The presence of contaminants in the air in concentrations that prevent the normal dispersive ability of the air, and that interfere with biological processes and human economics.

That fraction of annual energy demand supplied by a solar system.

Water saturated or strongly impregnated with salt.

see Air-Source Heat Pump.

Electromagnetic radiation in the wavelength range of 4 to 400 nanometers.

A movable plate used to control air flow; in a wood stove or fireplace, used to control the amount and direction of air going to the fire.

A building architectural element (vestibule) with two airtight doors that reduces the amount of air infiltration and exfiltration when the exterior most door is opened.

A material or structural element that inhibits air flow into and out of a building's envelope or shell. This is a continuous sheet composed of polyethylene, polypropylene, or extruded polystyrene. The sheet is wrapped around the outside of a house during ...

A mechanical device used for air circulation and to provide cooling.

The process of determining energy consumption, by various techniques, of a building or facility.

The maximum heat output (in Btu per hour) released by a burner with a stable flame and satisfactory combustion.

An ideal substance that absorbs all radiation falling on it, and reflecting nothing.

In reference to solid biomass fuels, such as wood, having zero moisture content.

An opening; in solar collectors, the area through which solar radiation is admitted and directed to the absorber.

A unit for measuring the extent that the outdoor daily average temperature (the mean of the maximum and minimum daily dry-bulb temperatures) falls below (in the case of heating, see Heating Degree Day), or falls above (in the case of cooling, see Cooling ...

A type of hydroturbine in which the entire generator is mounted inside the water passageway as an integral unit with the turbine. These installations can offer significant reductions in the size of the powerhouse.

The ratio of light reflected by a surface to the light falling on it.

The total cost of production divided by the total quantity produced.

A device that cools air by removing moisture from it.

Consist of three main layers. The top layer is near ambient and has low salt content. The bottom layer is hot, typically 160 F to 212 F (71 C to 100 C), and is very salty. The important gradient zone separates these zones. The gradient zone acts as a tran ...