In reference to a wind energy conversion device, the area through which the rotor blades spin, as seen when directly facing the center of the rotor blades.

A device used to interrupt or break an electrical circuit when an overload condition exists; usually installed in the positive circuit; used to protect electrical equipment.

A term used for lighting appliances; the ratio of lumens received on a flat surface to the light output, in lumens, from a lamp; used to evaluate the effectiveness of luminaries in delivering light.

A device for removing heat from a gas or liquid stream for air conditioning/cooling.

A process for making inexpensive Galium Arsenide (GaAs)photovoltaic cells in which a thin film of GaAs is grown atop a thick, single-crystal GaAs (or other suitable material) substrate and then is cleaved from the substrate and incorporated into a cell, a ...

A popular term used for a length of wood or steel used in or for wall framing.

The sum of the sensible and latent heat in a substance or fluid above a base point, usually 32 degrees Fahrenheit.

An electric motor rated at less than one horse power (hp).

A type of insulation made from virgin basalt, an igneous rock, and spun into loose fill or a batt. It is fire resistant and helps with soundproofing.

A company that specializes in undertaking energy efficiency measures under a contractual arrangement whereby the ESCo shares the value of energy savings with their customer.

The energy liberated in a chemical reaction, as in the combustion of fuels.

A region of electrical contact between two different materials.

A type of power generating facility that pumps water to a storage reservoir during off-peak periods, and uses the stored water (by allowing it to fall through a hydro turbine) to generate power during peak periods. The pumping energy is typically supplied ...

A window located high in a wall near the eaves that allows daylight into a building interior, and may be used for ventilation and solar heat gain.

A slab floor that sits directly on top of the surrounding ground.

An apparatus for measuring force or power, especially the power developed by a motor.

The ratio of chemical substances necessary for a reaction to occur completely.

A free and mobile conduction electron or hole in a semiconductor.

A liquid byproduct of wood combustion (or distillation) that condenses on the internal surfaces of vents and chimneys, which if not removed regularly, can corrode the surfaces and fuel a chimney fire.

An energy saving device in a heat pump that, during the cooling cycle, recycles some of the waste heat from the house to heat domestic water.