A type of house that has massive amounts of insulation, airtight construction, and controlled ventilation without sacrificing comfort, health, or aesthetics.

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

A particle of light that acts as an individual unit of energy.

The component of a solar energy heating system that collects solar radiation, and that contains components to absorb solar radiation and transfer the heat to a heat transfer fluid (air or liquid).

The relative extent that energy is required for a process.

A toilet that uses less water than a standard one during flushing, for the purpose of conserving water resources.

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

The amount of heated air, or heating capacity, to be supplied by a heating system; usually the maximum amount to be delivered based on a specified number of heating degree days or design outside temperature.

To influence the demand on a power source.

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

Infrared or radiant heat.

A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device.

Sunlight scattered by atmospheric particles and gases so that it arrives at the earth's surface from all directions and can not be focused.

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

In reference to solar photovoltaic devices, the growth of one crystal on the surface of another crystal. The growth of the deposited crystal is oriented by the lattice structure of the original crystal.

The number of cycles through which an alternating current passes per second; in the U.S. the standard for electricity generation is 60 cycles per second (60 Hertz).

A law that requires electric utilities to purchase electricity produced from qualifying power producers that use renewable energy resources or are cogenerators. Utilities are required to purchase power at a rate equal to the avoided cost of generating the ...

A building with more than 50 percent of its floorspace used for commercial activities, which include stores, offices, schools, churches, libraries, museums, health care facilities, warehouses, and government buildings except those on military bases.

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 group of solar photovoltaic modules connected together.