The division of foams into open-cell or closed-cell relates to the way in which blowing agent is lost from the
products. For open-cell foam, emissions of HFCs used as blowing agents are likely to occur during the
manufacturing process and shortly thereafter. In closed-cell foam, only a minority of emissions occur during the
manufacturing phase. Emissions therefore extend into the in-use phase, with often the majority of emission not
occurring until end-of-life (de-commissioning losses). Accordingly, emissions from closed cell foams can occur
over a period of 50 years or even longer from the date of manufacture.