An environmental resource for East Tennessee Businesses

Green Dictionary

Green Dictionary

Familiarize yourself with common terms used when discussing environmentally friendly practices and energy efficiency. Have a question or something you'd like to add? Email us at


Active solar heating - Collection units absorb heat from the sun and transfer it through pumps or fans to a shortage unit for later use, or directly to the building interior. These systems also contain an energy-storage system to provide heat at night or when the sun is not shining.

Active solar water heater - Collection units absorb heat from the sun and transfer it through pumps to a storage unit. The fluid in the storage unit conveys its heat to the domestic hot water of the building through a heat hanger. The system requires controls to regulate its operation.

Aerator - A device most installed on faucets to increase spray velocity, reduce splash, and save both water and energy.

Alternative fuels - Substitutes for traditional liquid, oil-derived motor vehicle fuels like gasoline and diesel. Includes mixtures of alcohol-based fuels with gasoline, methanol, ethanol, compressed natural gas, and others.

Alternative-Fueled Vehicle (AFV) - Vehicles powered by fuels other than those derived from petroleum: hybrid-electric, electric, natural-gas, bio-diesel, and fuel-cell

Annual solar savings - The annual solar savings of a solar building is the energy savings attributable to a solar feature relative to the energy requirements of a non-solar building.

American Society of Heating, Refrigerating and Air-Conditioning - International technical society organized to advance the arts and sciences of heating, ventilation, air-conditioning and refrigeration.


Bamboo flooring - Bamboo is a sustainable building material, a grass (not a wood) that annually produces new shoots. Individual stems are harvested from controlled forests every three to five years.

Benchmarking - The process to measure the performance of energy, water and recycling for comparison. The result is often a business case for making environmental improvements.

Biodegradable - Capable of decomposing naturally within a relatively short period of time.

Biomass - Organic material that can be converted to other useable forms of energy, such as methane gas or transportation fuels, such as ethanol and biodiesel.

Biodiesel - a transportation fuel that can be produced from left-over food products like vegetable oils and animal fats.

Biofuels - using recently living organisms like corn, soybean, and other plants to derive energy, often used to fuel vehicles.

Biogas - Gas composed mainly of methane and carbon dioxide that forms as a result of biological processes in sewage treatment plants, waste landfills, and livestock manure management systems. Can be captured and burned for heat or electricity generation.

Blackwater - Wastewater from toilets, urinals, and sinks with garbage disposals.

Building-Integrated Photovoltaics -- A term for the design and integration of photovoltaic technology into the building envelope, typically replacing conventional building materials. This integration may be in vertical facades, replacing view glass, spandrel glass, or other facade material; into semitransparent skylight systems; into roofing systems, replacing traditional roofing materials; into shading "eyebrows" over windows; or other building envelope systems.


Carbon footprint - A cumulative measure of the impact a product, service, activity, company, individual or other entity has on the environment, in terms of the amount of greenhouse gases produced, and measured in units of carbon dioxide. These impacts usually result from energy consumption, pollution, and other sources.

Carbon neutral - A combination of efficiency improvements (resulting in reduced carbon dioxide emissions), and purchases of carbon offsets that balance 100% of a carbon footprint.

Carbon offset - A reduction in carbon dioxide emissions by a project (such as rainforest preservation) that is sold to a purchaser to balance the purchaser's own emissions. The funds generated by the sale of offsets support the development of additional reductions.

Cell (battery) - A single unit of an electrochemical device capable of producing direct voltage by converting chemical energy into electrical energy. A battery usually consists of several cells electrically connected together to produce higher voltages. (Sometimes the terms cell and battery are used interchangeably).

Chlorofluorocarbons (CFCs) - Ozone-depleting constituent of the most widely used HVAC refrigerants.

Commercial Buildings Energy Consumption Survey (CBECS) - Department of Energy database logging actual building energy use figures.

Compact fluorescent light (CFL) - A type of fluorescent lamp that can be used in a regular light socket. Compared to incandescent lamps of the same luminous flux, CFLs use less energy and have a longer life.

Composting - A process whereby organic wastes, including food, paper, and yard wastes, decompose naturally and produce a material rich in minerals and ideal for gardening and farming as a soil conditioner or mulch, and for resurfacing or covering a landfill.

Compressed natural gas (CNG) - A substitute for gasoline (petrol) or diesel fuels. CNG is considered to be an environmentally "clean" alternative. It is made by compressing natural gas in a percentage range of 70% to 98%.

Concentrating solar power plants - Utility-scale generators that produce electricity by using mirrors or lenses to efficiently concentrate the sun's energy.

Conventional - Indicates the usual method of production. Used in contrast to green or environmentally-friendly production methods.


Daylighting - A method of illuminating building interiors with natural light and minimizing the use of artificial lighting. Common daylighting strategies include the proper orientation and placement of windows, the use of light wells, or light shafts.

Dematerialization - the reduction of total materials used in providing customers with products or services

Digital thermostat - Energy saving devices that are manually programmed to allow users to control temperature settings. Digital thermostats are more accurate than conventional thermostats and can be programmed with high and low set points. They can be used with most heating and cooling devices.

Distributed energy resources (DER) -- A variety of small, modular power-generating technologies that can be combined with energy management and storage systems and used to improve the operation of the electricity delivery system, whether or not those technologies are connected to an electricity grid.


Eco-friendly, Environmentally friendly - a loose term often used in marketing to inform consumers about an attribute of a product or service that has an environmental benefit. This term does not necessarily indicate all attributes of a product or service is environmentally benign.

Emissions - The release of any gas, particle, or vapor into the environment from a commercial, industrial, or residential source, including smokestacks, chimneys, and motor vehicles.

Energy audit - A survey that shows energy used in a facility, which helps find ways to use less energy.

Energy efficient - producing a high level of output or performance relative to the amount of energy consumed.

Energy Star - A joint program of the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy helping individuals and businesses save money and protect the environment through energy efficient products and practices. Devices carrying the Energy Star logo meet strict energy efficiency guidelines set by the program.

Environmental impact - Any change to the environment, good or bad, that wholly or partially results from industrial manufacturing activities, products or services.

Environmental Protection Agency (EPA) - Federal agency charged with setting and enforcing environmental regulations nationwide.

Environmental valuation - The inclusion of environmental costs and benefits into accounting practices using such mechanisms as taxes, tax incentives, and subsidies; by quantifying environmentally-related costs and revenues, better management decisions and increased investment in environmental protection and improvement are encouraged


Fair trade - A certification that evaluates the economic, social and environmental impacts of the production and trade of agricultural products, in particular: coffee, sugar, tea, chocolate, and others. Fair Trade principles include: fair prices, fair labor conditions, direct trade, democratic and transparent organizations, community development and environmental sustainability.

Fossil fuels - Fuels containing carbon that can be burned to provide heat that can be used directly. They all contain carbon formed through geologic processes over hundreds of millions of years. These include coal, petroleum, and natural gas.

Full sun - The amount of power density in sunlight received at the earth's surface at noon on a clear day (about 1,000 Watts/square meter).


Geothermal energy - Energy generated by heat from within the Earth. Recovered as steam or hot water and used it to heat buildings or generate electricity.

Geothermal heat pump - Used for space heating and cooling, as well as water heating. The system takes advantage of the Earth's constant underground temperature to transfer heat stored in the Earth or in ground water into a building during the winter, and transferring it out of the building and back into the ground during the summer.Also known as the ground source heat pump.

Gigawatt (GW) - A unit of power equal to 1 billion Watts; 1 million kilowatts, or 1,000 megawatts.

Green building - The practice of increasing the efficiency with which buildings use resources - energy, water and materials - while reducing building impacts on human health and the environment during the building's lifecycle - design, construction, operation, maintenance and removal. 

Green Building Certification Institute (GBCI) - An independent, third-party organization committed to ensuring precision in the design, development, and implementation of the processes used to increase and measure green building performance (certification) and green building practice (credentialing). Established in 2008 to administer project certifications and professional credentials and certificates within the framework of the U.S. Green Building Council's Leadership in Energy and Environmental Design Green Building Rating Systems

Green power - This is a term used to describe sources of energy that are considered to be environmentally friendly and non-polluting, such as geothermal, wind and solar power.

Green Seal - An environmental standard that focuses exclusively on developing environmental standards, and certifying products, practices, and operations.

Greenwashing - the process by which an organization, product or service publicly and misleadingly declares itself to be environmentally-friendly but internally participates in environmentally- or socially-unfriendly practices

Grey water - Any water that has been used in the home, except water from toilets, is called grey water. Dish, shower, sink, and laundry water comprise 50-80% of residential "waste" water. This may be reused for other purposes, especially landscape irrigation.


Hardscape - Paved areas such as streets and sidewalks, large business complexes and housing developments, and other industrial areas where the upper soil profile is no longer exposed to the actual surface of the Earth.

Hybrid system - A solar electric or photovoltaic system that includes other sources of electricity generation, such as wind or diesel generators.

Hybrid vehicle - Any vehicle that combines two or more sources of power that can directly or indirectly provide propulsion power is a hybrid. Common examples are diesel-electric industrial machines and gasoline-electric consumer vehicles.

Hydrogen cell - An energy conversion device that can efficiently capture and use hydrogen to generate pollution-free power for a variety of applications.

Hydropower - Electrical energy produced by falling or flowing water.


Incandescent light - An electric lamp in which a filament is heated to produce artificial light. Incandescent lighting consumes more energy and is less efficient than CFLs or LEDs.

Incident light - Light that shines onto the face of a solar cell or module.

Indoor air quality - The content of interior air that could affect health and comfort of building occupants.

ISPRA Guidelines - Guidelines for the assessment of photovoltaic power plants, published by the Joint Research Centre of the Commission of the European Communities, Ispra, Italy.



Kilowatt (kW) - A standard unit of electrical power equal to 1000 watts, or to the energy consumption at a rate of 1000 joules per second.

Kilowatt-hour (kWh) - 1,000 thousand watts acting over a period of 1 hour. The kWh is a unit of energy. 1 kWh=3600 kJ.

Kilowatt peak (kWp) - A measure of peak kilowatt output (e.g. of a photovoltaic system).


LCD - Liquid crystal display. LCD creates images on a flat surface by shining light through a combination of liquid crystals and polarized glass. In some cases, the energy-consumption of an average LCD display can be half to two-thirds of that for an average display

LED - Light-emitting diode. LEDs are small light sources that become illuminated by the movement of electrons through a semiconductor material. LED lighting is more efficient, durable, versatile and longer lasting than incandescent and fluorescent lighting.

LEED - The Leadership in Energy and Environmental Design Green Building rating system. LEED is a voluntary, consensus-based, national standard based on a four level certification program that encompasses design techniques for the building envelope and throughout the interior for new construction and renovations, as well as their operational program for existing properties.

LEED AP - LEED accredited professional. Credentials demonstrate current knowledge of green building technologies, best practices, and the rapidly evolving LEED Rating Systems.

Life-Cycle Cost - The estimated cost of owning and operating a photovoltaic system for the period of its useful life.

Load - The demand on an energy producing system; the energy consumption or requirement of a piece or group of equipment. Usually expressed in terms of amperes or watts in reference to electricity.


Megawatt (MW) - 1,000 kilowatts, or 1 million watts; standard measure of electric power plant generating capacity.

Megawatt-Hour - 1,000 kilowatt-hours or 1 million watt-hours.


National Electrical Code (NEC) - Contains guidelines for all types of electrical installations. The 1984 and later editions of the NEC contain Article 690, "Solar Photovoltaic Systems" which should be followed when installing a PV system.

National Electrical Manufacturers Association (NEMA) - This organization sets standards for some non-electronic products like junction boxes.

Net metering - allows photovoltaic customers to sell excess electricity back into the grid


Organic - Grown without the use of pesticides, synthetic fertilizers, sewage sludge, genetically modified organisms, or ionizing radiation. Animals that produce meat, poultry, eggs, and dairy products do not take antibiotics or growth hormones.


Passive solar - Refers to special siting, design or building materials that take advantage of the sun's position and availability to provide direct heating or lighting

Peak sun hours - The equivalent number of hours per day when solar irradiance averages 1,000 w/m2. For example, six peak sun hours means that the energy received during total daylight hours equals the energy that would have been received had the irradiance for six hours been 1,000 w/m2.

Peak watt - A unit used to rate the performance of solar cells, modules, or arrays; the maximum nominal output of a photovoltaic device, in watts (Wp) under standardized test conditions, usually 1,000 watts per square meter of sunlight with other conditions, such as temperature specified.

Permaculture - A design system that encompasses both "permanent agriculture" and "permanent culture." It teaches people to analyze existing energy flows (sun, rain, money, human energy) through such a system (a garden, a household, a business). Then it teaches them to position and interconnect all the elements in the system (whether existing or desired) in beneficial relationship to each other and to those energy flows. When correctly designed such a system will, like a natural ecosystem, become increasingly diverse and self-sustaining.

Photovoltaic energy - Sunlight is converted to electricity using photovoltaic or solar cells. Photovoltaic (PV) cells are semiconductor devices, usually made of silicon, which contain no liquids, corrosive chemicals or moving parts. They produce electricity as long as light shines on them, they require little maintenance, do not pollute and they operate silently, making photovoltaic energy the cleanest and safest method of power generation.

Photovoltaic array - An interconnected system of modules that function as a single electricity-producing unit. The modules are assembled as a discrete structure, with common support or mounting. In smaller systems, an array can consist of a single module.

Photovoltaic cell - The smallest semiconductor element within a module to perform the immediate conversion of light into electrical energy (direct current voltage and current). Also called a solar cell.

Photovoltaic conversion efficiency - The ratio of the electric power produced by a photovoltaic device to the power of the sunlight incident on the device.

Photovoltaic device - A solid-state electrical device that converts light directly into direct current electricity of voltage-current characteristics that are a function of the characteristics of the light source and the materials in and design of the device. Solar photovoltaic devices are made of various semiconductor materials including silicon, cadmium sulfide, cadmium telluride, and gallium arsenide, and in single crystalline, multicrystalline, or amorphous forms.

Photovoltaic panels - Devices using semiconductor material to directly convert sunlight into electricity. Power is produced when sunlight strikes the semiconductor material and crates an electrical current.

Polycrystalline silicon - A material used to make photovoltaic cells, which consist of many crystals unlike single-crystal silicon.

Post-consumer recycled content - Material that has been recovered after its use as a consumer product. Examples include fleece clothing made from pop bottles and reclaimed carpet tiles used for new tile backing.

Pre-consumer recycled content - Material that is diverted from the waste stream following an industrial process. This excludes reutilization of materials such as rework, regrind, or scrap capable of being reclaimed within the same process.



Recyclable content - Materials that can be recovered or diverted from the waste stream for recycling and reuse.

Recycled content - The percentage of recycled materials in a product, generally determined by weight.

Recycling - The series of activities, including collection, separation and processing, by which products or other materials are recovered from the solid waste stream for use in the form of raw materials for the manufacture of new products (other than fuel).

Renewable energy - Energy resources such as wind, hydropower, geothermal, biomass or solar power that produce indefinitely without being depleted.

Renewable resources - Resources that are created or produced at least as fast as they are consumed.


Semiconductor - Any material that has a limited capacity for conducting an electric current. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.

Silicon (Si) - A semi-metallic chemical element that makes an excellent semiconductor material for photovoltaic devices. It crystallizes in face-centered cubic lattice like a diamond. It's commonly found in sand and quartz (as the oxide).

Solar cooling - The use of solar thermal energy or solar electricity to power a cooling appliance. Photovoltaic systems can power evaporative coolers ("swamp" coolers), heat-pumps, and air conditioners.

Solar energy - Electromagnetic energy transmitted from the sun (solar radiation). The amount that reaches the earth is equal to one billionth of total solar energy generated, or the equivalent of about 420 trillion kilowatt-hours.

Solar panel - Array of photvoltaic cells that make use of renewable energy from the sun, and are a clean and environmentally sound means of collecting solar energy.

Solar thermal energy - refers to harnessing the sun's light to produce heat.

Sustainability - A characteristic or state whereby the needs of the present and local population can be met without compromising the ability of future generations or populations in other locations to meet their needs.

Standard Benchmark Energy Utilization Index - series of benchmark models based on 16 different commercial building types developed by the Department of Energy to provide complete descriptions for whole building energy analysis using EnergyPlus simulation software.



Ultraviolet - Electromagnetic radiation in the wavelength range of 4 to 400 nanometers.

United States Green Building Council (USGBC) - A national organization, founded in 1993, whose mission is to accelerate the adoption of green building practices, technologies, policies, and standards. USGBC established the LEED certification guidelines.


Volt - A unit of electrical force equal to that amount of electromotive force that will cause a steady current of one ampere to flow through a resistance of one ohm.

Voltage - The amount of electromotive force, measured in volts, that exists between two points.


Watt - The rate of energy transfer equivalent to one ampere under an electrical pressure of one volt. One watt equals 1/746 horsepower, or one joule per second. It is the product of voltage and current (amperage).

Wind Power - Power captured by using wind to move a turbine to generate electricity




Zero Emission Vehicles - California Air Resources Board designation for alternative-fuel vehicles.


American Hotel and Lodging Association

American Solar Energy Society

American Society of Heating, Refrigerating and Air-Conditioning

Associated Builders and Contractors Inc.

Department of Energy Office of Energy Efficiency and Renewable Energy

Energy Star

Frostburg State University

Green Building Certification Institute

Solar Energy Industries Association

Solar Energy International

U.S. Department of Energy

U.S. Energy Information Administration

U.S. Environmental Protection Agency

University of Wisconsin-Stevens Point

Western Washington University