CODES

ADOPTS WITH AMENDMENTS:

International Energy Conservation Code 2015 (IECC 2015)

Chapter 1 [CE] Scope and Administration

Chapter 2 [CE] Definitions

Chapter 3 [CE] General Requirements

Chapter 4 [CE] Commercial Energy Efficiency

Chapter 5 [CE] Existing Buildings

Chapter 6 [CE] Referenced Standards

Chapter 1 [RE] Scope and Administration

Chapter 2 [RE] Definitions

Chapter 3 [RE] General Requirements

Chapter 4 [RE] Residential Energy Efficiency

Chapter 5 [RE] Existing Buildings

Chapter 6 [RE] Referenced Standards

Appendix R1 RESIDENTIAL REQUIREMENTS

Appendix R2 FOAM PLASTIC DIAGRAMS

Appendix R3 SAMPLE WORKSHEETS FOR RESIDENTIAL AIR AND DUCT LEAKAGE TESTING

Appendix R4 ADDITIONAL VOLUNTARY CRITERIA FOR INCREASING ENERGY EFFICIENCY (High-Efficiency Residential Option)

This chapter applies to residential buildings.

R401.2 Compliance

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Projects shall comply with one of the following:
  1. Sections R401 through R404.
  2. Section R405 and the provisions of Sections R401 through R404 labeled "Mandatory."
  3. An energy rating index (ERI) approach in Section R406.
  4. North Carolina specific REScheck shall be permitted to demonstrate compliance with this code. Envelope requirements may not be traded off against the use of high efficiency heating or cooling equipment. No tradeoff calculations are needed for required termite inspection and treatment gaps.

R401.2.1 Tropical Zone

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

Residential buildings
in the tropical zone at elevations below 2,400 feet (731.5 m) above sea level shall be deemed to comply with this chapter where the following conditions are met:

1. Not more than one-half of the occupied space is air conditioned.

2. The occupied space is not heated.

3. Solar, wind or other renewable energy source supplies not less than 80 percent of the energy for service water heating.

4. Glazing in conditioned space has a solar heat gain coefficient of less than or equal to 0.40, or has an overhang with a projection factor equal to or greater than 0.30.

5. Permanently installed lighting is in accordance with Section R404.

6. The exterior roof surface complies with one of the options in Table C402.3 or the roof/ceiling has insulation with an R-value of R-15 or greater. If present, attics above the insulation are vented and attics below the insulation are unvented.

7. Roof surfaces have a minimum slope of 1/4 inch per foot of run. The finished roof does not have water accumulation areas.

8. Operable fenestration provides ventilation area equal to not less than 14 percent of the floor area in each room. Alternatively, equivalent ventilation is provided by a ventilation fan.

9. Bedrooms with exterior walls facing two different directions have operable fenestration on exterior walls facing two direction exterior walls facing two directions.

10. Interior doors to bedrooms are capable of being secured in the open position.

11. A ceiling fan or ceiling fan rough-in is provided for bedrooms and the largest space that is not used as a bedroom.

R401.3 Certificate (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A permanent certificate shall be completed by the builder or registered design professional and posted on a wall in the space where the furnace is located, a utility room or an approved location inside the building. Where located on an electrical panel, the certificate shall not cover or obstruct the visibility of the circuit directory label, service disconnect label or other required labels. The certificate shall list the predominant R-values of insulation installed in or on ceiling/roof, walls, foundation (slab, basement wall, crawlspace wall and floor) and ducts outside conditioned spaces; U-factors for fenestration and the solar heat gain coefficient (SHGC) of fenestration, and the results from any required duct system and building envelope air leakage testing done on the building. Where there is more than one value for each component, the certificate shall list the value covering the largest area. The certificate shall list the types and efficiencies of heating, cooling and service water heating equipment. Where a gas-fired unvented room heater, electric furnace or baseboard electric heater is installed in the residence, the certificate shall list "gas-fired unvented room heater," "electric furnace" or "baseboard electric heater," as appropriate. An efficiency shall not be listed for gas-fired unvented room heaters, electric furnaces or electric baseboard heaters. A permanent certificate shall be posted on or in the electrical distribution panel, in the attic next to the attic insulation card, or inside a kitchen cabinet or other approved location. The certificate shall not cover or obstruct the visibility of the circuit directory label, service disconnect label or other required labels. The builder, permit holder, or registered design professional shall be responsible for completing the certificate. The certificate shall list the predominant R-values of insulation installed in or on ceiling/roof, walls, foundation (slab, basement wall, crawlspace wall and floor) and ducts outside conditioned spaces; and the U-factors for fenestration and the solar heat gain coefficient (SHGC) of fenestration. Where there is more than one value for each component, the certificate shall list the value covering the largest area. The certificate shall indicate whether the building air leakage was visually inspected as required in Section R402.4.2.1 or provide results of the air leakage testing required in Section R402.4.2.2. The certificate shall provide results of the duct leakage test as required in Section R403.3.3. Appendix R1.1 contains a sample certificate.

R401.4 Additional voluntary criteria for increasing residential energy efficiency

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Appendix R4 contains additional voluntary measures for increasing residential energy efficiency beyond code minimums. Implementation of the increased energy efficiency measures is strictly voluntary at the option of the permit holder. The sole purpose of the appendix is to provide guidance for achieving additional residential energy efficiency improvements that have been evaluated to be those that are most cost effective for achieving an additional 10- to 15-percent improvement in energy efficiency beyond code minimums.
The building thermal envelope shall meet the requirements of Sections R402.1.1 through R402.1.5.

Exception: The following low-energy buildings, or portions thereof, separated from the remainder of the building by building thermal envelope assemblies complying with this section shall be exempt from the building thermal envelope provisions of Section R402.
  1. Those with a peak design rate of energy usage less than 3.4 Btu/h ft2 (10.7 W/m2) or 1.0 watt/ft2 of floor area for space-conditioning purposes.
  2. Those that do not contain conditioned space.

R402.1.1 Vapor Retarder

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Wall assemblies in the building thermal envelope shall comply with the vapor retarder requirements of Section R702.7 of the International Residential Code or Section 1405.3 of the International Building Code, as applicable.

R402.1.2 Insulation and Fenestration Criteria

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The building thermal envelope shall meet the requirements of Table R402.1.2, based on the climate zone specified in Chapter 3.

TABLE R402.1.2 INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENTa

CLIMATE
ZONE
FENESTRATION
U-FACTORb
SKYLIGHTb
U-FACTOR
GLAZED
FENESTRATION
SHGCb, e
CEILING
R-VALUE
WOOD
FRAME WALL
R-VALUE
MASS
WALL
R-VALUEi
FLOOR
R-VALUE
BASEMENTc
WALL
R-VALUE
SLABd
R-VALUE
& DEPTH
CRAWL
SPACEc
WALL
R-VALUE
1 NR 0.75 0.25 30 13 3/4 13 0 0 0
2 0.40 0.65 0.25 38 13 4/6 13 0 0 0
3 0.35 0.55 0.25 38 20 or 13+5h 8/13 19 5/13f 0 5/13
4 except
Marine
0.35 0.55 0.40 49 20 or 13+5h 8/13 19 10/13 10, 2 ft 10/13
5 and
Marine 4
0.32 0.55 NR 49 20 or 13+5h 13/17 30g 15/19 10, 2 ft 15/19
6 0.32 0.55 NR 49 20+5 or 13+10h 15/20 30g 15/19 10, 4 ft 15/19
7 and 8 0.32 0.55 NR 49 20+5 or 13+10h 19/21 38g 15/19 10, 4 ft 15/19

For SI: 1 foot = 304.8 mm.
a. R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity which is less than the label or design thickness of the insulation, the installed R-value of the insulation shall not be less than the R-value specified in the table.
b. The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration. Exception: Skylights may be excluded from glazed fenestration SHGC requirements in climate zones 1 through 3 where the SHGC for such skylights does not exceed 0.30.
c. "15/19" means R-15 continuous insulation on the interior or exterior of the home or R-19 cavity insulation at the interior of the basement wall. "15/19" shall be permitted to be met with R-13 cavity insulation on the interior of the basement wall plus R-5 continuous insulation on the interior or exterior of the home. "10/13" means R-10 continuous insulation on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall.
d. R-5 shall be added to the required slab edge R-values for heated slabs. Insulation depth shall be the depth of the footing or 2 feet, whichever is less in Climate Zones 1 through 3 for heated slabs.
e. There are no SHGC requirements in the Marine Zone.
f. Basement wall insulation is not required in warm-humid locations as defined by Figure R301.1 and Table R301.1.
g. Or insulation sufficient to fill the framing cavity, R-19 minimum.
h. The first value is cavity insulation, the second value is continuous insulation, so "13+5" means R-13 cavity insulation plus R-5 continuous insulation.
i. The second R-value applies when more than half the insulation is on the interior of the mass wall.
TABLE R402.1.2
INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENTa
CLIMATE ZONE FENESTRATION U-FACTORb, i SKYLIGHTb U-FACTOR GLAZED FENESTRATION SHGCb, k CEILING R-VALUEm WOOD FRAME WALL R-VALUE MASS WALL R-VALUEi FLOOR R-VALUE BASEMENTc, o WALL R-VALUE SLABd R-VALUE & DEPTH CRAWL SPACEc WALL R-VALUE
3 0.35 0.55 0.30 38 or 30cil 15 or 13+2.5h 5/13 or 5/10ci 19 5/13f 0 5/13
4 0.35 0.55 0.30 38 or 30cil 15 or 13+ 2.5h 5/13 or 5/10ci 19 10/15 10 10/15
5 0.35 0.55 NR 38 or 30cil 19n or 13+5h
or
15+3h
13/17 or 13/12.5ci 30g 10/15 10 10/19
For SI: 1 foot = 304.8 mm.
  1. R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity which is less than the label or design thickness of the insulation, the installed R-value of the insulation shall not be less than the R-value specified in the table.
  2. The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.
  3. “10/15” means R-10 continuous insulated sheathing on the interior or exterior of the home or R-15 cavity insulation at the interior of the basement wall or crawl space wall.
  4. For monolithic slabs, insulation shall be applied from the inspection gap downward to the bottom of the footing or a maximum of 24 inches below grade, whichever is less. For floating slabs, insulation shall extend to the bottom of the foundation wall or 24 inches, whichever is less. (See Appendix R2). R-5 shall be added to the required slab edge R-values for heated slabs.
  5. Deleted.
  6. Basement wall insulation is not required in warm-humid locations as defined by Figure R301.1 and Table R301.1.
  7. Or insulation sufficient to fill the framing cavity, R-19 minimum.
  8. The first value is cavity insulation, the second value is continuous insulation, so “13+5” means R-13 cavity insulation plus R-5 continuous insulation. If structural sheathing covers 25 percent or less of the exterior, insulating sheathing is not required where structural sheathing is used. If structural sheathing covers more than 25 percent of exterior, structural sheathing shall be supplemented with insulated sheathing of at least R-2.
  9. The second R-value applies when more than half the insulation is on the interior of the mass wall.
  10. In addition to the exemption in Section R402.3.3, a maximum of two glazed fenestration product assemblies having a U-factor no greater than 0.55 shall be permitted to be substituted for minimum code compliant fenestration product assemblies without penalty.
  11. In addition to the exemption in Section R402.3.3, a maximum of two glazed fenestration product assemblies having a SHGC no greater than 0.70 shall be permitted to be substituted for minimum code compliant fenestration product assemblies without penalty.
  12. R-30 shall be deemed to satisfy the ceiling insulation requirement wherever the full height of uncompressed R-30 insulation extends over the wall top plate at the eaves. Otherwise R-38 insulation is required where adequate clearance exists or insulation must extend to either the insulation baffle or within 1 inch of the attic roof deck.
  13. Table value required except for roof edge where the space is limited by the pitch of the roof; there the insulation must fill the space up to the air baffle.
  14. R -19 fiberglass batts compressed and installed in a nominal 2 × 6 framing cavity is deemed to comply. Fiberglass batts rated R-19 or higher compressed and installed in a 2 × 4 wall is not deemed to comply.
  15. Basement wall meeting the minimum mass wall specific heat content requirement may use the mass wall R-value as the minimum requirement.
Insulation material used in layers, such as framing cavity insulation, or continuous insulation shall be summed to compute the corresponding component R-value. The manufacturer's settled R-value shall be used for blown insulation. Computed R-values shall not include an R-value for other building materials or air films. Where insulated siding is used for the purpose of complying with the continuous insulation requirements of Table R402.1.2, the manufacturer's labeled R-value for insulated siding shall be reduced by R-0.6.

R402.1.4 U-Factor Alternative

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
An assembly with a U-factor equal to or less than that specified in Table R402.1.4 shall be permitted as an alternative to the R-value in Table R402.1.2.

TABLE R402.1.4 EQUIVALENT U-FACTORSa

CLIMATE
ZONE
FENESTRATION
U-FACTOR
SKYLIGHT
U-FACTOR
CEILING
U-FACTOR
FRAME
WALL
U-FACTOR
MASS WALL
U-FACTORb
FLOOR
U-FACTOR
BASEMENT
WALL
U-FACTOR
CRAWL
SPACE WALL
U-FACTOR
1 0.50 0.75 0.035 0.084 0.197 0.064 0.360 0.477
2 0.40 0.65 0.030 0.084 0.165 0.064 0.360 0.477
3 0.35 0.55 0.030 0.060 0.098 0.047 0.091c 0.136
4 except Marine 0.35 0.55 0.026 0.060 0.098 0.047 0.059 0.065
5 and Marine 4 0.32 0.55 0.026 0.060 0.082 0.033 0.050 0.055
6 0.32 0.55 0.026 0.045 0.060 0.033 0.050 0.055
7 and 8 0.32 0.55 0.026 0.045 0.057 0.028 0.050 0.055

a. Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source.
b. When more than half the insulation is on the interior, the mass wall U-factors shall be a maximum of 0.17 in Climate Zone 1, 0.14 in Climate Zone 2, 0.12 in Climate Zone 3, 0.087 in Climate Zone 4 except Marine, 0.065 in Climate Zone 5 and Marine 4, and 0.057 in Climate Zones 6 through 8.
c. Basement wall U-factor of 0.360 in warm-humid locations as defined by Figure R301.1 and Table R301.1.
TABLE R402.1.4
EQUIVALENT U-FACTORSa
CLIMATE ZONE FENESTRATION U-FACTORd SKYLIGHT U-FACTOR CEILING U-FACTOR FRAME WALL U-FACTOR MASS WALL U-FACTORb FLOOR U-FACTOR BASEMENT WALL U-FACTOR CRAWL SPACE WALL U-FACTOR
3 0.35 0.55 0.030 0.077 0.141 0.047 0.091c 0.136
4 0.35 0.55 0.030 0.077 0.141 0.047 0.059 0.065
5 0.35 0.55 0.030 0.061 0.082 0.033 0.059 0.065
  1. Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source.
  2. When more than half the insulation is on the interior, the mass wall U-factors shall be a maximum of 0.07 in Climate Zone 3, 0.07 in Climate Zone 4 and 0.054 in Climate Zone 5.
  3. Basement wall U-factor of 0.360 in warm-humid locations as defined by Figure R301.1 and Table R301.1.
  4. A maximum of two glazed fenestration product assemblies having a U-factor no greater than 0.55 and a SHGC no greater than 0.70 shall be permitted to be substituted for minimum code compliant fenestration product assemblies without penalty. When applying this note and using the REScheck “UA Trade-off” compliance method to allow continued use of the software, the applicable fenestration products shall be modeled as meeting the U-factor of 0.35 and the SHGC of 0.30, as applicable, but the fenestration products actual U-factor and actual SHGC shall be noted in the comments section of the software for documentation of application of this note to the applicable products. Compliance for these substitute products shall be verified compared to the allowed substituted maximum U-value requirement and maximum SHGC requirement, as applicable.
If the total building thermal envelope UA (sum of U-factor times assembly area) is less than or equal to the total UA resulting from using the U-factors in Table R402.1.4 (multiplied by the same assembly area as in the proposed building), the building shall be considered in compliance with Table R402.1.2. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The SHGC requirements shall be met in addition to UA compliance.

R402.2 Specific Insulation Requirements (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
In addition to the requirements of Section R402.1, insulation shall meet the specific requirements of Sections R402.2.1 through R402.2.13.R402.2.15.

R402.2.1 Ceilings With Attic Spaces

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where Section R402.1.2 would require R-38 insulation in the ceiling, installing R-30 over 100 percent of the ceiling area requiring insulation 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, where Section R402.1.2 would require R-49 insulation in the ceiling, installing R-38 over 100 percent of the ceiling area requiring insulation shall be deemed to satisfy the requirement for R-49 insulation wherever the full height of uncompressed R-38 insulation extends over the wall top plate at the eaves. This reduction shall not apply to the U-factor alternative approach in Section R402.1.4 and the total UA alternative in Section R402.1.5.

Exceptions:
  1. When insulation is installed in a fully enclosed attic floor system, as described in Appendix 1.2.1, R-30 shall be deemed compliant.
  2. In roof edge and other details such as bay windows, dormers, and similar areas where the space is limited, the insulation must fill the space up to the air baffle.

R402.2.2 Ceilings Without Attic Spaces

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where Section R402.1.2 would require R-38 insulation levels above R-30 and the design of the roof/ceiling assembly, including cathedral ceilings, bay windows and other similar areas, does not allow sufficient space for the required insulation, the minimum required insulation for such roof/ceiling assemblies shall be R-30. This reduction of insulation from the requirements of Section R402.1.2 shall be limited to 500 square feet (46 m2) or 20 percent of the total insulated ceiling area, whichever is less. This reduction shall not apply to the U-factor alternative approach in Section R402.1.4 and the total UA alternative in Section R402.1.5.

R402.2.3 Eave Soffit Baffle

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
For air-permeable insulations in vented attics, a baffle shall be installed adjacent to soffit and eave vents. Baffles shall maintain an opening equal or greater than the size of the vent. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material.

R402.2.4 Access Hatches and Doors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Horizontal access doorshatches from conditioned spaces to unconditioned spaces such as attics and crawl spaces shall be weatherstripped and insulated to a level equivalent to the insulation on the surrounding surfacesan R-10 minimum value and vertical doors to such spaces shall be weatherstripped and insulated to R-5. Access shall be provided to all equipment that prevents damaging or compressing the insulation. A wood-framed or equivalent baffle or retainer is required to be provided when loose-fill insulation is installed, the purpose of which is to prevent the loose-fill insulation from spilling into the living space when the attic access is opened, and to provide a permanent means of maintaining the installed R-value of the loose-fill insulation.

Exception:
  1. Full-size Vertical doors that provide access from conditioned to unconditioned spaces shall be permitted to meet the fenestration requirements of Table R402.1.2 based on the applicable climate zone specified in Chapter 3.
  2. Pull down stair systems shall be weatherstripped and insulated with a minimum R-5 insulation. The insulation shall not interfere with proper operation of the stair. Nonrigid insulation materials are not allowed. Additional insulation systems that enclose the stair system from above are allowed. Exposed foam plastic must meet the provisions of the Building Code or Residential Code, respectively.

R402.2.5 Mass Walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Mass walls for the purposes of this chapter shall be considered above-grade walls of concrete block, concrete, insulated concrete form (ICF), masonry cavity, brick (other than brick veneer), earth (adobe, compressed earth block, rammed earth) and solid timber/logs, or any other walls having a heat capacity greater than or equal to 6 Btu/ft2 × °F (123 kJ/m2 × K)meeting the following. Masonry or concrete walls having a mass greater than or equal to 30 pounds per square foot (146 kg/m2). Solid wood walls having a mass greater than 20 pounds per square foot (98 kg/m2). Any walls having a heat capacity greater than or equal to 6 Btu/ft2• °F [266 J/(m2 • K)]..
Steel-frame ceilings, walls, and floors shall meet the insulation requirements of Table R402.2.6 or shall meet the U-factor requirements of Table R402.1.4. The calculation of the U-factor for a steel-frame envelope assembly shall use a series-parallel path calculation method.

TABLE R402.2.6 STEEL-FRAME CEILING, WALL AND FLOOR INSULATION (R-VALUE)

WOOD FRAME
R-VALUE
REQUIREMENT
COLD-FORMED STEEL
EQUIVALENT R-VALUEa
Steel Truss Ceilingsb
R-30 R-38 or R-30 + 3 or R-26 + 5
R-38 R-49 or R-38 + 3
R-49 R-38 + 5
Steel Joist Ceilingsb
R-30 R-38 in 2 × 4 or 2 × 6 or 2 × 8 R-49
in any framing
R-38 R-49 in 2 × 4 or 2 × 6 or 2 × 8 or 2 × 10
Steel-Framed Wall, 16" on center
R-13 R-13 + 4.2 or R-19 + 2.1 or R-21 + 2.8 or
R-0 + 9.3 or R-15 + 3.8 or R-21 + 3.1
R-13 + 3 R-0 + 11.2 or R-13 + 6.1 or R-15 + 5.7 or
R-19 + 5.0 or R-21 + 4.7
R-20 R-0 + 14.0 or R-13 + 8.9 or R-15 + 8.5 or
R-19 + 7.8 or R-19 + 6.2 or R-21 + 7.5
R-20 + 5 R-13 + 12.7 or R-15 + 12.3 or R-19 + 11.6 or
R-21 + 11.3 or R-25 + 10.9
R-21 R-0 + 14.6 or R-13 + 9.5 or R-15 + 9.1 or
R-19 + 8.4 or R-21 + 8.1 or R-25 + 7.7
Steel Framed Wall, 24" on center
R-13 R-0 + 9.3 or R-13 + 3.0 or R-15 + 2.4
R-13 + 3 R-0 + 11.2 or R-13 + 4.9 or R-15 + 4.3 or
R-19 + 3.5 or R-21 + 3.1
R-20 R-0 + 14.0 or R-13 + 7.7 or R-15 + 7.1 or
R-19 + 6.3 or R-21 + 5.9
R-20 + 5 R-13 + 11.5 or R-15 + 10.9 or R-19 + 10.1 or
R-21 + 9.7 or R-25 + 9.1
R-21 R-0 + 14.6 or R-13 + 8.3 or R-15 + 7.7 or
R-19 + 6.9 or R-21 + 6.5 or R-25 + 5.9
Steel Joist Floor
R-13 R-19 in 2 × 6, or R-19 + 6 in 2 × 8 or 2 × 10
R-19 R-19 + 6 in 2 × 6, or R-19 + 12 in 2 × 8 or 2 × 10

a Cavity insulation R-value is listed first, followed by continuous insulation R-value.
b. Insulation exceeding the height of the framing shall cover the framing.

R402.2.7 Walls With Partial Structural Sheathing

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where Section R402.1.2 would require continuous insulation on exterior walls and structural sheathing covers 40 percent or less of the gross area of all exterior walls, the continuous insulation R-value shall be permitted to be reduced by an amount necessary to result in a consistent total sheathing thickness, but not more than R-3, on areas of the walls covered by structural sheathing. If structural sheathing covers 25 percent or less of the exterior, insulating sheathing is not required where structural sheathing is used. If structural sheathing covers more than 25 percent of exterior, structural sheathing shall be supplemented with insulated sheathing of at least R-2. This reduction shall not apply to the U-factor alternative approach in Section R402.1.4 and the total UA alternative in Section R402.1.5.

R402.2.8 Floors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Floor framing-cavity insulation shall be installed to maintain permanent contact with the underside of the subfloor decking. The distance between tension support wires or other devices that hold the floor insulation in place against the subfloor shall be no more than 18 inches. In addition, supports shall be located no further than 6 inches from each end of the insulation.

Exception: The floor framing-cavity insulation shall be permitted to be in contact with the topside of sheathing or continuous insulation installed on the bottom side of floor framing where combined with insulation that meets or exceeds the minimum wood frame wall R-value in Table 402.1.2 and that extends from the bottom to the top of all perimeter floor framing members.An enclosed floor cavity such as garage ceilings, cantilevers or buildings on pilings with an enclosed floor cavity with the insulation fully in contact with the lower air barrier. In this case, the band boards shall be insulated to maintain thermal envelope continuity.

R402.2.9 Basement Walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Walls associated with conditioned basements shall be insulated from the top of the basement wall down to 10 feet (3048 mm) below grade or to the basement floor, whichever is less. Walls associated with unconditioned basements shall meet this requirement unless the floor overhead is insulated in accordance with Sections R402.1.2 and R402.2.8. Foam plastic insulation applied to exterior of basement walls shall be provided with termite inspection and treatment gaps in accordance with Appendix R2.

R402.2.10 Slab-On-Grade Floors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table R402.1.2. The insulation shall extend downward from the top of the slab on the outside or inside of the foundation wall. Insulation located below grade shall be extended the distance provided in Table R402.1.2 by any combination of vertical insulation, insulation extending under the slab or insulation extending out from the building. Insulation extending away from the building shall be protected by pavement or by not less than 10 inches (254 mm) of soil. The top edge of the insulation installed between the exterior wall and the edge of the interior slab shall be permitted to be cut at a 45-degree (0.79 rad) angle away from the exterior wall. Slab-edge insulation is not required in jurisdictions designated by the code official as having a very heavy termite infestation. Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table R402.1.2. The top edge of the insulation installed between the exterior wall and the edge of the interior slab shall be permitted to be cut at a 45-degree (0.79 rad) angle away from the exterior wall. Slab edge insulation shall have a 2- inch termite inspection gap consistent with Appendix R2 of this code.

R402.2.11 Closed Crawl Space Walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
As an alternative to insulating floors over crawl spaces, crawl space walls shall be permitted to be insulated when the crawl space is not vented to the outside. Crawl space wall insulation shall be permanently fastened to the wall and extend downward from the floor to the finished grade level and then vertically and/or horizontally for at least an additional 24 inches (610 mm). Exposed earth in unvented crawl space foundations shall be covered with a continuous Class I vapor retarder in accordance with the International Building Code or International Residential Code, as applicable. All joints of the vapor retarder shall overlap by 6 inches (153 mm) and be sealed or taped. The edges of the vapor retarder shall extend not less than 6 inches (153 mm) up the stem wall and shall be attached to the stem wall. Where the floor above a closed crawl space is not insulated, the exterior crawlspace walls shall be insulated in accordance with Table R402.1.2.

     Wall insulation may be located in any combination of the outside and inside wall surfaces and within the structural cavities or materials of the wall system.

     Wall insulation requires that the exterior wall band joist area of the floor frame be insulated. Wall insulation shall begin 3 inches (76.2 mm) below the top of the masonry foundation wall and shall extend down to 3 inches (76.2 mm) above the top of the footing or concrete floor, 3 inches (76.2 mm) above the interior ground surface or 24 inches (609.6 mm) below the outside finished ground level, whichever is less. (See Appendix R1.2.2 details).

     Termite inspection, clearance, and wicking gaps are allowed in wall insulation systems. Insulation may be omitted in the gap area without energy penalty. The allowable insulation gap widths are listed in Table 402.2.11. If gap width exceeds the allowances, one of the following energy compliance options shall be met:
  1. Wall insulation is not allowed and the required insulation value shall be provided in the floor system.
  2. Compliance shall be demonstrated with energy trade-off methods provided by a North Carolina-specific version of REScheck or the UA Alternative method or Section R405.
TABLE R402.2.11
WALL INSULATION ALLOWANCES FOR TERMITE TREATMENT AND INSULATION GAPS</caption>
GAP WIDTH (inches) INSULATION LOCATION GAP
DESCRIPTION
Minimum Maximum
2 3 Outside Above grade inspection between top of insulation and bottom of siding
4 6 Outside Below grade treatment
3a 4a Inside Wall inspection between top of insulation and bottom of sill
3a 4a Inside Clearance/wicking space between bottom of insulation and top of ground surface, footing, or concrete floor
For SI: 1 inch = 25.4 mm.
  1. No insulation shall be required on masonry walls of 9 inches in height or less.
Insulation shall not be required on the horizontal portion of the foundation that supports a masonry veneer.

R402.2.13 Sunroom Insulation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Sunrooms enclosing conditioned space shall meet the insulation requirements of this code.

Exception: For sunrooms with thermal isolation, and enclosing conditioned space, the following exceptions to the insulation requirements of this code shall apply:
  1. The minimum ceiling insulation R-values shall be R-19 in Climate Zones 1 through 43 and 4 and R-24 in Climate Zones 5 through 8.
  2. The minimum wall R-value shall be R-13 in all climate zones. New walls separating a sunroom with a thermal isolation from conditioned space shall meet the building thermal envelope requirements of this code.

R402.2.14 Framed cavity walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The exterior thermal envelope wall insulation shall be installed in contact and continuous alignment with the building envelope air barrier. Insulation shall be free from installation gaps, voids, or compression. For framed walls, the cavity insulation shall be enclosed on all sides with solid rigid material or an air barrier material. Polyethylene shall not be allowed. Rim joists are not required to be enclosed on all sides. Wall insulation shall be enclosed at the following locations when installed on exterior walls prior to being covered by subsequent construction, consistent with the Appendix R1.2.3 of this code:
  1. Tubs.
  2. Showers.
  3. Stairs.
  4. Fireplace units (enclosed with rigid material only).

R402.2.15 Attic knee walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Enclosure of wall cavity insulation also applies to walls that adjoin attic spaces by placing a rigid material or air barrier material on the attic space side of the wall on the attic space side of the wall consistent with the Appendix R1.2.3 of this code. Joints shall be air sealed. Non-insulating Class I vapor retarders, such as polyethylene, shall not be allowed.
In addition to the requirements of Section R402, fenestration shall comply with Sections R402.3.1 through R402.3.5.
An area-weighted average of fenestration products shall be permitted to satisfy the U-factor requirements.
An area-weighted average of fenestration products more than 50-percent glazed shall be permitted to satisfy the SHGC requirements.

Dynamic glazing shall be permitted to satisfy the SHGC requirements of Table R402.1.2 provided the ratio of the higher to lower labeled SHGC is greater than or equal to 2.4, and the dynamic glazing is automatically controlled to modulate the amount of solar gain into the space in multiple steps. Dynamic glazing shall be considered separately from other fenestration, and area-weighted averaging with other fenestration that is not dynamic glazing shall not be permitted.

Exception: Dynamic glazing is not required to comply with this section when both the lower and higher labeled SHGC already comply with the requirements of Table R402.1.2.

R402.3.3 Glazed Fenestration Exemption

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Up to 15Either two glazed fenestration assemblies or up to 24 square feet (1.42.2 m2) of glazed fenestration per dwelling unit shall be permitted to be exempt from U-factor and SHGC requirements in Section R402.1.2. This exemption shall not apply to the U-factor alternative approach in Section R402.1.4 and the Total UA alternative in Section R402.1.5.

R402.3.4 Opaque Door Exemption

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Opaque doors separating conditioned from unconditioned space shall have a maximum U-factor of 0.35.

Exception: One side-hinged opaque door assembly up to 24 square feet (2.22 m2) in area is exempted from the U-factor requirement in Section R402.1.4.R402.1.2. This exemption shall not apply to the U-factor alternative approach in Section R402.1.4 and the total UA alternative in Section R402.1.5.

R402.3.5 Sunroom Fenestration

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Sunrooms enclosing conditioned space shall meet the fenestration requirements of this code.

Exceptions:
  1. For sunrooms with thermal isolation and enclosing conditioned space in Climate Zones 23 through 85, the maximum fenestration U-factor shall be 0.450.40 and the maximum skylight U-factor shall be 0.70.0.75. Sunrooms with cooling systems shall have a maximum fenestration SHGC of 0.40 for all glazing.
  2. A maximum of two glazed fenestration product assemblies having a U-factor no greater than 0.55 and, when cooling is provided, a SHGC no greater than 0.70 shall be permitted to be substituted for minimum code compliant fenestration product assemblies without penalty.
     New fenestration separating the sunroom with thermal isolation from conditioned space shall meet the building thermal envelope requirements of this code.

R402.4 Air Leakage control (Mandatory Requirements)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The building thermal envelope shall be constructed to limit air leakage in accordance with the requirements of Sections R402.4.1 through R402.4.4. The building thermal envelope shall be constructed to limit air leakage in accordance with the requirements of Sections R402.4.1 through R402.4.6.

R402.4.1 Building Thermal Envelope

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The building thermal envelope shall comply with Sections R402.4.1.1 and R402.4.1.2. The sealing methods between dissimilar materials shall allow for differential expansion and contraction. The building thermal envelope shall be durably sealed to limit infiltration. The sealing methods between dissimilar materials shall allow for differential expansion and contraction. For all homes, where present, the following shall be caulked, gasketed, weatherstripped or otherwise sealed with an air barrier material, or solid material consistent with Appendix R1.2.4 of this code:
  1. Blocking and sealing floor/ceiling systems and under knee walls open to unconditioned or exterior space.
  2. Capping and sealing shafts or chases, including flue shafts.
  3. Capping and sealing soffit or dropped ceiling areas.
  4. Sealing HVAC register boots and return boxes to subfloor or drywall.
  5. Seal exterior house wrap material joints and seams per manufacturer’s instructions or, if house wrap joints are not sealed, seal exterior sheathing and exposed band joist joints including perimeter joints and edges of these materials.
Exceptions:
  1. Spray foam in building thermal envelope wall systems.
  2. Wall sheathing joints where wall sheathing is fully glued to framing.

R402.4.1.1 Installation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The components of the building thermal envelope as listed in Table R402.4.1.1 shall be installed in accordance with the manufacturer's instructions and the criteria listed in Table R402.4.1.1, as applicable to the method of construction. Where required by the code official, an approved third party shall inspect all components and verify compliance.

TABLE R402.4.1.1 AIR BARRIER AND INSULATION INSTALLATION

COMPONENT AIR BARRIER CRITERIA INSULATION INSTALLATION CRITERIA
General requirements A continuous air barrier shall be installed in the building envelope.
The exterior thermal envelope contains a continuous air barrier.
Breaks or joints in the air barrier shall be sealed.
Air-permeable insulation shall not be used as a sealing material.
Ceiling/attic The air barrier in any dropped ceiling/soffit shall be aligned with the insulation and any gaps in the air barrier shall be sealed.
Access openings, drop down stairs or knee wall doors to unconditioned attic spaces shall be sealed.
The insulation in any dropped ceiling/soffit shall be aligned with the air barrier.
Walls The junction of the foundation and sill plate shall be sealed.
The junction of the top plate and the top of exterior
walls shall be sealed.
Knee walls shall be sealed.
Cavities within corners and headers of frame
walls shall be insulated by completely filling the
cavity with a material having a thermal resistance
of R-3 per inch minimum.
Exterior thermal envelope insulation for framed
walls shall be installed in substantial contact and
continuous alignment with the air barrier.
Windows, skylights and doors The space between window/door jambs and framing,
and skylights and framing shall be sealed.
Rim joists Rim joists shall include the air barrier. Rim joists shall be insulated.
Floors (including above garage and
cantilevered floors)
The air barrier shall be installed at any exposed edge
of insulation.
Floor framing cavity insulation shall be installed
to maintain permanent contact with the underside
of subfloor decking, or floor framing cavity
insulation shall be permitted to be in contact with
the top side of sheathing, or continuous insulation
installed on the underside of floor framing and
extends from the bottom to the top of all
perimeter floor framing members.
Crawl space walls Exposed earth in unvented crawl spaces shall be
covered with a Class I vapor retarder with
overlapping joints taped.
Where provided instead of floor insulation,
insulation shall be permanently attached to the
crawlspace walls.
Shafts, penetrations Duct shafts, utility penetrations, and flue shafts
opening to exterior or unconditioned space shall be
sealed.
Narrow cavities Batts in narrow cavities shall be cut to fit, or
narrow cavities shall be filled by insulation that
on installation readily conforms to the available
cavity space.
Garage separation Air sealing shall be provided between the garage and
conditioned spaces.
Recessed lighting Recessed light fixtures installed in the building
thermal envelope shall be sealed to the drywall.
Recessed light fixtures installed in the building
thermal envelope shall be air tight and IC rated.
Plumbing and wiring Batt insulation shall be cut neatly to fit around
wiring and plumbing in exterior walls, or
insulation that on installation readily conforms to
available space shall extend behind piping and
wiring.
Shower/tub on exterior wall The air barrier installed at exterior walls adjacent to
showers and tubs shall separate them from the
showers and tubs.
Exterior walls adjacent to showers and tubs shall
be insulated.
Electrical/phone box on exterior walls The air barrier shall be installed behind electrical or
communication boxes or air-sealed boxes shall be
installed.
HVAC register boots HVAC register boots that penetrate building thermal
envelope shall be sealed to the subfloor or drywall.
Concealed sprinklers When required to be sealed, concealed fire sprinklers
shall only be sealed in a manner that is recommended
by the manufacturer. Caulking or other adhesive
sealants shall not be used to fill voids between fire
sprinkler cover plates and walls or ceilings.

a. In addition, inspection of log walls shall be in accordance with the provisions of ICC-400.

R402.4.1.2 Testing

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The building or dwelling unit shall be tested and verified as having an air leakage rate not exceeding five air changes per hour in Climate Zones 1 and 2, and three air changes per hour in Climate Zones 3 through 8. Testing shall be conducted in accordance with ASTM E 779 or ASTM E 1827 and reported at a pressure of 0.2 inch w.g. (50 Pascals). Where required by the code official, testing shall be conducted by an approved third party. A written report of the results of the test shall be signed by the party conducting the test and provided to the code official. Testing shall be performed at any time after creation of all penetrations of the building thermal envelope.

During testing:
  1. Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed, beyond the intended weatherstripping or other infiltration control measures.
  2. Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed, but not sealed beyond intended infiltration control measures.
  3. Interior doors, if installed at the time of the test, shall be open.
  4. Exterior doors for continuous ventilation systems and heat recovery ventilators shall be closed and sealed.
  5. Heating and cooling systems, if installed at the time of the test, shall be turned off.
  6. Supply and return registers, if installed at the time of the test, shall be fully open.

R402.4.2 Fireplaces

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
New wood-burning fireplaces shall have tight-fitting flue dampers or doors, and outdoor combustion air. Where using tight-fitting doors on factory-built fireplaces listed and labeled in accordance with UL 127, the doors shall be tested and listed for the fireplace. Where using tight-fitting doors on masonry fireplaces, the doors shall be listed and labeled in accordance with UL 907.

R402.4.2 Air sealing

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Building envelope air tightness shall be demonstrated by compliance with Section R402.4.2.1 or R402.4.2.2. Appendix R3 contains optional sample worksheets for visual inspection or testing for the permit holder’s use only.

TABLE R402.4.2
AIR BARRIER INSPECTION
COMPONENT CRITERIA
Ceiling/attic Sealants or gaskets provide a continuous air barrier system joining the top plate of framed walls with either the ceiling drywall or the top edge of wall drywall to prevent air leakage. Top plate penetrations are sealed.

For ceiling finishes that are not air barrier systems such as tongue-and-groove planks, air barrier systems (for example, taped house wrap), shall be used above the finish.

Note: It is acceptable that sealants or gaskets applied as part of the application of the drywall will not be observable by the code official.
Walls Sill plate is gasketed or sealed to subfloor or slab.
Windows and doors Space between window and exterior door jambs and framing is sealed.
Floors (including above garage and cantilevered floors) The air barrier shall be installed at any exposed edge of insulation.
Penetrations Utility penetrations through the building thermal envelope, including those for plumbing, electrical wiring, ductwork, security and fire alarm wiring, and control wiring, shall be sealed.
Garage separation Air sealing is provided between the garage and conditioned spaces. An air barrier system shall be installed between the ceiling system above the garage and the ceiling system of interior spaces.
Ceiling penetrations Ceiling electrical box penetrations and ceiling mechanical box penetrations shall be caulked, gasketed, or sealed at the penetration of the ceiling finish. See
Appendix R1.2.4
.
Exception: Ceiling electrical boxes and ceiling mechanical boxes not penetrating the building thermal envelope.
Recessed lighting Recessed light fixtures are air tight, IC-rated, and sealed to drywall.
Exception: Fixtures in conditioned space.

R402.4.2.1 Visual inspection option

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Building envelope tightness shall be considered acceptable when items providing insulation enclosure in Section R402.2.14 and enclosure and air sealing in Section R402.2.15 and air sealing in Section R402.4.1 are addressed and when the items listed in Table R402.4.2, applicable to the method of construction, are certified by the builder, permit holder or registered design professional via the certificate in Appendix R1.1.

R402.4.2.2 Testing option

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Building envelope tightness shall be considered acceptable when items providing insulation enclosure in Section R402.2.14 and enclosure and air sealing in Section R402.2.15 and air sealing in Section R402.4.1 are addressed and when tested air leakage is less than or equal to one of the two following performance measurements:
  1. 0.30 CFM50/Square Foot of Surface Area (SFSA); or
  2. Five (5) air changes per hour (ACH50)
     when tested with a blower door fan assembly, at a pressure of 33.5 psf (50 Pa). A single point depressurization test (not temperature corrected) is sufficient to comply with this provision, provided that the blower door fan assembly has been certified by the manufacturer to be capable of conducting tests in accordance with ASTM E779 or ASTM E1827. Testing shall occur after rough in and after installation of penetrations of the building envelope, including penetrations for utilities, plumbing, electrical, ventilation and combustion appliances. Testing shall be reported by the permit holder, a North Carolina licensed general contractor, a North Carolina licensed HVAC contractor, a North Carolina licensed home inspector, a registered design professional, a certified BPI Envelope Professional or a certified HERS rater.

During testing:
  1. Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed;
  2. Dampers shall be closed, but not sealed, including exhaust, backdraft, and flue dampers;
  3. Interior doors shall be open;
  4. Exterior openings for continuous ventilation systems, air intake ducted to the return side of the conditioning system, and energy or heat recovery ventilators shall be closed and sealed;
  5. Heating and cooling system(s) shall be turned off; and
  6. Supply and return registers shall not be sealed.
     The air leakage information, building air leakage result, tester name, date, and contact information, shall be included on the certificate described in Section R401.3.

     For Test Criteria 1 above, the report shall be produced in the following manner: perform the blower door test and record the CFM50. Calculate the total square feet of surface area for the building thermal envelope (all floors, ceilings, and walls including windows and doors, bounding conditioned space) and record the area. Divide CFM50 by the total square feet and record the result. If the result is less than or equal to 0.30 CFM50/SFSA the envelope tightness is acceptable; or

     For Test Criteria 2 above, the report shall be produced in the following manner: Perform a blower door test and record the CFM50. Multiply the CFM50 by 60 minutes to create CFHour50 and record. Then calculate the total conditioned volume of the home and record. Divide the CFH50 by the total volume and record the result. If the result is less than or equal to 5 ACH50, the envelope tightness is acceptable.

R402.4.3 Fireplaces

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Site-built masonry fireplaces shall have flue dampers and comply with Section R1006 of the North Carolina Residential Code for combustion air.

R402.4.3 R402.4.4 Fenestration Air Leakage

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Windows, skylights and sliding glass doors shall have an air infiltration rate of no more than 0.3 cfm per square foot (1.5 L/s/m2), and swinging doors no more than 0.5 cfm per square foot (2.6 L/s/m2), when tested according to NFRC 400 or AAMA/WDMA/CSA 101/I.S.2/A440 by an accredited, independent laboratory and listed and labeled by the manufacturer.

Exception: Site-builtField-fabricated windows, skylights and doors.

R402.4.4 Rooms Containing Fuel-Burning Appliances

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
In Climate Zones 3 through 8, where open combustion air ducts provide combustion air to open combustion fuel burning appliances, the appliances and combustion air opening shall be located outside the building thermal envelope or enclosed in a room, isolated from inside the thermal envelope. Such rooms shall be sealed and insulated in accordance with the envelope requirements of Table R402.1.2, where the walls, floors and ceilings shall meet not less than the basement wall R-value requirement. The door into the room shall be fully gasketed and any water lines and ducts in the room insulated in accordance with Section R403. The combustion air duct shall be insulated where it passes through conditioned space to a minimum of R-8.

Exceptions:

1. Direct vent appliances with both intake and exhaust pipes installed continuous to the outside.

2. Fireplaces and stoves complying with Section R402.4.2 and Section R1006 of the International Residential Code.

R402.4.5 R402.4.6 Recessed Lighting

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Recessed luminaires installed in the building thermal envelope shall be sealed to limit air leakage between conditioned and unconditioned spaces. All recessed luminaires shall be IC-rated and labeled as having an air leakage rate not more than 2.0 cfm (0.944 L/s) when tested in accordance with ASTM E283 at a 1.57 psf (75 Pa) pressure differential. All recessed luminaires shall be sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.

R402.5 Maximum Fenestration U-Factor and SHGC (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The area-weighted average maximum fenestration U-factor permitted using tradeoffs from Section R402.1.5 or R405 shall be 0.48 in Climate Zones 4 and 5 and 0.40 in Climate Zones 6 through 8 for vertical fenestration, and 0.75 in Climate Zones 4 through 8 for skylights. The area-weighted average maximum fenestration SHGC permitted using tradeoffs from Section R405 in Climate Zones 1 through 3 shall be 0.50. The area-weighted average maximum fenestration U-factor permitted using trade-offs from Section R402.1.5 shall be 0.48. Maximum skylight U-factors shall be 0.65 in Climate Zones 4 and 5 and 0.60 in Climate Zone 3. The area-weighted average maximum fenestration SHGC permitted using trade-offs from Section R405 in Climate Zone 3 shall be 0.50.

Exception: A maximum of two glazed fenestration product assemblies having a U-factor no greater than 0.55 and a SHGC no greater than 0.70 shall be permitted to be substituted for minimum code compliant fenestration product assemblies without penalty.
At least one thermostat shall be provided for each separate heating and cooling system.

R403.1.1 Programmable Thermostat

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
When the primary heating system is a forced air furnace or heat pump, the thermostat controlling the primary heating or cooling system of the dwelling unit shall be capable of controlling the heating and cooling system on a daily schedule to maintain different temperature set points at different times of the day. This thermostat shall include 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). The thermostat shall initially be programmed by the manufacturer with a heating temperature set point no higher than 70°F (21°C) and a cooling temperature set point no lower than 78°F (26°C).

R403.1.2 Heat Pump Supplementary Heat (Mandatory)

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

     A heat strip outdoor temperature lockout thermostat 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 (2°C) and no higher than 40°F (4°C).

Exceptions:
  1. In lieu of a heat strip outdoor temperature lockout thermostat, the following time and temperature electric-resistance control may be used. After 6 minutes of compressor run time in heat mode, supplemental electric heat shall energize only if the leaving air temperature from the indoor coil is below 90°F (32°C). If the indoor coil leaving air temperature exceeds 100°F (38°C), supplemental heat shall automatically de-energize, but allow the compressor to continue to operate until the call is satisfied. No thermostat shall initiate supplemental electric heat at any time. Thermostat controlled emergency heat shall not be limited by outdoor temperature. Electric resistance supplemental heat during defrost shall operate normally without limitation.
  2. In lieu of a heat strip outdoor temperature lockout thermostat, a programmable indoor thermostat with the capability to minimize the use of supplementary electrical resistance heat using an automatic temperature ramp up control feature shall be acceptable.
Hot water boilers that supply heat to the building through one- or two-pipe heating systems shall have an outdoor setback control that lowers the boiler water temperature based on the outdoor temperature.

R403.3 Ducts

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ducts and air handlers shall be in accordance with Sections R403.3.1 through R403.3.5.R403.3.4.

R403.3.1 Insulation (Prescriptive Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Supply and return ducts in attics shall be insulated to a minimum of R-8 where 3 inches (76 mm) in diameter and greater and R-6 where less than 3 inches (76 mm) in diameter. Supply and return ducts in other portions of the building shall be insulated to a minimum of R-6 where 3 inches (76 mm) in diameter or greater and R-4.2 where less than 3 inches (76 mm) in diameter.

Exception: Ducts or portions thereof located completely inside the building thermal envelope.
Supply and return ducts in unconditioned space and outdoors shall be insulated to a minimum R-8. Supply ducts inside semi-conditioned space shall be insulated to a minimum R-4; return ducts inside conditioned and semi-conditioned space are not required to be insulated. Ducts located inside conditioned space are not required to be insulated other than as may be necessary for preventing the formation of condensation on the exterior of cooling ducts.

R403.3.2 Sealing (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ducts, air handlers, and filter boxes, and building cavities used as ducts shall be sealed. Joints and seams shall comply with either the International Mechanical Code or International Residential Code, as applicable.

Exceptions:

1. Air-impermeable spray foam products shall be permitted to be applied without additional joint seals.

2. For ducts having a static pressure classification of less than 2 inches of water column (500 Pa), additional closure systems shall not be required for continuously welded joints and seams, and locking-type joints and seams of other than the snap-lock and button-lock types.Deleted.

R403.3.2.1 Sealed Air Handler

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Air handlers shall have a manufacturer's designation for an air leakage of no more than 2 percent of the design air flow rate when tested in accordance with ASHRAE 193.

R403.3.3 Duct leakage (Prescriptive) and Duct Testing (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Ducts shall be pressure tested to determine air leakage by one of the following methods:

1. Rough-in test: Total leakage shall be measured with a pressure differential of 0.1 inch w.g. (25 Pa) across the system, including the manufacturer's air handler enclosure if installed at the time of the test. All registers shall be taped or otherwise sealed during the test.

2. Postconstruction test: Total leakage shall be measured with a pressure differential of 0.1 inch w.g. (25 Pa) across the entire system, including the manufacturer's air handler enclosure. Registers shall be taped or otherwise sealed during the test.

Exception: A duct air leakage test shall not be required where the ducts and air handlers are located entirely within the building thermal envelope.

A written report of the results of the test shall be signed by the party conducting the test and provided to the code official.
Duct testing and duct leakage shall be verified by compliance with either Section 403.3.3.1or 403.3.3.2. Duct testing shall be performed and reported by the permit holder, a NC licensed general contractor, a NC licensed HVAC contractor, a NC licensed Home Inspector, a registered design professional, a certified BPI Envelope Professional or a certified HERS rater. A single point depressurization, not temperature corrected, test is sufficient to comply with this provision, provided that the duct testing fan assembly(s) has been certified by the manufacturer to be capable of conducting tests in accordance with ASTM E1554-07.

The duct leakage information, including duct leakage test selected and result, tester name, date and contact information, shall be included on the certificate described in Section 401.3.

For the Test Criteria, the report shall be produced in the following manner: perform the HVAC system air leakage test and record the CFM25. Calculate the total square feet of Conditioned Floor Area (CFA) served by that system. Multiply CFM25 by 100, divide the result by the CFA and record the result. If the result is less than or equal to 5 CFM25/100SF for the “Total duct leakage” test or less than or equal to 4CFM25/100SF for the “Duct leakage to the outside” test, then the HVAC system air tightness is acceptable. Appendix 3C contains optional sample worksheets for duct testing for the permit holder’s use only.

Exceptions to testing requirements:
  1. Duct systems or portions thereof inside the building thermal envelope shall not be required to be leak tested.
  2. Installation of a partial system as part of replacement, renovation or addition does not require a duct leakage test.
  3. Duct systems (complete) serving areas of 750 sq. ft. or less shall not need to be required to be leak tested.

R403.3.3.1 Total duct leakage

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Total duct leakage shall be less than or equal to 5 cfm (141.6 L/min) per 100 square feet (9.29 m2) of conditioned floor area served by that system when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the entire system, including the manufacturer’s air handler enclosure. During testing:
  1. Block, if present, ventilation air duct(s) connected to the conditioning system.
  2. The duct air leakage testing equipment shall be attached to the largest return in the system or to the air handler.
  3. The filter shall be removed and the air handler power shall be turned off.
  4. Supply boots or registers and return boxes or grilles shall be taped, plugged, or otherwise sealed air tight.
  5. The hose for measuring the 25 Pascals of pressure differential shall be inserted into the boot of the supply that is nominally closest to the air handler.
  6. Specific instructions from the duct testing equipment manufacturer shall be followed to reach duct test pressure and measure duct air leakage.

R403.3.3.2 Duct leakage to the outside

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Conduct the test using fan pressurization of distribution system and building at a fixed reference pressure for combined supply and return leak. Duct leakage to the outside shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area served by that system when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the entire system, relative to the outside, including the manufacturer’s air handler enclosure.

During testing:
  1. Block, if present, the ventilation air duct(s) connected to the conditioning system.
  2. The duct air leakage testing equipment shall be attached to the largest return in the system or to the air handler.
  3. The filter shall be removed and the air handler power shall be turned off.
  4. Supply boots or registers and return boxes or grilles shall be taped, plugged, or otherwise sealed air tight or as tight as possible.
  5. The hose for measuring the 25 Pascals of pressure differential shall be inserted into the boot of the supply that is nominally closest to the air handler.
  6. Open all interconnecting doors in the building, close dampers for fireplaces and other operable dampers.
  7. Set up an envelope air moving/flow-regulating/flow measurement assembly, such as a blower door, following the manufacturer’s prescribed procedure.
  8. Specific instructions from the duct testing equipment manufacturer shall be followed to reach duct test pressure and measure duct air leakage used in combination with a blower door. Typical steps are as follows:
    1. Depressurize the ductwork system to 25 Pa using the measurement hose in Step 5 above.
    2. Depressurize the house to 25 Pa using an envelope air moving/flow-regulating/flow measurement assembly, such as a blower door.
    3. Correct the duct pressure to measure 0 Pa of pressure differential between the house and the ductwork system.
    4. Read the cfm of duct leakage using the procedures for the specific equipment being used. (Note that most automatically calculating pressure gauges cannot compute the CFM25 automatically with a duct-to-house difference in pressure of 0 Pa, so the gauge setting should be set to read CFM instead of CFM25).

R403.3.4 Duct Leakage (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The total leakage of the ducts, where measured in accordance with Section R403.3.3, shall be as follows:

1. Rough-in test: The total leakage shall be less than or equal to 4 cubic feet per minute (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area where the air handler is installed at the time of the test. Where the air handler is not installed at the time of the test, the total leakage shall be less than or equal to 3 cubic feet per minute (85 L/min) per 100 square feet (9.29 m2) of conditioned floor area.

2. Postconstruction test: Total leakage shall be less than or equal to 4 cubic feet per minute (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area.

R403.3.5 R403.3.4 Building Cavities (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Building framing cavities shall not be used as supply ducts or supply plenums.
Mechanical system piping capable of carrying fluids above 105°F (41°C) or below 55°F (13°C) shall be insulated to a minimum of R-3.

R403.4.1 Protection of Piping Insulation

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

R403.5 Service Hot Water Systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Energy conservation measures for service hot water systems shall be in accordance with Sections R403.5.1 through R403.5.4. All circulating service hot water piping shall be insulated to at least R-2. Circulating hot water systems shall include an automatic or readily accessible manual switch that can turn off the hot water circulating pump when the system is not in use.

R403.5.1 Heated Water Circulation and Temperature Maintenance Systems (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heated water circulation systems shall be in accordance with Section R403.5.1.1. Heat trace temperature maintenance systems shall be in accordance with Section R403.5.1.2. Automatic controls, temperature sensors and pumps shall be accessible. Manual controls shall be readily accessible.

R403.5.1.1 Circulation Systems

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

R403.5.1.2 Heat Trace Systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Electric heat trace systems shall comply with IEEE 515.1 or UL 515. Controls for such systems shall automatically adjust the energy input to the heat tracing to maintain the desired water temperature in the piping in accordance with the times when heated water is used in the occupancy.

R403.5.2 Demand Recirculation Systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A water distribution system having one or more recirculation pumps that pump water from a heated water supply pipe back to the heated water source through a cold water supply pipe shall be a demand recirculation water system. Pumps shall have controls that comply with both of the following:

1. The control shall start the pump upon receiving a signal from the action of a user of a fixture or appliance, sensing the presence of a user of a fixture or sensing the flow of hot or tempered water to a fixture fitting or appliance.

2. The control shall limit the temperature of the water entering the cold water piping to 104°F (40°C).

R403.5.3 Hot Water Pipe Insulation (Prescriptive)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Insulation for hot water pipe with a minimum thermal resistance (R-value) of R-3 shall be applied to the following:

1. Piping 3/4 inch (19.1 mm) and larger in nominal diameter.

2. Piping serving more than one dwelling unit.

3. Piping located outside the conditioned space.

4. Piping from the water heater to a distribution manifold.

5. Piping located under a floor slab.

6. Buried in piping.

7. Supply and return piping in recirculation systems other than demand recirculation systems.

R403.5.4 Drain Water Heat Recovery Units

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Drain water heat recovery units shall comply with CSA B55.2. Drain water heat recovery units shall be tested in accordance with CSA B55.1. Potable water-side pressure loss of drain water heat recovery units shall be less than 3 psi (20.7 kPa) for individual units connected to one or two showers. Potable water-side pressure loss of drain water heat recovery units shall be less than 2 psi (13.8 kPa) for individual units connected to three or more showers.
The building shall be provided with ventilation that meets the requirements of the International Residential Code or International Mechanical Code, as applicable, or with other approved means of ventilation. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.

R403.6.1 Whole-House Mechanical Ventilation System Fan Efficacy

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
When installed to function as a whole house mechanical ventilation system fans shall meet the efficacy requirements of Table R403.6.1.

Exception: Where whole-house mechanical ventilation fans are integral to tested and listed HVAC equipment, they shall be powered by an electronically commutated motor.

TABLE R403.6.1 WHOLE-HOUSE MECHANICAL VENTILATION SYSTEM FAN EFFICACY

FAN LOCATION AIR FLOW RATE MINIMUM
(CFM)
MINIMUM EFFICACYa
(CFM/WATT)
AIR FLOW RATE MAXIMUM
(CFM)
Range hoods Any 2.8 cfm/watt Any
In-line fan Any 2.8 cfm/watt Any
Bathroom, utility room 10 1.4 cfm/watt < 90
Bathroom, utility room 90 2.8 cfm/watt Any

For SI: 1 cfm = 28.3 L/min.
a. When tested in accordance with HVI Standard 916

R403.7 Equipment Sizing and Efficiency Rating (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Heating and cooling equipment shall be sized in accordance with ACCA Manual S based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies. New or replacement heating and cooling equipment shall have an efficiency rating equal to or greater than the minimum required by federal law for the geographic location where the equipment is installed. Heating and cooling equipment shall be sized in accordance with the North Carolina Mechanical Code or the North Carolina Residential Code. New heating and cooling systems shall have an efficiency rating equal to or greater than the minimum required by federal law for the geographic location where the equipment is installed.

R403.8 Systems Serving Multiple Dwelling Units (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Building mechanical systems and service water heating systems serving multiple dwelling units shall comply with Sections C403 and C404 of the IECC‒Commercial Provisions in lieu of Section R403.

R403.9 Snow Melt and Ice System Controls (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Snow- and ice-melting systems, supplied through energy service to the building, shall include automatic controls capable 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 (4.8°C).
The energy consumption of pools and permanent spas shall be in accordance with Sections R403.10.1 through R403.10.3.

R403.10.1 Heaters

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The electric power to heaters shall be controlled by a readily accessible on-off switch that is an integral part of the heater mounted on the exterior of the heater, or external to and within 3 feet (914 mm) of the heater. Operation of such switch shall not change the setting of the heater thermostat. Such switches shall be in addition to a circuit breaker for the power to the heater. Gas-fired heaters shall not be equipped with continuously burning ignition pilots. 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.
Time switches or other control methods that can automatically turn off and on according to a preset schedule shall be installed for heaters and pump motors. Heaters and pump motors that have built-in time switches shall be in compliance with this section.

Exceptions:

1. Where public health standards require 24-hour pump operation.

2. Pumps that operate solar- and waste-heat-recovery pool heating systems.

R403.10.3 Covers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Outdoor heated pools and outdoor permanent spas shall be provided with a Class 1 vapor-retardant cover or other approved vapor-retardant means.

Exception: Where more than 70 percent of the energy for heating, computed over an operation season, is from site-recovered energy, such as from a heat pump or solar energy source, covers or other vapor-retardant means shall not be required.Pools deriving over 70 percent of the energy from heating from site-recovered energy or solar energy source.

R403.11 Portable Spas (Mandatory)

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The energy consumption of electric-powered portable spas shall be controlled by the requirements of APSP-14.
Residential swimming pools and permanent residential spas that are accessory to detached one- and two-family dwellings and townhouses three stories or less in height above grade plane and that are available only to the household and its guests shall be in accordance with APSP-15.
Not less than 75 percent of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps or not less than 75 percent of the permanently installed lighting fixtures shall contain only high-efficacy lamps.

Exception: Low-voltage lighting.
Fuel gas lighting systems shall not have continuously burning pilot lights.

R405.1 Scope

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
This section establishes criteria for compliance using simulated energy performance analysis. Such analysis shall include heating, cooling and service water heating energy only those items identified in Table R405.5.2(1), as applicable. A North Carolina registered design professional is required to perform the analysis if required by North Carolina licensure laws.

R405.2 Mandatory Requirements

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Compliance with this section requires that the mandatory provisions identified in Section R401.2 R401.2(2) be met. All supply and return ducts not completely inside the building thermal envelope shall be insulated to a minimum of R-6.
Compliance based on simulated energy performance requires that a proposed residence (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.

Exception: The energy use based on source energy expressed in Btu or Btu per square foot of conditioned floor area shall be permitted to be substituted for the energy cost. The source energy multiplier for electricity shall be 3.16. The source energy multiplier for fuels other than electricity shall be 1.1.
Documentation of the software used for the performance design and the parameters for the building shall be in accordance with Sections R405.4.1 through R405.4.3.
Documentation verifying that the methods and accuracy of the compliance software tools conform to the provisions of this section shall be provided to the code official.

R405.4.2 Compliance Report

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Compliance software tools shall generate a report that documents that the proposed design complies with Section R405.3. A compliance report on the proposed design shall be submitted with the application for the building permit. Upon completion of the building, a compliance report based on the as-built condition of the building shall be submitted to the code official before a certificate of occupancy is issued. Batch sampling of buildings to determine energy code compliance for all buildings in the batch shall be prohibited.

Compliance reports shall include information in accordance with Sections R405.4.2.1 and R405.4.2.2. Where the proposed design of a building could be built on different sites where the cardinal orientation of the building on each site is different, compliance of the proposed design for the purposes of the application for the building permit shall be based on the worst-case orientation, worst-case configuration, worst-case building air leakage and worst-case duct leakage. Such worst-case parameters shall be used as inputs to the compliance software for energy analysis.
.

A compliance report shall include the following:
  1. Building street address, or other building site identification.
  2. A statement indicating that the proposed design complies with Section R405.3.
  3. An inspection checklist documenting the building component characteristics of the proposed design as indicated in Table R405.5.2(1). The inspection checklist shall show results for both the standard reference design and the proposed design with user inputs to the compliance software to generate the results.
  4. A site-specific energy analysis report that is in compliance with Section R405.3.
  5. The name of the individual performing the analysis and generating the report.
  6. The name and version of the compliance software tool.

R405.4.2.1 Compliance Report for Permit Application

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A compliance report submitted with the application for building permit shall include the following:

1. Building street address, or other building site identification.

2. A statement indicating that the proposed design complies with Section R405.3.

3. An inspection checklist documenting the building component characteristics of the proposed design as indicated in Table R405.5.2(1). The inspection checklist shall show results for both the standard reference design and the proposed design with user inputs to the compliance software to generate the results.

4. A site-specific energy analysis report that is in compliance with Section R405.3.

5. The name of the individual performing the analysis and generating the report.

6. The name and version of the compliance software tool.

R405.4.2.2 Compliance Report for Certificate of Occupancy

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A compliance report submitted for obtaining the certificate of occupancy shall include the following:

1. Building street address, or other building site identification.

2. A statement indicating that the as-built building complies with Section R405.3.

3. A certificate indicating that the building passes the performance matrix for code compliance and listing the energy saving features of the buildings.

4. A site-specific energy analysis report that is in compliance with Section R405.3.

5. The name of the individual performing the analysis and generating the report.

6. The name and version of the compliance software tool.
The code official shall be permitted to require the following documents:

1. Documentation of the building component characteristics of the standard reference design.

2. A certification signed by the builder providing the building component characteristics of the proposed design as given in Table R405.5.2(1).

3. Documentation of the actual values used in the software calculations for the proposed design.
Calculations of the performance design shall be in accordance with Sections R405.5.1 and R405.5.2.
Except as specified by this section, the standard reference design and proposed design shall be configured and analyzed using identical methods and techniques.

R405.5.2 Residence Specifications

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The standard reference design and proposed design shall be configured and analyzed as specified by Table R405.5.2(1). Table R405.5.2(1) shall include, by reference, all notes contained in Table R402.1.2.

TABLE R405.5.2(1) SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS

BUILDING COMPONENT STANDARD REFERENCE DESIGN PROPOSED DESIGN
Above-grade walls Type: mass wall if proposed wall is mass; otherwise wood frame. As proposed
Gross area: same as proposed As proposed
U-factor: as specified in Table R402.1.4 As proposed
Solar absorptance = 0.75 As proposed
Emittance = 0.90 As proposed
Basement and crawl space walls Type: same as proposed As proposed
Gross area: same as proposed As proposed
U-factor: from Table R402.1.4, with insulation layer on interior side of walls As proposed
Above-grade floors Type: wood frame As proposed
Gross area: same as proposed As proposed
U-factor: as specified in Table R402.1.4 As proposed
Ceilings Type: wood frame As proposed
Gross area: same as proposed As proposed
U-factor: as specified in Table R402.1.4 As proposed
Roofs Type: composition shingle on wood sheathing As proposed
Gross area: same as proposed As proposed
Solar absorptance = 0.75 As proposed
Emittance = 0.90 As proposed
Attics Type: vented with aperture = 1 ft2 per 300 ft2 ceiling area As proposed
Foundations Type: same as proposed As proposed
Foundation wall area above and below grade and soil characteristics: same as
proposed
As proposed
Opaque doors Area: 40 ft2 As proposed
Orientation: North As proposed
U-factor: same as fenestration from Table R402.1.4 As proposed
Vertical fenestration other than opaque doors Total areah =
(a)The proposed glazing area, where the proposed glazing area is less than 15
percent of the conditioned floor area
(b)15 percent of the conditioned floor area, where the proposed glazing area is
15 percent or more of the conditioned floor area
As proposed
Orientation: equally distributed to four cardinal compass orientations
(N, E, S & W).
As proposed
U-factor: as specified in Table R402.1.4 As proposed
SHGC: as specified in Table R402.1.2 except that for climates with no
requirement (NR) SHGC = 0.40 shall be used.
As proposed
Interior shade fraction: 0.92-(0.21 × SHGC for the standard reference design) 0.92-(0.21 × SHGC as proposed)
External shading: none As proposed
Skylights None As proposed
Thermally isolated sunrooms None As proposed
Air exchange rate Air leakage rate of 5 air changes per hour in climate zones 1 and 2, and 3 air changes per hour in climate zones 3 through 85 at a pressure of 0.2 inches w.g
(50 Pa). The mechanical ventilation rate shall be in addition to the air leakage
rate and the same as in the proposed design, but no greater than 0.01 × CFA + 7.5 × (Nbr + 1)
where:
CFA = conditioned floor area
Nbr = number of bedrooms
Energy recovery shall not be assumed for mechanical ventilation.
For residences that are not tested, the same air leakage rate as the standard reference design.
For tested residences, the measured air exchange ratea.
The mechanical ventilation rateb shall be in addition to the air leakage rate and shall be as proposed.


TABLE R405.5.2(1)‒continued SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS

BUILDING COMPONENT STANDARD REFERENCE DESIGN PROPOSED DESIGN
Mechanical ventilation None, except where mechanical ventilation is specified by the proposed design, in which case:
Annual vent fan energy use:
kWh/yr = 0.03942 × CFA + 29.565 × (Nbr + 1)
where:
CFA = conditioned floor area
Nbr = number of bedrooms
As proposed
Internal gains IGain = 17,900 + 23.8 × CFA + 4104 × Nbr (Btu/day per dwelling unit) Same as standard reference design.
Internal mass An internal mass for furniture and contents of 8 pounds per square foot
of floor area.
Same as standard reference
design, plus any additional mass
specifically designed as a thermal
storage elementc but not integral
to the building envelope or
structure.
Structural mass For masonry floor slabs, 80 percent of floor area covered by R-2 carpet
and pad, and 20 percent of floor directly exposed to room air.
As proposed
For masonry basement walls, as proposed, but with insulation required
by Table R402.1.4 located on the interior side of the walls
As proposed
For other walls, for ceilings, floors, and interior walls, wood frame construction As proposed
Heating systemsd, e As proposed for other than electric heating without a heat pump, where
the proposed design utilizes electric heating without a heat pump the
standard reference design shall be an air source heat pump meeting the
requirements of Section C403 of the IECC-Commercial Provisions.
Capacity: sized in accordance with Section R403.7
As proposed
Cooling systemsd, f As proposed
Capacity: sized in accordance with Section R403.7.
As proposed
Service water heatingd, e, f, g As proposed
Use: same as proposed design
As proposed
gal/day = 30 + (10 × Nbr)
Thermal distribution systems Duct insulation: From Section R403.2.1R403.3.1

A thermal distribution system efficiency (DSE) of 0.88 shall be applied
to both the heating and cooling system efficiencies for all systems other
than tested duct systems. For tested duct systems, the leakage rate shall
be 4 cfm (113.3 L/min) per 100 ft2 (9.29 m2) of conditioned floor area
at a pressure of differential of 0.1 inches w.g. (25 Pa).
As tested or as specified in Table
R405.5.2(2) if not tested. Duct
insulation shall be as proposedthe same as standard reference design.
Thermostat Type: Manual, cooling temperature setpoint = 75°F;
Heating temperature setpoint = 72°F
Same as standard reference

For SI: 1 square foot = 0.93 m2, 1 British thermal unit = 1055 J, 1 pound per square foot = 4.88 kg/m2, 1 gallon (US) = 3.785 L, °C = (°F-32)/1.8, 1 degree = 0.79 rad.
  1. Where required by the code official, testing shall be conducted by an approved party. Hourly calculations as specified in the ASHRAE Handbook of Fundamentals, or the equivalent shall be used to determine the energy loads resulting from infiltration.
  2. The combined air exchange rate for infiltration and mechanical ventilation shall be determined in accordance with Equation 43 of 2001 ASHRAE Handbook of Fundamentals, page 26.24 and the "Whole-house Ventilation" provisions of 2001 ASHRAE Handbook of Fundamentals, page 26.19 for intermittent mechanical ventilation.
  3. Thermal storage element shall mean a component not part of the floors, walls or ceilings that is part of a passive solar system, and that provides thermal storage such as enclosed water columns, rock beds, or phase-change containers. A thermal storage element must be in the same room as fenestration that faces within 15 degrees (0.26 rad) of true south, or must be connected to such a room with pipes or ducts that allow the element to be actively charged.
  4. For a proposed design with multiple heating, cooling or water heating systems using different fuel types, the applicable standard reference design system capacities and fuel types shall be weighted in accordance with their respective loads as calculated by accepted engineering practice for each equipment and fuel type present.
  5. For a proposed design without a proposed heating system, a heating system with the prevailing federal minimum efficiency shall be assumed for both the standard reference design and proposed design.
  6. For a proposed design home without a proposed cooling system, an electric air conditioner with the prevailing federal minimum efficiency shall be assumed for both the standard reference design and the proposed design.
  7. For a proposed design with a nonstorage-type water heater, a 40-gallon storage-type water heater with the prevailing federal minimum energy factor for the same fuel as the predominant heating fuel type shall be assumed. For the case of a proposed design without a proposed water heater, a 40-gallon storage-type water heater with the prevailing federal minimum efficiency for the same fuel as the predominant heating fuel type shall be assumed for both the proposed design and standard reference design.
  8. For residences with conditioned basements, R-2 and R-4 residences and townhouses, the following formula shall be used to determine glazing area:

    AF = As × FA × F

    where:
    AF = Total glazing area
    As = Standard reference design total glazing area.
    FA = (Above-grade thermal boundary gross wall area)/(above-grade boundary wall area + 0.5 × below-grade boundary wall area).
    F = (Above-grade thermal boundary wall area)/(above-grade thermal boundary wall area + common wall area) or 0.56, whichever is greater.
    and where:
    Thermal boundary wall is any wall that separates conditioned space from unconditioned space or ambient conditions.
    Above-grade thermal boundary wall is any thermal boundary wall component not in contact with soil.
    Below-grade boundary wall is any thermal boundary wall in soil contact.
    Common wall area is the area of walls shared with an adjoining dwelling unit.
    L and CFA are in the same units.
  9. l>
    TABLE R405.5.2(2) DEFAULT DISTRIBUTION SYSTEM EFFICIENCIES FOR PROPOSED DESIGNSa

    DISTRIBUTION SYSTEM CONFIGURATION AND CONDITION FORCED AIR SYSTEMS HYDRONIC SYSTEMSb
    Distribution system components located in unconditioned space 0.95
    Untested distribution systems entirely located in conditioned spacec 0.88 1
    "Ductless" systemsd 1

    For SI: 1 cubic foot per minute = 0.47 L/s, 1 square foot = 0.093 m2, 1 pound per square inch = 6895 Pa, 1 inch water gauge = 1250 Pa.
    1. Default values given by this table are for untested distribution systems, which must still meet minimum requirements for duct system insulation.
    2. Hydronic systems shall mean those systems that distribute heating and cooling energy directly to individual spaces using liquids pumped through closed-loop piping and that do not depend on ducted, forced airflow to maintain space temperatures.
    3. Entire system in conditioned space shall mean that no component of the distribution system, including the air-handler unit, is located outside of the conditioned space.
    4. Ductless systems shall be allowed to have forced airflow across a coil but shall not have any ducted airflow external to the manufacturer's air-handler enclosure.
Calculation software, where used, shall be in accordance with Sections R405.6.1 through R405.6.3.
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. Calculation of whole-building (as a single zone) sizing for the heating and cooling equipment in the standard reference design residence in accordance with Section R403.6.

3. Calculations that account for the effects of indoor and outdoor temperatures and part-load ratios on the performance of heating, ventilating and air-conditioning equipment based on climate and equipment sizing.

4. Printed code official inspection checklist listing each of the proposed design component characteristics from Table R405.5.2(1) determined by the analysis to provide compliance, along with their respective performance ratings (R-value, U-factor, SHGC, HSPF, AFUE, SEER, EF are some examples).
Performance analysis tools meeting the applicable provisions of Section R405 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.
When calculations require input values not specified by Sections R402, R403, R404 and R405, those input values shall be taken from an approved source.
This section establishes criteria for compliance using an Energy Rating Index (ERI) analysis.

R406.2 Mandatory Requirements

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Compliance with this section requires that the provisions identified in Sections R401 through R404 labeled as "mandatory" and Section R403.5.3 be met. The building thermal envelope shall be greater than or equal to levels of efficiency and Solar Heat Gain Coefficient in Table 402.1.1 or 402.1.3 of the 2009 International Energy Conservation Code. 2012 North Carolina Energy Conservation Code. Minimum standards associated with compliance shall be the ANSI RESNET ICC Standard 301—2014 “Standard for the Calculation and Labeling of the Energy Performance of Low-Rise Residential Buildings using an Energy Rating Index.” A North Carolina licensed design professional or certified HERS rater is required to perform the analysis if required by North Carolina licensure laws.

Exception: Supply and return ducts not completely inside the building thermal envelope shall be insulated to a minimum of R-6. Supply and return ducts in unconditioned space and outdoors shall be insulated to a minimum R-8. Supply ducts inside semi-conditioned space shall be insulated to a minimum R-4; return ducts inside conditioned and semi-conditioned space are not required to be insulated. Ducts located inside conditioned space are not required to be insulated other than as may be necessary for preventing the formation of condensation on the exterior of cooling ducts.
The Energy Rating Index (ERI) shall be a numerical integer value that is based on a linear scale constructed such that the ERI reference design has an Index value of 100 and a residential building that uses no net purchased energy has an Index value of 0. Each integer value on the scale shall represent a 1-percent change in the total energy use of the rated design relative to the total energy use of the ERI reference design. The ERI shall consider all energy used in the residential building.
The ERI reference design shall be configured such that it meets the minimum requirements of the 2006 International Energy Conservation Code prescriptive requirements.

The proposed residential building shall be shown to have an annual total normalized modified load less than or equal to the annual total loads of the ERI reference design.

R406.4 ERI-based Compliance

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Compliance based on an ERI analysis requires that the rated design be shown to have an ERI less than or equal to the appropriate value listed in Table R406.4Table R406.4.1 or Table R406.4.2, as applicable, when compared to the ERI reference design. TABLE R406.4 MAXIMUM ENERGY RATING INDEX

CLIMATE ZONE ENERGY RATING INDEX
1 52
2 52
3 51
4 54
5 55
6 54
7 53
8 53


TABLE R406.4.1
MAXIMUM ENERGY RATING INDEX (without calculation of on-site renewable energy)
CLIMATE ZONE Jan 1, 2019–Dec 31, 2022 Jan 1, 2023 and forward
3 65 61
4 67 63
5 67 63


555px"> ion>TABLE R406.4.2
MAXIMUM ENERGY RATING INDEX (including calculation of on-site renewable energy)
CLIMATE ZONE Jan 1, 2019–Dec 31, 2022 Jan 1, 2023 and forward
3 51 47
4 54 50
5 55 51

R406.5 Verification by Approved Agency

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Verification of compliance with Section R406 shall be completed by an approved third party.performed by the licensed design professional or certified HERS rater and the compliance documentation shall be provided to the code official. The code official shall inspect according to the requirements of Section R406.6.2.
Documentation of the software used to determine the ERI and the parameters for the residential building shall be in accordance with Sections R406.6.1 through R406.6.3.

R406.6.1 Compliance Software Tools

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Documentation verifying that the methods and accuracy of the compliance software tools conform to the provisions of this section shall be provided to the code official. Compliance software tools for this section shall be in compliance with ANSI RESNET ICC Standard 301—2014.

R406.6.2 Compliance Report

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Compliance software tools shall generate a report that documents that the ERI of the rated design complies with Sections R406.3 and R406.4. The compliance documentation shall include the following information:

1. Address or other identification of the residential building.

2. An inspection checklist documenting the building component characteristics of the rated design. The inspection checklist shall show results for both the ERI reference design and the rated design, and shall document all inputs entered by the user necessary to reproduce the results.

3. Name of individual completing the compliance report.

4. Name and version of the compliance software tool. Exception: Multiple orientations. Where an otherwise identical building model is offered in multiple orientations, compliance for any orientation shall be permitted by documenting that the building meets the performance requirements in each of the four (north, east, south and west) cardinal orientations.

R406.6.3 Additional Documentation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The code official shall be permitted to require the following documents:

1. Documentation of the building component characteristics of the ERI reference design.

2. A certification signed by the builder providing the building component characteristics of the rated design.

3. Documentation of the actual values used in the software calculations for the rated design.
Calculation software, where used, shall be in accordance with Sections R406.7.1 through R406.7.3.

R406.7.1 Minimum Capabilities

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Calculation procedures used to comply with this section shall be software tools capable of calculating the ERI as described in Section R406.3, and shall be in compliance with ANSI RESNET ICC Standard 301—2014. The software shall include the following capabilities:

1. Computer generation of the ERI reference design using only the input for the rated design.

The calculation procedure shall not allow the user to directly modify the building component characteristics of the ERI reference design.

2. Calculation of whole building, as a single zone, sizing for the heating and cooling equipment in the ERI reference design residence in accordance with Section R403.7.

3. Calculations that account for the effects of indoor and outdoor temperatures and part-load ratios on the performance of heating, ventilating and air-conditioning equipment based on climate and equipment sizing.

4. Printed code official inspection checklist listing each of the rated design component characteristics determined by the analysis to provide compliance, along with their respective performance ratings.

R406.7.2 Specific Approval

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Performance analysis tools meeting the applicable sections of Section R406 shall be approved. Tools are permitted to be approved based on meeting a specified threshold for a jurisdiction. The code official shall approve tools for a specified application or limited scope.

R406.7.3 Input Values

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
When calculations require input values not specified by Sections R402, R403, R404 and R405, those input values shall be taken from an approved source.
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