HVAC Terminology


AFUE: Annual Fuel Utilization Efficiency (AFUE) is a measure of a gas furnace’s efficiency in converting fuel to energy, but projecting the average thermal efficient for a complete heating season. A higher AFUE means greater energy efficiency. If your system is more than 15 years old, an AFUE rating may not be available. Simply find the serial number on the unit and contact the manufacturer—chances are they’ll be able to give you the information you’re looking for.

BTU: One British Thermal Unit (BTU) represents the amount of heat that is required to raise or lower the temperature of 1 pound of water by 1 degree Fahrenheit. Most air conditioners are measured using BTUs.

BTUh: Some systems measure their energy by British Thermal Units per Hour (BTUh). The energy that is extracted from your home by an air conditioner is measured in BTUs, while the cooling and heating capacities are referred to in BTUh. For reference, 12,000 BTUh is equal to 1 ton of cooling.

EER: Energy Efficiency Ratio (EER) of a cooling unit is determined by the output cooling divided by the electrical power input. As opposed to Seasonal Energy Efficiency Ratio (SEER), which is calculated over a range of outside temperatures, EER is typically determined by a set outside air temperature, a set inside air temperature and 50 percent relative humidity. For reference, 11 EER is roughly 12 SEER.

HSPF: The Heating Seasonal Performance Factor (HSPF) is used to measure the efficiency of a heat pump. The HSPF is a ratio of the heat output to electricity use over an average heating season. The higher the HSPF, the greater the energy efficiency.

SEER: Seasonal Energy Efficiency Ratio (SEER) measures air conditioning and heat pump cooling efficiency, which is calculated by the cooling output for a typical cooling season divided by the total electrical energy input during the same time frame. The higher the SEER rating, the greater the energy efficiency, and, in turn, the lower your energy cost.

Questions about what these HVAC basics mean for your home? Contact an American Standard Heating & Air Conditioning Customer Care Dealer to learn more.




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