The unit price of a good or service estimated from some base year in order to provide a consistent means of comparison.

The total diffuse and direct insolation on a horizontal surface, averaged over a specified period of time.

A salt, sodium sulfate decahydrate, that melts at 90 degrees Fahrenheit; a component of eutetic salts that can be used for storing heat.

A corporation, person, agency, authority or other legal entity that owns and/or operates facilities for the generation, transmission, distribution or sale of electricity primarily for use by the public.

In reference to a wind energy conversion system, the area of a turbine blade surface that first comes into contact with the wind.

The price paid for goods or services at the time of a transaction; a price that has not been adjusted to account for inflation.

An instrument for measuring solar radiation.

Solar collector thermal performance ratings based on collector efficiencies, usually expressed in Btu per hour for solar collectors under standard test or operating conditions for solar radiation intensity, inlet working fluid temperatures, and ambient te ...

A hydrocarbon gas obtained from underground sources, often in association with petroleum and coal deposits. It generally contains a high percentage of methane, varying amounts of ethane, and inert gases; used as a heating fuel.

A house built using passive solar design techniques.

The ratio of fuel energy input as heat per unit of net work output; a measure of a power plant thermal efficiency, generally expressed as Btu per net kilowatt-hour.

The minimum temperature at which combustion of a solid or fluid can occur.

A valve used to mix heated water with cold in a heating system to provide a desired water temperature for end use.

A coil of tungsten wire suspended in a vacuum or inert gas-filled bulb. When heated by electricity the tungsten "filament" glows.

The amount of heat that a material can absorb and store.

A building energy auditing technique for locating areas of low insulation in a building envelope by means of a thermographic scanner.

A solar energy conversion device that has a bowl shaped dish covered with a highly reflective surface that tracks the sun and concentrates sunlight on a fixed absorber, thereby achieving high temperatures, for process heating or to operate a heat (Stirlin ...

In alternating current, the current goes from zero potential or voltage to a maximum in one direction, back to zero, and then to a maximum potential or voltage in the other direction. The number of complete cycles per second determines the current frequen ...

A mainly flat surface for transmitting radiant energy.

A heating system that uses only outside air for combustion and vents combustion gases directly to the outdoors. These systems are less likely to backdraft and to negatively affect indoor air quality.