energy-efficient building property
(3) Energy-efficient building property The term “energy-efficient building property” means— (A) an electric heat pump water heater which yields a Uniform Energy Factor of at least 2.2 in the standard Department of Energy test procedure, (B) an electric heat pump which achieves the highest efficiency tier established by the Consortium for Energy Efficiency, as in effect on January 1, 2009 , (C) a central air conditioner which achieves the highest efficiency tier established by the Consortium for Energy Efficiency, as in effect on January 1, 2009 , and (D) a natural gas, propane, or oil water heater which has either a Uniform Energy Factor of at least 0.82 or a thermal efficiency of at least 90 percent.