ASHRAE Adjusts Metal Building Insulation Standards

On January 12, 2010, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) published a press release acknowledging that the thermal performance representations in the 90.1-1999 through 90.1-2007 Standards for typical over-the-purlin, over the-girt and sag-and-bag methods of insulating pre-engineered metal building roofs and walls do not reflect the performance of these assemblies as they are typically installed. The press release includes revised thermal performance representations that reflect typical installation practices that are proposed for inclusion in the upcoming 90.1-2010 Standard. The 90.1 Standard is the commercial building reference standard for state building energy codes under the federal energy policy act. The purpose of the 90.1 Standard is to provide minimum performance requirements for the energy-efficient design of buildings. The revised metal building insulation assembly U-Factors announced by ASHRAE indicate that typical single layer laminated over-the-purlin methods do not comply with the maximum assembly U-Factor for non-residential metal building roofs in all climate zones for 90.1-1999 through 90.1-2007 Standards. Typical double layer “sag-and-bag” methods of installation require R-16+R-19 or R-19+R-19 configurations to comply with the maximum assembly U-Factor in most climate zones in the 90.1-1999 through 90.1-2007 Standards. For more information on the new standards and your building’s compliance, contact Thermal Design at www.thermaldesign.com.