WACs > Title 51 > Chapter 51-11C > Section 51-11C-40213
Agency filings affecting this section
Section C402.1.3âComponent performance option.
C402.1.3 Component performance building envelope option.
C402.1.3.1 General. Buildings or structures whose design heat loss rate (UAp) and solar heat gain coefficient rate (SHGCÂ *Â Ap) are less than or equal to the target heat loss rate (UAt) and solar heat gain coefficient rate (SHGCÂ *Â At) shall be considered in compliance with this section. The stated U-factor, F-factor or allowable area of any component assembly, listed in Table C402.1.2 and Table C402.3, such as roof/ceiling, opaque wall, opaque door, fenestration, floor over conditioned space, slab-on-grade floor, radiant floor or opaque floor may be increased and the U-factor or F-factor for other components decreased, provided that the total heat gain or loss for the entire building envelope does not exceed the total resulting from compliance to the U-factors, F-factors or allowable areas specified in this section. Compliance shall be calculated in total for the building envelope for other than Group R spaces and for Group R spaces.
C402.1.3.2 Component U-factors. The U-factors for typical construction assemblies are included in Chapter 3 and Appendix A. These values shall be used for all calculations. Where proposed construction assemblies are not represented in Chapter 3 or Appendix A, values shall be calculated in accordance with the ASHRAE HandbookâFundamentals, using the framing factors listed in Appendix A. For envelope assemblies containing metal framing, the U-factor shall be determined by one of the following methods: 1. Results of laboratory measurements according to acceptable methods of test. 2. ASHRAE HandbookâFundamentals where the metal framing is bonded on one or both sides to a metal skin or covering. 3. The zone method as provided in ASHRAE HandbookâFundamentals. 4. Effective framing/cavity R-values as provided in Appendix A. When return air ceiling plenums are employed, the roof/ceiling assembly shall: a. For thermal transmittance purposes, not include the ceiling proper nor the plenum space as part of the assembly; and b. For gross area purposes, be based upon the interior face of the upper plenum surface. 5. Tables in ASHRAE 90.1-2010 Normative Appendix A.
C402.1.3.3 UA calculations. The target UAt and the proposed UAp shall be calculated using Equations C402-1 and C402-2 and the corresponding areas and U-factors from Table C402.1.2 and Table C402.3. For the target UAt calculation, the skylights shall be located in roof/ceiling area up to the maximum skylight area per Section C402.3.1 and the remainder of the fenestration allowed per Section C402.3.1 shall be located in the wall area.
C402.1.3.4 SHGC rate calculations. Solar heat gain coefficient shall comply with Table C402.3. The target SHGCAt and the proposed SHGCAp shall be calculated using Equations C402-3 and C402-4 and the corresponding areas and SHGCs from Table C402.3. [Statutory Authority: RCW 19.27A.025, 19.27A.045, 19.27.020, and 19.27.074. WSR 14-24-122, Â§ 51-11C-40213, filed 12/3/14, effective 1/3/15. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, Â§ 51-11C-40213, filed 2/1/13, effective 7/1/13.]