R-value (insulation) contain no trapped CFCs or HFCs (e.g., half-pound low density foams). On certain brands, twenty-year tests have shown no shrinkage or reduction in insulating value. This has led to controversy as how to rate the insulation of these products. Many manufacturers will rate the R-value at the time of manufacture; critics argue that a more fair assessment would be its settled value. The foam industry adopted the LTTR (Long-Term Thermal Resistance) method, which rates the R-value based on a 15-year weighted average. However, the LTTR effectively provides only an eight-year aged R-value, short in the scale of a building that
National Office of Building Technology and Administration National Office of Building Technology and Administration The National Office of Building Technology and Administration* () was a Norwegian government agency responsible for managing laws and rules related to building and construction, authorises rules related to documentation of construction materials and their properties, as well as approving companies related to the "Plan- and Building Act". The agency gives however jurisdiction to local municipalities, along with the County Governor, in appealing individual building permits. Since 1 January 2012, the office has taken on the title of Directorate of Building Quality (Norwegian: "Direktoratet for Byggkvalitet)." The Directorate of Building Quality is organized