The ratio of the percentage change in the quantity of a good or service demanded to the percentage change in the price.

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 area of glass that fits in the window frame.

The rate of heat flow required to maintain a specific indoor temperature; usually measured in Btu per hour.

Any device (or plant) that follows the sun's apparent movement across the sky.

A mainly flat surface for transmitting radiant energy.

In a given electrical circuit, the amount of current in amperes (i) is equal to the pressure in volts (V) divided by the resistance, in ohms (R).

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

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 measure of the amount of energy lost during the generation, transmission, and distribution of electricity.

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

Materials with various qualities that are applied to glass windows before installation. These coatings reduce radiant heat transfer through the window and also reflects outside heat and a portion of the incoming solar energy, thus reducing heat gain. The ...

A type of heating appliance similar to a fireplace, but much more efficient and clean burning. They are made of masonry and have long channels through which combustion gases give up their heat to the heavy mass of the stove, which releases the heat slowly ...

An elementary particle of an atom with a negative electrical charge and a mass of 1/1837 of a proton; electrons surround the positively charged nucleus of an atom and determine the chemical properties of an atom.

An electricity generating facility that uses geothermal energy.

A type of incandescent lamp with an interior coating of aluminum that reflects light to the front of the bulb. They are designed to spread light over specific areas.

Energy produced by the conversion of biomass directly to heat or to a liquid or gas that can be converted to energy.

Energy output from a system that equals energy input.

One thousand kilowatt-hours or 1 million watt-hours.

Power generated by a utility unit that operates at a very low capacity factor; generally used to meet short-lived and variable high demand periods.