Skip to main content


Defining AFUE, SEER and HSPF

Maximizing the energy efficiency of your heating and cooling system

The efficiency of your home comfort system is something you should know about. When you have high-efficiency equipment, you’ll experience increased energy savings that may translate into lower utility bills and more money in your pocket. Check out the Energy Savings Calculator to see how efficient your system is and whether it should be repaired or replaced.

Below are standard efficiency ratings that make it easy to compare the performance of different systems. Understanding their importance will help you choose a home comfort system that will not only save you money, but also save energy.

AFUE – Annual Fuel Utilization Efficiency

When you need to measure the thermal efficiency of your furnace or water heater, AFUE (Annual Fuel Utilization Efficiency) helps to determine the actual, annual, average efficiency of that piece of heating equipment. It measures the amount of heat actually delivered to your house compared to the amount of fuel that you must supply to the furnace. The U.S. Department of Energy determined that all furnaces sold in the U.S. must have a minimum AFUE of 78%.

SEER – Seasonal Energy Efficiency Ratio

Are you getting your money’s worth out of your air conditioner? Determining the SEER of your unit will help. SEER stands for Seasonal Energy Efficiency Ratio, the comparative method used to judge how efficiently your air conditioner performs. It’s one way to see if you’re getting real value out of the energy dollars you spend. The higher a unit’s SEER, the higher your unit’s energy efficiency, and the more efficiently your unit uses power. In January 2006 it became mandatory for all cooling units to have a minimum 13 SEER. Effective power use means you’re getting the best value for your energy dollar.

HSPF – Heating Seasonal Performance Factor

The HSPF (Heating Seasonal Performance Factor) is the most commonly used measure of the heating efficiency of heat pumps. The HSPF is a heat pump’s estimated seasonal heating output in BTUs divided by the amount of energy that it consumes in watt-hours. Typically, a high efficiency air conditioner or heat pump pays for itself in savings in a few years.