In 1992, most PIR insulation manufacturers changed their products’ blowing-agent components from a chlorofluorocarbon (CFC-11) to a hydrochlorofluorocarbon (HCFC-141b). PIR insulation manufactur­ers will again need to find a suitable blowing-agent replacement because the EPA will restrict the production of HCFCs, including HCFC-141b, as of January 1, 2003. It is unclear as to what specific blowing agent(s) PIR insulation manufacturers will use, or when products using new blowing agent(s) will enter the marketplace. Some manufacturers are test marketing products manufactured with hydrocarbon blowing agents. The physical properties and field performance of PIR insulation using the next generation of blowing agents(s) are also largely unknown at this time, although prelimi­nary data show comparable performance with current products.