Fahrenheit: A temperature scale in which the boiling point of water is 212 degrees and its freezing point is 32 degrees. To convert Fahrenheit to Celsius, subtract 32, multiply by 5, and divide the product by 9. For example:
Fan Coil: A component of a heating, ventilation and air conditioning system containing a fan and heating or cooling coil, used to distribute heated or cooled air.
Federal Energy Management Agency (FEMA): The federal agency in charge of disaster recovery in locations that have been declared disaster areas by a state's Governor and the President of the United States.
Federal Energy Regulatory Commission (FERC): An independent regulatory commission within the U.S. Department of Energy that has jurisdiction over energy producers that sell or transport fuels for resale in interstate commerce; the authority to set oil and gas pipeline transportation rates and to set the value of oil and gas pipelines for ratemaking purposes; and regulates wholesale electric rates and hydroelectric plant licenses.
Fenestration: In simplest terms, windows or glass doors. Technically, fenestration is described as any transparent or translucent material plus any sash, frame, mullion or divider. This includes windows, sliding glass doors, French doors, skylights, curtain walls and garden windows.
Fission: A release of energy caused by the splitting of an atom's nucleus. This is the energy process used in conventional nuclear power plants to make the heat needed to run steam electric turbines.
Fissionable Material: A substance whose atoms can be split by slow neutrons. Uranium–235, plutonium–239 and uranium–233 are fissionable materials.
Flat Plate: A device used to collect solar energy. It is a piece of metal painted black on the side facing the sun, to absorb the sun's heat.
Flexible Fuel Vehicle (FFV): A vehicle that can operate on either alcohol fuels such as methanol or ethanol or regular unleaded gasoline or any combination of the two from the same tank.
Flue Gas: Gas that is left over after fuel is burned and which is disposed of through a pipe or stack to the outer air.
Fluidized Bed Combustion: A process for burning powdered coal that is poured in a liquid–like stream with air or gases. The process reduces sulfur dioxide emissions from coal combustion.
Fluorescent Lamp: A tubular electric lamp that is coated on its inner surface with a phosphor and that contains mercury vapor whose bombardment by electrons from the cathode provides ultraviolet light which causes the phosphor to emit visible light either of a selected color or closely approximating daylight.
Fluorocarbon Gases: Propellants used in aerosol products and refrigerants that are believed to be causing depletion of the earth's ozone shield. See CFCs.
Force Majeure: A common law concept borrowed from the French civil law. "Force majeure" means superior or irresistible force that excuses a failure to perform. It has been defined by the United States Supreme Court as a cause that is "beyond the control and without the fault or negligence" of the party excused. Force majeure allows a company to allocate product or cease to deliver it altogether.
Forced Air Unit (FAU): A central furnace equipped with a fan or blower that provides the primary means for circulation of air.
Fractional Distillation: The process of refining crude oil into various oil products. The various products are separated out in the order of their boiling points.
Framing Effects: The effect of framing (wood or metal studs, joists, beams, etc.) on the overall U–value of a wall, roof, floor, window or other building surface. Framing generally increases the U–Value and decreases the R–Value of insulated surfaces.
Framing Percentage: The area of actual framing in an envelope assembly divided by the overall area of the envelope assembly. This percentage is used to calculate the overall U–Value of an assembly.
Frequency: The number of cycles which an alternating current moves through in each second. Standard electric utility frequency in the United States is 60 cycles per second, or 60 Hertz.
Fuel Cell: A device or an electrochemical engine with no moving parts that converts the chemical energy of a fuel, such as hydrogen, and an oxidant, such as oxygen, directly into electricity. The principal components of a fuel cell are catalytically activated electrodes for the fuel (anode) and the oxidant (cathode) and an electrolyte to conduct ions between the two electrodes, thus producing electricity.
Fuel Reprocessing (Nuclear): The means for obtaining usable, fissionable material from spent reactor fuel.
Fuel Rod (Nuclear): A long slender tube that holds fissionable material (fuel) for nuclear reactor use. Fuel rods are assembled into bundles called fuel elements or assemblies, which are loaded individually into the reactor core.
Fuel Security: See Energy Security.
Fusion Energy: A power source, now under development, based on the release of energy that occurs when atoms are combined under the most extreme heat and pressure. It is the energy process of the sun and the stars.