The angular position of the sun at solar noon with respect to the plane of the equator.

A naturally occurring radioactive gas found in the U.S. in nearly all types of soil, rock, and water. It can migrate into most buildings. Studies have linked high concentrations of radon to lung cancer.

A device used to simulate the angle of the sun for assessing shading potentials of building structures or landscape features.

The amount of BTU's/hour or kW's produced by a heating system from the burning of a fuel.

The amount of heat energy that may be converted into useful energy from a fuel.

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 two step process where in the first step natural gas is exposed to a high-temperature steam to produce hydrogen, carbon monoxide, and carbon dioxide. The second step is to convert the carbon monoxide with steam to produce additional hydrogen and carbon ...

A term used for a wind energy conversion device that produces electricity; typically having one, two, or three blades.

A type of vertical-axis wind machine that has long, thin blades in the shape of loops connected to the top and bottom of the axle; often called an "eggbeater windmill."

The interior heat gain due to heat conduction, convection, and radiation from the exterior into the interior, and from occupants and appliances.

A facility or piece of equipment that produces electricity.

A type of (geothermal) heat pump that uses well (ground) or surface water as a heat source. Water has a more stable seasonal temperature than air thus making for a more efficient heat source.

The wind speed and direction in an undisturbed flow.

Ratio of useful energy output of a device to the energy input, averaged over an entire heating season.

Houses that have earth berms around exterior walls.

A type of insulation material with fine, closed cells, containing a mixture of air and refrigerant gas. This insulation has a high R-value, good moisture resistance, and high structural strength compared to other rigid insulation materials.

A type of heat pump that uses sealed horizontal or vertical pipes, buried in the ground, as heat exchangers through which a fluid is circulated to transfer heat.

The housing around a motor that supports the active parts and protects them. They come in different varieties (open, protected) depending on the degree of protection required.

The maximum possible voltage across a photovoltaic cell; the voltage across the cell in sunlight when no current is flowing.

A drag-type wind machine that can react to wind from any direction.