Heads up: There are no amended sections in this chapter.
Projects shall comply with Sections identified as "mandatory" and with either sections identified as "prescriptive" or the performance approach in Section R405 .
A permanent certificate shall be completed and posted on or in the electrical distribution panel by the builder or registered design professional. The certificate shall not cover or obstruct the visibility of the circuit directory label, service disconnect label or other required labels. The certificate shall list the predominant R-values of insulation installed in or on ceiling/roof, walls, foundation (slab, basement wall, crawlspace wall and/or floor) and ducts outside conditioned spaces; U-factors for fenestration and the solar heat gain coefficient (SHGC) of fenestration, and the results from any required duct system and building envelope air leakage testing done on the building. Where there is more than one value for each component, the certificate shall list the value covering the largest area. The certificate shall list the types and efficiencies of heating, cooling and service water heating equipment. Where a gas-fired unvented room heater, electric furnace, or baseboard electric heater is installed in the residence, the certificate shall list "gas-fired unvented room heater," "electric furnace" or "baseboard electric heater," as appropriate. An efficiency shall not be listed for gas-fired unvented room heaters, electric furnaces or electric baseboard heaters.
The building thermal envelope shall meet the requirements of Table R402.1.1 based on the climate zone specified in Chapter 3 .
|3||0.35||0.55||0.25||38||20 or 13+5h||8/13||19||5/13f||0||5/13|
|4 except Marine||0.35||0.55||0.40||49||20 or 13+5h||8/13||19||10/13||10, 2 ft||10/13|
|5 and Marine 4||0.32||0.55||NR||49||20 or 13+5h||13/17||30g||15/19||10, 2 ft||15/19|
|6||0.32||0.55||NR||49||20+5 or 13+10h||15/20||30g||15/19||10, 4 ft||15/19|
|7 and 8||>0.32||0.55||NR||49||20+5 or 13+10h||19/21||38g||15/19||10, 4 ft||15/19|
For SI: 1 foot = 304.8 mm.
- R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity which is less than the label or design thickness of the insulation, the installed R-value of the insulation shall not be less than the R-value specified in the table.
- The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration. Exception: Skylights may be excluded from glazed fenestration SHGC requirements in Climate Zones 1 through 3 where the SHGC for such skylights does not exceed 0.30.
- "15/19" means R-15 continuous insulation on the interior or exterior of the home or R-19 cavity insulation at the interior of the basement wall. "15/19" shall be permitted to be met with R-13 cavity insulation on the interior of the basement wall plus R-5 continuous insulation on the interior or exterior of the home. "10/13" means R-10 continuous insulation on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall.
- R-5 shall be added to the required slab edge R-values for heated slabs. Insulation depth shall be the depth of the footing or 2 feet, whichever is less in Climate Zones 1 through 3 for heated slabs.
- There are no SHGC requirements in the Marine Zone.
- Basement wall insulation is not required in warm-humid locations as defined by Figure R301.1 and Table R301.1.
- Or insulation sufficient to fill the framing cavity, R-19 minimum.
- First value is cavity insulation, second is continuous insulation or insulated siding, so "13+5" means R-13 cavity insulation plus R-5 continuous insulation or insulated siding. If structural sheathing covers 40 percent or less of the exterior, continuous insulation R-value shall be permitted to be reduced by no more than R-3 in the locations where structural sheathing is used — to maintain a consistent total sheathing thickness.
- The second R-value applies when more than half the insulation is on the interior of the mass wall.
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 R402.1.3 shall be permitted as an alternative to the R-value in Table R402.1.1.
|MASS WALL |
|4 except Marine||0.35||0.55||0.026||0.057||0.098||0.047||0.059||0.065|
|5 and Marine 4||0.32||0.55||0.026||0.057||0.082||0.033||0.050||0.055|
|7 and 8||0.32||0.55||0.026||0.048||0.057||0.028||0.050||0.055|
- 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 Climate Zone 1, 0.14 in Climate Zone 2, 0.12 in Climate Zone 3, 0.087 in Climate Zone 4 except Marine, 0.065 in Climate Zone 5 and Marine 4, and 0.057 in Climate Zones 6 through 8.
- Basement wall U-factor of 0.360 in warm-humid locations as defined by Figure R301.1 and Table R301.1.
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 R402.1.3 (multiplied by the same assembly area as in the proposed building), the building shall be considered in compliance with Table R402.1.1. 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 R402.1.1 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 R402.1.3 and the total UA alternative in Section R402.1.4.
Where Section R402.1.1 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 R402.1.1 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 R402.1.3 and the total UA alternative in Section R402.1.4.
For air permeable insulations in vented attics, a baffle shall be installed adjacent to soffit and eave vents. Baffles shall maintain an opening equal or greater than the size of the vent. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material.
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 R402.2.6 or shall meet the U-factor requirements of Table R402.1.3. The calculation of the U-factor for a steel-frame envelope assembly shall use a series-parallel path calculation method.
|WOOD FRAME |
|COLD-FORMED STEEL |
|Steel Truss Ceilingsb|
|R-30||R-38 or R-30 + 3 or R-26 + 5|
|R-38||R-49 or R-38 + 3|
|R-49||R-38 + 5|
|Steel Joist Ceilingsb|
|R-30||R-38 in 2 × 4 or 2 × 6 or 2 × 8 R-49 |
in any framing
|R-38||R-49 in 2 × 4 or 2 × 6 or 2 × 8 or 2 × 10|
|Steel-Framed Wall 16" O.C.|
|R-13||R-13 + 4.2 or R-19 + 2.1 or R-21 + 2.8 or |
R-0 + 9.3 or R-15 + 3.8 or R-21 + 3.1
|R-13 + 3||R-0 + 11.2 or R-13 + 6.1 or R-15 + 5.7 or |
R-19 + 5.0 or R-21 + 4.7
|R-20||R-0 + 14.0 or R-13 + 8.9 or R-15 + 8.5 or |
R-19 + 7.8 or R-19 + 6.2 or R-21 + 7.5
|R-20 + 5||R-13 + 12.7 or R-15 + 12.3 or R-19 + 11.6 or |
R-21 + 11.3 or R-25 + 10.9
|R-21||R-0 + 14.6 or R-13 + 9.5 or R-15 + 9.1 or |
R-19 + 8.4 or R-21 + 8.1 or R-25 + 7.7
|Steel Framed Wall, 24" O.C|
|R-13||R-0 + 9.3 or R-13 + 3.0 or R-15 + 2.4|
|R-13 + 3||R-0 + 11.2 or R-13 + 4.9 or R-15 + 4.3 or |
R-19 + 3.5 or R-21 + 3.1
|R-20||R-0 + 14.0 or R-13 + 7.7 or R-15 + 7.1 or |
R-19 + 6.3 or R-21 + 5.9
|R-20 + 5||R-13 + 11.5 or R-15 + 10.9 or R-19 + 10.1 or |
R-21 + 9.7 or R-25 + 9.1
|R-21||R-0 + 14.6 or R-13 + 8.3 or R-15 + 7.7 or |
R-19 + 6.9 or R-21 + 6.5 or R-25 + 5.9
|Steel Joist Floor|
|R-13||R-19 in 2 × 6, or R-19 + 6 in 2 × 8 or 2 × 10|
|R-19||R-19 + 6 in 2 × 6, or R-19 + 12 in 2 × 8 or 2 × 10|
- 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 R402.1.1 and R402.2.7.
Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table R402.1.1. 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 R402.1.1 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 or International Residential Code, as applicable. All joints of the vapor retarder shall overlap by 6 inches (153 mm) and be sealed or taped. The edges of the vapor retarder shall extend 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.
All sunrooms enclosing conditioned space shall meet the insulation requirements of this code.
Exception: For sunrooms with thermal isolation, and enclosing conditioned space, the following exceptions to the insulation requirements of this code shall apply:
- The minimum ceiling insulation R-values shall be R-19 in Climate Zones 1 through 4 and R-24 in Climate Zones 5 through 8; and
- The minimum wall R-value shall be R-13 in all climate zones. Wall(s) separating a sunroom with a thermal isolation from conditioned space shall meet the building thermal envelope requirements of this code.
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.
All sunrooms enclosing conditioned space shall meet the fenestration requirements of this code.
Exception: For sunrooms with thermal isolation and enclosing conditioned space, in Climate Zones 4 through 8, the following exceptions to the fenestration requirements of this code shall apply:
The components of the building thermal envelope as listed in Table R402.4.1.1 shall be installed in accordance with the manufacturer's instructions and the criteria listed in Table R402.4.1.1, as applicable to the method of construction. Where required by the code official, an approved third party shall inspect all components and verify compliance.
|Air barrier and thermal barrier||A continuous air barrier shall be installed in the building envelope.|
Exterior thermal envelope contains a continuous air barrier.
Breaks or joints in the air barrier shall be sealed.
Air-permeable insulation shall not be used as a sealing material.
|Ceiling/attic||The air barrier in any dropped ceiling/soffit shall be aligned with the insulation and any gaps in the air barrier sealed.|
Access openings, drop down stair or knee wall doors to unconditioned attic spaces shall be sealed.
|Walls||Corners and headers shall be insulated and the junction of the foundation and sill plate shall be sealed.|
The junction of the top plate and top of exterior walls shall be sealed.
Exterior thermal envelope insulation for framed walls shall be installed in substantial contact and continuous alignment with the air barrier.
Knee walls shall be sealed.
|Windows, skylights and doors||The space between window/door jambs and framing and skylights and framing shall be sealed.|
|Rim joists||Rim joists shall be insulated and include the air barrier.|
(including above-garage and cantilevered floors)
|Insulation shall be installed to maintain permanent contact with underside of subfloor decking.|
The air barrier shall be installed at any exposed edge of insulation.
|Crawl space walls||Where provided in lieu of floor insulation, insulation shall be permanently attached to the crawlspace walls.|
Exposed earth in unvented crawl spaces shall be covered with a Class I vapor retarder with overlapping joints taped.
|Shafts, penetrations||Duct shafts, utility penetrations, and flue shafts opening to exterior or unconditioned space shall be sealed.|
|Narrow cavities||Batts in narrow cavities shall be cut to fit, or narrow cavities shall be filled by insulation that on installation readily conforms to the available cavity space.|
|Garage separation||Air sealing shall be provided between the garage and conditioned spaces.|
|Recessed lighting||Recessed light fixtures installed in the building thermal envelope shall be air tight, IC rated, and sealed to the drywall.|
|Plumbing and wiring||Batt insulation shall be cut neatly to fit around wiring and plumbing in exterior walls, or insulation that on installation readily conforms to available space shall extend behind piping and wiring.|
|Shower/tub on exterior wall||Exterior walls adjacent to showers and tubs shall be insulated and the air barrier installed separating them from the showers and tubs.|
|Electrical/phone box on exterior walls||The air barrier shall be installed behind electrical or communication boxes or air sealed boxes shall be installed.|
|HVAC register boots||HVAC register boots that penetrate building thermal envelope shall be sealed to the subfloor or drywall.|
|Fireplace||An air barrier shall be installed on fireplace walls. Fireplaces shall have gasketed doors.|
a. In addition, inspection of log walls shall be in accordance with the provisions of ICC-400.
The building or dwelling unit shall be tested and verified as having an air leakage rate of not exceeding 5 air changes per hour in Climate Zones 1 and 2, and 3 air changes per hour in Climate Zones 3 through 8. Testing shall be conducted with a blower door at a pressure of 0.2 inches w.g. (50 Pascals). Where required by the code official, testing shall be conducted by an approved third party. A written report of the results of the test shall be signed by the party conducting the test and provided to the code official. Testing shall be performed at any time after creation of all penetrations of the building thermal envelope.
- Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed, beyond the intended weatherstripping or other infiltration control measures;
- Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed, but not sealed beyond intended infiltration control measures;
- Interior doors, if installed at the time of the test, shall be open;
- Exterior doors for continuous ventilation systems and heat recovery ventilators shall be closed and sealed;
- Heating and cooling systems, if installed at the time of the test, shall be turned off; and
- Supply and return registers, if installed at the time of the test, shall be fully open.
New wood-burning fireplaces shall have tight-fitting flue dampers 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.
Exception: 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 having an air leakage rate not more than 2.0 cfm (0.944 L/s) when tested in accordance with ASTM E 283 at a 1.57 psf (75 Pa) pressure differential. All recessed luminaires shall be sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.
The area-weighted average maximum fenestration U-factor permitted using tradeoffs from Section R402.1.4 or R405 shall be 0.48 in Climate Zones 4 and 5 and 0.40 in Climate Zones 6 through 8 for vertical fenestration, and 0.75 in Climate Zones 4 through 8 for skylights. The area-weighted average maximum fenestration SHGC permitted using tradeoffs from Section R405 in Climate Zones 1 through 3 shall be 0.50.
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.
Ducts, air handlers, and filter boxes shall be sealed. Joints and seams shall comply with either the International Mechanical Code or International Residential Code, as applicable.
- Air-impermeable spray foam products shall be permitted to be applied without additional joint seals.
- Where a duct connection is made that is partially inaccessible, three screws or rivets shall be equally spaced on the exposed portion of the joint so as to prevent a hinge effect.
- Continuously welded and locking-type longitudinal joints and seams in ducts operating at static pressures less than 2 inches of water column (500 Pa) pressure classification shall not require additional closure systems.
Duct tightness shall be verified by either of the following:
- Postconstruction test: Total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (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 4 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the system, including the manufacturer's air handler enclosure. All registers 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 3 cfm (85 L/min) per 100 square feet (9.29 m2) of conditioned floor area.
Air handlers shall have a manufacturer's designation for an air leakage of no more than 2 percent of the design air flow rate when tested in accordance with ASHRAE 193.
Building framing cavities shall not be used as ducts or plenums.
Mechanical system piping capable of carrying fluids above 105°F (41°C) or below 55°F (13°C) shall be insulated to a minimum of R-3.
Piping insulation exposed to weather shall be protected from damage, including that caused by sunlight, moisture, equipment maintenance, and wind, and shall provide shielding from solar radiation that can cause degradation of the material. Adhesive tape shall not be permitted.
Insulation for hot water pipe with a minimum thermal resistance (R-value) of R-3 shall be applied to the following:
- Piping larger than 3/4 inch nominal diameter.
- Piping serving more than one dwelling unit.
- Piping from the water heater to kitchen outlets.
- Piping located outside the conditioned space.
- Piping from the water heater to a distribution manifold.
- Piping located under a floor slab.
- Buried piping.
- Supply and return piping in recirculation systems other than demand recirculation systems.
- Piping with run lengths greater than the maximum run lengths for the nominal pipe diameter given in Table R403.4.2.
All remaining piping shall be insulated to at least R-3 or meet the run length requirements of Table R403.4.2.
|Nominal Pipe Diameter of Largest Diameter Pipe in the Run (inch)||3/8||1/2||3/4||> 3/4|
|Maximum Run Length||30||20||10||5|
For SI: 1 inch = 25.4 mm, 1 foot 304.8 mm.
a. Total length of all piping from the distribution manifold or the recirculation loop to a point of use.
The building shall be provided with ventilation that meets the requirements of the International Residential Code or International Mechanical Code, as applicable, or with other approved means of ventilation. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.
When installed to function as a whole house mechanical ventilation system, fans shall meet the efficacy requirements of Table R403.5.1.
Exception: Where whole-house mechanical ventilation fans are integral to tested and listed HVAC equipment, they shall be powered by an electronically commutated motor.
|FAN LOCATION||AIR FLOW RATE MINIMUM
|AIR FLOW RATE MAXIMUM
|Range hoods||Any||2.8 cfm/watt||Any|
|In-line fan||Any||2.8 cfm/watt||Any|
|Bathroom, utility room||10||1.4 cfm/watt||< 90|
|Bathroom, utility room||90||2.8 cfm/watt||Any|
|For SI: 1 cfm = 28.3 L/min.|
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 heaters shall be equipped with a readily accessible on-off switch that is mounted outside of the heater to allow shutting off the heater without adjusting the thermostat setting. Gas-fired heaters shall not be equipped with constant burning pilot lights.
Time switches or other control method that can automatically turn off and on heaters and pumps according to a preset schedule shall be installed on all heaters and pumps. Heaters, pumps and motors that have built in timers shall be deemed in compliance with this requirement.
- 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 and inground permanently installed spas shall be provided with a vapor-retardant cover.
Exception: Pools deriving over 70 percent of the energy for heating from site-recovered energy, such as a heat pump or solar energy source computed over an operating season.
A minimum of 75 percent of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps or a minimum of 75 percent of the permanently installed lighting fixtures shall contain only high efficacy lamps.
Exception: Low-voltage lighting shall not be required to utilize high-efficiency lamps.
Fuel gas lighting systems shall not have continuously burning pilot lights.
This section establishes criteria for compliance using simulated energy performance analysis. Such analysis shall include heating, cooling, and service water heating energy only.
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 R405.3. 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 R405.5.2(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 R405.5.2(1).
- Documentation of the actual values used in the software calculations for the proposed design.
The standard reference design and proposed design shall be configured and analyzed as specified by Table R405.5.2(1). Table R405.5.2(1) shall include by reference all notes contained in Table R402.1.1.
|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 R402.1.3
Solar absorptance = 0.75
Remittance = 0.90
|Basement and crawl space walls||Type: same as proposed
Gross area: same as proposed
U-factor: from Table R402.1.3, with insulation layer on interior side of walls.
|Above-grade floors||Type: wood frame
Gross area: same as proposed
U-factor: from Table R402.1.3
|Ceilings||Type: wood frame
Gross area: same as proposed
U-factor: from Table R402.1.3
|Roofs||Type: composition shingle on wood sheathing
Gross area: same as proposed
Solar absorptance = 0.75
Emittance = 0.90
|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
|Doors||Area: 40 ft2
U-factor: same as fenestration from Table R402.1.3.
|Glazinga||Total areab =
(a) The proposed glazing area; where proposed glazing area is less than 15% of the conditioned floor area.
(b) 15% of the conditioned floor area; where the proposed glazing 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 R402.1.3||As proposed|
|SHGC: From Table R402.1.1 except that for climates with no requirement (NR) SHGC = 0.40 shall be used.
Interior shade fraction: 0.92-(0.21 × SHGC for the standard reference design)
External shading: none
0.92-(0.21 × SHGC as proposed)
|Thermally isolated sunrooms||None||As proposed|
|Air exchange rate||Air leakage rate of 5 air changes per hour in Climate Zones 1 and 2, and 3 air changes per hour in Climate Zones 3 through 8 at a pressure of 0.2 inches w.g (50 Pa). The mechanical ventilation rate shall be in addition to the air leakage rate and the same as in the proposed design,
but no greater than 0.01 × CFA + 7.5 × (Nbr + 1)
CFA = conditioned floor area
Nbr = number of bedrooms
Energy recovery shall not be assumed for mechanical ventilation.
|For residences that are not tested, the same air leakage rate as the standard reference design. For tested residences, the measured air exchange ratec. The mechanical ventilation rated shall be in addition to the air leakage rate and shall be as proposed.|
|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)
CFA = conditioned floor area
Nbr = number of bedrooms
|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 elemente 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 R402.1.3 located on the interior side of the walls
For other walls, for ceilings, floors, and interior walls, wood frame construction
|Heating systemsf, g||As proposed for other than electric heating without a heat pump. Where the proposed design utilizes electric heating without a heat pump the standard reference design shall be an air source heat pump meeting the requirements of Section R403 of the IECC—Commercial Provisions.
Capacity: sized in accordance with Section R403.6
|Cooling systemsf, h||As proposed
Capacity: sized in accordance with Section R403.6.
Heatingf, g, h, i
Use: same as proposed design
gal/day = 30 + (10 × Nbr )
|Thermal distribution systems||Thermal distribution system efficiency shall be as tested or as specified in Table R405.5.2(2) if not tested. Duct insulation shall be as proposed.|
|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.
Thermal boundary wall is any wall that separates conditioned space from unconditioned space or ambient conditions.
Above-grade thermal boundary wall is any thermal boundary wall component not in contact with soil.
Below-grade boundary wall is any thermal boundary wall in soil contact.
Common wall area is the area of walls shared with an adjoining dwelling unit.
L and CFA are in the same units.
- Where required by the code official, testing shall be conducted by an approved party. Hourly calculations as specified in the ASHRAE Handbook of Fundamentals, or the equivalent shall be used to determine the energy loads resulting from infiltration.
- 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 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|
For SI: 1 cubic foot per minute = 0.47 L/s, 1 square foot = 0.093m2, 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 R403.6.
- 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 R405.5.2(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 R405 shall be permitted to be approved. Tools are permitted to be approved based on meeting a specified threshold for a jurisdiction. The code official shall be permitted to approve tools for a specified application or limited scope