The capability of doing work; different forms of energy can be converted to other forms, but the total amount of energy remains the same.

A water heater that uses electricity to move heat from one place to another instead of generating heat directly.

For a wind turbine, the ratio of the speed of the tip of a turbine blade for which the power coefficient is at maximum.

A type of passive solar heating system where heat is collected in one area for use in another.

A unit of air cooling capacity; 12,000 Btu per hour.

A wall with high thermal mass used to store solar energy passively in a solar home. The wall absorbs solar energy and transfers it to the space behind the wall by means of radiation and by convection currents moving through spaces under, in front of, and ...

Defects, such as dangling bonds, induced in an amorphous silicon semiconductor upon initial exposure to light.

This represents three layers of glazing in a window with an airspace between the middle glass and the exterior and interior panes.

The load-carrying ability of an electric power plant during a specific time interval and period when related to the characteristics of the load to be/being supplied; determined by capability, operating power factor, and the portion of the load the station ...

The length of time that a product or appliance is expected to meet a certain level of performance under nominal operating conditions; in a luminaire, the period after which the lumen depreciation and lamp failure is at 70% of its initial value.

The structural materials and elements used to construct a wall.

An electromagnetic device that changes the voltage of alternating current electricity. It consists of an induction coil having a primary and secondary winding and a closed iron core.

An architectural feature used to shade exterior walls; usually made of a lattice of metal or wood; often covered by vines to provide additional summertime shading.

A measure of window glazing performance that is the ratio of the total solar heat gain through a specific window to the total solar heat gain through a single sheet of double-strength glass under the same set of conditions; expressed as a number between 0 ...

A region of electrical contact between two different materials.

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

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.

Also known as "power towers," these use fields of two-axis tracking mirrors known as heliostats. Each heliostat is individually positioned by a computer control system to reflect the sun's rays to a tower-mounted thermal receiver. The effect of many helio ...

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 ...

The voltage developed across a cell by the current flow through the resistance of the cell.