The Energy Crisis (as it was labeled) in the United States in the late 1970s initiated the widespread installation of above-deck thermal insulation boards on low-slope roof systems.
International Codes can be confusing. The 2012 International Energy Conservation Code (IECC) includes new standards for almost every component in the building envelope, and these standards are further increased in the new International Green Construction Code (IgCC), which serves as an overlay code.