An Energy Star unit is, essentially, a unit that uses less energy than standard options. They operate the same, but because they’re built with a focus on energy-efficiency, they let you save money and reduce your carbon footprint.
There are several acronyms you should know to determine your HVAC system efficiency. HVAC performance is rated based on these terms, and the requirements for an Energy Star rating are set by the Environmental Protection Agency.
EER (Energy Efficiency Ratio) measures the efficiency of a cooling system. It differs from the SEER because it measures efficiency based off of a single usage rather than the entire season.
AFUE (Annual Fuel Utilization Efficiency) is used for furnaces to measure how much fuel is sent out of the chimney instead of turned into heat. Energy-efficient heating is highly obtainable these days since most AFUE ratings are 97-98.5%.
HSPF (Heating Seasonal Performance Factor) measures heat pump efficiency over the course of a season, similar to SEER ratings. The current HSPF range is 7.7-13.