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CHAPTER 4 (RE) <br />RESIDENTIAL ENERGY EFFICIENCY <br />SECTION R401 <br />GENERAL <br />R401.1 Scope. This chapter applies to residential <br />buildings. , <br />R401.2 Compliance. Projects shall comply with one of <br />the following: <br />1. Sections 8401 through 8404. <br />2. Section R405 and the provisions of Sections R401 <br />through R404 labeled "Mandatory." <br />In addition, dwelling units and sleeping units in a <br />residential building shall comply with Section R406. <br />R401.3 Certificate (Mandatory). A permanent <br />certificate shall be completed by the builder or registered <br />design professional and posted on a wall in the space <br />where the furnace is located, a utility room, or an <br />approved location inside the building. When located on <br />an electrical panel, the certificate shall not cover or <br />obstruct the visibility of the circuit directory label, <br />service disconnect label, or other required labels. The <br />certificate shall list the predominant Xvalues of <br />insulation installed in or on ceiling/roof, walls, <br />foundation (slab, below -grade wall, and/or floor) and <br />ducts outside conditioned spaces; U -factors for <br />fenestration and the solar heat gain coefficient (SHGC) <br />of fenestration, and the results from any required duct <br />system and building envelope air leakage testing done on <br />the building. Where there is more than one value for each <br />component, the certificate shall list the value covering the <br />largest area. The certificate shall list the types and <br />efficiencies of heating, cooling and service water heating <br />equipment. Where a gas-fired unvented room heater, <br />electric furnace, or baseboard electric heater is installed <br />in the residence, the certificate shall list "gas-fired <br />unvented room heater," "electric furnace" or "baseboard <br />electric heater," as appropriate. An efficiency shall not be <br />listed for gas-fired unvented room heaters, electric <br />furnaces or electric baseboard heaters. <br />SECTION R402 <br />BUILDING THERMAL ENVELOPE <br />R402.1 General (prescriptive). the buildinp thermal <br />envelope shall meet the requirements ome.-9 . <br />1t�0�.i : i t ti roi►�li Et402 i:'"' e "". <br />Exception: The following buildings, or portions <br />thereof, separated from the remainder of the building <br />by building thermal envelope assemblies complying <br />with this code shall be exempt from the building <br />thermal envelope provisions of this code: <br />1. Those with a peak. design rate of energy usage less <br />than 3.4 Btulh • ftx (10.7 W/mz) or 1.0 walVe of <br />floor area for space conditioning purposes. <br />2. Those that do not contain conditioned space. <br />3. Greenhouses isolated from any conditioned space <br />and not intended for occupancy. _ <br />R402.1.1 Insulation and fenestration criteria. The <br />building thermal envelope shall meet the requirements <br />of Table 8.402.1.1 based ori the cclimate zone specified <br />in Chapter 3. <br />8402.1.2 R -value computation. insulation material <br />used in layers, such as framing cavity insulation or <br />continuous insulation, shall be summed to compute the <br />corresponding component R -value. The <br />manufacturces settled R -value shall be used for blowm <br />insulation. Computed R -values shall not include an <br />R -value for other building materials or air films. <br />Where insulated siding is used for the purpose of <br />complying with the continuous insulation <br />requirements of Table R402.1.1, the manufacturer <br />must supply an ICC Report that the R -tactor has been <br />certified, or use R-5 per inch for extruded polystyrene, <br />and R-6 per inch for polyisocyanurate rigid insulation. <br />R402.1.3 U -factor alternative. An assembly with a <br />U -factor equal to or less than that specified in Table <br />8402.1.3 shall be permitted as an alternative to the <br />R -value in Table R402.1.1. <br />R402.1.4 Total UA alternative. If the total building <br />thermal envelope UA (sum of U -factor times assembly <br />area) is Iess than or equal to the total UA resulting <br />from using the U -factors in Table R402.1.3 (multiplied <br />by the same assembly area as in the proposed <br />building), the building shall be considered in <br />compliance with Table R402.1.1. The U -factors for <br />typical construction assemblies are included in <br />Appendix A in chapter 51-1 l C WAC. These values <br />shall be used for all calculations. Where proposed <br />construction assemblies are not represented in <br />Appendix A, values shall be calculated in accordance <br />with the ASI IRAB Handbook ojFundamenlals using <br />the framing factors listed in Appendix A where <br />applicable and shall include the thermal bridging <br />effects of framing materials. The SHGC:, requirements <br />shall be met in addition to UA compliance. When <br />using RESeheck, the U -factors calculated by the <br />software based on component R -value descriptions are <br />acceptable. For the base building UA calculation, the <br />maximum glazing area is 15% of the floor area <br />R402,1.4 Vapor retarder, Wall assemblies in the <br />building thermal envelope shall comply with the vapor <br />retarder requirements of Section R702.7 of the <br />International Residential Code or Section 1405.3 of <br />the International Building Code, as applicable. <br />2015 Washington State Energy Code RE -17 <br />