Potential changes have been proposed for ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for Buildings Except Low-Rise Residential Buildings. Currently, Standard 90.1-2007 sets minimum requirements for the energy-efficient design of buildings, but 43 addenda already have been approved for the 2010 version. Most recently, changes proposed address metal buildings and energy stringencies in the standard. The 2010 version of the standard is expected to be published this fall.

Focusing on metal building assemblies, changes are proposed to Standard 90.1 Appendix A, “Rated R-Value of Insulation and Assembly U-Factor, C-Factor and F-Factor Determinations.” Studies by a metal building task group found that typical installation practices of single- and double-layer assemblies in Appendix A compress insulation and negatively affect the assembly’s thermal performance. As a result, the proposed Appendix A adds revised modeling equations to estimate the performance to compressed insulation in metal building assemblies and incorporates modified R-Values/U-Factors.

Nine other proposed addenda address lighting and energy efficiency, and would revise lighting power densities for both whole building and space-by-space compliance methods. Lighting power allowances in many buildings and space types would be reduced while industry-recommended lighting levels would remain. The goal of these addenda is to encourage designers to use more efficient lighting applications that provide more light without using more energy, notes Eric Richman, chair of the 90.1 subcommittee. Other related proposed changes address daylighting control requirements and changes to the envelope section to address elements such as high albedo roof and glazing products.

For more information on the proposed changes, to read the addenda, and to comment on the proposed changes, visit ashrae.org/publicreviews.