Are heat pump water heaters more efficient than conventional water heaters? What is the uniform energy factor?
Heat pump water heaters are much more efficient than gas, propane, or conventional electric water heaters. The uniform energy factor (UEF) is the new metric for rating the energy efficiency of water heaters. The higher the UEF, the higher the efficiency. Heat pump water heaters have UEF ratings between 3.0 and 3.5, while “efficient” gas and propane water heaters have UEF ratings between 0.65 and 0.70. Conventional electric water heaters have UEF ratings of about 0.95.