The space between a hanging ceiling and the floor above or roof; usually contains HVAC ducts, electrical wiring, fire suppression system piping, etc.

A widely used rate of return for performing economic analysis. This method solves for the interest rate that equates the equivalent worth of an alternative's cash receipts or savings to the equivalent worth of cash expenditures, including investments. The ...

A popular term for energy produced from renewable energy resources.

A device in which organic material is biochemically decomposed (digested) by anaerobic bacteria to treat the material and/or to produce biogas.

The process by which sunlight directly enters a building through the windows and is absorbed and stored in massive floors or walls.

The amount of energy produced as a percentage of the amount of energy consumed.

A unit of illuminance; equal to one lumen per square foot.

The two times of the year when the sun is apparently farthest north and south of the earth's equator; usually occurring on or around June 21 (summer solstice in northern hemisphere, winter solstice for southern hemisphere) and December 21 (winter solstice ...

The transfer of heat by means of air currents.

Salt mixtures with potential applications as solar thermal energy storage materials.

A heating unit where heat is distributed by means of convection or fans.

The net south-facing glazing area projected on a vertical plane. Also, the solid area covered at any instant by a wind turbine's blades from the perspective of the direction of the windstream (as opposed to the swept area).

The process of storing, or converting energy from one form to another, for later use; storage devices and systems include batteries, conventional and pumped storage hydroelectric, flywheels, compressed gas, and thermal mass.

A solar photovoltaic device with a specified area.

A measure of the quality of a light source by expressing the color appearance correlated with a black body.

An arrangement of photovoltaic cells or material mounted on a rigid flat surface with the cells exposed freely to incoming sunlight.

Pounds of pressure per square inch.

The tendency of the sunlight to electricity conversion efficiency of amorphous silicon photovoltaic devices to degrade (drop) upon initial exposure to light.

The minimum temperature at which sufficient vapor is released by a liquid or solid (fuel) to form a flammable vapor-air mixture at atmospheric pressure.

The amount of solar energy that passes through a glazing material, expressed as a percentage.