The loss in static pressure of a fluid (liquid or gas) in a system due to friction from obstructions in pipes, from valves, fittings, regulators, burners, etc, or by a breech or rupture of the system. Pressurization Testing

A device that removes airborne particles from breathable air. Negative ions are produced and give up their negative charge to the particles. These new negative particles are then attracted to the positive particles surrounding them. This accumulation proc ...

In reference to solar photovoltaic cell manufacure, a method of growing a large-size, high-quality crystal whereby coils heat a polycrystalline ingot placed atop a single-crystal seed. As the coils are slowly raised the molten interface beneath the coils ...

A power plant that produces electricity by the force of water falling through a hydro turbine that spins a generator.

In reference to solar thermal collectors, the condition where the heat transfer fluid is flowing through the collector loop under normal operating conditions.

The push or pull that alters the motion of a moving body or moves a stationairy body; the unit of force is the dyne or poundal; force is equal to mass time velocity divided by time.

A system in which a working fluid is used over and over without introduction of new fluid, as in a hydronic heating system or mechanical refrigeration system.

The material through which electricity is transmitted, such as an electrical wire, or transmission or distribution line.

A building with more than 50 percent of its floorspace used for commercial activities, which include stores, offices, schools, churches, libraries, museums, health care facilities, warehouses, and government buildings except those on military bases.

Sunlight scattered by atmospheric particles and gases so that it arrives at the earth's surface from all directions and can not be focused.

A type of heating system that provides heat from the resistance of an electrical current flowing through a conductor.

A slightly sloped roof, usually with a tar and gravel cover. Most commercial buildings use this kind of roof.

A device used to regulate motor speed, or, in a wind energy conversion system, to control the rotational speed of the rotor.

One millionth of a meter (10-6 m).

A high-efficiency photovoltaic device containing two or more cell junctions, each of which is optimized for a particular part of the solar spectrum.

The number of cycles through which an alternating current passes per second; in the U.S. the standard for electricity generation is 60 cycles per second (60 Hertz).

A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device.

Metal, usually galvanized sheet metal, used to provide protection against infiltration of precipitation into a roof or exterior wall; usually placed around roof penetrations such as chimneys.

A building heating, ventilation, and/or air conditioning system that distributes conditioned air to individual zones or rooms.

A passage for surplus water to flow over or around a dam.