CODES

ADOPTS WITH AMENDMENTS:

International Energy Conservation Code 2009 (IECC 2009)

Copyright

Preface

Effective Use of the International Energy Conservation Code

Ordinance

Chapter 1 Administration

Chapter 2 Definitions

Chapter 3 Climate Zones

Chapter 4 Residential Energy Efficiency

Chapter 5 Commercial Energy Efficiency

Chapter 6 Referenced Standards

Appendix 1 RESIDENTIAL REQUIREMENTS

Appendix 2 COMMERCIAL BUILDING REQUIREMENTS

Appendix 3 SAMPLE WORKSHEETS FOR RESIDENTIAL AIR AND DUCT LEAKAGE TESTING

Appendix 4 ADDITIONAL VOLUNTARY CRITERIA FOR INCREASING ENERGY EFFICIENCY (High Efficiency Residential Option)

Appendix 5 Statement of Compliance – HVAC System Installation

This chapter applies to residential buildings.

401.2 Compliance

STATE AMENDMENT

Projects shall comply with Sections 401, 402.4, 402.5, and 403.1, 403.2.2, 403.2.3, and 403.3 through 403.9 (referred to as the mandatory provisions) and either:

  1. Sections 402.1 through 402.3, 403.2.1 and 404.1 (prescriptive); or
  2. Section 405 (performance).; or
  3. 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 trade-off calculations are needed for required termite inspection and treatment gaps.

401.3 Certificate

STATE AMENDMENT
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 certificate shall be completed by the builder or registered design professional.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 /or floor) and ducts outside conditioned spaces; 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 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. The certificate shall indicate whether the building air leakage was visually inspected as required in 402.4.2.1 or provide results of the air leakage testing required in 402.4.2.2.The certificate shall provide results of duct leakage test required in Section 403.2.2. Appendix 1.1 contains a sample certificate.
Appendix 4 contains additional voluntary measures for increasing residential energy efficiency beyond code minimums. Implementation of the increased energy efficiency measures is 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 15-20% improvement in energy efficiency beyond code minimums.

The building thermal envelope shall meet the requirements of Table 402.1.1 based on the climate zone specified in Chapter 3.

TABLE 402.1.1
INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENT
a

CLIMATE
ZONE

FENESTRATION
U-FACTORb

SKYLIGHTb
U-FACTOR

GLAZED
FENESTRATION
SHGC
b, 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
SPACE
c
WALL
R-VALUE

1

1.2

0.75

0.30

30

13

3/4

13

0

0

0

2

0.65j

0.75

0.30

30

13

4/6

13

0

0

0

3

0.50j

0.65

0.30

30

13

5/8

19

5/13f

0

5/13

4 except
Marine

0.35

0.60

NR

38

13

5/10

19

10/13

10, 2 ft

10/13

5 and
Marine 4

0.35

0.60

NR

38

20 or 13+5h

13/17

30g

10/13

10, 2 ft

10/13

6

0.35

0.60

NR

49

20 or 13+5h

15/19

30g

15/19

10, 4 ft

10/13

7 and 8

0.35

0.60

NR

49

21

19/21

38g

15/19

10, 4 ft

10/13

TABLE 402.1.1
INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENTa
CLIMATE
ZONE
FENESTRATION
U-FACTORb, I
SKYLIGHTb
U-FACTOR
GLAZED
FENESTRATION
SHGCb, e, m
CEILINGk
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
3 0.35 0.65 0.30 30 13 5/10 19 10/13f 0 5/13
4 0.35 0.60 0.30 38 or 30
cont.j
15, 13+2.5h 5/10 19 10/13 10 10/13
5 0.35 0.60 NR 38 or 30
cont.j
19, 13+5, or
15 + 3e,h
13/17 30g 10/13 10 10/13

For SI: 1 foot = 304.8 mm.

a. R-values are minimums. U-factors and SHGC are maximums. R-19 batts compressed into a nominal 2 × 6 framing cavity such that the R-value is reduced by R-1 or more shall be marked with the compressed batt R-value in addition to the full thickness R-value.

b. The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.

c. “15/19” means R-15“10/13” means R-10 continuous insulated sheathing 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 insulated sheathing on the interior or exterior of the home. “10/13” means R-10 continuous insulated sheathing on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall or crawl space wall.

d. For monolithic slabs, insulation shall be applied from the inspection gap downward to the bottom of the footing or a maximum of 18 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. 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 Zones 1 through 3 for heated slabs.

e. There are no SHGC requirements in the Marine Zone.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.

f. Basement wall insulation is not required in warm-humid locations as defined by Figure 301.1 and Table 301.1.Figure N1101.2(1 and 2) and Table N1101.2.

g. Or insulation sufficient to fill the framing cavity, R-19 minimum.

h. “13+5” means R-13 cavity insulation plus R-5 insulated sheathing. 15+3 means R-15 cavity insulation plus R-3 insulated 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. 13+2.5 means R-13 cavity insulation plus R-2.5 sheathing.

i. For Mass Walls, the second R-value applies when more than half the insulation is on the interior of the mass wall.

j. For impact rated fenestration complying with Section R301.2.1.2 of the International Residential Code or Section 1608.1.2 of the International Building Code, the maximum U-factor shall be 0.75 in Zone 2 and 0.65 in Zone 3. 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” of the attic roof deck.


k. 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.

l. In addition to the exemption in Section 402.3.3, 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.

m. In addition to the exemption in Section 402.3.3, 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.
Insulation material used in layers, such as framing cavity insulation and insulating sheathing, shall be summed to compute the 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.

An assembly with a U-factor equal to or less than that specified in Table 402.1.3 shall be permitted as an alternative to the R-value in Table 402.1.1.

TABLE 402.1.3
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-FACTORd

CRAWL
SPACE

WALL U-FACTORc

1

1.20

0.75

0.035

0.082

0.197

0.064

0.360

0.477

2

0.65

0.75

0.035

0.082

0.165

0.064

0.360

0.477

3

0.50

0.65

0.035

0.082

0.141

0.047

0.091c

0.136

4 except Marine

0.35

0.60

0.030

0.082

0.141

0.047

0.059

0.065

5 and Marine 4

0.35

0.60

0.030

0.057

0.082

0.033

0.059

0.065

6

0.35

0.60

0.026

0.057

0.060

0.033

0.050

0.065

7 and 8

0.35

0.60

0.026

0.057

0.057

0.028

0.050

0.065

TABLE 402.1.3
EQUIVALENT U-FACTORSa
CLIMATE
ZONE
FENESTRATION
U-FACTORe
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-FACTORc
3 0.35 0.65 0.035 0.082 0.141 0.047 0.059 0.136
4 0.35 0.60 0.030 0.077 0.141 0.047 0.059 0.065
5 0.35 0.60 0.030 0.061 0.082 0.033 0.059 0.065

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 Zone 1, 0.14 in Zone 2, 0.12 in Zone 3, 0.10 in Zone 4 except Marine, and the same as the frame wall U-factor in Marine Zone 4 and Zones 5 through 8.

c. Basement wall U-factor of 0.360 in warm-humid locations as defined by Figure 301.1 and Table 301.2.Table 301.1 and Figure 301.2.

d. Foundation U-factor requirements shown in Table 402.1.3 include wall construction and interior air films but exclude soil conductivity and exterior air films. U-factors for determining code compliance in accordance with Section 402.1.4 (total UA alternative) of Section 405 (Simulated Performance Alternative) shall be modified to include soil conductivity and exterior air films.


e. 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 402.1.3 (multiplied by the same assembly area as in the proposed building), the building shall be considered in compliance with Table 402.1.1. 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.
When Section 402.1.1 would require R-38 in the ceiling, R-30 shall be deemed to satisfy the requirement for R-38 wherever the full height of uncompressed R-30 insulation extends over the wall top plate at the eaves. Similarly, R-38 shall be deemed to satisfy the requirement for R-49 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 402.1.3 and the total UA alternative in Section 402.1.4. Ceilings with attic spaces over conditioned space shall meet the insulation requirements in Table 402.1.1.

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.
Where Section 402.1.1 would require insulation levels above R-30 and the design of the roof/ceiling assemblydoes not allow sufficient space for the, 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 402.1.1 shall be limited to 500 square feet (46 m2) or 20 percent of the total insulated ceiling of ceiling surface area, whichever is less. This reduction shall not apply to the U-factor alternative approach in Section 402.1.3 and the total UA alternative in Section 402.1.4.
Access doorsHorizontal access hatches from conditioned spaces to unconditioned spaces (e.g., 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.

Exceptions:
  1. Pull down stair systems shall be weatherstripped and insulated to an R-5 insulation value such that the insulation does not interfere with proper operation of the stair. Non-rigid 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.
  2. Full size doors that are part of the building thermal envelope and provide a passageway to unconditioned spaces shall meet the requirements of exterior doors in Section 402.3.4.
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.

Steel- frame ceilings, walls and floors shall meet the insulation requirements of Table 402.2.5 or shall meet the U-factor requirements in Table 402.1.3. The calculation of the U-factor for a steel-frame envelope assembly shall use a series-parallel path calculation method.

Exception: In Climate Zones 1 and 2, the continuous insulation requirements in Table 402.2.4 shall be permitted to be reduced to R-3 for steel frame wall assemblies with studs spaced at 24 inches (610 mm) on center.

TABLE 402.2.5
STEEL-FRAME CEILING, WALL AND FLOOR INSULATION (R-VALUE)

WOOD FRAME
R-VALUE REQUIREMENT

COLD-FORMED STEEL
EQUIVALENT R-VALUE
a

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

R-13

R-13 + 5 or R-15 + 4 or R-21 + 3 or R-0 + 10

R-19

R-13 + 9 or R-19 + 8 or R-25 + 7

R-21

R-13 + 10 or R-19 + 9 or R-25 + 8

Steel Joist Floor

R-13

R-19 in 2 × 6

R-19 + 6 in 2 × 8 or 2 × 10

R-19

R-19 + 6 in 2 × 6

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.

402.2.6 Floors

STATE AMENDMENT
Floor 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: Enclosed floor cavity such as garage ceilings, cantilevers or buildings on pilings with 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.
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 402.1.1 and 402.2.6.
Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table 402.1.1. 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 402.1.1 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 a minimum of 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 infestationSlab edge insulation shall have 2" termite inspection gap consistent with Appendix 1.2.2 of this code.

402.2.9 Crawl Space Walls

STATE AMENDMENT
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. 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 at least 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 402.1.1.

     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 1.2.2 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 402.2.9. 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.
TABLE 402.2.9
WALL INSULATION ALLOWANCES
FOR TERMITE TREATMENT AND INSULATION GAPS
MAXIMUM GAP WIDTH (INCHES) INSULATION LOCATION GAP DESCRIPTION
3 Outside Above grade inspection between top of insulation and bottom of siding
6 Outside Below grade treatment
4a Inside Wall inspection between top of insulation and bottom of sill
4a Inside Clearance/wicking space between bottom of insulation and top of ground surface, footing, or concrete floor.
For SI: 1 inch = 25.4mm.
  1. No insulation shall be required on masonry wall of 9 inches in height or less.
Insulation shall not be required on the horizontal portion of the foundation that supports a masonry veneer.
The minimum ceiling insulation R-values shall be R-19 in Zones 1 through 4 and R-24 in Zones 5 through 83 and 4, and R-24 in Zone 5. The minimum wall R-value shall be R-13 in all zones. New wall(s) separating a sunroom from conditioned space shall meet the building thermal envelope requirements. Floor or slab insulation shall comply with values in Table 402.1.1.
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 rigid material or an air barrier material. 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 1.2.3 of this code:
  1. Tubs
  2. Showers
  3. Stairs
  4. Fireplace units
     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.
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.
Up to 15 square feet (1.4 m2) of glazed fenestration per dwelling unit shall be permitted to be exempt from U-factor and SHGC requirements in Section 402.1.1. This exemption shall not apply to the U-factor alternative approach in Section 402.1.3 and the Total UA alternative in Section 402.1.4.
Opaque doors separating conditioned and 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 402.1.1. This exemption shall not apply to the U-factor alternative approach in Section 402.1.3 and the total UA alternative in Section 402.1.4.
For Zones 4 through 8, The maximum fenestration U-factor shall be 0.500.40 and the maximum skylight U-factor shall be 0.75. Sunrooms with cooling systems shall have a maximum fenestration SHGC of 0.40 for all glazing.

      New windows and doors separating the sunroom from conditioned space shall meet the building thermal envelope requirements. Sunroom additions shall maintain thermal isolation; and shall be served by a separate heating or cooling system, or be thermostatically controlled as a separate zone of the existing system.

Exception: 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.
Where some or all of an entire existing fenestration unit is replaced with a new fenestration product, including frame, sash and glazing, the replacement fenestration unit shall meet the applicable requirements for U-factor and SHGC in Table 402.1.1.

The building thermal envelope shall be durably sealed with an air barrier system 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, suitable film or solid materialor solid material consistent with Appendix 1.2.4 of this code:

1. All joints, seams and penetrations.

2. Site-built windows, doors and skylights.

3. Openings between window and door assemblies and their respective jambs and framing.

4. Utility penetrations.

5. Dropped ceilings or chases adjacent to the thermal envelope.

6. Knee walls.

7. Walls and ceilings separating a garage from conditioned spaces.

8. Behind tubs and showers on exterior walls.

9. Common walls between dwelling units.

10. Attic access openings.

11. Rim joist junction.

12. Other sources of infiltration.

  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.

Building envelope air tightness and insulation installation shall be demonstrated to comply with one of the following options given by Section 402.4.2.1 or 402.4.2.2:

TABLE 402.4.2
AIR BARRIER AND INSULATION INSPECTION COMPONENT CRITERIA

COMPONENT

CRITERIA

Air barrier and thermal barrier

Exterior thermal envelope insulation for framed walls is installed in substantial contact and continuous alignment with building envelope air barrier.

Breaks or joints in the air barrier are filled or repaired.

Air-permeable insulation is not used as a sealing material.

Air-permeable insulation is inside of an air barrier.

Ceiling/attic

Air barrier in any dropped ceiling/soffit is substantially aligned with insulation and any gaps are sealed.

Attic access (except unvented attic), knee wall door, or drop down stair is sealed.

Walls

Corners and headers are insulated.

Junction of foundation and sill plate is sealed.

Windows and doors

Space between window/door jambs and framing is sealed.

Rim joists

Rim joists are insulated and include an air barrier.

Floors
(including above-garage and cantilevered floors)

Insulation is installed to maintain permanent contact with underside of subfloor decking.

Air barrier is installed at any exposed edge of insulation.

Crawl space walls

Insulation is permanently attached to walls.

Exposed earth in unvented crawl spaces is covered with Class I vapor retarder with overlapping joints taped.

Shafts, penetrations

Duct shafts, utility penetrations, knee walls and flue shafts opening to exterior or unconditioned space are sealed.

Narrow cavities

Batts in narrow cavities are cut to fit, or narrow cavities are filled by sprayed/blown insulation.

Garage separation

Air sealing is provided between the garage and conditioned spaces.

Recessed lighting

Recessed light fixtures are air tight, IC rated, and sealed to drywall.
Exception—fixtures in conditioned space.

Plumbing and wiring

Insulation is placed between outside and pipes. Batt insulation is cut to fit around wiring and plumbing, or sprayed/blown insulation extends behind piping and wiring.

Shower/tub on exterior wall

Showers and tubs on exterior walls have insulation and an air barrier separating them from the exterior wall.

Electrical/phone box on exterior walls

Air barrier extends behind boxes or air sealed-type boxes are installed.

Common wall

Air barrier is installed in common wall between dwelling units.

HVAC register boots

HVAC register boots that penetrate building envelope are sealed to subfloor or drywall.

Fireplace

Fireplace walls include an air barrier.

Building envelope air tightness shall be demonstrated by compliance with Section 402.4.2.1 or 402.4.2.2. Appendix 3 contains optional sample worksheets for visual inspection or testing for the permit holder’s use only.

TABLE 402.4.2
AIR BARRIER AND INSULATION INSPECTION COMPONENT CRITERIA
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)
Air barrier system is 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.
Duct boots Sealing HVAC register boots and return boxes to subfloor or drywall.
Recessed lighting Recessed light fixtures are air tight, IC rated, and sealed to drywall.
Exception—fixtures in conditioned space.

402.4.2.1 Testing Option

STATE AMENDMENT

Building envelope tightness and insulation installation shall be considered acceptable when tested air leakage is less than seven air changes per hour (ACH) when tested with a blower door at a pressure of 33.5 psf (50 Pa). 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.

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, intake, makeup air, backdraft and flue dampers;

3. Interior doors shall be open;

4. Exterior openings for continuous ventilation systems and heat recovery ventilators shall be closed and sealed;

5. Heating and cooling system(s) shall be turned off;

6. HVAC ducts shall not be sealed; and

7. Supply and return registers shall not be sealed.

Building envelope tightness shall be considered acceptable when items providing insulation enclosure in Section 402.2.12 and air sealing in Section 402.4.1 are addressed and when the items listed in Table 402.4.2, applicable to the method of construction, are certified by the builder, permit holder or registered design professional via the certificate in Appendix 1.1.
Building envelope tightness and insulation installation shall be considered acceptable when the items listed in Table 402.4.2, applicable to the method of construction, are field verified. Where required by the code official, an approved party independent from the installer of the insulation shall inspect the air barrier and insulation.

402.4.2.2 Testing option

STATE AMENDMENT
Building envelope tightness shall be considered acceptable when items providing insulation enclosure in Section 402.2.12 and air sealing in Section 402.4.1 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, not temperature corrected, test 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 E 779-03. 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 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.

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 401.3.

    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.

402.4.3 Fireplaces

STATE AMENDMENT
New wood-burning fireplaces shall have gasketed doors and outdoor combustion air. Site-built masonry fireplaces shall have doors and comply with Section R1006 of the North Carolina Residential Code for combustion air.

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 (by a body such as IAS or NFRC), independent laboratory and listed and labeled by the manufacturer.

Exceptions: Site-built windows, skylights and doors.

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 meeting ASTM E 283 when tested at 1.57 psf (75 Pa) pressure differential with no more than 2.0 cfm (0.944 L/s) of air movement from the conditioned space to the ceiling cavity. All recessed luminaires shall be sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.
The area-weighted average maximum fenestration U-factor permitted using trade-offs from Section 402.1.4 or 404 shall be 0.48 in Zones 4 and 5 and 0.40 in Zones 6 through 8 for vertical fenestration, and 0.75 in Zones 4 through 8 for skylights. The area-weighted average maximum fenestration SHGC permitted using trade-offs from Section 405 in Zones 1 through 3 shall be 0.500.40. Maximum skylight U-factors shall be 0.65 in zones 4 and 5 and 0.60 in zone 3. The area-weighted average maximum fenestration SHGC permitted using trade-offs from Section 405 in 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.
Where the primary heating system is a forced-air furnace, at least one thermostat per 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 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).
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 shall be provided to prevent supplemental heat operation in response to the thermostat being changed to a warmer setting. The lockout shall be set no lower than 35°F and no higher than 40°F.

Exception: In lieu of a heat strip outdoor temperature lockout, 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. If the indoor coil leaving air temperature exceeds 100°F, 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.
Maintenance instructions shall be furnished for equipment and systems that require preventive maintenance.

Supply ducts in attics shall be insulated to a minimum of R-8. All other ducts shall be insulated to a minimum of R-6.

Exception: Ducts or portions thereof located completely inside the building thermal envelope.

Supply and return ducts in unconditioned space and outdoors shall be in insulated to R-8. Supply ducts inside semi-conditioned space shall be insulated to 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.

All ducts, air handlers, filter boxes and building cavities used as ducts shall be sealed. Joints and seams shall comply with Section M1601.4.1 of the International Residential CodePart V–Mechanical, Section 603.9 of the North Carolina Residential Code. Duct testing shall be verified by compliance with Section 403.2.2.1 or 403.2.2.2..

Duct tightness shall be verified by either of the following:

1. Postconstruction test: Leakage to outdoors shall be less than or equal to 8 cfm (226.5 L/min) per 100 ft2 (9.29 m2) of conditioned floor area or a total leakage less than or equal to 12 cfm (12 L/min) per 100 ft2 (9.29 m2) of conditioned floor area 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. All register boots shall be taped or otherwise sealed during the test.

2. Rough-in test: Total leakage shall be less than or equal to 6 cfm (169.9 L/min) per 100 ft2 (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the roughed in system, including the manufacturer’s air handler enclosure. All register boots shall be taped or otherwise sealed during the test. If the air handler is not installed at the time of the test, total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 ft2 (9.29 m2) of conditioned floor area.

Exceptions: Duct tightness test is not required if the air handler and all ducts are located within conditioned space.

Total duct leakage less than or equal to 6 CFM (12 L/min) per 100 ft2(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, 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.
  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.
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 6 CFM (12 L/min) per 100 ft2 (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.)
     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 has been certified by the manufacturer to be capable of conducting tests in accordance with ASTM E 1554-07.

     The duct leakage information, including duct leakage 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 6 CFM25/100 SF 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.
Building framing cavities shall not be used as supply ducts.
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.
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.
Outdoor air intakes and Exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.
Heating and cooling equipment shall be sized in accordance with Section M1401.3 of the International Residential Code.

403.6.1 Equipment sizing

STATE AMENDMENT
Heating and cooling equipment shall be sized in accordance with the North Carolina Mechanical Code.
Equipment efficiencies shall comply with the current NAECA minimum standards.
Systems serving multiple dwelling units shall comply with Sections 503 and 504 in lieu of Section 403.
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, and no precipitation is falling and an automatic or manual control that will allow shutoff when the outdoor temperature is above 40°F.
Pools shall be provided with energy-conserving measures in accordanceand inground permanently installed spas shall comply with Sections 403.9.1 through 403.9.3.

403.9.1 Pool Heaters

STATE AMENDMENT
All pool heaters shall be equipped with a readily accessible on-off switch to allow shuttingthat is mounted outside of the heater to allow shutting off the heater without adjusting the thermostat setting. Pool heaters fired by natural gas shall not have continuouslyGas-fired heaters shall not be equipped with constant burning pilot lights.

403.9.2 Time Switches

STATE AMENDMENT

Time switches or other control method that can automatically turn off and on heaters and pumps according to a preset schedule shall be installed on swimming poolall heaters and pumps. Heaters, pumps and motors that have built-in timers shall be deemed in compliance with this requirement.

Exceptions:

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

2. Where pumps are required to operate solar- and waste-heat-recovery pool heating systems.

403.9.3 Pool Covers

STATE AMENDMENT

Heated pools shall be equippedand inground permanently installed spas shall be provided with a vapor-retardant pool cover on or at the water surface. Pools heated to more than 90°F (32°C) shall have a pool cover with a minimum insulation value of R-12.


Exception: Pools deriving over 60 percent of the energy for heating from site-recovered energy or solar energy source.Pools deriving over 70 percent of the energy for heating from site-recovered energy, such as a heat pump or solar energy source computed over an operating season.

A minimum of 5075 percent of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps.

405.1 Scope

STATE AMENDMENT
This section establishes criteria for compliance using simulated energy performance analysis. Such analysis shall include heating, cooling, and service water heating energy only. A North Carolina registered design professional is required to perform the analysis if required by North Carolina licensure laws.
Compliance with this section requires that the mandatory provisions identified in Section 401.2 be met. All supply and return ducts not completely inside the building thermal envelope shall be insulated to a minimum of R-6R-8. Supply ducts inside semi-conditioned space shall be insulated to R-4; return ducts inside semi-conditioned space are not required to be insulated.

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 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 shall generate a report that documents that the proposed design complies with Section 405.3. The compliance documentation shall include the following information:

1. Address or other identification of the residence;

2. An inspection checklist documenting the building component characteristics of the proposed design as listed in Table 405.5.2(1). The inspection checklist shall show results for both the standard reference design and the proposed design, and shall document all inputs entered by the user necessary to reproduce the results;

3. Name of individual completing the compliance report; and

4. Name and version of the compliance software tool.

Exception: Multiple orientations. When 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 cardinal (north, east, south and west) orientations.

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 405.5.2(1).

3. Documentation of the actual values used in the software calculations for the proposed design.

Except as specified by this section, the standard reference design and proposed design shall be configured and analyzed using identical methods and techniques.

The standard reference design and proposed design shall be configured and analyzed as specified by Table 405.5.2(1). Table 405.5.2(1) shall include by reference all notes contained in Table 402.1.1.

TABLE 405.5.2(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.

Gross area: same as proposed

U-factor: from Table 402.1.3

Solar absorptance = 0.75

Remittance = 0.90

As proposed

As proposed

As proposed

As proposed

As proposed

Basement and crawl space walls

Type: same as proposed

Gross area: same as proposed

U-factor: from Table 402.1.3, with insulation layer on
interior side of walls.

As proposed

As proposed

As proposed

Above-grade floors

Type: wood frame

Gross area: same as proposed

U-factor: from Table 402.1.3

As proposed

As proposed

As proposed

Ceilings

Type: wood frame

Gross area: same as proposed

U-factor: from Table 402.1.3

As proposed

As proposed

As proposed

Roofs

Type: composition shingle on wood sheathing

Gross area: same as proposed

Solar absorptance = 0.75

Emittance = 0.90

As proposed

As proposed

As proposed

As proposed

Attics

Type: vented with aperture = 1 ft2 per 300 ft2 ceiling area

As proposed

Foundations

Type: same as proposed foundation wall area above and below grade and soil characteristics: same as proposed.

As proposed

As proposed

Doors

Area: 40 ft2

Orientation: North

U-factor: same as fenestration from Table 402.1.3.

As proposed

As proposed

As proposed

GlazingaFenestrationb

Total areab, c =

(a)

The proposed glazingfenestration area; where proposed glazingfenestration area is less than 15% of the conditioned floor area.

(b)

15% of the conditioned floor area; where the proposed glazingfenestration area is 15% or more of the conditioned floor area.

Orientation: equally distributed to four cardinal compass orientations (N, E, S & W).

U-factor: from Table 402.1.3

SHGC: From Table 402.1.1 except that for climates with no requirement (NR) SHGC = 0.40 shall be used.

Interior shade fraction:

Summer (all hours when cooling is required) = 0.700.90

Winter (all hours when heating is required) = 0.850.90c

External shading: none

As proposed

As proposed

As proposed

As proposed

Same as standard reference designd

As proposed

Skylights

None

As proposed

Thermally isolated sunrooms

None

As proposed

(continued)

TABLE 405.5.2(1)—continued
SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS

BUILDING COMPONENT

STANDARD REFERENCE DESIGN

PROPOSED DESIGN

Air exchange rate

Specific leakage area (SLA)d = 0.00036 assuming no energy recovery 5 ACH50
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 continuous operation at 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 as the standard reference design. For tested residences, the measured air exchange rate.e The mechanical ventilation rate shall be in addition to the air leakage rate and shall be as proposed.f

For residences without mechanical ventilation that are tested in accordance with ASHRAE 119, Section 5.1, the measured air exchange ratee but not less than 0.35 ACH

For residences with mechanical ventilation that are tested in accordance with ASHRAE 119, Section 5.1, the measured air exchange ratee combined with the mechanical ventilation rate, f which shall not be less than 0.01 × CFA + 7.5
× (Nbr+1)

where:

CFA = conditioned floor area

Nbr = number of bedrooms

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 + ΔIGlighting
(Btu/day per dwelling unit)

Where ΔIGlighting represents the reduced internal gains from efficient lighting as defined by the lighting building component.

Same as standard reference designIGain = 17,900 + 23.8 × CFA + 4104 × Nbr + ΔIGlighting
(Btu/day per dwelling unit)

Where ΔIGlighting represents the reduced internal gains from efficient lighting as defined by the lighting building component.

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 elementg, f but not integral to the building envelope or structure

Structural mass

For masonry floor slabs, 80% of floor area covered by R-2 carpet and pad, and 20% of floor directly exposed to room air.

For masonry basement walls, as proposed, but with insulation required by Table 402.1.3 located on the interior side of the walls

For other walls, for ceilings, floors, and interior walls, wood frame construction

As proposed

As proposed

As proposed

Heating systemsg, h, i, j

As proposed

Capacity: sized in accordance with Section M1401.3 of the International Residential Codethe North Carolina Mechanical Code and North Carolina Residential Code.
Fuel type: same as proposed design

As proposed

Cooling systemsg, i, j, k

As proposed

Capacity: sized in accordance with Section M1401.3 of the International Residential Codethe North Carolina Mechanical Code and North Carolina Residential Code.

As proposed

Service water

heatingg, i, j, k

As proposed

Fuel type: Use: same as proposed design

As proposed

gal/day = 30 + (10 x Nbr)

Thermal distribution systems

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. Duct insulation: From Section 403.2.1. For tested duct systems, the
leakage rate shall be the applicable maximum rate from Section 403.2.2.

As tested or as specified in Table 405.5.2(2) if not tested

Thermostat

Type: Manual, cooling temperature setpoint = 75°F;

Heating temperature setpoint = 72°F

Same as standard reference

LightingkWh/yr = (455 + 0.80*CFA) + ΔkWh/yr

where:

ΔkWh/yr = [29.5 – 0.5189*CFA*50% – 295.12*50% + 0.0519*CFA]

Internal gains in the Standard Reference Design shall be reduced by 90% of the impact from efficient lighting, calculated in Btu/day using the following equation:

ΔIGlighting = -0.90*ΔkWh/yr*106/293/365
kWh/yr = (455 + 0.80 CFA) + ΔkWh/yr

where:
ΔkWh/yr = [29.5 – 0.5189*CFA *FL% – 295.12*FL% + 0.0519*CFA]

FL% = the ratio of qualifying light fixtures to all light fixtures in qualifying light fixture locations.

The proposed design shall not have FL% more than 50% from CFL.

Internal gains in the proposed design shall be reduced by 90% of the impact from efficient lighting, calculated in Btu/day using the following equation:

ΔIGlighting =0.90*ΔkWh/yr* 106/293/ 365

TABLE 405.5.2(1)—continued

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 (U.S.) = 3.785 L; °C = (°F-3)/1.8,
1 degree = 0.79 rad.

a. Glazing shall be defined as sunlight-transmitting fenestration, including the area of sash, curbing or other framing elements, that enclose conditioned space. Glazing includes the area of sunlight-transmitting fenestration assemblies in walls bounding conditioned basements. For doors where the sunlight-transmitting opening is less than 50 percent of the door area, the glazing area is the sunlight transmitting opening area. For all other doors, the glazing area is the rough frame opening area for the door including the door and the frame.

b. 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.

c. For fenestrations facing within 15 degrees (0.26 rad) of true south that are directly coupled to thermal storage mass, the winter interior shade fraction shall be permitted to be increased to 0.95 in the proposed design.

d. Where leakage area (L) is defined in accordance with Section 5.1 of ASHRAE 119 and where:

SLA = L/CFA

where L and CFA are in the same units.

e. Tested envelope leakage shall be determined and documented by an independent party approved by the code official. Hourly calculations as specified in the 2001 ASHRAE Handbook of Fundamentals, Chapter 26, page 26.21, Equation 40 (Sherman-Grimsrud model) or the equivalent shall be used to determine the energy loads resulting from infiltration.

f. 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.

g. 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.

h. 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.

i. 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. For electric heating systems, the prevailing federal minimum efficiency air-source heat pump shall be used for the standard reference design.

j. 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.

k. 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.

TABLE 405.5.2(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.

a. Default values given by this table are for untested distribution systems, which must still meet minimum requirements for duct system insulation.

b. 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.

c. 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.

d. 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 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 M1401.3 of the International Residential Codethe North Carolina Mechanical Code.

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 405.5.2(1) determined by the analysis to provide compliance, along with their respective performance ratings (e.g., R-value, U-factor, SHGC, HSPF, AFUE, SEER, EF, etc.).

Performance analysis tools meeting the applicable sections of Section 405 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 402, 403, 404 and 405, those input values shall be taken from an approved source.
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