When purchasing a furnace, heat pump or air conditioner, ALWAYS ask about its Efficiency Ratings. They will tell you how efficiently the unit uses fuel (gas, oil or electricity). The most-frequently used efficiency ratings are:
SEER (Seasonal Energy Efficiency Ratio): This ratio tells you the amount of cooling your system will deliver per dollar spent on electricity The SEER rating of any unit can range anywhere from 13 to 17. The higher the SEER the more efficient the system will be and the less it will cost in the long run to own and operate.
HSPF (Heating Seasonal Performance Factor): Similar to SEER, it is a measurement of efficiency of the heating portion of a heat pump. HSPF ratings range from 6.8 to 10; high-efficiency units have efficiencies of 7.5 HSPF or above.
AFUE (Annual Fuel Utilization Efficiency ratio): A measurement of the percent of heat produced by a furnace for every dollar of fuel consumed. The higher the AFUE rating, the lower the fuel costs. All furnaces manufactured today must meet at least 78%. Older furnaces (10 – 15 years or older) may fall below this minimum. Furnaces with AFUE ratings from 78% to 80% are considered mid-efficiency; ones with AFUE ratings above 90% are considered high-efficiency.
MERV (Minimum Efficiency Reporting Value): A filter rating system relating to the size of the holes in the filter that allow air to pass through. The higher the MERV rating, the smaller the holes and the higher the efficiency in capturing contaminants. MERV rating range from a low of 1 to a high of 16.
ENERGY STAR: An Environmental Protection Agency designation attached to HVAC products that meet or exceed guidelines for high-efficiency performance above the standard government minimums.