Glossary: G to I
A-C | D-F | G-I | J-L | M-O | P-R | S-U | V-Z
G
Generator: A generator is a power plant that produces electricity. Generators can be located centrally to serve a large number of customers or as distributed generation to serve an individual or smaller group of customers.
Global climate change (GCC): Global climate change is a significant alteration from one climatic condition to another, beyond the usual alterations in various climates throughout the globe, as the result of human activities. The greatest of these is fossil fuel combustion, which traps greenhouse gases in the atmosphere that cause gradual changes in Earth’s temperatures over hundreds of years. The term “global warming” may also be used but refers more specifically to temperature, whereas global climate change encompasses the broader changes associated with elevated greenhouse gas levels, such as dryer deserts, increased numbers of hurricanes, and warmer oceans. Learn more about global climate change.
Global warming: See global climate change.
Green building: A green building is a building that has been constructed or renovated to incorporate design techniques, technologies, and materials that minimize its overall environmental impacts. Among these reduced impacts are reduced fossil fuel use for electricity and heat, minimal site disruption, lower water consumption, and fewer pollutants used and released during construction and occupation. The term “high-performance building” is often used when referring specifically to the energy efficiency and productivity benefits of a building, whereas “green building” refers to the broader environmental considerations of a building, including high-performance aspects. Learn more about green buildings.
Green electricity provider: A utility or company that generates, purchases, or invests in electricity from renewable sources, such as wind or solar power, or biofuel, and sells it to customers for a small premium over standard electricity costs.
Greenhouse gases: While gases like carbon dioxide, methane, nitrous oxide, ozone, and water vapor naturally occur in earth’s atmosphere, human activities can artificially increase concentrations, notably through fossil fuel combustion to produce heat and electricity. These gases are dubbed greenhouse gases because they remain in the atmosphere and intensify the sun’s heat as it radiates to the earth, similar to a greenhouse’s glass walls heating and moisturizing the air inside of it. Greenhouse gases are the primary source of global climate change (GCC). Learn more about greenhouse gases and GCC.
H
Halocarbons: Halocarbons are entirely manmade chemicals, meaning that they are not found on their own in nature. When released into the atmosphere as greenhouse gases, they can significantly disrupt global climate patterns. There is a lower concentration of atmospheric halocarbons than other greenhouse gases, but the warming effects of halocarbons ranges from 3000 to 13,000 times that of carbon dioxide, and they remain in the atmosphere for hundreds of years. The most commonly known halocarbons are CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), and HFCs (hydroflurocarbons). Their most common use is in refrigeration and air conditioning technologies but they are also used heavily in the electric system infrastructure.
High-performance building: A high-performance building may be very similar to a green building but specifically aims to be energy efficient and provide productivity and health benefits to its occupants. Learn more about high-performance buildings from the Department of Energy.
High-performance windows and doors: These windows and doors are made of materials that seal out air leaks and reduce heat loss and gain, increasing the efficiency of a building.
Hydropower (Hydroelectricity): Hydropower, or hydroelectricity, is a clean energy technology that uses moving water to produce electricity. In a hydroelectric system, water flows downstream through a hydraulic turbine that spins and in turn rotates adjacent generators to transform the rotational energy into electricity. When the water exits the turbine it is returned to the stream or riverbed. Hydraulic turbines are generally located near dams that increase the height from which water falls to increase the potential for energy generation. Learn more about hydropower.
I
Independent System Operator of New England (ISO-NE): ISO-NE is the not-for-profit corporation responsible for the day-to-day reliable operation of New England's power generation and transmission system that represents an installed capacity of 32,000 megawatts. ISO-NE also oversees the region's wholesale electricity marketplace and manages regional power system planning.
Indoor air quality: Indoor air quality can have significant impacts on human health. Poor indoor air quality results from chemical, physical, or biological contaminants in indoor air, such as toxic paint gases, chemicals in carpeting and treated wood, mold, and dust mites. High levels of these contaminants in the air can cause moderate to severe health problems. Green buildings seek to improve indoor air quality by using building materials with low toxicity and proper ventilation systems.
Indoor environmental quality: Indoor environmental quality takes into consideration all impacts of the indoor environment on human health and performance, including indoor air quality, daylighting and views, and visual and thermal comfort. Green buildings seek to optimize indoor environmental quality through design that includes properly designed heating, ventilation, and air conditioning systems, abundant windows and proper use of daylighting, and well-sealed doors and windows.
Interconnection: The connection of an electric generator to the electric grid. The term "interconnection" is used rather than "connection" because the electric grid itself is a web of wires and substations that are interconnected to each other to provide multiple paths for electricity. Learn more about interconnection policies in Massachusetts.
Investor-owned utility: A publicly held utility that typically serves multiple towns or regions and often combines transmission and distribution services. Standards, rates, and other aspects of investor-owned utilities are regulated by the Massachusetts DTE. These utilities are also required under the Massachusetts Electric Restructuring Act of 1997 to collect energy efficiency and renewable energy funding for use in public funds.