A total life cycle cost divided into equal amounts.

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

see Peak Power

A device that measures the intensity of direct beam solar radiation.

An enzyme complex, produced by fungi and bacteria, capable of decomposing cellulose into small fragments, primarily glucose.

Turbines in which the rotor speed increases and decreases with changing wind speed, producing electricity with a variable frequency.

The component of a combustion device that regulates the amount of air entering the combustion chamber.

The pressure of the steam or water in a boiler as measured; usually expressed in pounds per square inch gauge (psig).

The ratio of solar collector array area to actual land area.

A means to increase the thermal efficiency of a steam electric generating system by converting some waste heat from the condenser into electricity. The heat engine in a bottoming cycle would be a condensing turbine similar in principle to a steam turbine ...

The mean wind speed over a specified period of time.

A light source composed of a metal base, a glass tube filled with an inert gas or a vapor, and base pins to attach to a fixture.

A drag-type wind machine that can react to wind from any direction.

The unit of magnetic field intensity equal to 1 dyne per unit pole.

A facility or piece of equipment that produces electricity.

A type of (geothermal) heat pump that uses well (ground) or surface water as a heat source. Water has a more stable seasonal temperature than air thus making for a more efficient heat source.

A device mounted in the vent connector that closes the vent when the heating unit is not firing. This traps heat inside the heating system and house rather than letting it draft up and out the vent system.

A heat storage system that uses a heat storage medium, and where the additional or removal of heat results in a change in temperature.

The housing around a motor that supports the active parts and protects them. They come in different varieties (open, protected) depending on the degree of protection required.

A compound used to make certain types of solar photovoltaic cells.