Glossary: S to U
A-C | D-F | G-I | J-L | M-O | P-R | S-U | V-Z
S
Site preservation: Site preservation is the minimal disruption of a building on its surrounding environment. Building reuse and use of existing building sites as opposed to previously unused land are the most impactful forms of site preservation. Buildings should not be located on sites that are environmentally fragile and should not interfere with the land’s natural hydrologic functions. Reducing stormwater runoff and using original trees and vegetation are additional ways to maintain the natural landscape.
Siting: The process of choosing a location for an electric generator. Siting is a particularly critical step for wind turbines, which can have significant impacts on local environments if not sited correctly. Siting not only entails selection of a site but also the process of involving a community, approval boards, and others in determining where a generator should be located.
Smog: Smog is air pollution mainly consisting of ozone and nitrogen oxides, which creates a visible brownish haze (particularly in cities in the summer). Smog can cause breathing problems and greatly reduces visibility in the air. Power plants and vehicles are major causes of smog. Learn more about smog from the U.S. Environmental Protection Agency.
Solar heating: Solar heating converts the sun’s power into heat for hot water, space heating, and swimming pools. Passive solar heating uses large windows to let in more light and warmth, while active solar heating uses specially designed mechanical systems to intensify the sun’s heat for use indoors. To learn more about solar heating, visit the U.S. Department of Energy’s Solar Heating website.
Solar hot water: The sun’s power can be used to heat water in homes and commercial buildings, which reduces the need for electricity and fossil fuel use in water heating. Solar energy is collected and used to heat the water, which is then stored in a tank. A conventional system provides extra heat as necessary. Active or passive systems can be installed. To learn more, visit the U.S. Department of Energy’s Solar Water Heating website.
Solar photovoltaics (PV): PV converts sunlight directly into electricity. PV is made from semiconductor materials, and does not create any pollution, noise, or other impacts on the environment. Homes and businesses may incorporate solar panels and arrays as a source of clean energy. Learn more about solar photovoltaics.
Solar photovoltaic array: A series of PV panels can be connected to each other to form an array of any size to provide the electricity needed for a home, office, or larger facility.
Solar photovoltaic cell: A PV cell is the most basic element of a solar photovoltaic system. Each cell is made from semiconductor materials, and creates an electrical charge in reaction to sunlight that can be transformed into a current of electricity.
Solar photovoltaic panel: A PV panel is one or more photovoltaic cells covered with a layer of glass, an anti-reflective sheet or coating, and a backing and frame to provide support for installation. It can be used as a source of clean power for homes and businesses, and multiple panels can be configured into an array.
Solar thermal electricity: See concentrating solar power.
Solar power: The sun's energy can be used to generate electricity, provide hot water, and to heat, cool, and light buildings. This can be achieved using solar photovoltaic panels, concentrating solar power, and passive solar design.
Spot network system: A section of the electric grid typically serving single large customers like hospitals, industrial facilities, and office buildings. A spot network system, as opposed to an area network or radial system, consists of two or more wires that serve one customer so that when one wire is not working, the others can still provide power to the customer. Because of the complexity of spot networks, interconnecting clean energy to such a system requires additional review by the local utility.
Substation: A substation is a point in the electric grid where electricity is either “stepped up” or “stepped down” to a different voltage to efficiently transfer the electricity over transmission and distribution lines.
Sulfur dioxide (SO2): Sulfur dioxide is a criteria pollutant that contributes to respiratory problems and the creation of acid rain. Sulfur dioxide is created by burning fossil fuels with trace amounts of sulfur, like coal and oil. Smaller amounts can be created during industrial metal processing. The major source of sulfur dioxide is the use of fossil fuels in electricity production. Lesser sources include other energy production and transportation.
Sulfur hexafluoride (SF6): Sulfur hexafluoride is a manmade greenhouse gas that is currently released only in very small quantities due to electric power equipment gas leaks and losses. These small quantities can still make a large impact on the global climate; SF6 has a global warming potential almost 24,000 times greater than carbon dioxide over a 100-year time horizon.
T
Thermal energy: Thermal energy is the use of heat as a source of energy. Thermal energy can be used directly or can be transformed into mechanical energy (using a steam engine) which can then be transformed into electrical energy. Thermal energy is usually measured in British thermal units (Btu).
Tight construction: Tight construction is the elimination of gaps and holes in a building’s exterior (envelope) through air-sealing and proper ventilation. This practice can eliminate unwanted drafts and pollutants and reduce energy bills.
Transformer: A transformer is an electrical device installed at a substation that transfers energy from one electrical circuit to another, and is often used to convert between high and low voltages and accordingly between low and high currents.
Transmission: The delivery of large amounts of electricity from regional power plants to local areas. The transmission system is connected to local distribution systems by substations that step down high-voltage transmission power for local distribution.
Transmission companies: The entities that own and operate regional transmission systems, delivering electricity over a network of transmission lines within states and regions.
U
Urban heat islands: Dark-colored surfaces such as roofs and pavement absorb heat from the sun more than light-colored surfaces. In urban areas, a combination of many dark surfaces plus a lack of shade plants, intensifies this effect and creates “urban heat islands.” These urban areas stay warmer than the surrounding suburbs and increase the need for electric cooling systems. One solution is the use of lighter-colored materials in building construction. The use of well-placed vegetation to increase shade or green roof systems can also minimize urban heat island effects and increase building energy efficiency.