Monday July 15 , 2024

Green FAQs

Glossary of Green Terms

Active Solar: A system using mechanical devices that transfer collected heat to a storage medium.

Biocides: An additive which will prevent growth of bacteria or fungi. Used in paints, floor coverings and sometimes in fabrics. They are toxic materials which are usually only safe in low concentrations.

Biodegradable: A material that will decompose into naturally occurring, harmless components with exposure to air, sunlight and/or moisture.

BRI (Building Related Illnesses): Illnesses caused by toxic off-gassing from building materials or molds, bacteria, etc. that can accumulate in HVAC systems and carpeting.

British Thermal Unit (BTU): The quantity of heat required to raise the temperature of one pound of water 1 deg. F., equal to 252 calories or the heat given off by a match.

Carbon Footprint: The total amount of carbon dioxide and other greenhouse gases emitted over the life cycle of a product or service.

CFLs: Compact fluorescent light bulbs, which are more energy-efficient and last longer than standard incandescent light bulbs.

Chlorofluorocarbons (CFCs): Chemicals manufactured from hydrocarbons, such as methane, chlorine, fluorine, or bromine. Used in refrigerants and solvents, they can destroy the ozone in the upper atmosphere when released. The EPA has banned their use by 1997.

Ecological Cost: The total impact on the environment including source depletion, pollution and degradation of habitats. That which impacts the least, costs the least.

Ecological Footprint: The land (and water) area that would be required to support a defined human population and material standard indefinitely.

Efficacy: The amount of light output (lumen) per watt of input electricity to a lamp.

Embodied Energy: The energy required to extract or manufacture, transport and install a product. A useful measure of ecological cost.

End-Use: The task or purpose for which energy is required. Examples include lighting dark spaces, cooking food, land-powering vehicles.

Energy Star: A program sponsored jointly by the U.S. Environmental Protection Agency and the U.S. Department of Energy that promotes energy-efficient products and practices for homes and businesses. (ENERGY STAR)

Expanded and Extruded Polystyrene (EPS): Polystyrene, a plastic that is formed with CFCs or HCFCs into pellets and compressed into sheets, or extruded into closed cell sheets and used for insulation. Sometimes known as “beadboard” or by the trade name “Styrofoam.”

Environmental Impact Statement (EIS): Detailed report required by the government and prepared by qualified engineers and landscape architects for large projects or those in environmentally sensitive areas.

Environmental Sustainability: Satisfying the needs of the present without diminishing the ability of future generations to meet their needs.

Fly Ash: A type of pozzolan suspended in flue gases during coal combustion, from which it is collected. Most commonly used to replace 15%-30% of Portland cement in a mix conforming to ASTM C618 Classified as either Class F or Class C, according to the regional type of coal burnt to produce it. Fly ash is also used for fill material, soil stabilization and waste remediation.

Formaldehyde: A colorless, flammable gas or liquid with a wide range of uses that gives it a ubiquitous presence in our everyday lives. Can be found in: tobacco smoke, automobile exhaust, cosmetics, medicines, dishwashing liquids, fabric softeners, carpet cleaners, lacquers, paints, wood products, foam insulation, and more. Used industrially in the manufacture of products such as: pesticides, fertilizers, latex rubber, photographic film, glues and adhesives, and more. Exposure has been linked to various forms of cancer, allergic reactions, respiratory problems including asthma, convulsions and even death. Also referred to as a VOC (see Volatile Organic Compounds).

Frost-Protected Shallow Foundation: A foundation which is 12 to 16 inches below grade and has been insulated to protect against frost heave, rather than extending to below the local frost line to protect against frost heave.

FSC-Certified Wood: The Forest Stewardship Council is an international non-profit organization that sets high standards for preservation of the world’s forests. The FSC not only addresses issues of flora and fauna, but also socio-economic factors, and respect for the rights of indigenous peoples in each country. FSC certification ensures that the wood chosen comes from a responsibly-managed and renewable source.

Geotextiles: A variety of fabrics made from recycled materials used in soil containment and stabilization.

Greenwashing: A term used to describe products that are labeled as “green” when in reality they are not.

Greywater: Water from sinks and baths that may be reused for watering, landscaping and other domestic purposes.

HCFC’s: Hydrochlorfluorocarbons or hydrogenated chlorofluorocarbons. Because they are less destructive to ozone, they are a substitute for CFCs, although less efficient as refrigerants and sometimes quite toxic.

HDPE: High-density polyethylene (see polyethylene).

HVAC: Heating, ventilating and air conditioning: The mechanical systems that heat, cool, ventilate, filter, humidify or treat air in buildings.

IAQ: Indoor air quality.

Infiltration: The air that leaks in around doors, windows, and electrical outlets, etc. which can be a major source of heat loss.

Laminated Veneer Lumber (LVL): Beams made from thin layers of wood, similar to thick pieces of plywood.

LDPE: Low-density polyethylene (see polyethylene)

LEED: The Leadership in Energy and Environmental Design Green Building Rating System, developed by the U.S. Green Building Council in 1998 as a way to encourage the development and implementation of green building practices. The LEED system is based on a whole-building approach, and evaluates building performance across six categories: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, and Innovation and Design Process. LEED projects must meet certain prerequisites and performance benchmarks within each category, and are then awarded Certified, Silver, Gold, or Platinum certification based upon the number of credits they achieve.

Life Cycle Cost Analysis: The total cost of a product of material including the initial cost and the long term maintenance costs. This approach can often be used to justify more expensive and energy efficient systems which save money over the life of the product.

Low-E: Low emissivity glazing has a thin metallic coating applied to glass or plastic. It reduces heat loss and solar heat gain through glazing.

MDF: Medium density fiberboard

Off-Gassing: Materials may give off gases, some of which are toxic. Implicated in a variety of ailments, some people are more sensitive than others to these gases.

Oriented Strand Board (OSB or “Flakeboard”): Wood panels made from wood fibers and chips that are mixed with resin and raked to orient them in the long direction of the panel to maximize strength. OSB, made from what is essentially a waste product, can replace plywood, saving lumber. A concern, similar to many manufactured products, is outgassing from the resin binder.

Ozone: A molecule that occurs naturally in the Earth’s atmosphere: both the upper atmosphere, the stratosphere, and the lower atmosphere, the troposphere. It is important to life on Earth primarily because it absorbs biologically harmful ultraviolet radiation, preventing it from reaching the Earth. See Ozone Depletion.

Parallel Strand Lumber: Beams made from strands of wood fiber mixed with resins and pressed into large beams.

Particle Board: Sawdust and resin compressed into sheets that can substitute for plywood in many situations.

Passive Solar: Systems that collect, move, and store heat using natural heat-transfer mechanisms such as conduction and air convection currents.

Perlite: Expanded volcanic glass, very light in weight and useful as insulation although it has a lower R-value than some materials. Can be added to plaster and is fire resistant.

Phenols: Hydrocarbons used to make resins and glues. Very toxic and may outgas.

Photovoltaics (PVs): Solid-state cells (typically made from silicon) that directly convert sunlight into electricity.


Polyethylene: A semi-transparent plastic used in sheets as vapor barriers or for packaging and containers. Made in high density (HDPE) and low density (LDPE) varieties. Low in toxicity, it produces low risk vapors when burned.

Polyethylene terephthalate (PET): Polyester fibers and sheet plastics such as recyclable soft drink bottles are made from this polyester resin.

Portland Cement: A type of cement made by burning limestone and clay. It is a basic ingredient in concrete.

Post-Consumer (% recycled content): Is made of such material as paper or glass that was recycled after being used which means it is kept out of the landfill.


Pre-Consumer (% recycled content): Refers to the leftovers in the manufacturing process. Using or selling this scrap is an old practice which doesn’t divert material from the landfill; it is not truly “recycled” because it has never been used.

Radon: An odorless gas that passes from some soil types into buildings and may cause cancer.

R-Value: A unit of thermal resistance, the opposite of thermal conductance. The higher the R value, the greater the insulating quality.

Renewable Resource: Resources that are created or produced at least as fast as they are consumed, so that nothing is depleted. If properly managed, renewable energy resources (e.g.., solar, hydro, wind power, biomass, and geothermal) should last as long as the sun shines, rivers flow, wind blows, and plants grow.

Solar Heat Gain Coefficient (SHGC): The fraction of total solar energy that enters a space through a window. The total solar gain through a windows equals the SHGC multiplied by the incident solar radiation. The Shading Coefficient (SC) is referenced frequently and equals the SHGC for a windows divided by 0.87 (assuming normal incidence).

Solvents: Liquids, usually petroleum based, that can dissolve solids and keep them in solution. May contribute to pollution through evaporation.

Stay-In-Place Insulating Formwork: Concrete formwork made from expanded or extruded polystyrene which is permanent in the structure of the building. Such formwork serves as an insulator and can reduce the amount of concrete required.


Superwindow: One of the new generation of glazing technologies, superwindows are double or triple-glazed window sandwiches which contain a center sheet of coated mylar “low-emissivity’ film and are filled with argon or krypton gas. This construction and the coatings on the film allows short-wave radiation (visible light) to pass through, but reflects long-wavelength radiation (infrared or heat) so heat can- not pass through. R-values of 4.5 or more are achieved.

Sustainability: Meeting the needs of the present without compromising the ability of future generations to meet their own needs. (As defined by the World Commission on the Environment and Development.)

Thermal Break: A material of low heat conductance used to reduce the flow of heat. For example, the vinyl separating the interior and exterior frames in some metal windows.

U-Value (Btu/hr-ft2-F): The reciprocal of R-value (that is, 1/R-value). This measures the energy flowing through a wall, roof, window, door, or floor per hour per each degree of temperature difference between the inside and outside air temperatures.

Vapor Barrier: The element in a wall, floor or ceiling that does not allow moisture or air to penetrate and is used to prevent condensation in insulation.

Vermiculite: A hydrous silicate of magnesium or iron which is expanded by heating to produce a lightweight fire resistant insulation.

Volatile Organic Compounds (VOCs): Carbon based gases given off by polymers, solvents or plasticizers.