all exterior lighting, other than low-voltage landscape lighting, shall comply with Sections 505.6.1 and 505.6.2.
Exception: Where approved because of historical, safety, signage or emergency considerations.
All exterior building grounds luminaires that operate at greater than 100 watts shall contain lamps having a minimum efficacy of 60 lumens per watt unless the luminaire is controlled by a motion sensor or qualifies for one of the exceptions under Section 505.6.2.

The total exterior lighting power allowance for all exterior building applications is the sum of the base site allowance plus the individual allowances for areas that are to be illuminated and are permitted in Table 505.6.2(2) for the applicable lighting zone. Tradeoffs are allowed only among exterior lighting applications listed in Table 505.6.2(2), Tradable Surfaces section. The lighting zone for the building exterior is determined from Table 505.6.2(1) unless otherwise specified by the local jurisdiction. Exterior lighting for all applications (except those included in the exceptions to Section 505.6.2) shall comply with the requirements of Section 505.6.1.

Exceptions: Lighting used for the following exterior applications is exempt when equipped with a control device independent of the control of the nonexempt lighting:
  1. Specialized signal, directional and marker lighting associated with transportation;
  2. Advertising signage or directional signage;
  3. Integral to equipment or instrumentation and is installed by its manufacturer;
  4. Theatrical purposes, including performance, stage, film production and video production;
  5. Athletic playing areas;
  6. Temporary lighting;
  7. Industrial production, material handling, transportation sites and associated storage areas;
  8. Theme elements in theme/amusement parks; and
  9. Used to highlight features of public monuments and registered historic landmark structures or buildings.
TABLE 505.6.2
LIGHTING POWER DENSITIES FOR BUILDING EXTERIORS
APPLICATIONS LIGHTING POWER DENSITIES
Tradable Surfaces (Lighting Power Densities for uncovered parking areas, building grounds, building entrances and exits, canopies and overhangs, and outdoor sales areas may be traded.)
Uncovered Parking Areas
Parking Lots and drives  0.15 W/ft2
Building Grounds
Walkways less than 10 feet wide 1.0 watts/linear foot
Walkways 10 feet wide or greater, plaza areas and special feature areas 0.2 W/ft2
Stairways 1.0 W/ft2
Building Entrances and Exits
Main entries 30 watts/linear foot of door width
Other doors 20 watts/linear foot of door width
Canopies and Overhangs
Canopies (free standing & attached and overhangs) 1.25 W/ft2
Outdoor Sales
Open areas (including vehicle sales lots)  0.5 W/ft2
Street frontage for vehicle sales lots in addition to "open area" allowance 20 watts/linear foot
Nontradable Surfaces (Lighting Power Density calculations for the following applications can be used only for the specific application and cannot be traded between surfaces or with other exterior lighting. The following allowances are in addition to any allowance otherwise permitted in the Tradable Surfaces section of this table.)
Building facades 0.2 W/ft2 for each illuminated wall or surface or 5.0 Watts/linear foot for each illuminated wall or surface length
Automated teller machines and night depositories 270 watts per location plus 90 watts per additional ATM per location
Entrances and gatehouse inspection stations at guarded facilities 1.25 W/ft2of uncovered area (covered areas are included in the Canopies and Overhangs section of Tradable Surfaces)
Loading areas for law enforcement, fire, ambulance and other emergency service vehicles 0.5 W/ft2 of uncovered area (covered areas are included in the Canopies and Overhangs section of Tradable Surfaces)
Drive-up windows at fast food restaurants 400 watts per drive-through
Parking near 24-hour retail entrances 800 watts per main entry
For SI: 1 foot = 304.8 mm, 1 watt per square foot = W/0.0929 m2 .

TABLE 505.6.2(1)
EXTERIOR LIGHTING ZONES
LIGHTING ZONE DESCRIPTION
1 Developed areas of national parks, state parks, forest land, and rural areas
2 Areas predominantly consisting of residential zoning, neighborhood business districts, light industrial with limited nighttime use and residential mixed use areas
3 All other areas
4 High-activity commercial districts in major metropolitan areas as designated by the local land use planning authority


TABLE 505.6.2(2)
INDIVIDUAL LIGHTING POWER ALLOWANCES FOR BUILDING EXTERIORS
    Zone 1 Zone 2 Zone 3 Zone 4
Base Site Allowance
(Base allowance may be used in tradable or nontradable surfaces.)
  500 W 600 W 750 W 1300 W
Tradable Surfaces (Lighting power densities for uncovered parking areas, building grounds, building entrances and exits, canopies and overhangs and outdoor sales areas may be traded.) Uncovered Parking Areas
Parking areas and drives 0.04 W/ft2 0.06 W/ft2 0.10 W/ft2 0.13 W/ft2
Building Grounds
Walkways less than
10 feet wide
0.7 W/linear foot 0.7 W/linear foot 0.8 W/linear foot 1.0 W/linear foot
Walkways 10 feet wide or greater, plaza areas
special feature areas
0.14 W/ft2 0.14 W/ft2 0.16 W/ft2 0.2 W/ft2
Stairways 0.75 W/ft2 1.0 W/ft2 1.0 W/ft2 1.0 W/ft2
Pedestrian tunnels 0.15 W/ft2 0.15 W/ft2 0.2 W/ft2 0.3 W/ft2
Building Entrances and Exits
Main entries 20 W/linear foot
of door width
20 W/linear foot
of door width
30 W/linear foot
of door width
30 W/linear foot
of door width
Other doors 20 W/linear foot
of door width
20 W/linear foot
of door width
20 W/linear foot
of door width
20 W/linear foot
of door width
Entry canopies 0.25 W/ft2 0.25 W/ft2 0.4 W/ft2 0.4 W/ft2
Sales Canopies
Free-standing and attached 0.6 W/ft2 0.6 W/ft2 0.8 W/ft2 1.0 W/ft2
Outdoor Sales
Open areas (including vehicle sales lots) 0.25 W/ft2 0.25 W/ft2 0.5 W/ft2 0.7 W/ft2
Street frontage for vehicle sales lots in addition to "open area" allowance No allowance 10 W/linear foot 10 W/linear foot 30 W/linear foot
Nontradable Surfaces (Lighting power density calculations for the following applications can be used only for the specific application and cannot be traded between surfaces or with other exterior lighting. The following allowances are in addition to any allowance otherwise permitted in the "Tradable Surfaces" section of this table.) Building facades No allowance 0.1 W/ft2 for each illuminated wall or surface or 2.5 W/linear foot for each illuminated wall or surface length 0.15 W/ft2 for each illuminated wall or surface or 3.75 W/linear foot for each illuminated wall or surface length 0.2 W/ft2 for each illuminated wall or surface or 5.0 W/linear foot for each illuminated wall or surface length
Automated teller machines and night depositories 270 W per location plus 90 W per additional ATM per location 270 W per location plus 90 W per additional ATM per location 270 W per location plus 90 W per additional ATM per location 270 W per location plus 90 W per additional ATM per location
Entrances and gatehouse inspection stations at guarded facilities 0.75 W/ft2 of covered and uncovered area 0.75 W/ft2 of covered and uncovered area 0.75 W/ft2 of covered and uncovered area 0.75 W/ft2 of covered and uncovered area
Loading areas for law enforcement, fire, ambulance and other emergency service vehicles 0.5 W/ft2 of covered
and uncovered area
0.5 W/ft2 of covered
and uncovered area
0.5 W/ft2 of covered
and uncovered area
0.5 W/ft2 of covered
and uncovered area
Drive-up windows/doors 400 W per drive-through 400 W per drive-through 400 W per drive-through 400 W per drive-through
Parking near 24-hour retail entrances 800 W per main entry 800 W per main entry 800 W per main entry 800 W per main entry
For SI: 1 foot = 304.8 mm, 1 watt per square foot = W/0.0929 m2.

505.6.3 Shielding of Exterior Building Lighting Fixtures

AMENDMENT
This section has been amended at the state or city level.
Only fully shielded fixtures shall be permitted unless a lighting plan is submitted showing that the use of alternative fixtures would provide greater energy efficiency than any comparable lighting plan using fully shielded fixtures.

Exceptions:
  1. Luminaires with an output of 150 Watts or less, or the equivalent light output.
  2. Luminaires intended to illuminate the façade of buildings or to illuminate other objects including flagpoles, landscape and water features, statuary and works of art.
  3. Luminaires for historic lighting on the premises of an historic building as defined in the North Carolina State Building Codes or within a designated historic district.
  4. Outdoor sports facility lighting of the participant sport area.
  5. Emergency exit discharge lighting.
  6. Low voltage landscape lighting.
  7. Sign illumination.
  8. Festoon lighting as defined in the NFPA 70.
  9. Temporary lighting for emergency, repair, construction, special events or similar activities.

505.7 Electrical Energy Consumption. (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level.

In buildings having individual dwelling units, provisions shall be made to determine the electrical energy consumed by each tenant by separately metering individual dwelling units.

Section 506 Total Building Performance

AMENDMENT
This section has been amended at the state or city level.

Section 506 Additional Prescriptive Compliance Requirements

AMENDMENT
This section has been amended at the state or city level.

506.1 Scope

AMENDMENT
This section has been amended at the state or city level.

506.1 Requirements

AMENDMENT
This section has been amended at the state or city level.
Commercial buildings are required to comply with one of the following sections:
  1. 506.2.1 More Efficient Mechanical Equipment;
  2. 506.2.2 Reduced Lighting Power Density;
  3. 506.2.3 Energy Recovery Ventilation Systems;
  4. 506.2.4 Higher Efficiency Service Water Heating;
  5. 506.2.5 On-Site Supply of Renewable Energy; or
  6. 506.2.6 Automatic Daylighting Control System.
At the time of plan submittal, the building jurisdiction shall be provided, by the submittal authority, documentation designating the intent to comply with Section 506.2.1, 506.2.2, 506.2.3, 506.2.4, 506.2.5, or 506.2.6.

506.2 Mandatory Requirements

AMENDMENT
This section has been amended at the state or city level.

506.2.1 Efficient Mechanical Equipment

AMENDMENT
This section has been amended at the state or city level.
This mechanical alternative compliance option is intended to allow the builder to meet the requirements of Section 506 by choosing to install efficient mechanical equipment.

Mechanical equipment choices that fulfill requirements for Section 506.2.1 shall comply with the following in addition to the requirements in Section 503:
  1. Package unitary equipment shall meet the minimum efficiency requirements in Tables 506.2.1(1) and 506.2.1(2);
  2. Package terminal air conditioners and heat pumps shall meet the minimum efficiency requirements in Table 506.2.1(3);
  3. Warm air furnaces and combination warm air furnaces/ air conditioning units shall meet the minimum efficiency requirements in Table 506.2.1(4);
  4. Boilers shall meet the minimum efficiency requirements in Table 506.2.1(5);
  5. Electric chillers shall meet the energy efficiency requirements in Table 506.2.1(6); and
  6. Absorption chillers shall meet the minimum efficiency requirements in Table 506.2.1(7).

506.2.2 Reduced Lighting Power Density

AMENDMENT
This section has been amended at the state or city level.
Whole Building Lighting Power Density (watts/SF) must comply with values 10 percent lower than those in Table 505.5.2. Compliance with this section is in addition to meeting the requirements of Section 505.

506.2.3 Energy Recovery Ventilation Systems

AMENDMENT
This section has been amended at the state or city level.
Buildings using 500 cfm or more outdoor air shall have heat or energy recovery ventilation systems for at least 80 percent of ventilation air. The recovery system shall provide a change in the enthalpy of the outdoor air supply of 50 percent or more of the difference between the outdoor air and return air at design conditions. Provision shall be made to bypass or control the energy recovery system to permit cooling with outdoor air where cooling with outdoor air is required.

506.2.4 High Efficiency Service Water Heating

AMENDMENT
This section has been amended at the state or city level.
Buildings must be of the following types to use this compliance method:
  1. Hotels or motels;
  2. Hospitals;
  3. Restaurants or buildings containing food preparation areas;
  4. Buildings with residential occupancies;
  5. Buildings with laundry facilities or other high process service water heating needs; or
  6. Buildings showing a service hot water load of 8 percent or more of total building energy loads as shown with an energy analysis as described in Section 507.
The building service water heating system shall have one of the following:
  1. Instantaneous fuel-fired water heating systems for all fuel-fired water heating systems;
  2. Electric heat pump water heating systems;
  3. Water heating provided by geothermal heat pumps; or
  4. Solar water heating systems sized to provide at least 40 percent of hot water requirements.

506.2.5 On-Site Supply of Renewable Energy

AMENDMENT
This section has been amended at the state or city level.
The building or surrounding property shall incorporate an on-site renewable energy system that supplies 3 percent or more of total building energy loads. On-site power generation using nonrenewable sources does not meet this requirement.

The jurisdiction shall be provided with an energy analysis as described in Section 506 that documents the renewable energy contribution to the building or a calculation demonstrating that the on-site supply of renewable energy:
  1. Is capable of providing at least 3 percent of the total energy load of the building; or
  2. Provides on-site renewable energy generation with a nominal (peak) rating of 175 BTU's or 0.50 watts per square foot of building.

506.2.6 Automatic Daylighting Control System

AMENDMENT
This section has been amended at the state or city level.
A minimum of 30 percent of the total conditioned floor area shall be daylight zones with automatic controls that control lights in the daylit areas separately from the non-daylit areas.

Controls for calibration adjustments to the lighting control device shall be accessible to owner authorized personnel. Each daylight control zone shall not exceed 2,500 square feet. Automatic daylighting controls must incorporate an automatic shut-off ability based on time or occupancy in addition to lighting power reduction controls.

Controls will automatically reduce lighting power in response to available daylight by either one of the following methods:
  1. Continuous dimming using dimming ballasts and daylight-sensing automatic controls that are capable of reducing the power of general lighting in the daylit zone continuously to less than 35 percent of rated power at maximum light output; or
  2. Stepped dimming using multi-level switching and daylight-sensing controls that are capable of reducing lighting power automatically. The system shall provide at least two control channels per zone and be installed in a manner such that at least one control step shall reduce power of general lighting in the daylit zone by 30 to 50 percent of rated power and another control step that reduces lighting power by 65 to 100 percent. Stepped dimming control is not appropriate in continuously occupied areas with ceiling heights of 14 feet or lower.

506.3 Performance-Based Compliance

AMENDMENT
This section has been amended at the state or city level.

506.4 Documentation

AMENDMENT
This section has been amended at the state or city level.

506.4.1 Compliance Report

AMENDMENT
This section has been amended at the state or city level.

506.4.2 Additional Documentation

AMENDMENT
This section has been amended at the state or city level.

506.5 Calculation Procedure

AMENDMENT
This section has been amended at the state or city level.

506.5.1 Building Specifications

AMENDMENT
This section has been amended at the state or city level.

506.5.2 Thermal Blocks

AMENDMENT
This section has been amended at the state or city level.

506.5.2.1 HVAC Zones Designed

AMENDMENT
This section has been amended at the state or city level.

506.5.2.2 HVAC Zones Not Designed

AMENDMENT
This section has been amended at the state or city level.

506.5.2.3 Multifamily Residential Buildings

AMENDMENT
This section has been amended at the state or city level.

506.6 Calculation Software Tools

AMENDMENT
This section has been amended at the state or city level.

506.6.1 Specific Approval

AMENDMENT
This section has been amended at the state or city level.

506.6.2 Input Values

AMENDMENT
This section has been amended at the state or city level.

Section 507 Total Building Performance

AMENDMENT
This section has been amended at the state or city level.

507.1 Scope

AMENDMENT
This section has been amended at the state or city level.
This section establishes criteria for compliance using total building performance. The following systems and loads shall be included in determining the total building performance: heating systems, cooling systems, service water heating, fan systems, lighting power, receptacle loads and process loads.

507.2 Mandatory Requirements

AMENDMENT
This section has been amended at the state or city level.
Compliance with this section requires that the criteria of Sections 502.4, 503.2, 504 and 505 be met.

507.3 Performance-Based Compliance

AMENDMENT
This section has been amended at the state or city level.
Compliance based on total building performance requires that a proposed building (proposed design) be shown to have an annual energy cost that is less than or equal to the annual energy cost of the standard reference design. Energy prices shall be taken from a source approved by the code official, such as the Department of Energy, Energy Information Administration's State Energy Price and Expenditure Report. Code officials shall be permitted to require time-of-use pricing in energy cost calculations. Nondepletable energy collected off site shall be treated and priced the same as purchased energy. Energy from nondepletable energy sources collected on site shall be omitted from the annual energy cost of the proposed design.

Exception: Jurisdictions that require site energy (1 kWh = 3413 Btu) rather than energy cost as the metric of comparison.

507.4 Documentation

AMENDMENT
This section has been amended at the state or city level.
Documentation verifying that the methods and accuracy of compliance software tools conform to the provisions of this section shall be provided to the code official.

507.4.1 Compliance Report

AMENDMENT
This section has been amended at the state or city level.
Compliance software tools shall generate a report that documents that the proposed design has annual energy costs less than or equal to the annual energy costs of the standard reference design. The compliance documentation shall include the following information:
  1. Address of the building;
  2. An inspection checklist documenting the building component characteristics of the proposed design as listed in Table 507.5.1(1). The inspection checklist shall show the estimated annual energy cost for both the standard reference design and the proposed design;
  3. Name of individual completing the compliance report; and
  4. Name and version of the compliance software tool.

507.4.2 Additional Documentation

AMENDMENT
This section has been amended at the state or city level.
The code official shall be permitted to require the following documents:
  1. Documentation of the building component characteristics of the standard reference design;
  2. Thermal zoning diagrams consisting of floor plans showing the thermal zoning scheme for standard reference design and proposed design;
  3. Input and output report(s) from the energy analysis simulation program containing the complete input and output files, as applicable. The output file shall include energy use totals and energy use by energy source and end-use served, total hours that space conditioning loads are not met and any errors or warning messages generated by the simulation tool as applicable;
  4. An explanation of any error or warning messages appearing in the simulation tool output; and
  5. A certification signed by the builder providing the building component characteristics of the proposed design as given in Table 507.5.1(1).

507.5 Calculation Procedure

AMENDMENT
This section has been amended at the state or city level.
Except as specified by this section, the standard reference design and proposed design shall be configured and analyzed using identical methods and techniques.

507.5.1 Building Specifications

AMENDMENT
This section has been amended at the state or city level.
The standard reference design and proposed design shall be configured and analyzed as specified by Table 507.5.1(1). Table 507.5.1(1) shall include by reference all notes contained in Table 502.2(1).



TABLE 507.5.1(1)
SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS

BUILDING COMPONENT CHARACTERISTICS

STANDARD REFERENCE DESIGN

PROPOSED DESIGN

Space use classification

Same as proposed

The space use classification shall be chosen in accordance with Table 505.5.2 for all areas of the building covered by this permit. Where the space use classification for a building is not known, the building shall be categorized as an office building.

Roofs

Type: Insulation entirely above deck

Gross area: same as proposed

U-factor: from Table 502.1.2

Solar absorptance: 0.75

Emittance: 0.90

As proposed

As proposed

As proposed

As proposed

As proposed

Walls, above-grade

Type: Mass wall if proposed wall is mass; otherwise steel-framed wall

Gross area: same as proposed

U-factor: from Table 502.1.2

Solar absorptance: 0.75

Emittance: 0.90

As proposed


As proposed

As proposed

As proposed

As proposed

Walls, below-grade

Type: Mass wall

Gross area: same as proposed

U-Factor: from Table 502.1.2 with insulation layer on interior side of walls

As proposed

As proposed

As proposed

Floors, above-grade

Type: joist/framed floor

Gross area: same as proposed

U-factor: from Table 502.1.2

As proposed

As proposed

As proposed

Floors, slab-on-grade

Type: Unheated

F-factor: from Table 502.1.2

As proposed

As proposed

Doors

Type: Swinging

Area: Same as proposed

U-factor: from Table 502.2(1)

As proposed

As proposed

As proposed

Glazing

Area:
  1. The proposed glazing area; where the proposed glazing area is less than 40 percent of above-grade wall area.
  2. 40 percent of above-grade wall area; where the proposed glazing area is 40 percent or more of the above-grade wall area.


U-factor: from Table 502.3

SHGC: from Table 502.3 except that for climates with no requirement (NR) SHGC = 0.40 shall be used

External shading and PF: None
For example, if the proposed building design has a glazing area equal to 45% of the above-grade wall area, the Standard Reference Design shall have a glazing area equal to 30% of the above-grade wall area. On the other hand, if the proposed design has a glazing fraction of 20%, the Standard Reference Design shall also have a glazing fraction of 20%.
As proposed











As proposed


As proposed





As proposed



Skylights

Area:
  1. The proposed skylight area; where the proposed skylight area is less than 3 percent of gross area of roof assembly.
  2. 3 percent of gross area of roof assembly; where the proposed skylight area is 3 percent or more of gross area of roof assembly.


U-factor: from Table 502.3

SHGC: from Table 502.3 except that for climates with no requirement (NR) SHGC = 0.40 shall be used.



As proposed











As proposed

As proposed

Lighting, interior

The interior lighting power shall be determined in accordance with Table 505.5.2. Where the occupancy of the building is not known, the lighting power density shall be 1.0 Watt per square foot (10.73 W/m2) based on the categorization of buildings with unknown space classification as offices.

As proposed

Lighting, exterior

The lighting power shall be determined in accordance with Table 505.6.2(2). Areas and dimensions of tradable and nontradable surfaces shall be the same as proposed.

As proposed

Internal gains

Same as proposed

Receptacle, motor and process loads shall be modeled and estimated based on the space use classification. All end-use load components within and associated with the building shall be modeled to include, but not be limited to, the following: exhaust fans, parking garage ventilation fans, exterior building lighting, swimming pool heaters and pumps, elevators, escalators, refrigeration equipment and cooking equipment.

Schedules

Same as proposed

Operating schedules shall include hourly profiles for daily operation and shall account for variations between weekdays, weekends, holidays and any seasonal operation. Schedules shall model the time-dependent variations in occupancy, illumination, receptacle loads, thermostat settings, mechanical ventilation, HVAC equipment availability, service hot water usage and any process loads. The schedules shall be typical of the proposed building type as determined by the designer and approved by the jurisdiction.

Mechanical ventilation

Same as proposed

As proposed, in accordance with Section 503.2.5.

Heating systems

Fuel type: same as proposed design

Equipment typea: from Tables 506.5.1(2) and 506.5.1(3)

Efficiency: from Tables 503.2.3(4) and 503.2.3(5)

Capacityb: sized proportionally to the capacities in the proposed design based on sizing runs, and shall be established such that no smaller number of unmet heating load hours and no larger heating capacity safety factors are provided than in the proposed design.
As proposed


As proposed




As proposed



As proposed















Cooling systems

Fuel type: same as proposed design

Equipment typec: from Tables 506.5.1(2) and 506.5.1(3)

Efficiency: from Tables 503.2.3(1), 503.2.3(2) and 503.2.3(3)

Capacityb: sized proportionally to the capacities in the proposed design based on sizing runs, and shall be established such that no smaller number of unmet cooling load hours and no larger cooling capacity safety factors are provided than in the proposed design.

Economizerd: same as proposed, in accordance with Section 503.4.1.



As proposed


As proposed




As proposed




As proposed



















As proposed




Service water heating

Fuel type: same as proposed

Efficiency: from Table 504.2

Capacity: same as proposed

Where no service water hot water system exists or is specified in
the proposed design, no service hot water heating shall be modeled.
As proposed


As proposed


As proposed









  1. Where no heating system exists or has been specified, the heating system shall be modeled as fossil fuel. The system characteristics shall be identical in both the standard reference design and proposed design.
  2. The ratio between the capacities used in the annual simulations and the capacities determined by sizing runs shall be the same for both the standard reference design and proposed design.
  3. Where no cooling system exists or no cooling system has been specified, the cooling system shall be modeled as an air-cooled single-zone system, one unit per thermal zone. The system characteristics shall be identical in both the standard reference design and proposed design.
  4. If an economizer is required in accordance with Table 503.3.1 (1), and if no economizer exists or is specified in the proposed design, then a supply air economizer shall be provided in accordance with Section 503.4.1.
TABLE 507.5.1(2)
HVAC SYSTEMS MAP

CONDENSER COOLING SOURCEa

HEATING SYSTEM CLASSIFICATIONb

STANDARD REFERENCE DESIGN HVC SYSTEM TYPEc

Single-zone
Residential System

Single-zone
Nonresidential System

All Other

Water/ground

Electric resistance

System 5

System 5

System 1

Heat pump

System 6

System 6

System 6

Fossil fuel

System 7

System 7

System 2

Air/none

Electric resistance

System 8

System 9

System 3

Heat pump

System 8

System 9

System 3

Fossil fuel

System 10

System 11

System 4

  1. Select "water/ground" if the proposed design system condenser is water or evaporatively cooled; select "air/none" if the condenser is air cooled. Closed-circuit dry coolers shall be considered air cooled. Systems utilizing district cooling shall be treated as if the condenser water type were "water." If no mechanical cooling is specified or the mechanical cooling system in the proposed design does not require heat rejection, the system shall be treated as if the condenser water type were "Air." For proposed designs with ground-source or groundwater-source heat pumps, the standard reference design HVAC system shall be water-source heat pump (System 6).
  2. Select the path that corresponds to the proposed design heat source: electric resistance, heat pump (including air source and water source), or fuel fired. Systems utilizing district heating (steam or hot water) and systems with no heating capability shall be treated as if the heating system type were "fossil fuel." For systems with mixed fuel heating sources, the system or systems that use the secondary heating source type (the one with the smallest total installed output capacity for the spaces served by the system) shall be modeled identically in the standard reference design and the primary heating source type shall be used to determine standard reference design HVAC system type.
  3. Select the standard reference design HVAC system category: The system under "single-zone residential system" shall be selected if the HVAC system in the proposed design is a single-zone system and serves a residential space. The system under "single-zone nonresidential system" shall be selected if the HVAC system in the proposed design is a single-zone system and serves other than residential spaces. The system under "all other" shall be selected for all other cases.
TABLE 507.5.1(3)
SPECIFICATIONS FOR THE STANDARD REFERENCE DESIGN HVAC SYSTEM DESCRIPTIONS

SYSTEM NO.

SYSTEM TYPE

FAN CONTROL

COOLING TYPE

HEATING TYPE

1

Variable air volume with parallel fan-powered boxesa

VAVd

Chilled watere

Electric resistance

2

Variable air volume with reheatb

VAVd

Chilled watere

Hot water fossil fuel boilerf

3

Packaged variable air volume with parallel fan-powered boxesa

VAVd

Direct expansionc

Electric resistance

4

Packaged variable air volume with reheatb

VAVd

Direct expansionc

Hot water fossil fuel boilerf

5

Two-pipe fan coil

Constant volumei

Chilled watere

Electric resistance

6

Water-source heat pump

Constant volumei

Direct expansionc

Electric heat pump and boilerg

7

Four-pipe fan coil

Constant volumei

Chilled watere

Hot water fossil fuel boilerf

8

Packaged terminal heat pump

Constant volumei

Direct expansionc

Electric heat pumph

9

Packaged rooftop heat pump

Constant volumei

Direct expansionc

Electric heat pumph

10

Packaged terminal air conditioner

Constant volumei

Direct expansion

Hot water fossil fuel boilerf

11

Packaged rooftop air conditioner

Constant volumei

Direct expansion

Fossil fuel furnace

For SI: 1 foot = 304.8 mm, 1 cfm/ft2 = 0.0004719, 1 Btu/h = 0.293/W, °C = [(°F) -32/1.8].

  1. VAV with parallel boxes: Fans in parallel VAV fan-powered boxes shall be sized for 50 percent of the peak design flow rate and shall be modeled with 0.35 W/cfm fan power. Minimum volume setpoints for fan-powered boxes shall be equal to the minimum rate for the space required for ventilation consistent with Section 503.4.5, Exception 5. Supply air temperature setpoint shall be constant at the design condition.
  2. VAV with reheat: Minimum volume setpoints for VAV reheat boxes shall be 0.4 cfm/ft2 of floor area. Supply air temperature shall be reset based on zone demand from the design temperature difference to a 10°F temperature difference under minimum load conditions. Design airflow rates shall be sized for the reset supply air temperature, i.e., a 10°F temperature difference.
  3. Direct expansion: The fuel type for the cooling system shall match that of the cooling system in the proposed design.
  4. VAV: Constant volume can be modeled if the system qualifies for Exception 1, Section 503.4.5. When the proposed design system has a supply, return or relief fan motor 25 horsepower (hp) or larger, the corresponding fan in the VAV system of the standard reference design shall be modeled assuming a variable speed drive. For smaller fans, a forward-curved centrifugal fan with inlet vanes shall be modeled. If the proposed design's system has a direct digital control system at the zone level, static pressure setpoint reset based on zone requirements in accordance with Section 503.4.2 shall be modeled.
  5. Chilled water: For systems using purchased chilled water, the chillers are not explicitly modeled and chilled water costs shall be based as determined in Sections 506.3 and 506.5.2. Otherwise, the standard reference design's chiller plant shall be modeled with chillers having the number as indicated in Table 506.5.1(4) as a function of standard reference building chiller plant load and type as indicated in Table 507.5.1(5) as a function of individual chiller load. Where chiller fuel source is mixed, the system in the standard reference design shall have chillers with the same fuel types and with capacities having the same proportional capacity as the proposed design's chillers for each fuel type. Chilled water supply temperature shall be modeled at 44°F design supply temperature and 56°F return temperature. Piping losses shall not be modeled in either building model. Chilled water supply water temperature shall be reset in accordance with Section 503.4.3.4. Pump system power for each pumping system shall be the same as the proposed design; if the proposed design has no chilled water pumps, the standard reference design pump power shall be 22 W/gpm (equal to a pump operating against a 75-foot head, 65-percent combined impeller and motor efficiency). The chilled water system shall be modeled as primary-only variable flow with flow maintained at the design rate through each chiller using a bypass. Chilled water pumps shall be modeled as riding the pump curve or with variable-speed drives when required in Section 503.4.3.4. The heat rejection device shall be an axial fan cooling tower with two-speed fans if required in Section 503.4.4. Condenser water design supply temperature shall be 85°F or 10°F approach to design wet-bulb temperature, whichever is lower, with a design temperature rise of 10°F. The tower shall be controlled to maintain a 70°F leaving water temperature where weather permits, floating up to leaving water temperature at design conditions. Pump system power for each pumping system shall be the same as the proposed design; if the proposed design has no condenser water pumps, the standard reference design pump power shall be 19 W/gpm (equal to a pump operating against a 60-foot head, 60-percent combined impeller and motor efficiency). Each chiller shall be modeled with separate condenser water and chilled water pumps interlocked to operate with the associated chiller.
  6. Fossil fuel boiler: For systems using purchased hot water or steam, the boilers are not explicitly modeled and hot water or steam costs shall be based on actual utility rates. Otherwise, the boiler plant shall use the same fuel as the proposed design and shall be natural draft. The standard reference design boiler plant shall be modeled with a single boiler if the standard reference design plant load is 600,000 Btu/h and less and with two equally sized boilers for plant capacities exceeding 600,000 Btu/h. Boilers shall be staged as required by the load. Hot water supply temperature shall be modeled at 180°F design supply temperature and 130°F return temperature. Piping losses shall not be modeled in either building model. Hot water supply water temperature shall be reset in accordance with Section 503.4.3.4. Pump system power for each pumping system shall be the same as the proposed design; if the proposed design has no hot water pumps, the standard reference design pump power shall be 19 W/gpm (equal to a pump operating against a 60-foot head, 60-percent combined impeller and motor efficiency). The hot water system shall be modeled as primary only with continuous variable flow. Hot water pumps shall be modeled as riding the pump curve or with variable speed drives when required by Section 503.4.3.4.
  7. Electric heat pump and boiler: Water-source heat pumps shall be connected to a common heat pump water loop controlled to maintain temperatures between 60°F and 90°F. Heat rejection from the loop shall be provided by an axial fan closed-circuit evaporative fluid cooler with two-speed fans if required in Section 503.4.2. Heat addition to the loop shall be provided by a boiler that uses the same fuel as the proposed design and shall be natural draft. If no boilers exist in the proposed design, the standard reference building boilers shall be fossil fuel. The standard reference design boiler plant shall be modeled with a single boiler if the standard reference design plant load is 600,000 Btu/h or less and with two equally sized boilers for plant capacities exceeding 600,000 Btu/h. Boilers shall be staged as required by the load. Piping losses shall not be modeled in either building model. Pump system power shall be the same as the proposed design; if the proposed design has no pumps, the standard reference design pump power shall be 22 W/gpm, which is equal to a pump operating against a 75-foot head, with a 65-percent combined impeller and motor efficiency. Loop flow shall be variable with flow shutoff at each heat pump when its compressor cycles off as required by Section 503.4.3.3. Loop pumps shall be modeled as riding the pump curve or with variable speed drives when required by Section 503.4.3.4.
  8. Electric heat pump: Electric air-source heat pumps shall be modeled with electric auxiliary heat. The system shall be controlled with a multistage space thermostat and an outdoor air thermostat wired to energize auxiliary heat only on the last thermostat stage and when outdoor air temperature is less than 40°F.
  9. Constant volume: Fans shall be controlled in the same manner as in the proposed design; i.e., fan operation whenever the space is occupied or fan operation cycled on calls for heating and cooling. If the fan is modeled as cycling and the fan energy is included in the energy efficiency rating of the equipment, fan energy shall not be modeled explicitly.
TABLE 507.5.1(4)
NUMBER OF CHILLERS

TOTAL CHILLER PLANT CAPACITY

NUMBER OF CHILLERS

≤ 300 tons

1

> 300 tons, < 600 tons

2, sized equally

≥ 600 tons

2 minimum, with chillers added so that no chiller is larger than 800 tons, all sized equally

For SI: 1 ton = 3517 w.


TABLE 507.5.1(5)
WATER CHILLER TYPES

INDIVIDUAL CHILLER PLANT CAPACITY

ELECTRIC CHILLER TYPE

FOSSIL FUEL CHILLER TYPE

≤ 100 tons

Reciprocating

Single-effect absorption, direct fired

> 100 tons, < 300 tons

Screw

Double-effect absorption, direct fired

≥ 300 tons

Centrifugal

Double-effect absorption, direct fired

For SI: 1 ton = 3517 w.

507.5.2 Thermal Blocks

AMENDMENT
This section has been amended at the state or city level.
The standard reference design and proposed design shall be analyzed using identical thermal blocks as required in Section 507.5.2.1, 507.2.2 or 507.5.2.3.

507.5.2.1 HVAC Zones Designed

AMENDMENT
This section has been amended at the state or city level.
Where HVAC zones are defined on HVAC design drawings, each HVAC zone shall be modeled as a separate thermal block.

Exception: Different HVAC zones shall be allowed to be combined to create a single thermal block or identical thermal blocks to which multipliers are applied provided:
  1. The space use classification is the same throughout the thermal block.
  2. All HVAC zones in the thermal block that are adjacent to glazed exterior walls face the same orientation or their orientations are within 45 degrees (0.79 rad) of each other.
  3. All of the zones are served by the same HVAC system or by the same kind of HVAC system.

507.5.2.2 HVAC Zones Not Designed

AMENDMENT
This section has been amended at the state or city level.
Where HVAC zones have not yet been designed, thermal blocks shall be defined based on similar internal load densities, occupancy, lighting, thermal and temperature schedules, and in combination with the following guidelines:
  1. Separate thermal blocks shall be assumed for interior and perimeter spaces. Interior spaces shall be those located more than 15 feet (4572 mm) from an exterior wall. Perimeter spaces shall be those located closer than 15 feet (4572 mm) from an exterior wall.
  2. Separate thermal blocks shall be assumed for spaces adjacent to glazed exterior walls: a separate zone shall be provided for each orientation, except orientations that differ by no more than 45 degrees (0.79 rad) shall be permitted to be considered to be the same orientation. Each zone shall include floor area that is 15 feet (4572 mm) or less from a glazed perimeter wall, except that floor area within 15 feet (4572 mm) of glazed perimeter walls having more than one orientation shall be divided proportionately between zones.
  3. Separate thermal blocks shall be assumed for spaces having floors that are in contact with the ground or exposed to ambient conditions from zones that do not share these features.
  4. Separate thermal blocks shall be assumed for spaces having exterior ceiling or roof assemblies from zones that do not share these features.

507.5.2.3 Multifamily Residential Buildings

AMENDMENT
This section has been amended at the state or city level.
Residential spaces shall be modeled using one thermal block per space except that those facing the same orientations are permitted to be combined into one thermal block. Corner units and units with roof or floor loads shall only be combined with units sharing these features.

507.6 Calculation Software Tools

AMENDMENT
This section has been amended at the state or city level.
Calculation procedures used to comply with this section shall be software tools capable of calculating the annual energy consumption of all building elements that differ between the standard reference design and the proposed design and shall include the following capabilities.
  1. Computer generation of the standard reference design using only the input for the proposed design. The calculation procedure shall not allow the user to directly modify the building component characteristics of the standard reference design.
  2. Building operation for a full calendar year (8760 hours).
  3. Climate data for a full calendar year (8760 hours) and shall reflect approved coincident hourly data for temperature, solar radiation, humidity and wind speed for the building location.
  4. Ten or more thermal zones.
  5. Thermal mass effects.
  6. Hourly variations in occupancy, illumination, receptacle loads, thermostat settings, mechanical ventilation, HVAC equipment availability, service hot water usage and any process loads.
  7. Part-load performance curves for mechanical equipment.
  8. Capacity and efficiency correction curves for mechanical heating and cooling equipment.
  9. Printed code official inspection checklist listing each of the proposed design component characteristics from Table 507.5.1(1) determined by the analysis to provide compliance, along with their respective performance ratings (e.g., R-value, U-factor, SHGC, HSPF, AFUE, SEER, EF, etc.).

507.6.1 Specific Approval

AMENDMENT
This section has been amended at the state or city level.
Performance analysis tools meeting the applicable sub-sections of Section 507 and tested according to ASHRAE Standard 140 shall be permitted to be approved. Tools are permitted to be approved based on meeting a specified threshold for a jurisdiction. The code official shall be permitted to approve tools for a specified application or limited scope.

507.6.2 Input Values

AMENDMENT
This section has been amended at the state or city level.
When calculations require input values not specified by Sections 502, 503, 504 and 505, those input values shall be taken from an approved source.
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