A description of how well people in a lighted space can see to do visual tasks and how visually comfortable they feel in that space.

The amount of heat introduced to a space from all heat producing sources, such as building occupants, lights, appliances, and from the environment, mainly solar energy.

Alternating current is carried by conductors and a ground to residential, commercial, or industrial consumers. The waveform of the phase power appears as a single continuous sine wave at the system frequency whose amplitude is the rated voltage of the pow ...

Any coefficient used to calculate heat transmission by conduction, convection, or radiation through materials or structures.

A unit of pressure for a fluid, commonly used in water pumping and hydropower to express height a pump must lift water, or the distance water falls. Total head accounts for friction head losses, etc.

The process of cooling by which a heat absorbing media absorbs heat from one source and radiates the heat away.

All the components of the appliance used to condition interior air of a building.

A type of window glass that contains special tints that cause the window to absorb as much as 45% of incoming solar energy, to reduce heat gain in an interior space. Part of the absorbed heat will continue to be passed through the window by conduction and ...

To exceed the design capacity of a device.

Any gaseous, liquid, or solid fuel used for indoor space heating.

A gas that does not react with other substances; e.g. argon or krypton; sealed between two sheets of glazing to decrease the U-value (increase the R-Value) of windows.

The alignment of a building along a given axis to face a specific geographical direction. The alignment of a solar collector, in number of degrees east or west of true south.

A measure of the amount of light incident on a surface; measured in foot-candles or Lux.

Alternating current in which three separate pulses are present, identical in frequency and voltage, but separated 120 degrees in phase.

A measure of the number of cycles or wavelengths of electrical energy per second; U.S. electricity supply has a standard frequency of 60 hertz.

The space within a building or structure that is normally occupied by people, and that may be conditioned (heated, cooled and/or ventilated).

A generic term for an electrical conductor.

The flow of heat from one area to another by conduction, convection, and/or radiation. Heat flows naturally from a warmer to a cooler material or space.

A graph representing the relationship between the power available from the wind and the wind speed. The power from the wind increases proportionally with the cube of the wind speed.

An idealized process in which a working fluid (water, air, ammonia, etc) successively changes its state (from a liquid to a gas and back to a liquid) for the purpose of producing useful work or energy, or transferring energy.