SubdivisionA subdivision occurs as the result of dividing land into lots for sale or development.
Subdivision Rules and RegulationsProcedures, requirements, and provisions governing the subdivision of land that is specified in formal Rules and Regulations promulgated by a city or town…
SubdrainageA land area (basin) bounded by ridges or similar topographic features, encompassing only part of a watershed.
SubsidenceSinking or settlement of the land surface, due to any of several processes. As commonly used, the term relates to the vertical downward movement of…
SubsistenceThe practices by which a group or individual acquires food, such as through hunting and gathering, fishing, and agriculture.
SubstationAn electrical installation containing power conversion (and sometimes generation) equipment, such as transformers, compensators, and circuit breakers.
Substrate1. A compound that is altered by an enzyme. 2. Food source for growing cells or micro-organisms. 3. Material on which a sedentary organism lives and grows.
SuccessionA series of dynamic changes by which one group of organisms succeeds another through stages leading to potential natural community or climax.
Sulfur dioxide (SO<sub>2</sub>)(SO2)SO2 is a key pollutant in the formation of acid rain and contributes to the formation of fine particles that are associated with significant negative…
Sulfur oxides (SO<sub>x</sub>)(SOx)Compounds containing sulfur and oxygen, such as sulfur dioxide (SO2) and sulfur trioxide (SO3).
Sun Path DiagramA circular projection of the sky vault onto a flat diagram used to determine solar positions and shading effects of landscape features on a solar energy…
Sun Tempered BuildingA building that is elongated in the east-west direction, with the majority of the windows on the south side.
Sunk costA cost already incurred and therefore not considered in making a current investment decision.
SunspaceA room that faces south (in the northern hemisphere), or a small structure attached to the south side of a house.
Super Insulated HousesA type of house that has massive amounts of insulation, airtight construction, and controlled ventilation without sacrificing comfort, health, or…
Super WindowA popular term for highly insulating window with a heat loss so low it performs better than an insulated wall in winter, since the sunlight that it admits…
Superconducting Magnetic Energy Storage (SMES)(SMES)SMES technology uses the superconducting characteristics of low-temperature materials to produce intense magnetic fields to store energy.
SuperconductivityThe abrupt and large increase in electrical conductivity exhibited by some metals as the temperature approaches absolute zero.
Superheated steamSteam at a given pressure which is above the temperature which corresponds to boiling temperature at that given pressure.
Supplementary HeatA heat source, such as a space heater, used to provide more heat than that provided by a primary heating source.
Supply DuctThe duct(s) of a forced air heating/cooling system through which heated or cooled air is supplied to rooms by the action of the fan of the central heating…
Supply SideTechnologies that pertain to the generation of electricity.
Surface expressionRefers to the physical expression of seismic activity at the ground exterior in the form of a fault rupture or fissure.
Surface ruptureThe breakage of ground along the surface trace of a fault caused by the intersection of the fault surface area ruptured in an earthquake with the Earth's…
Surface textureThe visual manifestations of the interplay of light and shadow created by the variations in the top of an object or landscape.
Surface WaterWater on the Earth's surface that is directly exposed to the atmosphere, as distinguished from water in the ground (groundwater).
Surface Water LoopIn this type of closed-loop geothermal heat pump installation, the fluid-filled plastic heat exchanger pipes are coiled into circles and submerged at…
Surplus electricityElectricity produced by cogeneration equipment in excess of the needs of an associated factory or business.
Suspended solidsWaste particles suspended in water. Suspended solids can harbor harmful microorganisms and toxic chemicals.
SustainableAn ecosystem condition in which biodiversity, renewability, and resource productivity are maintained over time.
Sustainable DevelopmentDevelopment with the goal of preserving environmental quality, natural resources and livability for present and future generations.
Sustained yieldThe maintenance in perpetuity of regular, periodic harvest of wood resources from forest land without damaging the productivity of the land.
SwaleA low place in a tract of land, usually moister, and often having denser vegetation than the adjacent higher land.
Swamp CoolerA popular term used for an evaporative cooling device.
SwapsAn exchange of streams of payments over time according to specified terms. A common type is a fixed-for-floating swap, in which one party agrees to pay a…
Swarm (seismic swarm)A localized surge of earthquakes, with no one shock being conspicuously larger than all other shocks of the swarm.
Swept AreaIn reference to a wind energy conversion device, the area through which the rotor blades spin, as seen when directly facing the center of the rotor blades.
Synchronous GeneratorAn electrical generator that runs at a constant speed and draws its excitation from a power source external or independent of the load or transmission…
Synchronous InverterAn electrical inverter that inverts direct current electricity to alternating current electricity, and that uses another alternating current source, such…
Synchronous MotorA type of motor designed to operate precisely at the synchronous speed with no slip in the full-load speeds (rpm).
SyngasA syntheses gas produced through gasification of biomass. Syngas is similar to natural gas and can be cleaned and conditioned to form a feedstock for…
syringylA component of lignin, normally only found in hardwood lignins. It has a six-carbon aromatic ring with two methoxyl groups attached.
System MixThe proportion of electricity distributed by a power provider that is generated from available sources such as coal, natural gas, petroleum, nuclear…
Tailpipe EmissionsEmissions produced through fuel combustion during a vehicle's operation.
TakeUnder the Bald and Golden Eagle Protection Act, it means to pursue, shoot, shoot at, poison, wound, kill, capture, trap, collect, destroy, molest, or…
TakingA taking occurs when a government action violates the 5th Amendment property rights of a landowner by taking a piece of property without offering fair…
TallowAnimal fat that can be used to produce biodiesel.
TalusRock debris accumulated at the base of the cliff or slope from which they have broken off.
Tankless Water HeaterA water heater that heats water before it is directly distributed for end use as required; a demand water heater.
TARA liquid product of thermal processing of carbonaceous materials.
Task LightingAny light source designed specifically to direct light a task or work performed by a person or machine.
Tax Increment FinancingA program designed to leverage private investment for economic development projects in a manner that enhances the benefits accrued to the public interest.
TaxonomyThe science of categorization, or classification, of things based on a predetermined system.
Technical Response ServiceFor assistance with technical questions about alternative fuels and advanced vehicles, email the Technical Response Service at technicalresponse@icfi.
TectonicRefers to the rock-deforming processes and resulting structures that occur over large sections of the lithosphere.
Temperature Humidity IndexAn index that combines sensible temperature and air humidity to arrive at a number that closely responds to the effective temperature; used to relate…
Temperature ZonesIndividual rooms or zones in a building where temperature is controlled separately from other rooms or zones.
Temperature/Pressure Relief ValveA component of a water heating system that opens at a designated temperature or pressure to prevent a possible tank, radiator, or delivery pipe rupture.
Tempering ValveA valve used to mix heated water with cold in a heating system to provide a desired water temperature for end use.
Tennessee Valley Authority (TVA)(TVA)A federal agency established in 1933 to develop the Tennessee river valley region of the southeastern U.S.
TephraA general term for fragments of volcanic rock and lava, regardless of size, that are blasted into the air by explosions or carried upward by hot gases in…
Termite ShieldA construction element that inhibits termites from entering building foundations and walls.
TerraceA step-like surface, bordering a valley floor or shoreline, that represents the former position of a floodplain, lake, or sea shore.
TerrainTopographic layout and features of a tract of land or ground.
Tertiary periodThe earliest period of the Cenozoic era, beginning about 65 million years ago and ending 2.6 million years ago.
Tertiary volcanics (Tv)(Tv)Volcanic rocks deposited during the Tertiary period (between 2.8 and 65 million years ago).
TextureThe visual manifestations of light and shadow created by the variations in the surface of an object or landscape.
Texture contrastsVisual contrasts between different objects or landscapes resulting from different visual manifestations of the interplay of light and shadow created by…
ThermA unit of heat containing 100,000 British thermal units (Btu).
Thermal Balance PointThe point or outdoor temperature where the heating capacity of a heat pump matches the heating requirements of a building.
Thermal CapacitanceThe ability of a material to absorb and store heat for use later.
Thermal coverVegetative condition, generally with greater than 70% canopy closure and 40 feet in height, that can significantly ameliorate weather effects such as…
Thermal EfficiencyA measure of the efficiency of converting a fuel to energy and useful work; useful work and energy output divided by higher heating value of input fuel…
Thermal EnergyThe energy developed through the use of heat energy.
Thermal Energy StorageThe storage of heat energy during power provider off-peak times at night, for use during the next day without incurring daytime peak electric rates.
Thermal Envelope HousesAn architectural design (also known as the double envelope house), sometimes called a "house-within-a-house," that employs a double envelope with a…
Thermal inertiaThe amount of heat energy that must be present in, preserved, or added to a system (in this case, a CSP facility) before it can function as designed.
Thermal Resistance (R-Value)This designates the resistance of a material to heat conduction. The greater the R-value the larger the number.
Thermal resourceA facility that produces electricity by using a heat engine to power an electric generator.
Thermal Storage Walls (Masonry or Water)A thermal storage wall is a south-facing wall that is glazed on the outside. Solar heat strikes the glazing and is absorbed into the wall, which conducts…
Thermal waterA water body (usually a spring or its outflow) that is produced by geothermally heated groundwater.
ThermochemicalHeat and pressure-based chemical reactions that produce energy. Through gasification (heating biomass by partial oxidation to produce synthesis gas) and…
thermochemical conversionThe use of heat to change substances chemically to produce energy products.
ThermocoupleA device consisting of two dissimilar conductors with their ends connected together.
Thermodynamic CycleAn idealized process in which a working fluid (water, air, ammonia, etc) successively changes its state (from a liquid to a gas and back to a liquid) for…
ThermodynamicsA study of the transformation of energy from one form to another, and its practical application. (see Law(s) of Thermodynamics above).
Thermoelectric (power) water useWater used in generating electricity with steam-driven turbine generators. Power plants that burn coal and oil are examples of thermoelectric-power…
Thermography(ther-MAH-gruh-fee) In medicine, a procedure in which a heat-sensing infrared camera is used to record the surface heat produced by different parts of the…
Thermophotovoltaic CellA device where sunlight concentrated onto a absorber heats it to a high temperature, and the thermal radiation emitted by the absorber is used as the…
ThermopileA large number of thermocouples connected in series.
ThermosiphonThe natural, convective movement of air or water due to differences in temperature.
Thermosiphon SystemThis passive solar hot water system consists relies on warm water rising, a phenomenon known as natural convection, to circulate water through the…
ThermostatA device used to control temperatures; used to control the operation of heating and cooling devices by turning the device on or off when a specified…
Thin filmA layer of semiconductor material, such as copper indium diselenide or gallium arsenide, a few microns or less in thickness, used to make solar…