Statutes, codes, and regulations
Washington Administrative Code
Title 51 - Enterprise Services, Department of (Building Code Council)
Chapter 51-11R - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Residential
Section 51-11R-40215 - Target/Proposed UA equations

Wash. Admin. Code § 51-11R-40215

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Current through Register Vol. 24-24, December 15, 2024
Section 51-11R-40215 - Target/Proposed UA equations

EQUATION 1 - GROUP R OCCUPANCY TARGET UA

UAT = UWAW + UBGWABGW + UVGAVG + UOGAOG + UFAF + URCARC + UDAD + FSPS + FBGSPBGS

Where:

UAT = The target combined thermal transmittance of the gross exterior wall, floor and roof/ceiling area.

UW = The thermal transmittance value of the opaque above grade wall found in Table R402.1.2.

AW = Opaque above grade wall area.

UBGW = The thermal transmittance value of the below grade opaque wall found in Table R402.1.2.

ABGW = Opaque below grade wall area.

UVG = The thermal transmittance value of the fenestration found in Table R402.1.2.

AVG = (a) The proposed glazing area; where proposed fenestration glazing area is less than 15 percent of the conditioned floor area, minus AOG.

(b) 15 percent of the conditioned floor area; where the proposed fenestration glazing area is 15 percent or more of the conditioned floor area, minus AOG.

UOG = The thermal transmittance value of the skylight glazing found in Table R402.1.2.

AOG = Skylight glazing area (if the proposed AOG exceeds 15 percent, the target AOG shall be 15 percent of the total floor area of the conditioned space).

UF = The thermal transmittance value of the floor found in Table R402.1.2.

AF = Floor area over unconditioned space.

URC = The thermal transmittance value of the ceiling found in Table R402.1.2.

ARC = Roof/ceiling area.

UD = The thermal transmittance value of the fenestration found in Table R402.1.2.

AD = Opaque door area.

FS = Concrete slab on grade component F-factor found in Table R402.1.2.

PS = Lineal ft. of concrete slab on grade perimeter.

FBGS = Concrete below grade slab component F-factor found in Table R402.1.2.

PBGS = Lineal ft. of concrete below grade slab perimeter.

EQUATION 2 - GROUP R OCCUPANCY PROPOSED UA

UA = UWAW + UBGWABGW + UVGAVG + UOGAOG + UFAF + URCARC + UDAD + FSPS + FBGSPBGS

Where:

UA = The combined thermal transmittance of the gross exterior wall, floor and roof/ceiling assembly area.

UW = The thermal transmittance of the opaque above grade wall area.

AW = Opaque above grade wall area.

UBGW = The thermal transmittance value of the below grade opaque wall.

ABGW = Opaque below grade wall area.

UVG = The thermal transmittance value of the fenestration glazing.

Avg = Fenestration glazing area, including windows in exterior doors.

UOG = The thermal transmittance value of the skylight glazing.

AOG = Skylight glazing area.

UF = The thermal transmittance of the floor.

AF = Floor area over unconditioned space.

URC = The thermal transmittance of the ceiling.

ARC = Ceiling area.

UD = The thermal transmittance value of the opaque door area.

AD = Opaque door area.

FS = Concrete slab on grade component F-factor.

PS = Lineal ft. of concrete slab on grade perimeter.

FBGS = Concrete below grade slab component F-factor.

PBGS = Lineal ft. of concrete below grade slab perimeter.

NOTE:

Where more than one type of wall, window, roof/ceiling, door and skylight is used, the U and A terms for those items shall be expanded into subelements as:

UW1AW1 + UW2AW2 + UW3AW3 +...etc.

NOTE:

Below grade walls: The wall is assumed to extend from the slab upward to the top of the mud sill for the distance specified in Table A104.1, with 6 inches of concrete wall extending above grade. This will be calculated separately from above grade walls using the wall height that best describes the system.

Wash. Admin. Code § 51-11R-40215

Adopted by WSR 20-01-047, Filed 12/9/2019, effective 7/1/2020
Amended by WSR 23-02-060, Filed 1/3/2023, effective 7/1/2023