Alternative Energy: Energy from sources other than fossil fuels (coal, natural gas), such as renewable sources like wind, sun, or running water.

Asbestos: A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted its use in manufacturing and construction.

Biodegradable: Able to decompose or break down by a natural process without harm to the environment.

Building Envelope: The exterior surface of a building's construction--the walls, windows, floors, roof, and floor. Also called building shell.

Carbon Footprint: The total amount of carbon dioxide emitted over a given time by a person, organization, or state. Usually expressed in equivalent tons of carbon dioxide (CO2).

Carbon Monoxide:  A colorless, odorless, highly poisonous gas, CO, formed by the incomplete combustion of carbon or a carbonaceous material, such as gasoline.

Chlorofluorocarbons: Any of a class of organic compounds in which the hydrogen atoms of a hydrocarbon are replaced with those of chlorine and fluorine; formerly used as refrigerants and aerosol can propellants but withdrawn due to causing damage to the ozone layer.

Clean Fuels:  Blends or substitutes for gasoline fuels, including compressed natural gas, methanol, ethanol, and liquefied petroleum gas.

Climate Change: Long-term significant change in the weather patterns of an area or the Earth.

Compact Fluorescent Light Bulbs (CFLs): A kind of fluorescent lamp that uses less power and last longer than regular incandescent bulbs of the same perceived power of light.

Compostable: Organic matter that will break down naturally in a compost bin. Items can include coffee filters, grounds, paper towels, and food items except for dairy, meat, and bones.

Demand Hot Water System: Hot water heaters designed to provide instantaneous hot water, rather than storing preheated hot water in a tank. Such devices can serve an entire home, or be "point-of-use", serving an individual water use. Benefits include elimination of "standby losses," or energy wasted keeping stored water warm, and with point of use devices, reduction or elimination of water wasted waiting for water to get warm, as well as conductive losses as water travels through pipes. Electric demand systems tend to use a large amount of energy; gas-fired units with standing pilot lights loose much of their efficiency due to the ongoing pilot light.

DOE (Department of Energy): Governmental department whose mission is to advance energy technology and promote related innovation in the U.S.
Dual-flush Toilets:  A cistern that has two buttons, one of which releases only half the amount of water held in the cistern. Designed to conserve water by letting consumers choose either a low-flush or full-flush capacity.

Durability: A factor that affects the life cycle performance of a material or assembly. All other factors being equal, the more durable item is environmentally preferable, as it means less frequent replacement. However, durability is rendered moot as a factor if the material is replaced for aesthetic reasons prior to it actually wearing out.

Eco-chic:  A product or good that is both eco-friendly and hip.

Eco-friendly Products: Made with ecology and the environment in mind.

Ecosystem: The interconnectedness of organisms (plants, animals, microbes) with each other and their environment.

Emission Controls: Any measure that limits and reduces the release of emissions.

Energy Efficiency: Products and systems that use less energy but maintain the same result or performance.

Energy Star: A joint program of the U.S. Environmental Protection Agency and Department of Energy dedicated to helping consumers save money and protect the environment through energy-efficient products and practices.

Environmental Footprint: The environmental impact of a company produced by the raw materials and nonrenewable resources/products it wastes.

Ethanol Fuel: Ethanol (ethyl alcohol), is the same type of alcohol found in alcoholic beverages. It can be used as a fuel, mainly as a biofuel alternative to gasoline, and is widely used in cars in Brazil. Because it is easy to manufacture and process, and can be made from very common materials, such as sugar cane, it is steadily becoming a promising alternative to gasoline throughout much of the world.

Formaldehyde: A gas used widely in production of adhesives, plastics, preservatives, and fabric treatments and commonly emitted by indoor materials that are made with its compounds.

Fossil Fuel:  Fuel created from decomposed plants and animals such as oil, natural gas, and coal. Burning these fuels generates carbon dioxide.

FSC-certified: Wood or paper products showing this label have been approved under the Forest Stewardship Council as products compliant with sustainable forestry practices.

Geothermal Energy:  Heat under the ground used to heat water and make steam to turn generator turbines and make electricity.

Global Warming: A progressive and sustained rise in the earth's average temperature. Thought to be caused by the greenhouse effect and responsible for climate change and changes in global climate patterns.
 
Going Green:  A phrase referring to individual action that a person can consciously take to curb harmful effects on the environment through consumer habits, behavior, and lifestyle.

Gray Water: Water that has been used in the home such as dish, shower, sink, or laundry water that is nondrinkable, but may be used for other purposes such as landscape irrigation or flushing toilets.

Green Building: A building designed to increase efficiency with the resources it uses, such as energy, water, and material or land, minimizing the negative impact on our environment and helping to keep occupants healthy.

Green Design: A term used in the building, furnishings, and product industries to indicate design sensitive to environmentally-friendly, ecological issues.

Greenhouse Effect: The process by which the planet is warmed by its atmosphere through the trapping and build-up of heat near the Earth's surface. Some of the heat flowing back toward space from the Earth's surface is absorbed by water vapor, carbon dioxide, ozone, and several other gases in the atmosphere and then reradiated back toward the Earth's surface. If the atmospheric concentrations of these greenhouse gases rise, the average temperature of the lower atmosphere will gradually increase.

Greenhouse Gas: Any gas, such as carbon dioxide or CFCs, that contributes to the greenhouse effect when released into the atmosphere.

HERS (Home Energy Rating System):  A standardized system for rating the energy-efficiency of residential buildings.

High Efficiency: General term for technologies and processes that require less energy, water, or other inputs to operate. A goal in sustainable building is to achieve high efficiency in resource use when compared to conventional practice. Setting specific targets in efficiency for systems (e.g., using only EPA Energy Star certified equipment, furnaces with an Annual Fuel Utilization Efficiency rating above 90%, etc.) and designs (e.g., watts per square foot targets for lighting) help put this general goal of efficiency into practice.

Home Sealing: A process for improving the envelope of the homethe outer walls, ceiling, windows and floor.

Hybrid: A car that runs on both electric battery and fuel, making the gas mileage extremely efficient and also produces fewer emissions which help control pollution in the environment.

Hydroelectric: Energy obtained by converting the energy of moving water. 

Indoor Air Quality: Air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which 80% or more people exposed do not express dissatisfaction. 

Nonrenewable Resource: A natural resource that can't be replenished because the rate of formation is slower than the rate of consumption. Fossil fuels, metals, other minerals and groundwater are nonrenewable.

Organic Products:  Made from natural resources as well as food or food products grown free of artificial chemicals. Organic materials are often certified by a regulatory body.

Ozone Depletion:  Deconstruction of the earth's ozone layer.

Passive Solar Design:  Uses the natural movement of heat and air within the home to maintain comfortable temperatures, operating with little or no mechanical assistance. The design uses standard construction features to maximize the benefits the home receives from the sun, local breezes, landscape features, and shade trees, and uses a simple system to collect and store solar energy with no controls.

Photovoltaic: Capable of producing a voltage when exposed to radiant energy, especially light, such as a solar cell.

Post-Consumer Waste:  Waste created from unused portions of a product such as packaging, Kleenex, batteries, or other common items that are routinely discarded.

Radon: A colorless naturally occurring, radioactive, inert gas formed by radioactive decay of radium atoms in soil or rocks. Design strategies help reduce the amount of radon infiltration into a building and remove the gas that does infiltrate.

Recyclable: Able to be recycled or re-used in some way.

Recycling: Collecting and reprocessing a resource so it can be used again. An example is collecting aluminum cans, melting them down, and using the aluminum to make new cans or other aluminum products.

Reforestation:  Replanting of forests on lands that have recently been harvested.

Renewable Materials: A raw material that can be replenished within a reasonable amount of time. Example, bamboo and sustainable-harvested woods are renewable. Gold and precious stones are not renewable.
 
Renewable Energy:  Energy obtained from naturally replenished sources such as sun, rain, wind, tides, and geothermal heat.

Repurpose: Taking a thing or a material and using it for a purpose not originally intended.

RESNET (Residential Energy Services Network): The national association of energy rating providers.

R-Value: Measures a materials ability to slow down or resist the transfer of heat energy, also called thermal resistance. The greater the R-value, the better the resistance, the better the insulation.

Solar Power: The technology that we use to obtain energy from sunlight.

Sustainability: Configuring human activity so that a society and its economy can meet present needs without compromising the environment and working to maintain the productivity of natural ecosystems for the future.

Thermodynamics: The study of energy, specially the movement of energy.

Thermal Boundary: The border between conditioned and unconditioned space where insulation should be placed.

Volatile Organic Compounds (VOCs): Substances produced from solids and liquids that convert to gases, such as benzene and methylene chloride, that may have short- and long-term adverse health effects. Avoid products that contain VOCs, which can be found in paints and adhesives.