WAC 51-11-1334 Solar heat gain coefficient rate calculations. Solar heat gain coefficient shall comply with Section 1323.3. The target SHGCA_t and the proposed SHGCA_p shall be calculated using Equation 13-3 and 13-4 and the corresponding areas and SHGCs from Table 13-1 or 13-2.

Equation 13-1:

Target UA_[t]

UA_t	=	U_ratA_rat + U_ogratA_ograt + U_ortA_ort + U_ogortA_ogort + U_wtA_wt + U_vgtA_vgt + U_dtA_dt + U_ftA_ft + F_stP_st + U_bgwtA_bgwt
UA_t	=	The target combined specific heat transfer of the gross roof/ceiling assembly, exterior wall and floor area.
Where:
U_rat	=	The thermal transmittance value for roofs over attics found in Table 13-1 or 13-2.
U_ograt	=	The thermal transmittance for overhead glazing found in Table 13-1 or 13-2 which corresponds to the proposed total glazing area as a percent of gross exterior wall area.
U_ort	=	The thermal transmittance value for other roofs found in Table 13-1 or 13-2.
U_ogort	=	The thermal transmittance for overhead glazing found in Table 13-1 or 13-2 which corresponds to the proposed total glazing area as a percent of gross exterior wall area.
U_wt	=	The thermal transmittance value for opaque walls found in Table 13-1 or 13-2.
U_vgt	=	The thermal transmittance value for vertical glazing found in Table 13-1 or 13-2 which corresponds to the proposed total glazing area as a percent of gross exterior wall area.
U_dt	=	The thermal transmittance value for opaque doors found in Table 13-1 or 13-2.
U_ft	=	The thermal transmittance value for floors over unconditioned space found in Table 13-1 or 13-2.
F_st	=	The F-factor for slab-on-grade and radiant slab floors found in Table 13-1 or 13-2.
U_bgwt	=	The thermal transmittance value for opaque walls found in Table 13-1 or 13-2.
A_dt	=	The proposed opaque door area, A_d.
A_ft	=	The proposed floor over unconditioned space area, A_f.
P_st	=	The proposed lineal feet of slab-on-grade and radiant slab floor perimeter, P_s.
A_bgwt	=	The proposed below grade wall area, A_bgw.
and;
if the total amount of glazing area as a percent of gross exterior wall area does not exceed the maximum allowed in Table 13-1 or 13-2:
A_rat	=	The proposed roof over attic area, A_ra.
A_ograt	=	The proposed overhead glazing area in roofs over attics, A_ogra.
A_ort	=	The proposed other roof area, A_or.
A_ogort	=	The proposed overhead glazing area in other roofs, A_ogor.
A_wt	=	The proposed opaque above grade wall area, A_w.
A_vgt	=	The proposed vertical glazing area, A_vg.
or;
if the total amount of glazing area as a percent of gross exterior wall area exceeds the maximum allowed in Table 13-1 or 13-2:
A_rat	=	The greater of: the proposed roof over attic area, and the gross roof over attic area minus A_ograt.
A_ograt	=	The lesser of: proposed overhead glazing area in roofs over attics, and the maximum allowed glazing area from Table 13-1 or 13-2.
A_ort	=	The greater of: the proposed other roof area, and the gross other roof area minus A_ogort.
A_ogort	=	The lesser of: the proposed overhead glazing area in other roofs, and the maximum allowed glazing area from Table 13-1 or 13-2 minus A_ograt.
A_wt	=	The greater of: proposed opaque above grade wall area, and the gross exterior above grade wall area minus A_dt minus A_vgt.
A_vgt	=	The lesser of: the proposed vertical glazing area, and the maximum allowed glazing area from Table 13-1 or 13-2 minus A_ograt minus A_ogort.

EQUATION 13-2

Proposed UA_p

UA_p	=	U_raA_ra+U_orA_or+U_ogA_og+U_wA_w+U_dA_d+U_vgA_vg+U_fA_f+F_sP_s+U_bgwA_bgw
		Where:
		UA_p	=	The combined proposed specific heat transfer of the gross exterior wall, floor and roof/ceiling assembly area.
		U_ra	=	The thermal transmittance of the roof over attic area.
		A_ra	=	Opaque roof over attic area.
		U_or	=	The thermal transmittance of the other roof area.
		A_or	=	Opaque other roof area.
		U_og	=	The thermal transmittance for the overhead glazing
		A_og	=	Overhead glazing area.
		U_w	=	The thermal transmittance of the opaque wall area.
		A_w	=	Opaque above grade wall area (not including opaque doors).
		U_vg	=	The thermal transmittance of the vertical glazing area.
		A_vg	=	Vertical glazing area.
		U_d	=	The thermal transmittance value of the opaque door area.
		A_d	=	Opaque door area.
		U_f	=	The thermal transmittance of the floor over unconditioned space area.
		A_f	=	Floor area over unconditioned space.
		F_s	=	Slab-on-grade or radiant floor component F-factor.
		P_s	=	Lineal feet of slab-on-grade or radiant floor perimeter.
		U_bgw	=	The thermal transmittance value of the below grade wall area.
		A_bgw	=	Below grade wall area as defined in Tables 13-1 or 13-2.
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 sub-elements as:
				U_w1A_w1+U_w2A_w2+U_w3A_w3+...etc.

EQUATION 13-3

Target SHGCA_t

SHGCA_t	=	SHGC_t (A_ograt + A_ogort + A_vgt)
Where:
SHGCA_t	=	The target combined specific heat gain of the target glazing area.
SHGC_t	=	The solar heat gain coefficient for glazing found in Table 13-1 or 13-2 which corresponds to the proposed total glazing area as a percent of gross exterior wall area, and
A_ograt, A_ogort, and A_vgt are defined under Equation 13-1.

EQUATION 13-4

Proposed SHGCA_p

SHGCA_p	=	SHGC_ogA_og + SHGC_vgA_vg
Where:
SHGCA_t	=	The combined proposed specific heat gain of the proposed glazing area.
SHGC_og	=	The solar heat gain coefficient of the overhead glazing.
A_og	=	The overhead glazing area.
SHGC_vg	=	The solar heat gain coefficient of the vertical glazing.
A_vg	=	The vertical glazing area.

TABLE 13-1

BUILDING ENVELOPE REQUIREMENTS FOR CLIMATE ZONE 1

MINIMUM INSULATION R-VALUES OR

MAXIMUM COMPONENT U-FACTORS FOR ZONE 1

�� Building Components

Space Heat Type	Components
	Roofs Over Attic³	All Other Roofs³	Opaque Walls^1,2	Opaque Doors	Floor Over Uncond Space	Slab On Grade⁵
1. Electric resistance heat^**	R-38 or U = 0.031	R-30 or U = 0.034	R-19 or U = 0.062	U = 0.60	R-30 or U = 0.029	R-10 or F = 0.54
2. All others including Heat pumps and VAV	R-30 or U = 0.036	R-21 or U = 0.046	(a) Metal framing: R-19 or U = 0.109 (b) Wood framing and framing other than metal: R-19 or U = 0.062	U = 0.60	R-19 or U = 0.056	R-10 or F = 0.54

**	Compliance with nominal prescriptive R-values requires wood framing.

MAXIMUM GLAZING AREAS AND U-FACTORS AND

MAXIMUM GLAZING SOLAR HEAT GAIN COEFFICIENTS

FOR ZONE 1

�� Glazing

Maximum Glazing Area as % of Wall	0% to 30%			>30% to 45%
	Maximum U-Factor		Max. SHGC⁴	Maximum U-Factor		Max. SHGC⁴
	VG	OG		VG	OG
1. Electric resistance heat	0.40	0.60	0.40	PRESCRIPTIVE PATH NOT ALLOWED
2. All others including heat pumps and VAV	0.55	0.70	0.45	0.45	0.60	0.40

Footnotes
1.	Below Grade Walls:
	When complying by the prescriptive approach, Section 1322:

a)	Walls insulated on the interior shall use opaque wall values,
b)	Walls insulated on the exterior shall use a minimum of R-10 insulation,
c)	Walls shall be insulated for the first 10 feet below grade. (There shall be no credit for those portions of below grade walls and footings that are more than 10 feet below grade, and those portions below 10 feet shall not be included in the gross exterior wall area).

When complying by the component performance approach, Section 1331:

a)	Walls insulated on the interior shall use the opaque wall values when determining U_bgwt,
b)	Walls insulated on the exterior shall use a target U-factor of U = 0.070 for U_bgwt,
c)	The calculations shall include the first 10 feet of walls below grade. (Those portions of below grade walls and footings that are more than 10 feet below grade shall not be included in the gross exterior wall area and shall not be included when determining A_bgwt and A_bgw).

2.	Concrete Masonry Walls: If the area weighted heat capacity of the total opaque above grade wall is a minimum of 9.0 Btu/ft² � �F, then:��
	a. The area weighted average U-factor may be increased to U-0.15 maximum, or minimum additional R-5.7 continuous insulation uninterrupted by framing; or
	b. The wall may be ASTM C90 concrete block walls, ungrouted or partially grouted at 32 in. or less on center vertically and 48 in. or less on center horizontally, with ungrouted cores filled with material having a maximum thermal conductivity of 0.44 Btu-in/h � ft² � �F.
	� Individual walls with heat capacities less than 9.0 Btu/ft² � �F and below grade walls shall meet opaque wall requirements listed above.
	� Glazing shall comply with the glazing requirements listed above.

3.	Roof Types: A roof over attic is where the roof structure has at least 30 inches clear distance from the top of the bottom chord of a truss or ceiling joist to the underside of the sheathing at the roof ridge, and the ceiling is attached to the ceiling joist or the bottom of the truss or ceiling joist. Anything else is considered all other roofs.
4.	SHGC (Solar Heat Gain Coefficient per Section 1312.2): May substitute Maximum Shading Coefficient (SC) for SHGC (See Chapter 2 for definition of Shading Coefficient).
5.	Radiant Floors: Where insulation is required under the entire slab, radiant floors shall use a minimum of R-10 insulation or F = 0.55 maximum. Where insulation is not required under the entire slab, radiant floors shall use R-10 perimeter insulation according to Section 1311.6 or F = 0.78 maximum.

TABLE 13-2

BUILDING ENVELOPE REQUIREMENTS

FOR CLIMATE ZONE 2

MINIMUM INSULATION R-VALUES OR

MAXIMUM COMPONENT U-FACTORS FOR ZONE 2

�� Building Components

Space Heat Type	Components
	Roofs Over Attic³	All Other Roofs³	Opaque Walls^1,2	Opaque Doors	Floor Over Uncond Space	Slab On Grade
1. Electric resistance heat^**	R-38 or U = 0.031	R-30 or U = 0.034	R-24 or U = 0.044	U = 0.60	R-30 or U = 0.029	R-10 or F = 0.54
2. All others including Heat pumps and VAV	R-38 or U = 0.031	R-25 or U = 0.039	(a) Metal framing: R-13 cavity insul. +R-3.8 continuous insul. or U = 0.084 (b) Wood framing and framing other than metal: R-19 or U = 0.062	U = 0.60	R-21 or U = 0.047	R-10 or F = 0.54

**	Compliance with nominal prescriptive R-values requires wood framing.

MAXIMUM GLAZING AREAS AND U-FACTORS AND

MAXIMUM GLAZING SOLAR HEAT GAIN COEFFICIENTS

FOR ZONE 2

�� Glazing

Maximum Glazing Area as % of Wall	0% to 30%			>30% to 45%
	Maximum U-Factor		Max. SHGC⁴	Maximum U-Factor		Max. SHGC⁴
	VG	OG		VG	OG
1. Electric resistance heat	0.40	0.60	0.40	PRESCRIPTIVE PATH NOT ALLOWED
2. All others including heat pumps and VAV	0.55	0.70	0.45	0.45	0.60	0.40

Footnotes
1.	Below Grade Walls:
	When complying by the prescriptive approach, Section 1322:

a)	Walls insulated on the interior shall use opaque wall values,
b)	Walls insulated on the exterior shall use a minimum of R-12 insulation,
c)	Walls shall be insulated for the first 10 feet below grade. (There shall be no credit for insulating those portions of below grade walls and footings that are more than 10 feet below grade, and those portions below 10 feet shall not be included in the gross exterior wall area.)

When complying by the component performance approach, Section 1331:

a)	Walls insulated on the interior shall use the opaque wall values when determining U_bgwt,
b)	Walls insulated on the exterior shall use a target U-factor of U = 0.061 for U_bgwt,
c)	The calculations shall include the first 10 feet of walls below grade. (Those portions of below grade walls and footings that are more than 10 feet below grade shall not be included in the gross exterior wall area and shall not be included when determining A_bgwt and A_bgw.)

2.	Concrete Masonry Walls: If the area weighted heat capacity of the total opaque above grade wall is a minimum of 9.0 Btu/ft² � �F, then the U-factor may be increased to 0.123 maximum, or minimum additional R-7.6 continuous insulation uninterrupted by framing.
	� Individual walls with heat capacities less than 9.0 Btu/ft² � �F and below grade walls shall meet opaque wall requirements listed above.
	� Glazing shall comply with the glazing requirements above.

3.	Roof Types: A roof over attic is where the roof structure has at least 30 inches clear distance from the top of the bottom chord of a truss or ceiling joist to the underside of the sheathing at the roof ridge, and the ceiling is attached to the ceiling joist or the bottom of the truss or ceiling joist. Anything else is considered all other roofs.
4.	SHGC (Solar Heat Gain Coefficient per Section 1312.2): May substitute Maximum Shading Coefficient (SC) for SHGC (See Chapter 2 for definition of Shading Coefficient).
5.	Radiant Floors: Where insulation is required under the entire slab, radiant floors shall use a minimum of R-10 insulation or F = 0.55 maximum. Where insulation is not required under the entire slab, radiant floors shall use R-10 perimeter insulation according to Section 1311.6 or F = 0.78 maximum.

[Statutory Authority: RCW 19.27A.022, 19.27A.025, 19.27A.045, and chapters 19.27 and 34.05 RCW. 07-01-089, � 51-11-1334, filed 12/19/06, effective 7/1/07. Statutory Authority: RCW 19.27A.025, 19.27A.045 and chapters 19.27, 19.27A, and 34.05 RCW. 05-01-013, � 51-11-1334, filed 12/2/04, effective 7/1/05. Statutory Authority: RCW 19.27A.025, 19.27A.045. 01-03-010, � 51-11-1334, filed 1/5/01, effective 7/1/01; 98-03-003, � 51-11-1334, filed 1/8/98, effective 7/1/98. Statutory Authority: RCW 19.27A.025. 93-21-052, � 51-11-1334, filed 10/18/93, effective 4/1/94.]

NOTES:

Reviser's note: RCW 34.05.395 requires the use of underlining and deletion marks to indicate amendments to existing rules, and deems ineffectual changes not filed by the agency in this manner. The bracketed material in the above section does not appear to conform to the statutory requirement.

Reviser's note: The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency.