Glossary of Terms

Energy jargon explained

Glossary of Energy Terms

What do all the terms on the site mean?

Following is a glossary of terms for heating, cooling and indoor air quality products.

AFUE Annualized Fuel Utilization Efficiency, a measure of furnace efficiency. The higher the percentage of AFUE, the lower the cost to operate the equipment. For example, for an 85% AFUE rated furnace, 85 cents of every fuel dollar stays in the home and 15 cents is lost out the flue.
Air handler/coil blower The indoor part of an air conditioner or heat pump that moves cooled or heated air throughout the ductwork of your home. An air handler is usually a furnace or a blower coil.
Air sealing Stopping air leakage to reduce energy waste.
Blower door A device created to measure and locate air leaks in a home, used as part of a Wesson Energy home audit.
Btu A measurement of heat energy. One Btu is the amount of heat required to raise one pound of water by one degree Fahrenheit.
Carbon Monoxide (CO) An odorless, dangerous gas that is produced when carbon burns with insufficient air.
Central air conditioning system A cooling system that uses ducts to distribute cold air to a home. As the air circulates it warms and then returns to a centrally located air handler and outdoor compressor to be cooled again.
Condenser coil The outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the outdoor temperature and thermostat setting. Also called an outdoor coil.
Damper A flap in ductwork that can be adjusted to regulates airflow and direct air to the areas that need it most.
DOE The Department of Energy, the federal agency which sets industry efficiency standards and monitors the consumption of energy.
Ductwork The series of pipes or channels through which conditioned air travels from the heating or cooling equipment into and throughout the home.
Energy Star A federal designation attached to products that meet or exceed efficiency performance. Choosing Energy Star products helps lower a home’s energy usage.
EPA Environmental Protection Agency. The government agency tasked with protecting our environment and enforcing federal environmental regulations. The EPA oversees the Energy Star program.
Evaporator coil The part of the air conditioner/heat pump located inside the air handler or attached to the furnace. It absorbs the heat from the indoor environment of a home. Also called an indoor coil.
Heat exchanger Part of a furnace which transfers heat to the surrounding air, which is then circulated in a home.
Heat pump A heating unit that heats or cools by moving heat. During the winter, a heat pump collects heat from outdoor air and sends it to the home’s air ducts. In the summer, it does the opposite and removes heat from inside and releases it outdoors.
Horizontal flow Equipment which is positioned on its side and circulates air in one end and out the other. Ideal for the narrow space requirements in an attic or crawl space installation.
HSPF Heating Seasonal Performance Factor. Measures the heating efficiency of heat pumps. The higher the rating, the more efficient the pump.
Humidifier An indoor air quality device that introduces moisture to air combating unhealthy dry conditions.
Himidistat A device used to maintain humidity at a certain point. The equivalent of a thermostat for humidity instead of temperature.
HVAC Heating, Ventilation and Air Conditioning.
MERV rating Minimum Efficiency Reporting Value. This rating is for air filters and purifiers. Higher numbers translate to more effective air filtration.
SEER Seasonal Electrical Efficiency Ratio. Similar to miles per gallon in vehicle operation. The higher the SEER, the less it will cost to operate that piece of equipment.
Refridgerant A chemical used to create the cooling effect of an air conditioner. Most residential air conditioning units contain the standard R-22 refrigerant, or Freon. R-22 is being phased out by the EPA.
Split system A heating and cooling system in which some components are located inside the structure of the house and some are located outside.
Thermidistat A device which combines the properties of a thermostat and a humidistat to monitor temperature and humidity.
Ton Measures cooling capacity. Equal to 12,000 Btu per hour).
Two-stage operation This means the HVAC equipment has two levels of operation.
Upflow Refers to an upright installing air handler or furnace where air circulates through a side or bottom and out the top. Used in closet, attic and basement installations.
Zoning A method of controlling different areas of a home separately, allowing for reduced energy usage and increased comfort.