Sustainability Glossary

Sustainability Glossary


Our Socket Sustainability Glossary gives you the low down on all the terminology you will need to navigate the Socket website.



British Thermal Unit (Btu)

A British thermal unit (Btu) is a measure of the heat content of fuels. It is the quantity of heat required to raise the temperature of 1 pound of liquid water by 1 degree Fahrenheit at the temperature that water has its greatest density (approximately 39 degrees Fahrenheit).

Source: U.S. Energy Information Administration

CO2 Equivalent

Carbon dioxide equivalent is a measure used to compare the emissions from various greenhouse gases based upon their global warming potential. For example, the global warming potential for methane over 100 years is 21. This means that emissions of one million metric tons of methane is equivalent to emissions of 21 million metric tons of carbon dioxide. The use of carbon equivalents (MMTCE) is declining.

Source: The Organisation for Economic Co-operation and Development (OECD)

Carbon Capture and Sequestration

Carbon capture and sequestration (CCS) is a set of technologies that can greatly reduce carbon dioxide emissions from new and existing coal- and gas-fired power plants, industrial processes, and other stationary sources of carbon dioxide. It is a three-step process that includes capture of carbon dioxide from power plants or industrial sources; transport of the captured and compressed carbon dioxide (usually in pipelines); and underground injection and geologic sequestration, or permanent storage, of that carbon dioxide in rock formations that contain tiny openings or pores that trap and hold the carbon dioxide.

Source: United States Environmental Protection Agency

Carbon Credits

A carbon credit is a financial instrument that allows the holder, usually an energy company, to emit one ton of carbon dioxide. Credits are awarded to countries or groups that have reduced their greenhouse gases below their emission quota. Carbon credits can be legally traded in the international market at their current market price. The premise of the system is that a government or another body can regulate the total tons of carbon dioxide emitted but is given some flexibility as to how exactly the regulation is accomplished. Carbon credit systems place a cost on carbon emissions by creating credits valued against one ton of hydrocarbon fuel. A carbon credit, then, is essentially a permit that allows the receiver to burn a specified amount of hydrocarbon fuel over a specified period of time.

Source: Investopedia

Chlorofluorocarbon (CFCs)

Chlorofluorocarbons (also known as Freon) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. The manufacture of such compounds has been phased out (and replaced with products such as R-410A) by the Montreal Protocol because they contribute to ozone depletion in the upper atmosphere.

Source: Earth System Research Laboratory- Global Monitoring Division

Climate Change

Climate change is a change in the typical or average weather of a region or city. This could be a change in a region's average annual rainfall, for example. Or it could be a change in a city's average temperature for a given month or season.

Source: NASA

Carbon Neutral

Carbon neutrality, or having a net zero carbon footprint, refers to achieving net zero carbon emissions by balancing a measured amount of carbon released with an equivalent amount sequestered or offset, or buying enough carbon credits to make up the difference. It is used in the context of carbon dioxide releasing processes, associated with transportation, energy production and industrial processes.

Source: Go-Green

Direct Digital Control (DDC)

A mode of control wherein digital computer outputs are used to directly control a process. A computer control technique that sets the final control-elements position directly by the computer output. Used to distinguish from analog control.

Source: Center for Chemical Process Safety

Ecological Footprint

The impact of human activities measured in terms of the area of biologically productive land and water required to produce the goods consumed and to assimilate the wastes generated. More simply, it is the amount of the environment necessary to produce the goods and services necessary to support a particular lifestyle.

Source: World Wildlife Fund


Emissions is the term used to describe the gases and particles which are put into the air or emitted by various sources.

Source: United States Environmental Protection Agency

Energy Efficiency


The use of technology that requires less energy to perform the same function. Using a compact fluorescent light bulb that requires less energy rather than using an incandescent bulb to produce the same amount of light is an example of energy efficiency.

Source: U.S. Energy Information Administration

Energy Use Intensity(EUI)

The EUI expresses a building’s energy use as a function of its size or other characteristics. The EUI is expressed as energy per square foot per year. It’s calculated by dividing the total energy consumed by the building in one year (measured in kBtu or GJ) by the total gross floor area of the building.

Source: EnergyStar

Greenhouse Gases

Any gas that absorbs infrared radiation in the atmosphere. Greenhouse gases include carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.

Source: United States Environmental Protection Agency

Grid Tied Solar Power System

A grid tied solar power system is a solar powered system which is connected to the power grid. While the sun is shining the photovoltaic solar panels convert the sun’s rays into electricity. Electricity generated by the system can be used for your home and business. Any excess power requirements which your solar panels can not supply will be taken from the power grid. When the power grid is running properly, your home or business will use power generated from your solar panels and/or pull electricity from the grid. If at any time you generate more electricity from your solar panels as your current power requirements this excess power will feed back into the power grid. This excess power fed back into the power grid can give you credits on your electricity bill.

Source: Renewable Energy South Africa

Heat Island

An urban area characterized by temperatures higher than those of the surrounding non-urban area. As urban areas develop, buildings, roads, and other infrastructure replace open land and vegetation. These surfaces absorb more solar energy, which can create higher temperatures in urban areas.

Source: United States Environmental Protection Agency


1000 watts, used to measure the energy consumption of large devices.

Source: U.S. Energy Information Administration


The SI derived unit of power. Power is the rate at which work is done, or the rate at which energy is expended. One watt is equal to one joule per second. This unit is used both in mechanics and in electricity. The unit was named after James Watt (1736-1819), the British engineer.

Source: Surface Engineering Forum

Kilowatt Hour

A measurement of energy - the number of kilowatts generated or consumed in one hour.

Source: U.S. Energy Information Administration

Load Shedding (also known as a rolling blackout)

The deliberate shutdown of electric power in a part or parts of a power-distribution system, generally to prevent the failure of the entire system when the demand strains the capacity of the system.



One megawatt (MW) = 1,000,000 watts. Used to measure the output of a power plant or the amount of electricity required by an entire city.

Source: Union of Concerned Scientists

Natural Gas

combustible mixture of gaseous hydrocarbons (molecules containing only carbon and hydrogen atoms) that accumulates in porous sedimentary rocks, especially those yielding petroleum, consisting usually of over 80 percent methane together with minor amounts of ethane, propane, butane, nitrogen, and, sometimes, helium


Net Metering

A billing mechanism that credits solar energy system owners for the electricity they add to the grid. Net metering allows residential and commercial customers who generate their own electricity from solar or wind power to feed electricity they do not use back into the grid.

Source: Solar Energy Industries Association

Net Zero

A building that produces enough renewable energy to meet its own annual energy consumption requirements, thereby reducing the use of non-renewable energy in the building sector.

Source: Office of Energy Efficiency & Renewable Energy

Peak Load

Peak load is the maximum or highest demand of electric power over time. these fluctuations can be measured over various time intervals (day, week, year). By utility definition, it is the single time (usually an hour or half hour) of highest demand throughout the day.

Source: Aquicore



A type of photocell that changes light from the sun into electricity, used in solar panels

Source: Cambridge Dictionary

Potable Water

A potable water supply is one which is drinkable. Potable water must be free of pathogens (disease causing organisms), have a desirable taste, odor (smell), color, turbidity (cloudiness), and contain no harmful chemicals. Natural water from a river, lake or borehole usually has to be treated to make it potable.

Source: Chemgym

Renewable Energy

Any energy resource that is naturally regenerated over a short time scale and derived directly from the sun (such as thermal, photochemical, and photoelectric), indirectly from the sun (such as wind, hydropower, and photosynthetic energy stored in biomass), or from other natural movements and mechanisms of the environment (such as geothermal and tidal energy). Renewable energy does not include energy resources derived from fossil fuels, waste products from fossil sources, or waste products from inorganic sources.

Source: Texas Renewable Energy Industries Alliance(TREIA)

Solar Thermal

Solar Thermal Energy (STE) is a technology for harnessing solar energy for thermal energy (heat).

Source: Evergreen Energy

Stormwater Runoff

Stormwater runoff is water from rain or melting snow that “runs off” across the land instead of seeping into the ground. This runoff usually flows into the nearest stream, creek, river, lake or ocean. The runoff is not treated in any way; runoff water can pick up and carry many substances that pollute water. Some - like pesticides, fertilizers, oil and soap – are harmful in any quantity. Others – like sediment from construction, bare soil, or agricultural land, or pet waste, grass clippings and leaves – can harm creeks, rivers and lakes in sufficient quantities.

Source: North Carolina Department of Environment and Natural Resources


Development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Consisting of three pillars, sustainable development seeks to achieve, in a balanced manner, economic development, social development and environmental protection.

Source: United Nations


The Intergovernmental Panel on Climate Change is the international body for assessing the science related to climate change. The IPCC was set up in 1988 by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation.

Source: Intergovernmental Panel on Climate Change


Upcycling is taking an item that is no longer needed or wanted and giving it new life as something that is either useful or creative.

Source: Upcycle Magazine


Urea formaldehyde resin is a highly crosslinked thermosetting polymer primarily made up of urea and formaldehyde with formaldehyde acting as the crosslinker. Urea formaldehyde resins are stable, fast curing and highly customizable making them an excellent choice for a wide array of applications, such as decorative laminates, air filtration, coated and bonded abrasives, and wood composites. During the 1970s, urea-formaldehyde foam insulation (UFFI) was used in many homes. However, few homes are now insulated with UFFI. When formaldehyde is present in the air at levels exceeding 0.1 ppm, some individuals may experience adverse effects such as watery eyes; burning sensations in the eyes, nose, and throat; coughing; wheezing; nausea; and skin irritation. In 1980, laboratory studies showed that exposure to formaldehyde could cause nasal cancer in rats. This finding raised the question of whether formaldehyde exposure could also cause cancer in humans. In 1987, the U.S. Environmental Protection Agency (EPA) classified formaldehyde as a probable human carcinogen under conditions of unusually high or prolonged exposure.

Source: Hexion, National Cancer Institute

VOC – Volatile Organic Compounds

Volatile organic compounds, sometimes referred to as VOCs, are organic compounds that easily become vapors or gases. Along with carbon, they contain elements such as hydrogen, oxygen, fluorine, chlorine, bromine, sulfur or nitrogen. Volatile organic compounds are released from burning fuel, such as gasoline, wood, coal, or natural gas. They are also released from solvents, paints, glues, and other products that are used and stored at home and at work. Many volatile organic compounds are also hazardous air pollutants. Volatile organic compounds, when combined with nitrogen oxides, react to form ground-level ozone, or smog, which contributes to climate change.

Source: U.S. National Library of Medicine-Tox Town




An area of land that drains water, sediment and dissolved materials to a common receiving body or outlet. The term is not restricted to surface water runoff and includes interactions with subsurface water. Watersheds vary from the largest river basins to just acres or less in size.


Source: U.S. Environmental Protection Agency