York Champion packaged gas/electric units use electricity for air conditioning and propane or natural gas for heating—both functions are contained in one cabinet designed for outdoor installation to save space indoors. In warm weather, you’ll get up to 13.7 SEER air-conditioning efficiency depending on the model. In cool weather, heating efficiencies are as high as 80% AFUE. ENERGY STAR qualified central air conditioners meet or exceed US Environmental Protection Agency energy efficiency standards. Read more