The angle between true south and the point on the horizon directly below the sun.

The flow of air down a flue/chimney and into a house caused by low indoor air pressure that can occur when using several fans or fireplaces and/or if the house is very tight.

The pressure of the air at sea level; one standard atmosphere at zero degrees centigrade is equal to 14.695 pounds per square inch (1.033 kilograms per square centimeter).

An outdoor temperature, usually 20 to 45 degrees Fahrenheit, at which a heatpump's output equals the heating demand. Below the balance point, supplementary heat is needed.

An energy storage device composed of one or more electrolyte cells.

The heat liberated by the combustion of a unit quantity of a fuel under specific conditions; measured in calories.

A method for making sheets of polycrystalline silicon (for solar photovlotaic devices) in which molten silicon is drawn upward by capillary action through a mold.

Fans in which the direction of the flow of the air from inlet to outlet remains unchanged; includes propeller, tubaxail, and vaneaxial type fans.

A generator producing alternating current by the rotation of its rotor, and which is powered by a primary mover.

The fibrous material remaining after the extraction of juice from sugarcane; often burned by sugar mills as a source of energy.

Solar radiation that is not scattered by dust or water droplets.

A type of air compressor in which air is compressed in a series of stages as it flows axaily through a decreasing tubular area.

Single-celled organisms, free-living or parasitic, that break down the wastes and bodies of dead organisms, making their components available for reuse by other organisms.

A solar day; an interval between successive transits of the sun's center across an observer's meridian; the time thus measured is not equal to clock time.

A device for optimizing the anaerobic digestion of biomass and/or animal manure, and possibly to recover biogas for energy production. Digester types include batch, complete mix, continuous flow (horizontal or plug-flow, multiple-tank, and vertical tank), ...

The ratio of light output of a fluorescent lamp operated on a ballast to the light output of a lamp operated on a standard or reference ballast.

The amount of heat given off by a person at rest in a comfortable environment; approximately 50 Btu per hour (Btu/h).

The amount of money needed to purchase equipment, buildings, tools, and other manufactured goods that can be used in production.

The non-combustible residue of a combusted substance composed primarily of alkali and metal oxides.

A turbine in which the flow of a steam or gas is essentially parallel to the rotor axis.