A method of financial and economic analysis used to determine present and future values of investments or expenses.

A window located on the roof of a structure to provide interior building spaces with natural daylight, warmth, and ventilation.

Freshly cut, unseasoned, wood.

A plot of a wind energy conversion device's power output versus wind speed.

A coating applied to the surface of the glazing of a window to reduce heat transfer through the window.

A chemical element, of atomic number 14, that is semi-metallic, and an excellent semiconductor material used in solar photovoltaic devices; commonly found in sand.

A measure of the unavailable or unusable energy in a system; energy that cannot be converted to another form.

The region between an n-layer and a p-layer in a single material, photovoltaic cell.

A type of anaerobic digester that has a horizontal tank in which a constant volume of material is added and forces material in the tank to move through the tank and be digested.

Energy that is capable or available for doing work; the time rate at which work is performed, measured in horsepower, Watts, or Btu per hour. Electric power is the product of electric current and electromotive force.

The amount of energy produced as a percentage of the amount of energy consumed.

A renewable energy system that includes two different types of renewable energy technologies that produce the same type of energy; for e.g., a wind turbine and a solar photovoltaic array combined to meet a power demand.

The interior area of a building, calculated in square feet or meters.

A water and energy conserving device that limits the amount of water that a faucet or showerhead can deliver.

The fossil fuels: coal, oil, and natural gas.

Solar energy systems that collect or absorb solar energy for useful purposes. Can be used to generate high temperature heat (for electricity production and/or process heat), medium temperature heat (for process and space/water heating and electricity gene ...

see Solar Spectrum above.

The air that is supplied to the combustion chamber of a furnace.

The power required to energize the magnetic field of a generator.

Usually refers to ethanol to 160 to 200 proof.