HFCs are potent greenhouse gases, the use of which is growing rapidly. They are used as replacements for ozone-depleting substances (CFCs and HCFCs) in refrigerators, air conditioners and insulation materials. RIVM assesses their contribution to the greenhouse effect, both now and for the future. RIVM also advises several governments on HFC emission reduction measures. RIVM conducts research in collaboration with various American institutes.