The Center for Environmental Innovation in Roofing and the Polyisocyanurate Insulation Manufacturers Association (PIMA) have released the “Roof and Wall Thermal Design Guide: Applying the Prescriptive Insulation Standards of the 2012 I-Codes.” The guide, which is available for free download here, provides information on the prescriptive thermal value tables in the 2012 International Energy Conservation Code (IECC), as well as references to these tables in the 2012 International Green Construction Code (IgCC). The prescriptive thermal values for roof and wall insulation in the 2012 IECC tables differ from those in ASHRAE Standard 90.1 and the IgCC addresses insulation via instructions for installation rather than through tables. The new guide aims to translate the information from the prescriptive tables into roof and wall R-value tables for the most common forms of commercial opaque roof and wall construction.