The conversion of the complex carbohydrates in organic material into energy.

The area between the layers of glazing (panes) of a window.

A pump for circulating the heat transfer fluid in a hydronic heating system.

A colorless, pungent, gas (NH3) that is extremely soluble in water, may be used as a refrigerant; a fixed nitrogen form suitable as fertilizer.

A long, underground metal or plastic pipe through which air is drawn. As air travels through the pipe it gives up some of its heat to the soil, and enters the house as cooler air.

An electricity supplier rate structure in which the per unit price of electricity decreases as the amount of energy increases. Normally only available to very large consumers.

The mean wind speed over a specified period of time.

A component of a hydropower plant; a pipe that delivers water to the turbine.

The interior heat gain due to heat conduction, convection, and radiation from the exterior into the interior, and from occupants and appliances.

The amount of power a wind turbine can produce at its rated wind speed, e.g., 100 kW at 20 mph. The rated wind speed generally corresponds to the point at which the conversion efficiency is near its maximum. Because of the variability of the wind, the amo ...

A device used by energy auditors to pressurize a building to locate places of air leakage and energy loss.

A type of combustion heating appliance in which the combustion gases are vented to the outside, either with a fan (forced) or by natural convection.

An apparatus for converting the energy available in the wind to mechanical energy that can be used to power machinery (grain mills, water pumps) and to operate an electrical generator.

A heat exchanger coil in which a fluid such as water is circulated and a fan blows air over the coil to distribute heat or cool air to the different rooms.

The downward facing structural element that is directly opposite the floor.

The amount of heat energy that may be converted into useful energy from a fuel.

The ratio of the maximum demand on an electricity generating and distribution system to the total connected load on the system; usually expressed as a percentage.

The heating capacity of a steam boiler; expressed in Btu per hour (Btu/h), or horsepower, or pounds of steam per hour.

A generic term for a glazed opening that allows daylight to enter into a building and can be opened for ventilation.

The complex process by which organic matter is decomposed by anaerobic bacteria. The decomposition process produces a gaseous byproduct often called "biogas" primarily composed of methane, carbon dioxide, and hydrogen sulfide.