Researchers at the National Institute of Standards and Technology (NIST) have just completed a multiyear study to identify the “best” candidates for future use as air conditioning refrigerants that will have the lowest impact on the climate.
Unfortunately, all 27 fluids NIST identified as the best from a performance viewpoint are at least slightly flammable, which is not allowed under U.S. safety codes for most end uses. Several fluids among the list of refrigerants are highly flammable, including propane, the fuel for outdoor grills.