Ratio of useful energy output of a device to the energy input, averaged over an entire heating season.

A term used for a wind energy conversion device that produces electricity; typically having one, two, or three blades.

A type of turbine in which combusted, pressurized gas is directed against a series of blades connected to a shaft, which forces the shaft to turn to produce mechanical energy.

A heat absorbing reaction or a reaction that requires heat.

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

A type of lamp having a lens of heavy durable glass that focuses the light. They have longer lifetimes with less lumen depreciation than standard incandescents.

A type of heat pump that uses sealed horizontal or vertical pipes, buried in the ground, as heat exchangers through which a fluid is circulated to transfer heat.

The point or outdoor temperature where the heating capacity of a heat pump matches the heating requirements of a building.

A type of wind turbine in which the axis of rotation is perpendicular to the wind stream and the ground.

To heat a gaseous mixture to the temperature at which combustion takes place.

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

The process of transmitting electricity over one or more separately owned electric transmission and distribution systems. (See Wholesale and Retail Wheeling.)

A type of insulation, composed of small diameter pink, yellow, or white glass fibers, formed into blankets or batts, or used in loose-fill and blown-in applications.

The production of an electric current in a conductor by the variation of a magnetic field in its vicinity.

A group of wind turbines interconnected to a common utility system through a system of transformers, distribution lines, and (usually) one substation. Operation, control, and maintenance functions are often centralized through a network of computerized mo ...

The unit of illuminance equivalent to 1lumen per square meter.

A charge for the maximum rate at which energy is used during peak hours of a billing period. That part of a utility service charged for on the basis of the possible demand as distinguished from the energy actually consumed.

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 ...

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

The amount of energy service or useful energy delivered per unit of energy input. Often used in reference to lighting systems, where the visible light output of a luminary is relative to power input; expressed in lumens per Watt; the higher the efficacy v ...