A frequently used room or area that is maintained at a more comfortable level than the rest of the house; also known as a "warm room."

The highest wind speed at which a wind turbine stops producing power.

In reference to solar photovoltaic devices, the growth of one crystal on the surface of another crystal. The growth of the deposited crystal is oriented by the lattice structure of the original crystal.

Waste water from a household source other than a toilet. This water can be used for landscape irrigation depending upon the source of the greywater.

A type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0.13 to 1.3 Pascal. The yellow light and large size make them applicable to lighting streets and parking lots.

A method of controlling a wind turbine's speed by varying the orientation, or pitch, of the blades, and thereby altering its aerodynamics and efficiency.

Air that provides the necessary oxygen for complete, clean combustion and maximum heating value.

A solar collector in which the absorber is contained in a sealed glass tube, thereby providing for relatively high temperature heat gain.

Ethyl alcohol (C2H5OH)

The direct, diffuse, and reflected solar radiation that strikes a surface.

The temperature of the air as measured by a standard thermometer.

The heat produced by combusting a specific quantity and volume of fuel in an oxygen-bomb colorimeter under specific conditions.

The vacancy where an electron would normally exist in a solid; behaves like a positively charged particle.

A battery that uses lithium in the negative electrode and a metal sulfide in the positive electrode, and the electrolyte is molten salt; can store large amounts of energy per unit weight.

A popular term used for an evaporative cooling device.

The process of converting municipal solid waste to energy and/or recovering materials for recycling.

A term used to describe a technologically advanced window system that contains glazing that can change or switch its optical qualities when a low voltage electrical signal is applied to it, or in response to changes in heat or light.

Nonglossy paint with a relatively high absorptance.

An electric current taking a shorter or different path than intended.

Any wholly or partially enclosed space in which combustion takes place.