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.

States that energy cannot be created or destroyed, but only changed from one form to another. First Law efficiency measures the fraction of energy supplied to a device or process that it delivers in its output. Also called the law of conservation of energ ...

The amount of useful energy produced by a system less the amount of energy required to produce the fuel.

Features and vegetation on the outside of or surrounding a building for aesthetics and energy conservation.

A type of water heater that circulates water through a heat exchanger in a boiler. The heated water then flows into an insulated storage tank.

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.

One thousand kilowatts, or 1 million watts; standard measure of electric power plant generating capacity.

A wood-burning appliance for space and/or water heating and/or cooking.

A configuration of an electrical circuit in which the voltage is the same across the terminals. The positive reference direction for each resistor current is down through the resistor with the same voltage across each resistor.

The heat that flows from the building interior, through the building envelope to the outside environment.

A measure of the efficiency of converting a fuel to energy and useful work; useful work and energy output divided by higher heating value of input fuel times 100 (for percent).

A type of water heater that has no storage tank thus eliminating storage tank standby losses. Cold water travels through a pipe into the unit, and either a gas burner or an electric element heats the water only when needed.

An electrical inverter that inverts direct current electricity to alternating current electricity, and that uses another alternating current source, such as an electric power transmission and distribution network (grid), for voltage and frequency referenc ...

A hydrocarbon gas obtained from underground sources, often in association with petroleum and coal deposits. It generally contains a high percentage of methane, varying amounts of ethane, and inert gases; used as a heating fuel.

The ratio of the minimum amount of work or energy required to perform a task to the amount actually used.

The unit price of a good or service estimated from some base year in order to provide a consistent means of comparison.

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.

In reference to a wind energy conversion system, the area of a turbine blade surface that first comes into contact with the wind.

A house built using passive solar design techniques.

The process by which materials expel or release gasses.