The ratio of the minimum amount of work or energy required to perform a task to the amount actually used.

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

The total amount of electric energy loss in an electric system between the generation source and points of delivery.

A device that produces mechanical energy directly from two heat reservoirs of different temperatures. A machine that converts thermal energy to mechanical energy, such as a steam engine or turbine.

Thermosyphon systems use a separate storage tank located above the collector. Liquid warmed in the collector rises naturally above the collector, where it is kept until it is needed. The liquid can be either water or a glycol solution. If the fluid is wat ...

A measure of the average amount of a specified pollutant or material emitted for a specific type of fuel or process.

An aluminum foil fabricated insulator with backings applied to provide a series of closed air spaces with highly reflective surfaces.

The replacement of a non-functional or ineffective lamp with a new, more efficient lamp.

The process of producing electricity by transforming other forms or sources of energy into electrical energy; measured in kilowatt-hours.

The change in direction of a ray of light when it passes through one media to another with differing optical densities.

The ability to send or wheel electric power to a customer over a transmission and distribution system that is not owned by the generator (seller) of the power.

The amount of time required for positive cash flows to equal the total investment costs.

A lamp where the light beam is focused 2 inches ahead of the lamp reducing the amount of light trapped in the fixture.

The maximum value of natural solar insolation.

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 ...

The value of a personal portfolio, product, or investment after depreciation and interest on debt capital are subtracted from operating income. It can also be thought of as the equivalent worth of all cash flows relative to a base point called the present ...

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.

A configuration of an electrical circuit in which the positive lead is connected to the negative lead of another energy producing, conducting, or consuming device. The voltages of each device are additive, whereas the current is not.

An electricity generating facility that uses geothermal energy.

The amount (percent) of light that is reflected by a surface relative to the amount that strikes it.