Minimum r-value assembly listed in Prescriptive tables The chart below summarizes a hand full of metal building roof and wall R-value assemblies that make up the vast majority of the prescriptive requirements going as far back as ASHRAE 90.1-2004 Standard. For a more complete analysis of 90.1-2013 specifically relating to metal buildings visit our CodeAnalysis. Revised U-factors reflect installed performance expectations for roof assemblies which were found to be overstated up to 35% and wall assemblies up to 42% when comparing to all previous versions of ASHRAE Standard 90.1 dating back to their 1999 Standard.ĪSHRAE published their news release regarding the revised U-factors for compressed metal building roof and wall insulation assemblies in January 2010 and are now finally implemented in their 2013 Standard. Corrections in default u-factor roofĪcknowledges dramatic performance reduction from all of ASHRAE's previously published U-factors of traditional compressed laminated insulation in roof and walls. Previously industry has published performance values of 20% to 40% greater than the typical installed performance which are technically unsupported. Pre-engineered metal buildings represent at least 50% of the low rise non-residential US market and the changes to insulating metal buildings will make a huge impact. Modifications to Roof and Wall Assembly Descriptions.Corrections in Default U-factor Roof and Wall Tables.Newly Published ASHRAE Standard 90.1-2013ĪSHRAE publishes new 2013 energy standard incorporating major revisions:

Ashrae standard 90.1 2013 pdf