A heat exchanger in a solar water heating system that has two distinct walls between the heat transfer fluid and the domestic water, to ensure that there is no mixing of the two.

Water heated for residential washing, bathing, etc.

The amount of money required to secure a specified cash flow at a future date at a specified return.

The unoccupied, and usually unfinished and unconditioned space between the floor, foundation walls, and the slab or ground of a building.

The relative extent that energy is required for a process.

This type of heat pump is known as an air-to air system.

A utility owned by stockholders or other investors; sometimes referred to as a private utility, in contrast to a public utility that is owned by a government agency or cooperative.

An energy band in a semiconductor in which electrons can move freely in a solid, producing a net transport of charge.

One millionth of a meter (10-6 m).

A device or material with a high resistance to electricity flow.

A building heating, ventilation, and/or air conditioning system that distributes conditioned air to individual zones or rooms.

The ratio of actual power being used in a circuit, expressed in watts or kilowatts, to the power that is apparently being drawn from a power source, expressed in volt-amperes or kilovolt-amperes.

The physical process by which a liquid or solid is transformed into the gaseous state. For this process a mechanical device uses the outside air's heat to evaporate water that is held by pads inside the cooler. The heat is drawn out of the air through thi ...

A colorless, odorless, tasteless gas composed of one molecule of Carbon and four of hydrogen, which is highly flammable. It is the main constituent of "natural gas" that is formed naturally by methanogenic, anaerobic bacteria or can be manufactured, and w ...

Waste water from a household source other than a toilet. This water can be used for landscape irrigation depending upon the source of the greywater.

A curve that displays load values on the horizontal axis in descending order of magnitude against the percent of time (on the vertical axis) that the load values are exceeded.

A power plant that produces electricity by the force of water falling through a hydro turbine that spins a generator.

Infrared or radiant heat.

In reference to solar thermal collectors, the condition where the heat transfer fluid is flowing through the collector loop under normal operating conditions.

A concrete pad that sits on gravel or crushed rock, well-compacted soil either level with the ground or above the ground.