Division 7 Ebook Page 564 CMU Energy Codes and Standards Tech Bulletin

Technical Bulletin CMU-01 ENCLOSURE SOLUTIONS Energy Codes and Standards Air Leakage and Prescriptive Wall Insulation Requirements Energy Codes and Standards Owens Corning Enclosure Solutions has a variety of insulation, air barrier, and air/water sealing accessory options that make it easy to specify compliance with energy codes and standards. ASHRAE 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings 1 , establishes minimum energy efficiency requirements for most commercial buildings including larger residential buildings. Excluded are single-family, multi-family three stories or less above grade, and manufactured homes. The International Energy Conservation Code 2 (IECC) is a similar standard that is also widely adopted. The International Green Construction Code 3 (IgCC) contains building energy performance criteria like the other two standards, but it also covers sustainable design concepts. For building envelope design the IgCC generally prescribes higher energy performance requirements than the other two. ASHRAE 189.1 4 , a design standard for high performance green buildings, is designated in Section 301.1.1 of the IgCC as an alternate to the IgCC. Adoption and Compliance Many building code jurisdictions in the United States have adopted an edition of either ASHRAE 90.1, or the similar IECC. Compliance paths in general include either a combination of prescriptive/mandatory thermal performance specifications, a combination of mandatory/building envelope trade-off options, or the Energy Cost Budget Method variations on the compliance paths including prescriptive minimum R-values, maximum U-factors, as well as conducting actual thermal testing on assemblies. The IgCC and ASHRAE 189.1 are not as widely adopted, but some architects/owners, such as the United States Army Corps of Engineers (USACE), choose to design to their goals of greater sustainability. Limiting Air Leakage ASHRAE 90.1 (2013 edition, Section, the IECC (2015 edition, Section C402.5.1), and the IgCC (2012 edition, Section 605.1.2.1) require that the building envelope be designed and constructed with a continuous air barrier. The ASHRAE 90.1 and IECC standards require wall assemblies to demonstrate an air leakage rate to not exceed 0.04 cfm/ft 2 at a pressure of 75 Pa (1.57 psf) when tested in accordance with ASTM E2357 5 . Owens Corning Enclosure Solutions provides multiple options for air barrier systems that meet these requirements while also meeting the NFPA 285 resistance to fire propagation standard. It is always recommended to verify performance with the air barrier manufacturer. For complete information regarding installing Owens Corning FOAMULAR XPS with taped joints as the air and water resistive barrier, see the Owens Corning Enclosure Solutions technical bulletin CMU-03 regarding ASTM E2357 and ASTM E331 testing. The IgCC requires the air leakage rate be determined for the entire building thermal envelope. The leakage rate must be less than 0.25 cfm/ft 2 at a pressure differential of 75 Pa (1.57 psf) when tested in accordance with ASTM E779 6 . Entire building thermal envelope testing is conducted after rough-in and after installation of penetrations of the building envelope, including but not limited to utilities, HVAC, plumbing and electrical service and equipment. Envelope Thermal Performance The table "Prescriptive R Requirements for Mass Walls, Above Grade" charts R by climate zone for mass (concrete masonry unit, CMU) walls as listed in ASHRAE 90.1, the IECC, and ASHRAE 189.1 when used as an alternate to the IgCC. Because the edition adopted varies by jurisdiction, several 90.1 editions are summarized including 2004, 2007, 2010 and 2013. The IECC-2012 and 2015, and ASHRAE 189.1 2011 and 2014 editions are also summarized. The table shows prescribed continuous insulation R-value. The table shows only the prescriptive requirements for "non-residential" (commercial) and "residential" (as defined by ASHRAE 90.1) buildings and applies to buildings that are heated and/or cooled. The standards also provide prescriptive insulation values for "semi-heated" buildings that are not shown in this table. This technical bulletin does not provide complete design requirements. See the applicable standard for complete building performance and design compliance requirements.

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