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Chapter 4 [RE] Residential Energy Efficiency

Section R401 General

R401.1 Scope

This chapter applies to residential buildings.

R401.2 Compliance

Projects shall comply with one of the following:
  1. Sections R401 through R404.
  2. Section R405 and the provisions of Sections R401 through R404 labeled "Mandatory."
  3. In addition, dwelling units and sleeping units in a residential building shall comply with Section R406.

R401.3 Certificate (Mandatory)

A permanent certificate shall be completed by the builder or registered design professional and posted on a wall in the space where the furnace is located, a utility room, or an approved location inside the building. When located on an electrical panel, the certificate shall not cover or obstruct the visibility of the circuit directory label, service disconnect label, or other required labels. The certificate shall list the predominant R-values of insulation installed in or on ceiling/roof, walls, foundation (slab, below-grade 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.

Section R402 Building Thermal Envelope

R402.1 General (Prescriptive)

The building thermal envelope shall meet the requirements of Sections R402.1.1 through R402.1.5.

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

R402.1.1 Vapor Retarder

The building thermal envelope shall meet the requirements of Table R402.1.1 based on the climate zone specified in Chapter 3.

TABLE R402.1.1
INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENTa

CLIMATE ZONE 5 AND MARINE 4
FENESTRATION U-FACTORb 0.30
SKYLIGHTb U-FACTOR 0.50
GLAZED FENESTRATION SHGCb, e NR
CEILING R-VALUEk 49
WOOD FRAME WALLg, m,n R-VALUE 21 int
Mass Wall R-Valuei 21/21
FLOOR R-VALUE 30
BELOW-GRADEc,mWALL R-VALUE 10/15/21 int + TB
SLABd R-VALUE & DEPTH 10, 2 ft

For SI: 1 foot = 304.8 mm, ci = continuous insulation, int = intermediate framing.
a   R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity which is less than the label or design thickness of the insulation, the compressed R-value of the insulation from Appendix Table A101.4 shall not be less than the R-value specified in the table.
b   The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.
c   "10/15/21 +TB" means R-10 continuous insulation on the exterior of the wall, or R-15 continuous insulation on the interior of the wall, or R-21 cavity insulation plus a thermal break between the slab and the basement wall at the interior of the basement wall. "10/15/21 +TB" 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 wall. "TB" means thermal break between floor slab and basement wall.
d   R-10 continuous insulation is required under heated slab on grade floors. See R402.2.9.1.
e   There are no SHGC requirements in the Marine Zone.
f   Reserved.
g   Reserved.
h   Reserved.
i   The second R-value applies when more than half the insulation is on the interior of the mass wall.
j   Reserved.
k   For single rafter- or joist-vaulted ceilings, the insulation may be reduced to R-38.
l   Reserved.
m   Int. (intermediate framing) denotes standard framing 16 inches on center with headers insulated with a minimum of R-10 insulation.
n   Log and solid timber walls with a minimum average thickness of 3.5 inches are exempt from this insulation requirement.

R402.1.2 R-Value Computation

Insulation material used in layers, such as framing cavity insulation or continuous insulation, shall be summed to compute the corresponding component R-value. The manufacturer's settled R-value shall be used for blown insulation. Computed R-values shall not include an R-value for other building materials or air films. Where insulated siding is used for the purpose of complying with the continuous insulation requirements of Table R402.1.1, the manufacturer must supply an ICC Report that the R-factor has been certified, or use R-5 per inch for extruded polystyrene, and R-6 per inch for polyisocyanurate rigid insulation.

R402.1.3 U-factor Alternative

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.

TABLE R402.1.3
EQUIVALENT U-FACTORSa

CLIMATE ZONE 5 AND MARINE 4
FENESTRATION U-FACTOR 0.30
SKYLIGHT U-FACTOR 0.50
CEILING U-FACTOR 0.026
WOOD FRAME WALL U-FACTOR 0.056
Mass Wall U-FACTOR 0.056
FLOOR U-FACTOR 0.029
BELOW-GRADE WALL U-FACTOR 0.042

a Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source or as specified in Section R402.1.3.

b Reserved.
c Reserved.

R402.1.4 Total UA Alternative

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 U-factors for typical construction assemblies are included in Appendix A in chapter 51-11C WAC. These values shall be used for all calculations. Where proposed construction assemblies are not represented in Appendix A, values shall be calculated in accordance with the ASHRAE Handbook of Fundamentals using the framing factors listed in Appendix A where applicable and shall include the thermal bridging effects of framing materials. The SHGC requirements shall be met in addition to UA compliance. When using REScheck, the U-factors calculated by the software based on component R-value descriptions are acceptable. For the base building UA calculation, the maximum glazing area is 15% of the floor area.

R402.1.5 Vapor Retarder

Wall assemblies in the building thermal envelope shall comply with the vapor retarder requirements of Section R702.7 of the International Residential Code or Section 1405.3 of the International Building Code, as applicable.

R402.2 Specific Insulation Requirements (Prescriptive)

In addition to the requirements of Section R402.1, insulation shall meet the specific requirements of Sections R402.2.1 through R402.2.11.

R402.2.1 Ceilings With Attic Spaces

Where Section R402.1.1 would require R-49 in the ceiling, installing R-38 over 100 percent of the ceiling area requiring insulation shall be deemed to satisfy the requirement for R-49 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.

R402.2.1.1 Loose Insulation in Attic Spaces

Open-blown or poured loose fill insulation may be used in attic spaces where the slope of the ceiling is not more than 3 feet in 12 and there is at least 30 inches of clear distance from the top of the bottom chord of the truss or ceiling joist to the underside of the sheathing at the roof ridge.

R402.2.2 Reserved

R402.2.3 Eave Baffle

For air permeable insulations in vented attics, a baffle shall be installed adjacent to soffit and eave vents. Baffles shall maintain an opening equal or greater than the size of the vent. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material.

R402.2.4 Access Hatches and Doors

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.

Exception: Vertical doors that provide access from conditioned to unconditioned spaces shall be permitted to meet the fenestration requirements of Table R402.1.1.

R402.2.5 Mass Walls

Mass walls for the purposes of this chapter shall be considered above-grade walls of concrete block, concrete, insulated concrete form (ICF), masonry cavity, brick (other than brick veneer), earth (adobe, compressed earth block, rammed earth) and solid timber/logs, or any other walls having a heat capacity greater than or equal to 8 Btu/ft2 × °F (123 kJ/m3 × K).

R402.2.6 Steel-Frame Ceilings, Walls and Floors

Steel-frame ceilings, walls, and floors shall meet the U-factor requirements of Table R402.1.3.

R402.2.7 Floors

Floor framing cavity insulation shall be installed to maintain permanent contact with the underside of the subfloor decking. Insulation supports shall be installed so spacing is no more than 24-inches on center. Foundation vents shall be placed so that the top of the vent is below the lower surface of the floor insulation.

Exceptions:
  1. The floor framing cavity insulation shall be permitted to be in contact with the topside of sheathing or continuous insulation installed on the bottom side of floor framing where combined with insulation that meets or exceeds the minimum Wood Frame R-value in Table R402.1.1 and extends from the bottom to the top of all perimeter floor framing members.
  2. When foundation vents are not placed so that the top of the vent is below the lower surface of the floor insulation, a permanently attached baffle shall be installed at an angle of 30° from horizontal, to divert air flow below the lower surface of the floor insulation.
  3. Substantial contact with the surface being insulated is not required in enclosed floor/ceiling assemblies containing ducts where full R-value insulation is installed between the duct and the exterior surface.

R402.2.8 Below-Grade Walls

Below-grade exterior wall insulation used on the exterior (cold) side of the wall shall extend from the top of the below-grade wall to the top of the footing and shall be approved for below-grade use. Above-grade insulation shall be protected. Insulation used on the interior (warm) side of the wall shall extend from the top of the below-grade wall to the below-grade floor level and shall include R-5 rigid board providing a thermal break between the concrete wall and the slab.

R402.2.9 Slab-on-Grade Floors

The minimum thermal resistance (R-value) of the insulation around the perimeter of unheated or heated slab-on-grade floors shall be as specified in Table R402.1.1. The insulation shall be placed on the outside of the foundation or on the inside of the foundation wall. The insulation shall extend downward from the top of the slab for a minimum distance as shown in the table or to the top of the footing, whichever is less, or downward to at least the bottom of the slab and then horizontally to the interior or exterior for the total distance shown in the table. A two-inch by two-inch (maximum) pressure treated nailer may be placed at the finished floor elevation for attachment of interior finish materials. Insulation extending away from the building shall be protected by pavement or by a minimum of 10 inches (254 mm) of soil.

R402.2.9.1 Heated Slab-on-Grade Floors (Mandatory)

The entire area of a heated slab-on-grade floor shall be thermally isolated from the soil with a minimum of R-10 insulation. The insulation shall be an approved product for its intended use. If a soil gas control system is present below the heated slab-on-grade floor, which results in increased convective flow below the heated slab-on-grade floor, the heated slab-on-grade floor shall be thermally isolated from the sub-slab gravel layer. R-10 heated slab-on-grade floor insulation is required for all compliance paths.

R402.2.10 Reserved

R402.2.11 Masonry Veneer

Insulation shall not be required on the horizontal portion of the foundation that supports a masonry veneer.

R402.3 Fenestration (Prescriptive)

In addition to the requirements of Section R402, fenestration shall comply with Sections R402.3.1 through R402.3.5.

R402.3.1 U-factor

An area-weighted average of fenestration products shall be permitted to satisfy the U-factor requirements.

R402.3.2 Glazed Fenestration SHGC

An area-weighted average of fenestration products more than 50 percent glazed shall be permitted to satisfy the SHGC requirements.

R402.3.3 Glazed Fenestration Exemption

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 R402.1.1. This exemption shall not apply to the U-factor alternative approach in Section R402.1.3 and the total UA alternative in Section R402.1.4.

R402.3.4 Opaque Door Exemption

One side-hinged opaque door assembly up to 24 square feet (2.22 m2) in area is exempted from the U-factor requirement in Section R402.1.1. This exemption shall not apply to the U-factor alternative approach in Section R402.1.3 and the total UA alternative in Section R402.1.4.

R402.3.5 Reserved

R402.4 Air Leakage (Mandatory)

The building thermal envelope shall be constructed to limit air leakage in accordance with the requirements of Sections R402.4.1 through R402.4.5.

R402.4.1 Building Thermal Envelope

The building thermal envelope shall comply with Sections R402.4.1.1 and R402.4.1.2. The sealing methods between dissimilar materials shall allow for differential expansion and contraction.

R402.4.1.1 Installation

The components of the building thermal envelope as listed in Table R402.4.1.1 shall be installed in accordance with the manufacturer's instructions and the criteria listed in Table R402.4.1.1, as applicable to the method of construction. Where required by the code official, an approved third party shall inspect all components and verify compliance.

TABLE R402.4.1.1 AIR BARRIER AND INSULATION INSTALLATION

COMPONENT AIR BARRIER CRITERIAa INSULATION CRITERIAa
General Requirements 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.
Cavity insulation installation   All cavities in the thermal envelope shall be filled with insulation. The density of the insulation shall be at the manufacturers' product recommendation and said density shall be maintained for all volume of each cavity. Batt type insulation will show no voids or gaps and maintain an even density for the entire cavity. Batt insulation shall be installed in the recommended cavity depth. Where an obstruction in the cavity due to services, blocking, bracing or other obstruction exists, the batt product will be cut to fit the remaining depth of the cavity. Where the batt is cut around obstructions, loose fill insulation shall be placed to fill any surface or concealed voids, and at the manufacturers' specified density. Where faced batt is used, the installation tabs must be stapled to the face of the stud. There shall be no compression to the batt at the edges of the cavity due to inset stapling installation tabs.

Insulation that upon installation readily conforms to available space shall be installed filling the entire cavity and within the manufacturers' density recommendation.
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.		 The insulation in any dropped ceiling/soffit shall be aligned with the air barrier.
Batt insulation installed in attic roof assemblies may be compressed at exterior wall lines to allow for required attic ventilation.
Walls 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.
Knee walls shall be sealed.		 Cavities within corners and headers of frame
walls shall be insulated by completely filling the
cavity with a material having a thermal resistance
of R-3 per inch minimum.
Exterior thermal envelope insulation for framed
walls shall be installed in substantial contact and
continuous alignment with the air barrier.
Windows, skylights and doors The space between window/door jambs and framing
and skylights and framing shall be sealed.
Rim Joists Rim joists shall include the air barrier. Rim joists shall be insulated.
Floors (including above garage and
cantilevered floors)		 The air barrier shall be installed at any exposed edge
of insulation.		 Floor framing cavity insulation shall be installed
to maintain permanent contact with the underside
of subfloor decking or floor framing cavity
insulation shall be permitted to be in contact with
the top side of sheathing or continuous insulation
installed on the underside of floor framing and
extend from the bottom to the top of all
perimeter floor framing members.
Crawl space walls Exposed earth in unvented crawl spaces shall be
covered with a Class I, black vapor retarder with
overlapping joints taped.		 Where provided instead of floor insulation,
insulation shall be permanently attached to the
crawlspace walls.
Shafts, penetrations Duct shafts, utility penetrations, and flue shafts
opening to exterior or unconditioned space shall be
sealed.
Narrow cavities Batts in narrow cavities shall be cut to fit and installed to the correct density without any voids or gaps or compression, or
narrow cavities shall be filled by insulation that
on installation readily conforms to the available
cavity space.
Garage separation Air sealing shall be provided between the garage and
conditioned spaces.
Recessed lighting Recessed light fixtures installed in the building
thermal envelope shall be sealed to the drywall.		 Recessed light fixtures installed in the building
thermal envelope shall be air tight and IC rated.
Plumbing and wiring Batt insulation shall be cut neatly to fit around
wiring and plumbing in exterior walls. There shall be no voids or gaps or compression where cut to fit.
Insulation that on installation readily conforms to
available space shall extend behind piping and
wiring.
Shower/tub on exterior wall The air barrier installed at exterior walls adjacent to
showers and tubs shall separate them from the
showers and tubs.		 Exterior walls adjacent to showers and tubs shall
be insulated.
Electrical/phone box on exterior wall The air barrier shall be installed behind electrical or
communication boxes or air-sealed boxes shall be
installed.
HVAC register boots HVAC register boots that penetrate building thermal
envelope shall be sealed to the subfloor or drywall.
Concealed sprinklers When required to be sealed, concealed fire sprinklers
shall only be sealed in a manner that is recommended
by the manufacturer. Caulking or other adhesive
sealants shall not be used to fill voids between fire
sprinkler cover plates and walls or ceilings.

IC = insulation contact

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

R402.4.1.2 Testing

The building or dwelling unit shall be tested and verified as having an air leakage rate of not exceeding 5 air changes per hour. 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. Once visual inspection has confirmed sealing (see Table R402.4.1.1), operable windows and doors manufactured by small business shall be permitted to be sealed off at the frame prior to the test.

During testing:
  1. Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed, beyond the intended weatherstripping or other infiltration control measures;
  2. Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed, but not sealed beyond intended infiltration control measures;
  3. Interior doors, if installed at the time of the test, shall be open, access hatches to conditioned crawl spaces and conditioned attics shall be open;
  4. Exterior openings for continuous ventilation systems and heat recovery ventilators shall be closed and sealed;
  5. Heating and cooling systems, if installed at the time of the test, shall be turned off; and
  6. Supply and return registers, if installed at the time of the test, shall be fully open.
Exceptions:
  1. Additions less than 500 square feet of conditioned floor area.
  2. Additions tested with the existing home having a combined maximum air leakage rate of 7 air changes per hour. To qualify for this exception, the date of construction of the existing house must be prior to the 2009 Washington State Energy Code.

R402.4.2 Fireplaces

New wood-burning fireplaces shall have tight-fitting flue dampers or doors and outdoor combustion air. When using tight-fitting doors on factory-built fireplaces listed and labeled in accordance with UL 127, the doors shall be tested and listed for the fireplace. Where using tight-fitting doors on masonry fireplaces, the doors shall be listed and labeled in accordance with UL 907.

R402.4.3 Air Leakage of Fenestration Air Leakage

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:
  1. Field-fabricated fenestration products (windows, skylights and doors).
  2. Custom exterior fenestration products manufactured by a small business provided they meet the applicable provisions of Chapter 24 of the International Building Code. Once visual inspection has confirmed the presence of a gasket, operable windows and doors manufactured by small business shall be permitted to be sealed off at the frame prior to the test.

R402.4.4 Rooms Containing Fuel-Burning Appliances Combustion Air Openings

Where open combustion air ducts provide combustion air to open combustion, space conditioning fuel burning appliances, the appliances and combustion air openings shall be located outside of the building thermal envelope, or enclosed in a room isolated from inside the thermal envelope. Such rooms shall be sealed and insulated in accordance with the envelope requirements of Table R402.1.1, where the walls, floors and ceilings shall meet the minimum of the below-grade wall R-value requirement. The door into the room shall be fully gasketed and any water lines and ducts in the room insulated in accordance with Section R403. The combustion air duct shall be insulated where it passes through conditioned space to a minimum of R-8.
Exceptions:
  1. Direct vent appliances with both intake and exhaust pipes installed continuous to the outside.
  2. Fireplaces and stoves complying with Section R402.4.2 and Section R1006 of the International Residential Code.

R402.4.5 Recessed Lighting

Recessed luminaires installed in the building thermal envelope shall be Type IC-rated and certified under ASTM E283 as having an air leakage rate not more than 2.0 cfm (0.944 L/s) when tested at a 1.57 psf (75 Pa) pressure differential and shall have a label attached showing compliance with this test method. All recessed luminaires shall be sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.

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

The area-weighted average maximum fenestration U-factor permitted using tradeoffs from Section R402.1.4 or R405 shall be 0.48 for vertical fenestration, and 0.75 for skylights.

Section R403 Systems

R403.1 Controls (Mandatory)

At least one thermostat shall be provided for each separate heating and cooling system.

R403.1.1 Programmable Thermostat

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. The thermostat shall allow for, at a minimum, a 5-2 programmable schedule (weekdays/weekends) and be capable of providing at least two programmable setback periods per day. This thermostat shall include the capability to set back or temporarily operate the system to maintain zone temperatures down to 55°F (13°C) or up to 85°F (29°C). The thermostat shall initially be programmed by the manufacturer with a heating temperature set point no higher than 70°F (21°C) and a cooling temperature set point no lower than 78°F (26°C). The thermostat and/or control system shall have an adjustable deadband of not less than 10°F.
Exceptions:
  1. Systems controlled by an occupant sensor that is capable of shutting the system off when no occupant is sensed for a period of up to 30 minutes.
  2. Systems controlled solely by a manually operated timer capable of operating the system for no more than two hours.

R403.1.2 Heat Pump Supplementary Heat (Mandatory)

Unitary air cooled heat pumps shall include controls that minimize supplemental heat usage during start-up, set-up, and defrost conditions. These controls shall anticipate need for heat and use compression heating as the first stage of heat. Controls shall indicate when supplemental heating is being used through visual means (e.g., LED indicators). Heat pumps equipped with supplementary heaters shall be installed with controls that prevent supplemental heater operation above 40°F. At final inspection the auxiliary heat lock out control shall be set to 35°F or less.

R403.2 Hot Water Boiler Outdoor Temperature Setback

Hot water boilers that supply heat to the building through one- or two-pipe heating systems shall have an outdoor temperature setback control that lowers the boiler water temperature based on the outdoor temperature.

R403.3 Ducts

Ducts and air handlers shall be in accordance with Sections R403.3.1 through R403.3.5.

R403.3.1 Insulation (Prescriptive)

Ducts outside the building thermal envelope shall be insulated to a minimum of R-8. Ducts within a concrete slab or in the ground shall be insulated to R-10 with insulation designed to be used below grade.

Exception: Ducts or portions thereof located completely inside the building thermal envelope. Ducts located in crawl spaces do not qualify for this exception.

R403.3.2 Sealing (Mandatory)

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.
Exceptions:
  1. Air-impermeable spray foam products shall be permitted to be applied without additional joint seals.
  2. For ducts having a static pressure classification of less than 2 inches of water column (500 Pa), additional closure systems shall not be required for continuously welded joints and seams, and locking-type joints and seams of other than the snap-lock and button-lock types.

R403.3.2.1 Sealed Air Handler

Air handlers shall have a manufacturer's designation for an air leakage of no more than 2 percent of the design air flow rate when tested in accordance with ASHRAE 193.

R403.3.3 Duct Testing (Mandatory)

Ducts shall be leak tested in accordance with WSU RS-33, using the maximum duct leakage rates specified.
Exception: The total leakage test or leakage to the outdoors is not required for ducts and air handlers located entirely within the building thermal envelope. For forced air ducts, a maximum of 10 linear feet of return ducts and 5 linear feet of supply ducts may be located outside the conditioned space. All metallic ducts located outside the conditioned space must have both transverse and longitudinal joints sealed with mastic. If flex ducts are used, they cannot contain splices. Flex duct connections must be made with nylon straps and installed using a plastic strapping tensioning tool. Ducts located in crawl spaces do not qualify for this exception.

A written report of the results of the test shall be signed by the party conducting the test and provided to the code official.

R403.3.4 Duct Leakage (Prescriptive) (Mandatory)

The total leakage of the ducts, where measured in accordance with Section R403.3.3, shall be as follows:
  1. 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.
  2. Postconstruction test: Leakage to outdoors shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area or 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.

R403.3.5 Building Cavities (Mandatory)

Building framing cavities shall not be used as ducts or plenums. Installation of ducts in exterior walls, floors or ceilings shall not displace required envelope insulation.

R403.4 Mechanical System Piping Insulation (Mandatory)

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-6.
Exception: Up to 200 feet of hydronic system piping installed within the conditioned space may be insulated with a minimum of 1/2 -inch insulation with a k value of 0.28.

R403.4.1 Protection of Piping Insulation

Piping insulation exposed to weather shall be protected from damage, including that caused by sunlight, moisture, equipment maintenance, and wind, and shall provide shielding from solar radiation that can cause degradation of the material. Adhesive tape shall not be permitted.

R403.5 Service Hot Water Systems

Energy conservation measures for service hot water systems shall be in accordance with Sections R403.5.1 through R403.5.5.

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

Heated water circulation systems shall be in accordance with Section R403.5.1.1. Heat trace temperature maintenance systems shall be in accordance with Section R403.5.1.2. Automatic controls, temperature sensors and pumps shall be accessible. Manual controls shall be readily accessible.

R403.5.1.1 Circulation Systems

Heated water circulation systems shall be provided with a circulation pump. The system return pipe shall be a dedicated return pipe or a cold water supply pipe. Gravity and thermo-syphon circulation systems shall be prohibited. Controls for circulating hot water system pumps shall start the pump based on the identification of a demand for hot water within the occupancy. The controls shall automatically turn off the pump when the water in the circulation loop is at the desired temperature and when there is no demand for hot water.

R403.5.1.2 Heat Trace Systems

Electric heat trace systems shall comply with IEEE 515.1 or UL 515. Controls for such systems shall automatically adjust the energy input to the heat tracing to maintain the desired water temperature in the piping in accordance with the times when heated water is used in the occupancy.

R403.5.2 Demand Recirculation Systems

A water distribution system having one or more recirculation pumps that pump water from a heated water supply pipe back to the heated water source through a cold water supply pipe shall be a demand recirculation water system. Pumps shall have controls that comply with both of the following:
  1. The control shall start the pump upon receiving a signal from the action of a user of a fixture or appliance, sensing the presence of a user of a fixture or sensing the flow of hot or tempered water to a fixture fitting or appliance.
  2. The control shall limit the temperature of the water entering the cold water piping to 104°F (40°C).

R403.5.3 Hot Water Pipe Insulation (Prescriptive)

Insulation for hot water pipe, both within and outside the conditioned space, shall have a minimum thermal resistance (R-value) of R-3.
Exception: Pipe insulation is permitted to be discontinuous where it passes through studs, joists or other structural members and where the insulated pipes pass other piping, conduit or vents, provided the insulation is installed tight to each obstruction.

R403.5.4 Drain Water Heat Recovery Units

Drain water heat recovery units shall comply with CSA 55.2. Drain water heat recovery units shall be in accordance with CSA 55.1. Potable water-side pressure loss of drain water heat recovery units shall be less than 3 psi (20.7 kPa) for individual units connected to one or two showers. Potable water-side pressure loss of drain water heat recovery units shall be less than 2 psi (13.8 kPa) for individual units connected to three or more showers.

R403.5.5 Electric Water Heater Insulation

All electric water heaters in unheated spaces or on concrete floors shall be placed on an incompressible, insulated surface with a minimum thermal resistance of R-10.

R403.6 Mechanical Ventilation (Mandatory)

The building shall be provided with ventilation that meets the requirements of the International Residential Code or International Mechanical Code, as applicable, or with other approved means of ventilation. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.

R403.6.1 Whole-House Mechanical Ventilation System Fan Efficacy

Mechanical ventilation system fans shall meet the efficacy requirements of Table R403.6.1.

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


TABLE R403.6.1
MECHANICAL VENTILATION SYSTEM FAN EFFICACY

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

R403.7 Equipment Sizing and Efficiency Rating (Mandatory)

Heating and cooling equipment shall be sized in accordance with ACCA Manual S based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies. The output capacity of heating and cooling equipment shall not be greater than that of the smallest available equipment size that exceeds the loads calculated, including allowable oversizing limits. New or replacement heating and cooling equipment shall have an efficiency rating equal to or greater than the minimum required by federal law for the geographic location where the equipment is installed.

R403.7.1 Electric Resistance Zone Heated Units

All detached one- and two-family dwellings and multiple single-family dwellings (townhouses) up to three stories in height above grade plan using electric zonal heating as the primary heat source shall install an inverter-driven ductless mini-split heat pump in the largest zone in the dwelling. Building permit drawings shall specify the heating equipment type and location of the heating system.

Exception: Total installed heating capacity of 2Kw per dwelling or less.

R403.8 Systems Serving Multiple Dwelling Units (Mandatory)

Systems serving multiple dwelling units shall comply with Sections C403 and C404 of the WSEC--Commercial Provisions in lieu of Section R403.

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

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.

R403.10 Pools and Permanent Spa Energy Consumption (Mandatory)

Pools and permanent spas shall comply with Sections R403.10.1 through R403.10.4.2.

R403.10.1 Heaters

The electric power to heaters shall be controlled by a readily accessible on-off switch that is an integral part of the heater mounted on the exterior of the heater, or external to and within 3 feet (914 mm) of the heater. Operation of such switch shall not change the settings of the heater thermostat. Such switches shall be in addition to a circuit breaker for the power to the heater. Gas-fired heaters shall not be equipped with constant burning pilot lights.

R403.10.2 Time Switches

Time switches or other control method that can automatically turn off and on according to a preset schedule shall be installed for heaters and pump motors. Heaters and pump motors that have built-in time switches shall be deemed in compliance with this requirement.
Exceptions:
  1. Where public health standards require 24-hour pump operation.
  2. Pumps that operate solar- and waste-heat-recovery pool heating systems.

R403.10.3 Covers

Outdoor heated pools and outdoor permanent spas shall be provided with a vapor-retardant cover, or other approved vapor-retardant means.

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

R403.10.4 Residential Pool Pumps

Pool pump motors may not be split-phase or capacitor start-induction run type.

R403.10.4.1 Two-Speed Capability

  1. Pump motors: Pool pump motors with a capacity of 1 hp or more shall have the capability of operating at two or more speeds with low speed having a rotation rate that is no more than one-half of the motor's maximum rotation rate.
  2. Pump controls: Pool pump motor controls shall have the capability of operating the pool pump with at least two speeds. The default circulation speed shall be the lowest speed, with a high speed override capability being for a temporary period not to exceed one normal cycle.

R403.10.4.2 Pump Operation

Circulating water systems shall be controlled so that the circulation pump(s) can be conveniently turned off, automatically or manually, when the water system is not in operation.

R403.11 Portable Spas (Mandatory)

The energy consumption of electric-powered portable spas shall be controlled by the requirements of APSP-14.

R403.12 Residential Pools and Permanent Residential Spas

Residential swimming pools and permanent residential spas that are accessory to detached one- and two-family dwellings and townhouses three stories or less in height above grade plane and that are available only to the household and its guests shall be in accordance with APSP-15.

Section R404 Electrical Power and Lighting Systems

R404.1 Lighting Equipment (Mandatory)

A minimum of 75 percent of lamps in permanently installed lighting fixtures shall be high-efficacy lamps.

R404.1.1 Lighting Equipment (Mandatory)

Fuel gas lighting systems shall not have continuously burning pilot lights.

Section R405 Simulated Performance Alternative (Performance)

R405.1 Scope

This section establishes criteria for compliance using simulated energy performance analysis. Such analysis shall include heating, cooling, and service water heating energy only.

R405.2 Mandatory Requirements

Compliance with this section requires that the mandatory provisions identified in Section R401.2 be met. All supply and return ducts not completely inside the building thermal envelope shall be insulated to a minimum of R-8.

R405.3 Performance-Based Compliance

Compliance based on simulated energy performance requires that a proposed residence (proposed design) be shown to have an annual energy consumption based on site energy expressed in Btu and Btu per square foot of conditioned floor area as follows:

  1. For structures less than 1,500 square feet of conditioned floor area, the annual energy consumption shall be less than or equal to 80 percent of the annual energy consumption of the standard reference design.
  2. For structures 1,500 to 5,000 square feet of conditioned floor area, the annual energy consumption shall be no more than 72 percent of the standard reference design.
  3. For structures over 5,000 square feet of conditioned floor area, the annual energy consumption shall be no more than 66 percent of the standard reference design.
Exception: For structures serving Group R-2 occupancies, the annual energy consumption shall be less than or equal to 85 percent of the annual energy consumption of the standard reference design.

R405.4 Documentation

Documentation of the software used for the performance design and the parameters for the building shall be in accordance with Sections R405.4.1 through R405.4.3.

R405.4.1 Compliance Software Tools

Documentation verifying that the methods and accuracy of the compliance software tools conform to the provisions of this section shall be provided to the code official.

R405.4.2 Compliance Report

Compliance software tools shall generate a report that documents that the proposed design complies with Section R405.3. A compliance report on the proposed design shall be submitted with the application for the building permit. Upon completion of the building, a compliance report based on the as-built condition of the building shall be submitted to the code official before a certificate of occupancy is issued. Batch sampling of buildings to determine energy code compliance for all buildings in the batch shall be prohibited.

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

R405.4.2.1 Compliance Report for Permit Application

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

R405.4.2.2 Compliance Report for Certificate of Occupancy

A compliance report submitted for obtaining the certificate of occupancy shall include all of the following:
  1. Building street address, or other building site identification.
  2. A statement indicating that the as-built building complies with Section R405.3.
  3. A certificate indicating that the building passes the performance matrix for code compliance and the energy saving features of the buildings.
  4. A site-specific energy analysis report that is in compliance with Section R405.3.
  5. Name of the individual performing the analysis and generating the report.
  6. Name and version of the compliance software tool.

R405.4.3 Additional Documentation

The code official shall be permitted to require the following documents:
  1. Documentation of the building component characteristics of the standard reference design.
  2. A certification signed by the builder providing the building component characteristics of the proposed design as given in Table R405.5.2(1).
  3. Documentation of the actual values used in the software calculations for the proposed design.

R405.5 Calculation Procedure

Calculations of the performance design shall be in accordance with Sections R405.5.1 and R405.5.2.

R405.5.1 General

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

R405.5.2 Residence Specifications

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.

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

BUILDING COMPONENT STANDARD REFERENCE DESIGN PROPOSED DESIGN
Above-grade walls Type: Mass wall if proposed wall is mass; otherwise wood frame. As proposed
Gross area: Same as proposed As proposed
U-factor: From Table R402.1.3 As proposed
Solar absorptance = 0.75 As proposed
Emittance = 0.90 As proposed
Below-grade walls Type: Same as proposed As proposed
Gross area: Same as proposed As proposed
U-factor: From Table R402.1.3, 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 R402.1.3 As proposed
Ceilings Type: Wood frame As proposed
Gross area: Same as proposed As proposed
U-factor: From Table R402.1.3 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 wall area above and below-grade As proposed
Soil characteristics: Same as
proposed		 As proposed
Opaque doors Area: 40 ft2 As proposed
Orientation: North As proposed
U-factor: Same as fenestration from Table R402.1.3 As proposed
Vertical fenestration other than opaque doorsa Total areah =
(a) The proposed glazing area; where the 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		 As proposed
Orientation: Equally distributed to four cardinal compass orientations
(N, E, S & W).		 As proposed
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.		 As proposed
Interior shade fraction: 0.92-(0.21 × SHGC for the standard reference design) 0.92-(0.21 × SHGC as proposed)
External shading: None As proposed
Skylights None As proposed
Air exchange rate Air leakage rate of 5 air changes per hour at a pressure of 0.2 inches w.g (50 Pa). The mechanical ventilation rate shall be in addition to the air leakage
rate and the same as in the proposed design, but no greater than 0.01 × CFA + 7.5 × (Nbr + 1)
where:
CFA = conditioned floor area
Nbr = number of bedrooms
-Energy recovery shall not be assumed for mechanical ventilation.		 For residences that are not tested, the same air leakage rate as the standard reference design.
For tested residences, the measured air exchange ratea.
The mechanical ventilation rateb shall be in addition to the air leakage rate and shall be as proposed.


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

BUILDING COMPONENT STANDARD REFERENCE DESIGN PROPOSED DESIGN
Mechanical ventilation None, except where mechanical ventilation is specified by the proposed design, in which case:
Annual vent fan energy use:
kWh/yr = .03942 × CFA + 29.565 × (Nbr + 1)
where:
CFA = conditioned floor area
Nbr = number of bedrooms		 As proposed
Internal gains IGain = 17,900 + 23.8 × CFA + 4104 × Nbr (Btu/day per dwelling unit) Same as standard reference design.
Internal mass An internal mass for furniture and contents of 8 pounds per square foot
of floor area.		 Same as standard reference
design, plus any additional mass
specifically designed as a thermal
storage elementc but not integral
to the building envelope or
structure.
Structural mass For masonry floor slabs, 80% 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 R402.1.3 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 systemsd, e Where the proposed design utilizes electric heating without a heat pump the standard reference design shall be an air source heat pump meeting the requirements of Section C403 of the WSEC—Commercial Provisions.
For all other systems, the same system type as proposed, and the same system efficiency required by prevailing minimum federal standard.
Capacity: Sized in accordance with Section R403.6		 As proposed
Cooling systemsd, f Same system type as proposed. Same system efficiency as required by prevailing minimum federal standard.
Capacity: Sized in accordance with Section R403.6.		 As proposed
Service water heatingd, e, f, g Same system type as proposed. Same system efficiency as required by prevailing minimum federal standard.
Use: Same as proposed design		 As proposed
gal/day = 30 + (10 × Nbr)
Thermal distribution systems Duct insulation: From Section R403.3.3

A thermal distribution system efficiency (DSE) of 0.93 shall be applied to both the heating and cooling system efficiencies for all systems.		 As specified in Table
R405.5.2(2)
Thermostat Type: Manual, cooling temperature setpoint = 75°F;
Heating temperature setpoint = 72°F 		Same as standard reference

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

    AF = As × FA × F

    Where:

    AF = Total fenestration area.
    As = Standard reference design total fenestration area.
    FA = (Above-grade thermal boundary gross wall area)/(above-grade boundary wall area + 0.5 x below-grade boundary wall area).
    F = (Above-grade thermal boundary wall area)/(above-grade thermal boundary wall area + common wall area) or 0.56, whichever is greater.
    and where:
    Thermal boundary wall is any wall that separates conditioned space from unconditioned space or ambient conditions.
    Above-grade thermal boundary wall is any thermal boundary wall component not in contact with soil.
    Below-grade boundary wall is any thermal boundary wall in soil contact.
    Common wall area is the area of walls shared with an adjoining dwelling unit.
    L and CFA are in the same units.

TABLE R405.5.2(2)
DEFAULT DISTRIBUTION SYSTEM EFFICIENCIES FOR PROPOSED DESIGNSa

DISTRIBUTION SYSTEM
CONFIGURATION AND CONDITION		 DISTRIBUTION
SYSTEM EFFICIENCY
Distribution system components located in unconditioned space  0.88
Distribution systems entirely located in conditioned spaceb  0.93
Zonal systemsc  1.00

For SI: 1 cubic foot per minute = 0.47 L/s, 1 square foot = 0.093 m2, 1 pound per square inch = 6895 Pa, 1 inch water gauge = 1250 Pa.
  1. Values given by this table are for distribution systems, which must still meet all prescriptive requirements for duct and pipe system insulation and leakage.
  2. 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. All components must be located on the interior side of the thermal envelope (inside the insulation) and also inside of the air barrier. Refrigerant compressors and piping are allowed to be located outside.
  3. Zonal systems are systems where the heat source is located within each room. 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. Hydronic systems do not qualify.

R405.6 Calculation Software Tools

Calculation software, where used, shall be in accordance with Sections R405.6.1 through R405.6.3.

R405.6.1 Minimum Capabilities

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. 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.
  2. 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.
  3. 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.).

R405.6.2 Specific Approval

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.

R405.6.3 Input Values

When calculations require input values not specified by Sections R402, R403, R404 and R405, those input values shall be taken from an approved source.

Section R406 Additional Energy Efficiency Requirements

R406.1 Scope

This section establishes options for additional criteria to be met for one- and two-family dwellings and townhouses, as defined in Section 101.2 of the International Residential Code, and dwelling units in residential buildings to demonstrate compliance with this code.

R406.2 Additional Energy Efficiency Requirements (Mandatory)

Each dwelling unit in a residential building shall comply with sufficient options from Table R406.2 so as to achieve the following minimum number of credits:
  1. Small Dwelling Unit: ........................1.5 credits
    Dwelling units less than 1500 square feet in conditioned floor area with less than 300 square feet of fenestration area. Additions to existing building greater than 500 square feet of heated floor area but less than 1500 square feet.
  2. Medium Dwelling Unit: .................. 3.5 credits
    All dwelling units that are not included in #1 or #3.

    Exception: Dwelling units serving R-2 occupancies shall require 2.5 credits.
  3. Large Dwelling Unit: ...................... 4.5 credits
    Dwelling units exceeding 5000 square feet of conditioned floor area.

    Exception: Dwelling units serving R-2 occupancies shall require 2.5 credits.
  4. Additions less than 500 square feet:. 0.5 credits
    The drawings included with the building permit application shall identify which options have been selected and the point value of each option, regardless of whether separate mechanical, plumbing, electrical, or other permits are utilized for the project.

TABLE 406.2
ENERGY CREDITS

OPTION DESCRIPTION CREDIT(S)
1a EFFICIENT BUILDING ENVELOPE 1a:
Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.28
Floor R-38
Slab on grade R-10 perimeter and under entire slab
Below grade slab R-10 perimeter and under entire slab
or
Compliance based on Section R402.1.4: Reduce the Total UA by 5%.		  0.5
 1b EFFICIENT BUILDING ENVELOPE 1b:
Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.25
Wall R-21 plus R-4 ci
Floor R-38
Basement wall R-21 int plus R-5 ci
Slab on grade R-10 perimeter and under entire slab
Below grade slab R-10 perimeter and under entire slab
or
Compliance based on Section R402.1.4: Reduce the Total UA by 15%.		  1.0
 1c EFFICIENT BUILDING ENVELOPE 1c:
Prescriptive compliance is based on Table R402.1.1 with the following modifications: Vertical fenestration U = 0.22
Ceiling and single-rafter or joist-vaulted R-49 advanced
Wood frame wall R-21 int plus R-12 ci
Floor R-38
Basement wall R-21 int plus R-12 ci
Slab on grade R-10 perimeter and under entire slab
Below grade slab R-10 perimeter and under entire slab
or
Compliance based on Section R402.1.4: Reduce the Total UA by 30%.		  2.0
1da EFFICIENT BUILDING ENVELOPE 1d:
Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.24		 0.5
2a AIR LEAKAGE CONTROL AND EFFICIENT VENTILATION 2a:
Compliance based on R402.4.1.2: Reduce the tested air leakage to 3.0 air changes per hour maximum
and
All whole house ventilation requirements as determined by Section M1507.3 of the International Residential Code shall be met with a high efficiency fan (maximum 0.35 watts/cfm), not interlocked with the furnace fan. Ventilation systems using a furnace including an ECM motor are allowed, provided that they are controlled to operate at low speed in ventilation only mode.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the maximum tested building air leakage and shall show the qualifying ventilation system.		 0.5
2b

 AIR LEAKAGE CONTROL AND EFFICIENT VENTILATION 2b:
Compliance based on Section R402.4.1.2: Reduce the tested air leakage to 2.0 air changes per hour maximum
and
All whole house ventilation requirements as determined by Section M1507.3 of the International Residential Code shall be met with a heat recovery ventilation system with minimum sensible heat recovery efficiency of 0.70.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the maximum tested building air leakage and shall show the heat recovery ventilation system.		 1.0
2c AIR LEAKAGE CONTROL AND EFFICIENT VENTILATION 2c:
Compliance based on Section R402.4.1.2: Reduce the tested air leakage to 1.5 air changes per hour maximum
and
All whole house ventilation requirements as determined by Section M1507.3 of the International Residential Code shall be met with a heat recovery ventilation system with minimum sensible heat recovery efficiency of 0.85.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the maximum tested building air leakage and shall show the heat recovery ventilation system.		 1.5
3ab HIGH EFFICIENCY HVAC EQUIPMENT 3a:
Gas, propane or oil-fired furnace with minimum AFUE of 94%, or Gas, propane or oiled-fired boiler with minimum AFUE of 92%
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the heating equipment type and the minimum equipment efficiency.		 1.0
3bb HIGH EFFICIENCY HVAC EQUIPMENT 3b:
Air-source heat pump with minimum HSPF of 9.0
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the heating equipment type and the minimum equipment efficiency.		 1.0
3cb HIGH EFFICIENCY HVAC EQUIPMENT 3c:
Closed-loop ground source heat pump; with a minimum COP of 3.3
or
Open loop water source heat pump with a maximum pumping hydraulic head of 150 feet and minimum COP of 3.6
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the heating equipment type and the minimum equipment efficiency.		 1.5
3db HIGH EFFICIENCY HVAC EQUIPMENT 3d:
Ductless Split System Heat Pumps, Zonal Control: In homes where the primary space heating system is zonal electric heating, a ductless heat pump system shall be installed and provide heating to the largest zone of the housing unit.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the heating equipment type and the minimum equipment efficiency.		 1.0
4 HIGH EFFICIENCY HVAC DISTRIBUTION SYSTEM:
All heating and cooling system components installed inside the conditioned space. This includes all equipment and distribution system components such as forced air ducts, hydronic piping, hydronic floor heating loop, convectors and radiators. All combustion equipment shall be direct vent or sealed combustion.
For forced air ducts: A maximum of 10 linear feet of return ducts and 5 linear feet of supply ducts may be located outside the conditioned space. All metallic ducts located outside the conditioned space must have both transverse and longitudinal joints sealed with mastic. If flex ducts are used, they cannot contain splices. Flex duct connections must be made with nylon straps and installed using a plastic strapping tensioning tool. Ducts located outside the conditioned space must be insulated to a minimum of R-8.
Locating system components in conditioned crawl spaces is not permitted under this option.
Electric resistance heat and ductless heat pumps are not permitted under this option.
Direct combustion heating equipment with AFUE less than 80% is not permitted under this option.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the heating equipment type and shall show the location of the heating and cooling equipment and all the ductwork.		 1.0
5a EFFICIENT WATER HEATING 5a:
All showerhead and kitchen sink faucets installed in the house shall be rated at 1.75 GPM or less. All other lavatory faucets shall be rated at 1.0 GPM or less.c
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the maximum flow rates for all showerheads, kitchen sink faucets, and other lavatory faucets.		 0.5
5b EFFICIENT WATER HEATING 5b:
Water heating system shall include one of the following:
Gas, propane or oil water heater with a minimum EF of 0.74
or
Water heater heated by ground source heat pump meeting the requirements of Option 3c.
or
For R-2 occupancy, a central heat pump water heater with an EF greater than 2.0 that would supply DHW to all the units through a central water loop insulated with R-8 minimum pipe insulation.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the water heater equipment type and the minimum equipment efficiency.		 1.0
5c EFFICIENT WATER HEATING 5c:
Water heating system shall include one of the following:
Gas, propane or oil water heater with a minimum EF of 0.91
or
Solar water heating supplementing a minimum standard water heater. Solar water heating will provide a rated minimum savings of 85 therms or 2000 kWh based on the Solar Rating and Certification Corporation (SRCC) Annual Performance of OG-300 Certified Solar Water Heating Systems.
or
Electric heat pump water heater with a minimum EF of 2.0 and meeting the standards of NEEA's Northern Climate Specifications for Heat Pump Water Heaters.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall specify the water heater equipment type and the minimum equipment efficiency and, for solar water heating systems, the calculation of the minimum energy savings.		 1.5
5d EFFICIENT WATER HEATING 5d:
A drain water heat recovery unit(s) shall be installed, which captures waste water heat from all the showers, and has a minimum efficiency of 40% if installed for equal flow or a minimum efficiency of 52% if installed for unequal flow. Such units shall be rated in accordance with CSA B55.1 and be so labeled.
To qualify to claim this credit, the building permit drawings shall include a plumbing diagram that specifies the drain water heat recovery units and the plumbing layout needed to install it and labels or other documentation shall be provided that demonstrates that the unit complies with the standard.		 0.5
6 RENEWABLE ELECTRIC ENERGY:
For each 1200 kWh of electrical generation per housing unit provided annually by on-site wind or solar equipment a 0.5 credit shall be allowed, up to 3 credits. Generation shall be calculated as follows:
For solar electric systems, the design shall be demonstrated to meet this requirement using the National Renewable Energy Laboratory calculator PVWATTs. Documentation noting solar access shall be included on the plans.
For wind generation projects designs shall document annual power generation based on the following factors:
The wind turbine power curve; average annual wind speed at the site; frequency distribution of the wind speed at the site and height of the tower.
To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall show the photovoltaic or wind turbine equipment type, provide documentation of solar and wind access, and include a calculation of the minimum annual energy power production.		 0.5

  1. Projects using this option may not use Option 1a, 1b or 1c.
  2. Projects may only include credit from one space heating option, 3a, 3b, 3c or 3d. When a housing unit has two pieces of equipment (i.e., two furnaces) both must meet the standard to receive the credit.
  3. Plumbing Fixtures Flow Ratings. Low flow plumbing fixtures (water closets and urinals) and fittings (faucets and showerheads) shall comply with the following requirements:

    1. Residential bathroom lavatory sink faucets: Maximum flow rate - 3.8 L/min (1.0 gal/min) when tested in accordance with ASME A112.18.1/CSA B125.1.
    2. Residential kitchen faucets: Maximum flow rate - 6.6 L/min (1.75 gal/min) when tested in accordance with ASME A112.18.1/CSA B125.1.
    3. Residential showerheads: Maximum flow rate - 6.6 L/min (1.75 gal/min) when tested in accordance with ASME A112.18.1/CSA B125.1.