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.




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 dioxide (CO2) capture and sequestration (CCS) is a set of technologies that can greatly reduce CO2 emissions from new and existing coal- and gas-fired power plants and large industrial sources. CCS is a three-step process that includes:

  • Capture of CO2 from power plants or industrial processes

  • Transport of the captured and compressed CO2 (usually in pipelines).

  • Underground injection and geologic sequestration (also referred to as storage) of the CO2 into deep underground rock formations. These formations are often a mile or more beneath the surface and consist of porous rock that holds the CO2. Overlying these formations are impermeable, non-porous layers of rock that trap the CO2 and prevent it from migrating upward.

Source: United States Environmental Protection Agency

Carbon Credits

A carbon credit (often called a carbon offset) is a financial instrument that represents a tonne of CO2 (carbon dioxide) or CO2e (carbon dioxide equivalent gases) removed or reduced from the atmosphere from an emission reduction project, which can be used, by governments, industry or private individuals to offset damaging carbon emissions that they are generating.

Source: Carbon Neutral

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

Climate 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 Controls

Digital Data Control (DDC) is the automated control of a condition or process by a digital device (computer). DDC takes a centralized network-oriented approach. All instrumentation is gathered by various analog and digital converters which use the network to transport these signals to the central controller.

Source: Wikipedia

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 Use


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

A grid-tied electrical system, also called tied to grid or grid tie system, is a semi-autonomous electrical generation or grid energy storage system which links to the mains to feed excess capacity back to the local mains electrical grid. When insufficient electricity is generated, or the batteries are not fully charged, electricity drawn from the mains grid can make up the shortfall.

Source: Wikipedia

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)

An intentionally-engineered electrical power outage in which electricity delivery is stopped for non-overlapping periods of time over geographical regions. Rolling blackouts are a last-resort measure used by an electric utility company in order to avoid a total blackout of the power system. They are usually in response to a situation in which the demand for electricity exceeds the power supply capability of the network.

Source: TeachEngineering


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

Source: Union of Concerned Scientists

Natural Gas

Natural gas is a hydrocarbon, which means it is made up of compounds of hydrogen and carbon. The simplest hydrocarbon is methane; it contains one carbon atom and four hydrogen atoms.

Source: Alberta Energy

Net Metering

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. It is a billing mechanism that credits solar energy system owners for the electricity they add to the grid.

Source: Solar Energy Industries Association

Net Zero

An energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy.

Source: Office of Energy Efficiency & Renewable Energy

Peak Load

The maximum load in a stated period of time. Usually it is the maximum integrated load over an interval of one hour which occurs during the year, month, week, or day. It is used interchangeably with Peak Demand and Peak Power.


Photovoltaic (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect.

Source: OpenEI

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: Legacy-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


Meeting the needs of today without compromising the needs of future generations. It is about improving the standard of living by protecting human health, conserving the environment, using resources efficiently and advancing long-term economic competitiveness. It requires the integration of environmental, economic and social priorities into policies and programs and requires action at all levels--citizens, industry, and governments.

Source: Environment and Climate Change-Canada


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


The process of transforming by-products, waste materials, useless, or unwanted products into new materials or products of better quality or for better environmental value.

Source: Wikipedia


Also known as urea-methanal, named so for its common synthesis pathway and overall structure, is a non-transparent thermosetting resin or plastic, made from urea and formaldehyde heated in the presence of a mild base such as or pyridine. These resins are used in adhesives, finishes, MDF, and molded objects. Urea-formaldehyde foam insulation (UFFI) was used extensively in the 1970s. Homeowners used UFFI as wall cavity filler at the time in order to conserve energy. In the 1980s, concerns began to develop about formaldehyde vapor emitted in the curing process, as well as from the breakdown of old foam. Emission rates exceeding 3.0 - 5.0 parts per million (ppm) causes a variety of adverse health effects impacting the eyes, nose, and respiratory system. Consequently, its use was discontinued.

Source: Wikipedia

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