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.

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.

A device that converts heat or sunlight directly to electricity, invented by Standford Ovshinsky, that has a unique glass composition that changes from an electrically non-conducting state to a semiconducting state.

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 ...

The price paid for goods or services at the time of a transaction; a price that has not been adjusted to account for inflation.

Site planning that accounts for natural solar heating and cooling processes and their relationship to building shape, orientation, and siting.

A type of motor designed to operate precisely at the synchronous speed with no slip in the full-load speeds (rpm).

A coil of tungsten wire suspended in a vacuum or inert gas-filled bulb. When heated by electricity the tungsten "filament" glows.

A company or individual that is not directly regulated as a utility. These entities produce power for their own use and/or sell it to regulated utilities.

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.

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

The change in heat content that occurs with a change in phase and without change in temperature.

The regular periodic arrangement of atoms or molecules in a crystal of semiconductor material.

The rate at which electricity is delivered to or by a system, part of a system, or piece of equipment expressed in kilowatts, kilovoltamperes, or other suitable unit, at a given instant or averaged over a specified period of time.

The ratio of the percentage change in the quantity of a good or service demanded to the percentage change in the price.

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 thermodynamic cycle that is an ideal standard for comparing performance of heat-engines, steam power plants, steam turbines, and heat pump systems that use a condensable vapor as the working fluid; efficiency is measured as work done divided by sensib ...

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.

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

To exceed the design capacity of a device.