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.

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

The weight of oxygen taken up mainly as a result of the oxidation of the constituents of a sample of water by biological action; expressed as the number of parts per million of oxygen taken up by the sample from water originally saturated with air, usuall ...

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

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

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 building construction technique used to create a continuous air retarder that uses the drywall, gaskets, and caulking. Gaskets are used rather than caulking to seal the drywall at the top and bottom. Although it is an effective energy-saving technique, ...

The minimum demand experienced by a power plant.

The grilled opening into a room by which the amount of warm air from a furnace can be directed or controlled; may include a damper.

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

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

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

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

The ratio of the average load on (or power output of) a generating unit or system to the capacity rating of the unit or system over a specified period of time.

The component of a combustion device that regulates the amount of air entering the combustion chamber.

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

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

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.