We use different rating systems to measure energy efficiency for different heating and cooling products. A higher number means better efficiency.
AFUE – Your furnace’s Annual Fuel Utilization Efficiency number tells you how much of the energy it uses is being converted to heat. Look for AFUE ratings of 90% or higher for gas furnaces.
SEER – The Seasonal Energy Efficiency Ratio describes the cooling efficiency of air conditioners and heat pumps. New products should have SEER ratings of at least 13. The most efficient systems have ratings over 20.
HSPF – The Heating Seasonal Performance Factor is how we measure a heat pump’s heating efficiency. It’s a ratio of heat output to electricity used. Modern heat pumps are required to have a minimum HSPF of 7.7.
COP – The heating efficiency of geothermal heat pumps is often measured using the Coefficient of Performance.
EER – Energy Efficiency Rating is another measure of cooling efficiency. It is the ratio of a product’s cooling output (in British thermal units) to the watts of power it uses.