This chapter applies to residential buildings.
A permanent certificate shall be posted on or in the electrical distribution 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 be completed by the builder or registered design professional. 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 building thermal envelope shall meet the requirements of Table 402.1.1 based on the climate zone specified in Chapter 3.
For SI: 1 foot = 304.8 mm.
|
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 | 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 |
- 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.
- The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.
- "15/19" means R-15 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.
- 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.
- There are no SHGC requirements in the Marine Zone.
- Basement wall insulation is not required in warm-humid locations as defined by Figure 301.1 and Table 301.1.
- Or insulation sufficient to fill the framing cavity, R-19 minimum.
- "13+5" means R-13 cavity insulation plus R-5 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.
- The second R-value applies when more than half the insulation is on the interior of the mass wall.
- For impact rated fenestration complying with Section R301.2.2 of the International Residential Code Section 1609.1.2 of the International Building Code, the maximum U-factor shall be 0.75 in Zone 2 and 0.65 in Zone 3.
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.
|
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
|
- Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source.
- 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.
- Basement wall U-factor of 0.360 in warm-humid locations as defined by Figure 301.1 and Table 301.1.
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.
Where Section 402.1.1 would require insulation levels above R-30 and the design of the roof/ceiling assembly 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 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 doors 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 surfaces. 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.
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 402.2.5 shall be permitted to be reduced to R-3 for steel frame wall assemblies with studs spaced at 24 inches (610 mm) on center.
|
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
|
|
|
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
|
- Cavity insulation R-value is listed first, followed by continuous insulation R-value.
- Insulation exceeding the height of the framing shall cover the framing.
Floor insulation shall be installed to maintain permanent contact with the underside of the subfloor decking.
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 infestation.
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. 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.
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 8. 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.
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.
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 0.50 and the maximum skylight U-factor shall be 0.75. New windows and doors separating the sunroom from conditioned space shall meet the building thermal envelope requirements.
Where some or all of an existing fenestration unit is replaced with a new fenestration product, including sash and glazing, the replacement fenestration unit shall meet the applicable requirements for U-factor and SHGC in Table 402.1.1.
The building thermal envelope shall be durably sealed to limit infiltration. The sealing methods between dissimilar materials shall allow for differential expansion and contraction. The following shall be caulked, gasketed, weatherstripped or otherwise sealed with an air barrier material, suitable film or solid material:
- All joints, seams and penetrations.
- Site-built windows, doors and skylights.
- Openings between window and door assemblies and their respective jambs and framing.
- Utility penetrations.
- Dropped ceilings or chases adjacent to the thermal envelope.
- Knee walls.
- Walls and ceilings separating a garage from conditioned spaces.
- Behind tubs and showers on exterior walls.
- Common walls between dwelling units.
- Attic access openings.
- Rim joist junction.
- Other sources of infiltration.
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:
|
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.
|
|
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 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 50 PA (1 psf). 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:
- Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed;
- Dampers shall be closed, but not sealed, including exhaust, intake, makeup air, backdraft and flue dampers;
- Interior doors shall be open;
- Exterior openings for continuous ventilation systems and heat recovery ventilators shall be closed and sealed;
- Heating and cooling system(s) shall be turned off;
- HVAC ducts shall not be sealed; and
- Supply and return registers shall not be sealed.
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.
New wood-burning fireplaces shall have gasketed doors and outdoor 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, 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 405 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 0.50.
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.
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.
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 Code.
Duct tightness shall be verified by either of the following:
- 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.
- 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.
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.
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.
All pool heaters shall be equipped with a readily accessible on-off switch to allow shutting off the heater without adjusting the thermostat setting. Pool heaters fired by natural gas or LPG shall not have continuously burning pilot lights.
Time switches that can automatically turn off and on heaters and pumps according to a preset schedule shall be installed on swimming pool heaters and pumps.
Exceptions:
- Where public health standards require 24-hour pump operation.
- Where pumps are required to operate solar- and waste-heat-recovery pool heating systems.
Heated pools shall be equipped 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.
A minimum of 50 percent of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps.
This section establishes criteria for compliance using simulated energy performance analysis. Such analysis shall include heating, cooling, and service water heating energy only.
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-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 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:
- Address or other identification of the residence;
- 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;
- Name of individual completing the compliance report; and
- 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:
- Documentation of the building component characteristics of the standard reference design.
- A certification signed by the builder providing the building component characteristics of the proposed design as given in Table 405.5.2(1).
- 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.
| 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: from Table 402.1.3 | As proposed | |
| Solar absorptance = 0.75 | As proposed | |
| Remittance = 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 402.1.3, 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: from Table 402.1.3 | As proposed | |
| Ceilings | Type: wood frame | As proposed |
| Gross area: same as proposed | As proposed | |
| U-factor: from Table 402.1.3 | 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 foundation | As proposed |
| wall area above and below grade and soil characteristics: same as proposed. | As proposed | |
| Doors | Area: 40 ft2 | As proposed |
| Orientation: North | As proposed | |
| U-factor: same as fenestration from Table 402.1.3. | As proposed | |
| Glazinga |
Total areab =
|
As proposed |
| Orientation: equally distributed to four cardinal compass orientations (N, E, S & W). | As proposed | |
| U-factor: from Table 402.1.3 | As proposed | |
| SHGC: From Table 402.1.1 except that for climates with no requirement (NR) SHGC = 0.40 shall be used. | As proposed | |
Interior shade fraction:
|
Same as standard reference design | |
| External shading: none | As proposed | |
| Skylights | None | As proposed |
| Thermally isolated sunrooms | None | As proposed |
| Air exchange rate | Specific leakage area (SLA)e = 0.00036 assuming no energy recovery |
For residences that are not tested, the same as the standard reference design. For residences without mechanical ventilation that are tested in accordance with ASHRAE 119, Section 5.1, the measured air exchange ratef 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
(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 elementg, 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. | As proposed |
| For masonry basement walls, as proposed, but with insulation required by Table 402.1.3 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 systemsi, h | As proposed Capacity: sized in accordance with Section M1401.3 of the International Residential Code |
As proposed |
| Cooling systemsh | As proposed Capacity: sized in accordance with Section M1401.3 of the International Residential Code |
As proposed |
| Service H2O heatingh, k, i | As proposed 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 |
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.
- 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.
- 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. - 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.
- 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. - 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
| 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.
- Default values given by this table are for untested distribution systems, which must still meet minimum requirements for duct system insulation.
- 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.
- 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.
- 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:
- 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.
- 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 Code.
- 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.
- 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.