Green Glossary

absorption - The process by which incident light energy is converted to another form of energy, usually heat.

acid leachate - Water that has become acidic after seepage through landfills; potentially very damaging to fish habitats and drinking water supplies.

adaptation - In lighting design, the process by which the human visual system becomes accustomed to more or less light, resulting from a change in the sensitivity of the eye to light.

adapted plants - Plants that reliably grow well in a given habitat with minimal attention from humans in the form of winter protection, pest protection, water irrigation, or fertilization once root systems are established in the soil. Adapted plants are considered to be low maintenance but not invasive. See also, native plants, invasive species.

adsorption - Adhesion of the molecules of a gas, liquid, or dissolved substance to a surface.

advanced framing - This is a house-framing strategy/technique in which lumber use is optimized to save material and improving the energy performance of the building. Regular framing techniques leave a large amount of wasted wood that needs to be thrown away.

aerator - A device installed on sink faucets to reduce their water use and the energy needed to heat water. Faucet aerators, coupled with low-flow shower heads, can reduce your home's water use by 50%. If an aerator is already installed on your faucet, it will have its rated flow imprinted on the side. This should read 2.75 gpm (gallons per minute) or lower.

air barrier - Building assembly components/products that work as a system to restrict air flow through the building. An air barrier may or may not act as a vapor barrier. The air barrier can be on the exterior and/or the interior.

air handler - A fan that a furnace, central air-conditioner, or heat pump uses to distribute heated or cooled air throughout the house.

air pollution - Airborne contaminants or pollutants that adversely affect the environment or human health.

air-source heat pump - Heat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps.

airtight drywall - Use of drywall with carefully sealed edges and joints that serves as an interior air barrier in building assemblies.

albedo - Percentage of light reflected off a surface; a material with high albedo is highly reflective.

allergen - A substance capable of causing an allergic reaction because of an individual sensitivity to that substance.

alternative Energy - energy sources that are not one of the major energy sources currently used such as nuclear, hydro, or coal.

ambient lighting - Lighting in an area from any source that produces general illumination, as opposed to task lighting.

ammonium sulfate - Flame retardant commonly used in cellulose insulation. Borates are also used.

anc - Active Noise Cancellation involves reducing a sound field through the interaction of a primary sound source with an actively controlled identical secondary sound that is 180 degrees out of phase.

asbestos - Mineral fiber once commonly used in building materials, including insulation, fireproof siding, and resilient flooring; a known human carcinogen causing lung cancer, asbestos is no longer used in the United States.

a-weighting - System of modifying measured sound-pressure levels to simulate the response of the human ear to different sound frequencies.

backdrafting - A potentially dangerous indoor air quality problem in which combustion gases escape into the house instead of going up the chimney.

bacteria sink - Porous material that allows the growth of biological contaminants within the material.

baffle - A single opaque or translucent element used to diffuse or shield a surface from direct or unwanted light.

bakeout - A process used to remove VOCs by elevating the temperature in an unoccupied, fully furnished, and ventilated building.

balanced ventilation - Ventilation system in which fans exhaust stale indoor air and bring in fresh outdoor air in equal amounts; often includes heat recovery or heat and moisture recovery

ballasts - Electrical required by certain lamp types, especially fluorescents.

batch solar water heater - Solar water heater in which potable water is heated where it is stored. Also referred to as an integral collector storage (ICS) solar water heater.

binder - Glue used in manufacturing wood products, such as medium-density fiberboard (MDF), particleboard, and engineered lumber. Most binders are made with formaldehyde. Two types of binders include urea-formaldehyde binder and methyl diisocyanate (MDI) binder.

bioaccumulation - How animals and plants secrete toxins in their tissues from their environment.

bioaerosol - An aerosolized particle originating from a living thing.

bio-based material - Material made from living matter, like agricultural crops. Bio-based materials are usually biodegradable.

biodegradable - A material or substance which, when left exposed to nature, will decompose without harmful effects to the environment.

biodegradable - Breaking down of materials with help from microorganisms.

bioengineering - The use of living plants, or a combination of living and non-living materials, to stabilize slopes and drainage ways.

biological contaminants - These include bacteria, viruses, molds, pollen, animal and human dander, insect and arachnid excreta.

biomass - Plant material such as trees, grasses and crops that can be converted to heat energy to produce electricity.

biophilia - Theory developed by biologist Edward O. Wilson suggesting that humans have an innate affinity for nature.

blower door test - Test used to determine a home’s air tightness. A powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s air tightness can be determined. Operating the blower also exaggerates air leakage and permits a specialized contractor to find and seal the leakage areas.

blowing agent - Compound used in producing foam insulation. Mixed as a liquid with the foam ingredients under pressure, the blowing agent evaporates, creating gas bubbles that provide the insulation. Until recently, most blowing agents (HCFCs and CFCs) depleted Earth’s protective ozone later; except for extruded polystyrene, the industry has now switched to ozone safe blowing agents.

blown-in batt - A method of installing loose insulation in wall cavities, using a powerful blower and a fabric containment screen.

boiler - System used to heat water for hydronic heating. Most boilers are gas-fired or oil-fired, although some are electric or wood-fired; a boiler can also heat water for domestic uses through a thankless coil or an indirect water heater.

brightness - The subjective perception of relative luminance in a space or on a surface.

brownfield - The U.S. Environmental Protection Agency's (EPA) designation for existing facilities or sites that have been abandoned or underused because of real or perceived environmental contamination. The EPA sponsors an initiative to help mitigate these health risks and return the facility or land to renewed use.

buildable land - The portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes public streets and other public rights of way, land occupied by non-residential structures, public parks, and land excluded from residential development by law.

building - The complete, outfitted, and furnished operational in every way, and ready for immediate occupancy and use.

building envelope - The entire perimeter of a building enclosed by its roof, walls and foundation. Properly designed, the envelope can minimize temperature gain or loss and moisture infiltration.

building integrated photovoltaics (bipv) - Solar panels that have been integrated into the design of the building or structure.

building-related illness (bri) - Serious and diagnosable health conditions, usually of the respiratory system, that can be attributed to specific air quality problems within a building.

building pressurization - The air pressure within a building relative to the air pressure outside. Positive building pressurization is usually desirable to avoid infiltration of unconditioned and unfiltered air. Positive pressurization is maintained by providing adequate outdoor makeup air to the HVAC system to compensate for exhaust and leakage.

building-related illness (bri) - Clinically verifiable diseases that are attributed to a specific source or pollutant within a building and are more serious than Sick Building syndrome (SBS) condition. The symptoms of the disease persist after the occupant leaves the building, unlike SBS in which the occupant experiences relief shortly after leaving the building.

built environment - The man-made creation of or alterations to a specific area, including its natural resources. On a home site, this includes everything that has been construction.

capillary forces - Forces that lift or pull water through porous materials, such as concrete.

captured rainwater - Through the use of appropriate roofing materials and gutter systems, rainwater can be harvested or collected then stored for future non-potable use such as showers and hand washing. (See also Graywater)

carbon dioxide - Greenhouse gas increasing global warming. Also known as CO2 - chemical abbreviation.

carbon neutral or carbon neutrality - the term used to describe the actions of organizations, businesses and individuals taking action to remove as much carbon dioxide from the atmosphere as each put in to it.

carbon offset - The act of mitigating one's carbon emissions, often purchased through a carbon offset provider that uses the money for carbon-sequestering activities including tree planting, renewable energy, energy conservation and methane capture.

carbon offsets - Measures taken to make up for carbon dioxide released into the atmosphere.

carbon tax - A proposed tax charge on carbon dioxide emissions because of burning fossil fuels.

carbon-neutral house - House that, on an annual basis, does not result in a net release of carbon dioxide, which is a greenhouse gas that contributes to global warming, into the atmosphere.

catchment area - The surface area on a roof that captures rainwater for direction into a rainwater harvesting system.

cavity-fill insulation - Insulation installed in the space created by wall, ceiling, roof, or floor framing, most commonly fiberglass-batt, spray-applied or dense-pack cellulose, or spray polyurethane.

ceiling cavity - The cavity formed by the ceiling, the plane of the luminaries, and the wall surfaces between them.

certified wood - Under the guidance of the Forest Stewardship Council (FSC), wood-based materials used in building construction that are supplied from sources that comply with sustainable forestry practices, protecting trees, wildlife habitat, streams and soil.

chain of custody - The verification of certified wood.

checkdam - Low dam of stone, wood, or other material used for holding and spreading runoff and sediment in a swale.

chlorofluorocarbons (cfc) - A group of volatile gases believed to deplete the ozone layer of the Earth's stratosphere. These gases have been discontinued from use as refrigerants and as blowing agents used to make foam.

cistern - Vessel for storing water, such as that collected with a rainwater-harvesting system.

cladding - Materials used to enclose a house, providing protection against weather.

climate change - The variation of the average temperatures, rainfall and other measures of global or regional climate over time, whether caused by natural processes, humanity's influence or a combination of both.

closed-loop control - A control system that utilizes measurement of a controlled variable for feedback. Based on the measured feedback, the control system alters its output in an attempt to force the controlled variable to reach a given set point.

closed-loop solar water heater - Solar water heater in which an electric pump circulates a freeze-protected heat-transfer fluid through the collector and heat exchanger within a storage tank.

co2-based high-limit ventilation control - A ventilation strategy that monitors the CO2 concentration in a building zone or in the return air duct from the zone. If the CO2 concentration approaches a predetermined high limit, the outdoor airflow controller is reset to provide additional ventilation. This process supplements standard ventilation-control strategies by providing additional ventilation for unexpected occupancy.

colour (temperature of a source) - In general terms, a means of defining the relative whiteness of a light source, specifically the absolute temperature (degrees Kelvin) of a blackbody radiator having a chromaticity equal to that of the light source.

combustion efficiency- Efficiency at which a fuel is burned in a combustion appliance when operating at its rated output; the combustion efficiency is always higher than the annual fuel utilization efficiency (AFUE).

commission internationale de l'eclairge (cie) - International lighting commission whose standards, procedures, and definitions are in general use in Europe, but less widely accepted in North America.

commissioning - Process of testing a home after a construction or renovation project to ensure that all of the home’s systems are operating correctly and at maximum efficiency.

composite lumber - Lumber made from plastic (often high-density polyethylene) and wood fiber or other agricultural byproducts. Composite lumber often contains recycled content.

composite wood - A product consisting of wood or plant particles or fibers bonded together by a synthetic resin or binder. Examples include plywood, particle-board, OSB, MDF, composite door cores.

compost - Breaking down of materials into dirt.

composting system - Outdoor bins for converting vegetable scraps, garden trimmings, and other plant matter into a rich, high-organic-content soil amendment. An alternative for indoor use is a worm bin.

concrete masonry unit (cmu) - Block made of concrete used for wall construction. The hollow cores can be filled with concrete to reinforce walls.

conduction - Movement of heat through a material as kinetic energy is transferred from molecule to molecule. The handle of an iron skillet on the stove gets hot due to heat conduction. R-value is a measure of resistance to conductive heat flow.

constructed wetland - Any of a variety of designed systems that approximate natural wetlands, use aquatic plants, and can be used to treat wastewater or runoff.

construction - That complete sequence or series of activities and actions that begin with the building Site and results in the completed Structure.

contrast sensitivity - The ability to detect the presence of luminance differences.

convection - Movement of heat from one place to another by physically transferring heated fluid molecules, usually air or water. Natural convection is the natural movement of that heat; forced convection relies on fans or pumps.

cool pavements - Materials and construction methods used in roads, driveways, parking lots, sidewalks, and other hard surfaces, which perform to reduce the absorption, retention and emittance of solar heat, thus minimizing urban heat island effect. Techniques to achieve cool pavements include the use of coloration, materials, porosity and other processes that promote solar reflectivity and cooling through augmented air filtration and evaporation.

co-product - All those things that result from the process that undergo some further processing to be converted to materials or things that have subsequent use and/or value.

cradle to grave - Term used to describe the environmental impact a product has from it’s creation to destruction.

cradle-to-cradle - A concept introduced by architect William McDonough that prescribes at the end of a product's useful life, the product will decompose entirely with no negative environmental impact; otherwise it can be used as post-consumer material when recycled into a new product.

cradle-to-grave - With no consideration for sustainability, these types of products are used for a period of time and then discarded, often long before their useful life is actually complete.

cradle-to-grave analysis - Analysis of the impact of a product from the beginning of its source gathering processes, through the end of its useful life, to disposal of all waste products. Cradle-to-cradle is a related term signifying the recycling or reuse of materials at the end of their first useful life.

cri - Colour Rendering Index is a value ranging from 0 to 100 where 100 represents light with identical qualities of sunlight.

cripple studs - Studs in a wall system that support headers above (and below) windows or doors; indiscriminately placed, these additional studs can result in extra heat loss because they do not insulate as well as the insulation in the wall cavity.

critical zone - Any location in a building with contaminant sources sufficiently strong enough that proper control of ventilation, with no margin for error, is crucial for maintaining the immediate comfort of occupants. Critical zones may include conference rooms, smoking rooms, cafeterias, washrooms, auditoriums, or anywhere occupancy can rapidly change.

cross-linked polyethylene (pex) - Specialized type of polyethylene plastic that is strengthened by cross linking (chemical bonds formed in addition to the usual bonds in the polymerization process). PEX is used primarily as tubing for hot and cold water distribution and radiant-floor heating.

cullet - Crushed, waste glass that is returned for recycling.

current loop - In electrical wiring, a situation in which separation of hot and neutral leads results in higher than-normal electromagnetic fields (EMFs).

cut-off angle - The critical viewing angle beyond which a source can no longer be seen because of an obstruction (such as a baffle or overhang).

daylight factor (df) - The ratio of daylight illumination at a given point on a given plane, from an obstructed sky of assumed or known illuminance distribution, to the light received on a horizontal plane from an unobstructed hemisphere of this sky, expressed as a percentage. Direct sunlight is excluded for both values of illumination. The daylight factor is the sum of the sky component, the external reflected component, and the internal reflected component. The interior plane is usually a horizontal work plane. If the sky condition is the CIE standard overcast condition, then the DF will remain constant regardless of absolute exterior illuminance.

Daylighting - N Use of sunlight for daytime lighting needs.

decibel (db) - Unit of sound level or sound-pressure level. It is ten times the logarithm of the square of the sound pressure divided by the square of reference pressure, 20 micropascals.

degree day - Measure of heating or cooling requirements based on the average outdoor temperature. To calculate the number of heating degree days of a given day, find the average of the maximum and minimum outdoor temperatures and subtract that from 65°F. The annual number of heating degree days is a measure of the severity of the climate and is used to determine expected fuel use for heating. Cooling degree days, which measure air-conditioning requirements, are calculated by subtracting the average outdoor temperature from an indoor base temperature, usually 75°F.

demand water heater - Water heater that heats water only as needed; there is no storage tank and thus no standby heat loss. This is also known as a tankless water heater.

demand-controlled ventilation (dcv) co2-based - A ventilation-control strategy in which the concentration of CO2 is the measured variable that is controlled to a set point by modulating outdoor airflow. With this strategy, only human source contaminants are considered. CO2DCV will not comply with either procedure of ASHRAE Standard 62-1989.

densitometer - A photometer for measuring the optical density (the opposite of transmittance) of materials.

detention - In storm water management, ponding of runoff in pools and basins for water-quality improvement and flood prevention.

direct component - That portion of light energy, from sources such as the sky or sun, that reaches a specified location without any significant diffusion.

direct sunlight (beam sunlight) - That portion of daylight arriving at a specified location directly from the sun, without diffusion.

double wall - Construction system in which two layers of studs are used to provide a thicker-than-normal wall system to accommodate extra insulation. The two walls are often separated by several inches to reduce thermal bridging through the studs and to provide additional space for insulation.

drain back solar water heater - Solar water heater in which water or another heat-transfer fluid is pumped through the collector and drains back to a tank in the house when the pump turns off.

drip irrigation system - An irrigation system that slowly applies water to the root system of plants to maximize transpiration while minimizing wasted water and topsoil runoff. Drip irrigation usually involves a network of pipes and valves that rest on the soil or underground at the root zone.

dual-flush toilet - Toilet that provides two flush levels: a full-volume flush for use with solid wastes and a reduced-volume flush (often half the volume) when only liquid waste and paper need to be flushed.

duct blaster - Calibrated air-flow measurement system developed to test the air tightness of forced-air duct systems. All outlets for the duct system except for the one being tested are sealed off and the system is either pressurized or depressurized; the work needed by the fan to maintain a given pressure difference provides a measure of duct leakage.

earth hour - an annual global event run by the World Wildlife Fund (WWF) where people turn off their lights in support of action on climate change. Earth Hour is on the last Saturday in March.

eco friendly - a term used to describe a product or service that is more sensitive to the environment. This is an unregulated term, so ensure you understand why the product or service is marketed this way to avoid being mislead by green washing.

economizer controls - HVAC system controls that operate mixed air dampers to mix return and outdoor air to obtain air of a temperature appropriate for free cooling Economizer controls are used during periods when outdoor air requires less cooling energy input than return air.

ecosystem - A self sufficient environment formed by biological and physical characteristics existing together and in one place.

ecosystem - An Ecosystem is an ecological community together with its environment, functioning as a unit.

efficacy - In lighting design, a measure of the luminous efficiency of a specified light source, expressed in lumens per watt. For day lighting, this is the quotient of visible light incident on a surface to the total light energy on that surface. For electric sources, this is the quotient of the total luminous flux emitted by the total lamp power input.

electric-resistance heat - Heat provided by electricity in which high-resistance wires convert electric current directly into heat. See heat pump.

electromagnetic field (emf) - Field given off by electric current flow. Some health experts are concerned that the magnetic field component of EMFs may be harmful or even cause cancer. Magnetic fields are stronger near current in which there is separation between the positive and neutral leads.

electromagnetic spectrum - A continuum of electric and magnetic radiation encompassing all wavelengths from electricity, radio, and microwaves at the low-frequency end of the spectrum, to infrared, visible light, and ultraviolet light in the midrange, to x-rays and gamma rays at the high-frequency end.

embodied energy - All the energy used to grow, extract and manufacture a product including the amount of energy needed to transport it to the jobsite and complete the installation.

embodied energy - Embodied Energy is the total energy sequestered from a stock within the earth in order to produce a specific good or service including extraction, manufacture, and transportation to market.

embodied energy - Energy that goes into making a product, including energy for transporting both the raw materials and the finished product.

emission - The output of greenhouse gases and other pollutants from mechanical, industrial, transportation or other processes.

emission - gases or exhausts produced by human activity. one of the new going-green-terminology phrases that almost sounds a bit "scary" is becoming popular…

endocrine disruptor - chemical that mimics natural hormones, such as estrogen, and may interfere with reproductive development or alter. endocrine disruptors include such commonly used chemicals as phthalate plasticizers (used in pvc plastic), and bisphenol-a (used in epoxies and polycarbonate plastic).

energy conservation - saving energy by reducing how much is used.

energy consumption - the amount of energy used. This is typically used to measure appliances and electronics to determine how energy efficient they are.

energy efficient - Products and systems that use less energy to perform as well or better than standard products. While some have higher up-front costs, energy-efficient products cost less to operate over their lifetime.

energy factor - Efficiency measure for rating the energy performance of dishwashers, clothes washers, water heaters, and certain other appliances; the higher the number, the greater the efficiency. A “modified energy factor” accounts for certain adjustments according to accepted test procedures.

energy star™ rating - The label given by the EPA and the U.S. Department of Energy (DOE) to appliances and products that exceed federal energy efficiency standards. This label helps consumers identify products that will save energy and money.

energy vampires - Refers to electric appliances that continue to use energy after they are supposedly turned off.

energy-efficient mortgage (eem) - Special type of mortgage in which the lending institution raises the allowable mortgage amount for a given earnings level, since energy-saving features in the house will reduce the monthly operating costs, thus leaving more money available to pay the mortgage.

fenestration - Any opening, or arrangement of openings, in a building (normally filled with glazing) that admits daylight and any devices in the immediate proximity of the opening that affect light distribution (such as baffles, louvers, draperies, overhangs, light shelves, jambs, sills, and other light-diffusing materials). Fiber optics

fiber-cement siding - Siding material made from wood fiber and portland cement that is highly durable, moisture resistant, and fire proof. Developed in New Zealand, the material is becoming common as a siding material in North America.

finger-jointed - High-quality lumber formed by joining small pieces of wood glued end to end, so named because the joint looks like interlocked fingers.

flashing - Material, usually sheet metal, rubber, or plastic, installed to keep rain from entering a building. When properly installed in a wall or roof assembly, flashing sheds rain to the exterior.

floor cavity ratio - A number indicating floor cavity proportions calculated from length, width, and height. The floor cavity is formed by the work plane, the floor, and the wall surfaces between them.

flush out - To help ensure the indoor air quality, mechanical systems are operated for a minimum of two weeks using 100 percent outside air at the end of construction and prior to building occupancy.

flushout - A process used to remove VOCs from a building by operating the building HVAC system at 100 percent outside air for a specific period of time.

fly ash - The fine ash waste collected from the gases of coal combustion, smelting, or waste incineration.

forced-air heating - Heat distribution system in which heat is delivered by forcing warm air through a network of ducts. A furnace or heat pump typically generates the warm air.

fair trade - USA certification code that verifies that farmers have received a fair price for their products. They have received credit and are helped with assistance to their business on the road to being self-sufficient economically.

fenestration - Any opening, or arrangement of openings, in a building (normally filled with glazing) that admits daylight and any devices in the immediate proximity of the opening that affect light distribution (such as baffles, louvers, draperies, overhangs, light shelves, jambs, sills, and other light-diffusing materials). Fiber optics

fiber-cement siding - Siding material made from wood fiber and portland cement that is highly durable, moisture resistant, and fire proof. Developed in New Zealand, the material is becoming common as a siding material in North America.

finger-jointed - High-quality lumber formed by joining small pieces of wood glued end to end, so named because the joint looks like interlocked fingers.

flashing - Material, usually sheet metal, rubber, or plastic, installed to keep rain from entering a building. When properly installed in a wall or roof assembly, flashing sheds rain to the exterior.

floor cavity ratio - A number indicating floor cavity proportions calculated from length, width, and height. The floor cavity is formed by the work plane, the floor, and the wall surfaces between them.

flush out - To help ensure the indoor air quality, mechanical systems are operated for a minimum of two weeks using 100 percent outside air at the end of construction and prior to building occupancy.

fly ash - The fine ash waste collected from the gases of coal combustion, smelting, or waste incineration.

formaldehyde - Chemical found in many building products; most binders used for manufactured wood products are formaldehyde compounds. Reclassified by the United Nations International Agency for Research on Cancer (IARC) in 2004 as a known human carcinogen. See also phenol-formaldehyde binder and urea-formaldehyde binder.

free range - Way of farming which allow animals to roam freely and not be caged.

fuel cell - A Fuel Cell is a device that converts the energy of a fuel, (Hydrogen, natural gas, methanol, gasoline, etc.) and an oxidant (air or oxygen) into useable electricity.

fuel cell - Electrochemical device similar to a battery in which electricity is generated by chemically reacting hydrogen with oxygen, producing electricity, water vapor, and heat.

fuel consumption - the amount of fuel used. This is often used to describe how much fuel a vehicle will use as shown by a rating of Liters per 100 Kilometers (L/100 KM) or Miles Per Gallon (MPG).

fuel economy - the measurement of how little fuel is used. This is most frequently used to describe how efficient vehicles are, using a rating of Liters per 100 Kilometers (L/100 KM) or Miles Per Gallon (MPG).

fuel efficiency - a term used to describe how little fuel is used. This is most frequently used to describe how efficient vehicles are, using a rating of Litters per 100 Kilometers (L/100 KM) or Miles Per Gallon (MPG).

fungi - Parasitic lower plants (including molds and mildew) lacking chlorophyll and needing organic material and moisture to germinate and grow.

furnishing and outfitting - That complete sequence or series of activities and actions that begin with the Structure and results in the completed Building.

gas mileage - a term used to describe how much fuel is used by a vehicle so it can be compared to other vehicles. This is described in Miles Per Gallon (MPG) or Liters per 100 Kilometers (L/100 KM).

generally regarded as safe (gras) - A designation given to products (originally foods) that have been in use for many generations without apparent toxic effects.

geotextiles - Cloth or cloth like materials intended for use in the soil, usually for filtering or containing soil water. Some types are used to prevent or control erosion.

geothermal - "Geothermal" literally means "earth heat." It is often used to describe two different types of alternative energy source. "True" geothermal energy is less commonly used. It draws on energy generated in the earth's core, about 4,000 miles below the surface, via steam and hot water produced inside the earth to heat buildings or generate electricity. More common are geothermal heating and cooling systems that capitalize on the relatively constant temperature of the ground to transfer heat. These systems don't actually use the geothermal energy generated deep within the earth; instead, they use a heat-transfer liquid to move heat from a few feet below ground into a house during cold months, and from the house to the ground during hot months.

glare - The effect produced by luminance within one's field of vision that is sufficiently greater than the luminance to which one's eyes are adapted; it can cause annoyance, discomfort, or loss in visual performance and visibility.

glare index - A value for predicting the presence of glare as a result of daylight entering an area. The glare index is affected by the size and relative position of fenestration, orientation to the sun, sky luminance, and interior luminances. The glare index is similar to the index of sensation and the discomfort glare rating, which are used for electric lighting applications.

global warming - this is an outdated term – see climate change. Global warming describes the gradual warming of the earth's surface caused by an increase in greenhouse gasses. Due to a greater understanding of our atmosphere, the scientific community now understands that climate change will result in shifts in temperatures, where some regions may get cooler.

global warming potential - Measure of how a given mass of greenhouse gas is estimated to contribute to global warming compared against carbon dioxide, which is given a value of 1.0.

green - Used in reference to being environmentally friendly.

green chaos - A term coined by Scott Bennett referring to the confusion of going green. Read more about green chaos.

green electricity - Electricity generated from renewable energy sources, such as photovoltaic’s (solar power), wind power, biomass, and small-scale hydropower. (Large, conventional hydropower sources usually are not included in definitions of green electricity.)

green energy - this is electricity that has been produced using renewable resources, such as wind or solar, which do not create greenhouse gasses.

green lifestyle/living - Consideration of life choices made which will have consequences on the environment.

green products - a general term used to describe products that are better for the environment. This is an unregulated term, so use caution when you see this claim.

green technology - Devoted to the conservation of energy, green building, soil health, smart electricity and more.

greenapsis - The process a company undergoes in order to become a "green" company.

greenguardª - Established performance-based standards to define goods such as building materials, interior furnishings, furniture, cleaning and maintenance products, electronic equipment and personal care products with low chemical and particle emissions for use indoors. The standards establish certification procedures including test methods, allowable emissions levels, product sample collection and handling, testing type and frequency, and program application processes and acceptance.

greenhouse effect - The Greenhouse Effect is a natural warming process of the earth. When the sun's energy reaches the earth some of it is reflected back to space and the rest is absorbed. The absorbed energy warms the earth's surface which then emits heat energy back toward space as long wave radiation. This outgoing long wave radiation is partially trapped by greenhouse gases such as carbon dioxide, methane and water vapour which then radiate the energy in all directions, warming the earth's surface and atmosphere. Without these greenhouse gases the earth's average surface temperature would be about 33 degrees Celsius cooler.

greenhouse gas - A gas in the atmosphere that traps some of the sun's heat and preventing it from escaping into space. Greenhouse gases are vital for making the Earth habitable, but increasing greenhouse gases contribute to climate change. Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone.

greenhouse gases (ghg) - Some Greenhouse Gases (or GHG) occur naturally in the atmosphere, while others result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases. Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned. Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills, and the raising of livestock. Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of solid waste and fossil fuels. Very powerful greenhouse gases that are not naturally occurring include hydro fluorocarbons (HFCs), per fluorocarbons (PFCs), and sulfur hexafluoride (SF6), which are generated in a variety of industrial processes.

greywater - Wastewater generated from domestic processes such as washing dishes, laundry and bathing. Greywater makes up 50-80% of residential wastewater. Greywater can be used for irrigation, reducing water waste. See also, blackwater.

ground light - Visible radiation from the sun and sky, reflected by exterior surfaces below the plane of the horizon. See external reflected component.

ground-source heat pump - Heat pump that relies on the relatively constant temperatures underground as the heat source and heat sink. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps.

gut rehab - Building renovation in which the walls are gutted (reduced to the wall framing and sometimes sheathing), then insulated, sheathed, and finished.

hazardous waste – By products of society with physical, chemical or infectious characteristics that pose hazards to the environment and human health when improperly handled.

heat distribution - System for delivering heat throughout a house. See forced-air heating and hydronic heating.

heat exchanger - Device that allows for transfer of heat from one material to another. An air-to-air heat exchanger, or heat-recovery ventilator, transfers heat from an outgoing airstream to an incoming airstream. A copper-pipe heat exchanger in a solar water heater tank transfers heat from the heat-transfer fluid circulating through a solar collector into the potable water in the storage tank.

heat island effect - Heat island effect The incidence of higher air and surface temperatures caused by solar absorption and re-emission from roads, buildings and other structures. See also, cool pavements.

heat pump - Heating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump.

heat-recovery ventilator (hrv) - Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger. See also energy-recovery ventilator.

herbicide - Chemicals that stop plants from growing or even kills them.

high performance green building - These buildings include design features that conserve water and energy; use space, materials and resources efficiently; minimize construction waste; and create healthy indoor environments.

high-efficiency particulate air (hepa) filter - A designation for very fine air filters (usually exceeding 98 percent atmospheric efficiency) typically used only in surgeries, clean rooms, or other specialized applications.

high-efficiency toilet (het) - Toilet that provides at least 20% water savings over the federal standard of 1.6 gallons per flush and still meets the most rigorous standards for flush performance.

home performance audit - An energy audit that also includes inspections and testing assessing moisture flow, combustion safety, thermal comfort, indoor air quality, and durability.

home run plumbing system - Water distribution piping system in which individual plumbing lines extend from a central manifold to each plumbing fixture or water using appliance. The piping is typically cross-linked polyethylene (PEX). Because diameter of the tubing can be matched to the flow of the fixture or appliance, hot water can be delivered more quickly.

humus - Decomposed organic material that is an essential component of fertile soil; produced through composting.

hybrid cars - used to describe vehicles that use more than one fuel source. The most popular example of this is the Toyota Prius, which uses an electric motor as well as a traditional engine to power the car. Not all hybrids are equal, so fuel economy is the best way to understand which hybrids are most efficient.

hydro chlorofluorocarbon (hcfc) - Though not without some negative environmental impacts, these substances are used to replace CFCs because they are less damaging to the ozone layer. HCFCs are slated to be banned along with CFCs by 2030.

hydroelectric energy - also known as hydro, this is electricity that is created using the flow of water. This is typically done by damming up a lake to create enough force from the water to turn a generator.

hydrogen sulphide - A very odorous, toxic, and explosive gas produced by some bacteria in the absence of oxygen. It produces acids on contact with water.

hydronic heating - Heat distribution system in which hot water produced by a boiler is circulated through pipes and baseboard radiators or tubing in a radiant floor. Also called baseboard hot-water heating.

hydronic system - A heating or cooling system that relies on the circulation of water as the heat-transfer medium. A typical example is a boiler with hot water circulated through radiators.

hypersensitivity - Extremely high sensitivity of an individual to certain substances.

i joists - A manufactured wood product so named because its section looks like an upper case I. The top and bottom chord are lumber or laminated wood, and the vertical web is plywood or oriented strand board.

illuminance - The density of the luminous flux incident on a surface, expressed in foot candles or lux. This term should not be confused with illumination (i.e., the act of illuminating or state being illuminated).

impact isolation class (iic) - A single-number rating system designed to provide a comparison between different floor/ceiling constructions for structure-borne impact transmission between vertically adjoining spaces. The IIC is calibrated so that comparable ratings for sound transmission class (STC) give equivalent degrees of protection. The IIC is measured with a standardized tapping machine to generate impact noise, measuring it in the space below at the one-third octave bands between 100 and 3150 hertz. The iiC is calculated using the ASTM E989-84 "Standard Classification for Determination of impact isolation Class."

impervious surface - Surface that does not permit storm water runoff to infiltrate the ground. See also porous paving.

indirect water heater - Water heater that draws heat from a boiler used for space heating. The boiler eats water in a separate, insulated tank via a water-to-water heat exchanger. See also tankless coil.

indoor air quality (IAQ) - According to the U.S. Environmental Protection Agency and National Institute of Occupational Safety and Health, the definition of good indoor air quality includes (1) introduction and distribution of adequate ventilation air; (2)control of airborne contaminants; and (3) maintenance of acceptable temperature and relative humidity. According to ASHRAE Standard 62-1989, indoor air quality is defined as air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80 percent or more) of the people exposed do not express dissatisfaction.

indoor air quality procedure - One of two procedures listed in ASHRAE Standard 62-1989 to determine appropriate ventilation rates for buildings. The IAQ Procedure provides a method of measuring and controlling outdoor airflow in order to keep harmful substances diluted to acceptable levels. It is inherently a more rigorous strategy than the Ventilation Rate Procedure because it considers all contaminants. implementation of this procedure is difficult because of monitoring costs and insufficient knowledge about acceptable concentration levels for the thousands of combinations of potential indoor contaminants.

infiltration - In storm water management, entry of runoff into the soil.
Insulated Concrete Form (ICF) - Hollow insulated forms, usually made from expanded polystyrene (EPS), used for building walls (foundation and above ground), that are stacked and stabilized and then filled with concrete, which provides the wall structure.

integral collector storage (ics) solar water heater - Solar water heater in which potable water is heated in the same place it is stored.

integrated design team - A term referring to all individuals involved in a project from very early in the design process, including the design professionals (architect, engineers, landscape architect and interior designer); the owner's representatives (investors, developers, building users, facility managers and maintenance personnel); and the general contractor and subcontractors.

integrated pest management (ipm) - An environmentally sound system of controlling landscape pests, which includes well-timed nontoxic treatments and understanding of the pests life cycles.

interior furnishings - Those temporary or semi-permanent systems and components which are generally required for the normal utilization of the Building for its intended purpose. Examples, interior design elements, paint, furniture, some types of flooring, ceilings, and walls, etc. (J.A. Tshudy, Part IV, Section C)

international standards organization (iso) - This international nongovernmental standard-setting body, founded in 1947, includes representatives of national standard development organizations, such as the American National Standards Institute (ANSI) in the U.S. ISO defines terms and develops worldwide standards that frequently become law or form the basis of industry norms.

invasive vegetation - An exotic plant adapted to very similar growing conditions as those found in the region to which it is imported. Because such a species usually has no natural enemies (pests, diseases, or grazers), it flourishes, disrupting the native ecosystem and forcing out native plant species, resulting in habitat loss, water-table modification, and other serious problems.

inverse square law - In lighting design, the law that states that the illuminance at a point on a surface varies proportionately with the intensity of a point source, and inversely to the square of the distance between that source and that surface.

inverter - Device for converting direct-current (DC) electricity into the alternating-current (AC) form required for most home uses. An inverter is necessary if home-generated electricity is to be fed into the electricity grid through a net-metering arrangements.

ippc - Government Panel investigating impact, and solutions for the changing climate.

irradiance (E) - The amount (or density) of light energy incident on a surface.

kilowatt-hour (kwh) - Measure of electricity consumption; a 100-watt light bulb burning for ten hours consumes 1 kWh.

laminated veneer lumber - A manufactured wood product similar to plywood but made in thick sections with all the grain oriented one way for use as beams.

landfill - A place to bury garbage, waste.

lead - Toxic heavy metal often found in paints made or applied before 1978. When renovating, follow proper lead-abatement procedures to avoid lead poisoning.

lead ventilation - Ventilation of an unoccupied building space immediately prior to its occupancy. Lead ventilation is performed to dilute contaminants from building and HVAC sources to acceptable levels by the time occupants arrive.

led - Replacing the usual light-bulbs, known as Light Emitting Diode.

leed - LEED or Leaders in Energy and Environmental Design is a building environmental certification program developed and operated by the U.S. Green Building Council.

legionnaires disease - A sometimes fatal lung infection caused by the Legionella bacteria, first identified at a Legionnaires convention in Philadelphia in 1976.

level spreaders - A storm water management device installed parallel to a slope that changes concentrated flow to sheet flow.

life-cycle - The consecutive, interlinked stages of a product, beginning with raw materials acquisition and manufacture and continuing with its fabrication, manufacture, construction, and use, and concluding with any of a variety of recovery, recycling, or waste management options.

life-cycle analysis (lca) - Life-Cycle-Analysis or Assessment (or LCA) is the study of the environmental impacts of a product or service over its entire life cycle, from the extraction of raw materials, through to the consumption and final disposal of the product. It is a concept and a method to evaluate the environmental effects of a product or activity holistically, by analyzing the entire life cycle of a particular product, process, or activity. Life-cycle assessment is typically described in three complementary phases: inventory analysis, impact assessment, and improvement assessment.

life-cycle cost (lcc) - Economic cost of a product or building over its expected life, including both first cost (purchase cost) and operating cost.

life-cycle cost (lcc) of material - The costs accruing throughout the service life of a material. Life-cycle costs address the capital costs involved in production, maintenance, and disposal, and can also include other environmentally related capital costs and societal costs.

light adaptation - The process by which the retina becomes adapted to a luminance greater than about 1.0 foot-lambert.

light pollution - Nighttime lighting that escapes into the night sky. Light pollution can interfere with the day-night patterns of ecosystems, disrupt the flights of migrating birds, interfere with sea turtle nesting in coastal areas, and hinder astronomical observation.

light shelf – A horizontal device positioned (usually above eye level) to reflect daylight onto the ceiling and to shield direct sunlight from the area immediately adjacent to the window. The light shelf may project into the room, beyond the exterior wall plane, or both. The upper surface of the shelf may be specular or nonspecular but should be highly reflective (that is, having 80 percent or greater reflectance).

lignin - The naturally occurring polymer in wood that binds the cellulose fibers together.

localvore - A localvore is someone who eats food grown or produced locally. This reduces the impact on the environment by avoiding food that is shipped long distances. It also helps support local farmers and the local economy.

louver - A series of baffles used to shield a light source from view at certain angles or to absorb unwanted light. The baffles are usually arranged in a geometric pattern.

low toxic - This refers to the degree to which a product is poisonous to people or other living organisms.

low-conductivity gas fill - Transparent gas installed between two or more panes of glass in a sealed, insulated window that resists the conduction of heat more effectively than air. The fill boosts a window’s R-value and reduces its U-factor.

low-emissivity (low-e) coating - Very thin metallic coating on glass or plastic window glazing that reduces heat loss through the window. The coating emits less radiant energy (heat radiation), which makes it, in effect, reflective to that heat. The coating boosts a window’s R-value and reduces its U-factor.

lumen method (day lighting) - A method of estimating the interior illuminance from window day lighting at three locations within a room, based on empirical studies.

luminaire - A complete electric lighting unit, including housing, lamp, and focusing and/or diffusing elements; informally referred to as fixture.

luminance - Luminous intensity of a surface in a given direction.

luminous flux - The rate of flow of light, analogous to the rate of flow of a fluid.

make-up air - Outside air supplied to replace household air that was used in a combustion appliance or exhausted through a ventilation system.

material safety data sheets (msdss) - OSHA-required documents supplied by manufacturers of potentially hazardous products. MSDSs contain information regarding potentially significant airborne contaminants, precautions, steps for inspection, health effects, odor description, volatility, expected contaminants from combustion, reactivity, and procedures for cleanup.

matte surface - Surface from which the reflection is predominantly diffuse, with or without a negligible specular component.

mechanical ventilation - Ventilation system using one or more fans to exhaust stale indoor air from a home as a way to ensure adequate indoor air quality. See exhaust only ventilation and balanced ventilation.

mineral fibers - Very fine insulation fibers made from glassy minerals that have been melted and spu and are. hazardous to inhale.

mixed air - The mixture of outdoor air and return air in an HVAC system. When filtered and conditioned, mixed air becomes supply air.

monitor - A raised section of roof that includes a vertically (or near vertically) glazed aperture, for the purpose of daylight illumination .

native plants - Plants that have evolved within their own ecological habitats, and are not invasive within their own native ranges. Native plants provide food and shelter to indigenous wildlife, stabilize shorelines and fields, etc., growing in balance with surrounding plant and animal species. See also, adapted plants, invasive species.

native vegetation - A plant whose presence and survival in a specific region is not due to human intervention. Certain experts argue that plants imported to a region by prehistoric peoples should be considered native. The term for plants that are imported and then adapt to survive without human cultivation is naturalized.

natural cooling - Use of environmental phenomena to cool buildings, e.g., natural ventilation, evaporative cooling, and radiative cooling.

net metering - Arrangement through which a homeowner who produces electricity using photovoltaics or wind power can sell excess electricity back to the utility company, running the electricity meter backward. The utility effectively buys the power at the retail price, but the amount of electricity the utility company will “buy” in a given month is limited to the amount that the homeowner buys; any excess electricity is purchased at a much lower, wholesale price. See grid-connected power system.

nit (nt) - Unit of luminance equal to one candela per square meter. No-build option scenario against which the true environmental cost-effectiveness of building concepts can be evaluated.

noise criteria (NC) - Series of curves of octave-band sound pressure levels from 63 to 8000 Hertz. They are commonly used in the United States to rate interior noise levels.

noise reduction (NR) - The simple loss of sound level that occurs in passing through a medium. Most often noise reduction refers to a single octave or one-third octave-band noise.

noise reduction coefficient (nrc) - Average of the sound absorption coefficient of the four octave bands 250, 500, 1,000, and 2,000 Hertz rounded to the nearest 0.05.

non-point-source pollution - Runoff contamination from an overall site or land use and not discharged from a single pipe, such as sediment from construction sites, oils from parking lots, or fertilizers and pesticides washed from farm fields.

non-renewable - A finite resource.

obsolete building - A Building that for one reason or another has reached the end of its current useful life.

octave band - A group of frequencies whose lower boundary is one-half of the upper boundary. In acoustics, the first nine octave bands are identified by their center frequencies of 31.5, 63, 125, 250, 500, 1,000, 2,000, 4,000, and 8,000 Hertz. The 31.5 band is also referred to as the band number 0, and 63 Hertz is band number 1.

offgas/outgas - A process of evaporation or chemical decomposition through which vapors are released from materials.

off gassing - Release of volatile chemicals from a material or product. See also volatile organic compounds.

on-center - As used in house construction, the distance from the center of one framing member to the center of another. In wood-frame construction, studs are typically 16 or 24 inches on-center.

on-demand hot water circulation - System that quickly delivers hot water to a bathroom or kitchen when needed, without wasting the water that has been sitting in the hot-water pipes, which circulates back to the water heater.

on-site wastewater system - Treatment and disposal of wastewater (sewage) from a house that is not connected to a municipal sewer system; most on-site systems include a septic tank and leach field.

open-web wood joists - Wood joists built as flat trusses, using small-dimension lumber for web pieces. These are also available with stamped steel webs.

operating cost - Cost of operating a device or building; including energy, maintenance, and repairs.

operating energy - Energy required to operate a device or building.

organic food - No fertilizers, sewage, or pesticides are used to grow plants.

orientation - The relation of a building and its associated fenestration and interior surfaces to compass direction and, therefore, to the location of the sun.

oriented strand board (osb) - A manufactured wood sheet product made from large flakes of wood pressed together with glue, usually a dry phenolic type. OSB is used for structural sheathing and subfloors.

oxidizer - Any agent or process that receives electrons during a chemical reaction.

ozone layer - Defined by the EPA as the protective layer of atmosphere, 15 miles above the ground, that absorbs some of the sun's ultraviolet rays, reducing the amount of potentially harmful radiation reaching the Earth's surface. Ozone depletion is caused by the breakdown of certain chlorine- and/or bromine-containing compounds such as CFCs or halons.

passive solar heating - Building design in which solar energy provides a significant portion of the heating without fans or pumps; the building itself serves as the solar collector and heat storage system.

payback period - Length of time it takes for an investment to pay for itself. For example, water and energy savings from replacing an old showerhead with a new, water-saving model can often pay back the investment in a few months; the payback period for a photovoltaic power system will be much longer.

peak watt - Highest possible unit of rated power output, (for example, from a photovoltaic (PV) module in full sunlight), as distinct from its output at any given moment, which may be lower.

perlite - A lightweight, expanded mineral bead; highly flame-resistant and with good insulating value.
PHANTOM LOAD - Same meaning as Energy Vampires.

phenolic laminate - A high-pressure laminated sheet made from paper and phenol formaldehyde resin, commonly used for furniture and kitchen cabinet surfaces.

photocells - Light-sensing cells used to activate controllers at dawn or dusk.

photovoltaics (pv) - Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.

pier foundation - Building foundation consisting of piers instead of continuous walls. Piers are resource-efficient because they avoid the need for continuous foundation walls.

plasticizers - Chemicals added to soft plastics to preserve their flexibility. These agents off gas slowly, eventually rendering the plastic brittle.

point method - A method of estimating the illuminance at various locations in a building, using photometric data.

pollution prevention - Reducing the amount of energy, materials, packaging or water in the design, manufacturing or purchasing of products or materials in an effort to increase efficient use of resources, reduce toxicity and eliminate waste.

polyethylene terepthalate (pet) - A polyester plastic used widely in soft drink bottles.

polyisocyanurate (polyiso) - Type of rigid foam insulation used in above-grade walls and roofs, typically with a foil facing on both sides. This kind of insulation was made with ozone-depleting HCFC-141b blowing agent, but manufacturers have switched to ozone-safe hydrocarbons.

polymers - Any molecule chain made up from repeated elements, for example, plastics and adhesives.

polypropylene - A common flexible plastic usually spun into fiber for rope and woven goods.

polyurethane foam - Insulation material made from polyol and isocyanate and a blowing agent that causes it to expand, typically sprayed into wall cavities or sprayed on roofs. Both open-cell and higher-density closed-cell products are used.

polyvinyl chloride (pvc) - Most common plastic in building construction, widely used in such applications as drainage piping, flooring, exterior siding, window construction, and electrical wire. Also known as vinyl.

portland cement - Building material made from limestone, gypsum, and shale or clay, which when mixed with water, binds sand and gravel into concrete. Portland cement was invented in 1824 by Joseph Aspdin, a British stone mason, who named it after a natural stone quarried on the Isle of Portland off the British coast.

post-consumer - A material or finished product that served its intended use as a consumer item. It may be recycled and incorporated into building materials and identified as containing post-consumer recycled content or recovered material.

post-industrial recycled content - Post Industrial Recycled Content is waste that is produced during the manufacturing process that is recycled back into the industrial process. In many cases, industry was already recycling this material back into the process and thus post industrial recycled content is not as significant as post consumer. See post consumer recycled content.

potable water - Water considered safe for drinking and cooking.

powder coating - A durable finishing method for metals using a dry, powdered plastic that is heat-fused onto the surface. No solvent is required and practically no waste produced.

pozzolan - Any silicon or silicon-aluminum material - which when finely divided and mixed with moisture, reacts with calcium hydroxide to form a cementitious compound. Common examples of pozzolans include fly ash, blast furnace slag, volcanic ash, silica fume, and rice hull ash.

pre-consumer recycled material - A material that is removed from source gathering or production processes (such as scrap, breakage, or returned inventory) and returned to the original manufacturing process or an alternative process. Pre-consumer recycled materials have not yet reached a consumer for the intended use.

pressure dose - A method of pumping wastewater to subsurface leaching fields in which soils or slopes are a limiting factor. Typical leach fields operate with gravity.

pressure-assist toilet - Toilet that uses air pressure, generated as the toilet tank refills, to produce a more forceful flush; some high-efficiency toilets (HETs) rely on pressure-assist technology.

primary input - A thing or things that represent the key or fundamental elements that are operated upon by the process and lead to the Primary output of the process. For a specific life cycle analysis, the Primary inputs of each process in the life cycle sequence need to be clearly defined in terms of what, when, and where. In general, the Primary input of one process will be the Primary output of the previous process.

radiant energy (radiation) - Energy traveling in the form of electromagnetic waves, measured in units of energy such as joules, ergs, or kilowatthours.

radiant-floor heating - Heat distribution system in which a floor serves as a low-temperature radiator. When used with hydronic heating, hot water is usually circulated through tubing embedded in a concrete slab; alternatively, the tubing can be installed on the underside of wood subflooring, although the benefit of thermal mass is lost.

radiation - Movement of energy via electromagnetic waves.

rainscreen - A method of constructing walls in which the cladding is separated from a membrane by an airspace that allows pressure equalization to prevent rain from being forced in. Often used for high-rise buildings or for buildings in windy locations.

rainscreen - Construction detail appropriate for all but the driest climates to prevent moisture entry and to extend the life of siding and sheathing materials, most commonly produced by installing thin strapping to hold the siding away from the sheathing by a one-quarter to three-quarters of an inch.

raised heel truss - Preconstructed roof truss designed to allow room at the eaves (above exterior walls) for large amounts of insulation. (Standard roof trusses have sufficient depth for adequate insulation near the eaves.)

rapidly renewable - Materials that are not depleted when used, but are typically harvested from fast growing sources and do not require unnecessary chemical support. Examples include bamboo, flax, wheat, wool and certain types of wood.

recyclability - The ability of a product or material to be recovered or otherwise diverted from the solid waste stream for the purpose of recycling.

recycle - Finding alternate uses for something instead of throwing it away as garbage.

recycling - A series of activities including collection, separation and processing by which products or materials are recovered from the solid waste stream for use in the form of raw materials in the manufacture of new products other than fuel for producing heat or power by combustion.

reduce, reuse, recycle - Commonly referred to as the 3 r's of green living. The credo for going-green-terminology.

reflectance - The ratio of reflected light flux to incident light flux.

reflected glare - Glare resulting from specular reflection of high luminances in polished, or glossy, surfaces in the field of view. See also Veiling reflection.

reflection - The process by which incident light flux leaves a surface, or medium, from the incident side, without a change in frequency.

reflective roofing - Roofing material that reflects most of the sunlight striking it to help reduce cooling loads. The Energy Star Cool Roof program certifies roofing materials that meet specified standards for reflectivity.

refrigerant - Compound used in refrigerators, air conditioners, and heat pumps to transfer heat from one place to another (using the Rankine cycle), thus cooling or heating a space. Most refrigerants today are hydro chlorofluorocarbons (HCFCs), which deplete the ozone layer.

releasable adhesives/dry adhesives - A dry, tacky adhesive that holds a carpet or other finish in place but can be easily removed. After removal it leaves no residue and can be reattached.

remanufacturing - Industrial process in which worn-out products are restored to like-new condition.

renewable - A renewable product can be grown or naturally replenished or cleansed at a rate that exceeds human depletion of the resource.

renewable energy technologies - Active, passive, and photovoltaic strategies integrated into building design.

renewable resources - these are natural resources that continually regenerate such as wind power, solar, or hydro. An example of a non-renewable resource is coal.

repurpose - Same meaning as "recycle."

resource efficiency - A practice in which the primary consideration of material use begins with the concept of Reduce

return air - Air that has circulated through a building as supply air and has been returned to the HVAC system for additional conditioning or release from the building.

reuse - Recycle - Repair" stated in descending order of priority. This concept may be applied in everyday life to help promote a sustainable society. In design, begin by reducing the amount of material that is specified; find ways to reuse materials, recycle products or product waste; specify products made from recycled materials; and repair or restore products instead of replacing them.

reverberation time (rt) - The amount of time it takes for sound to decay 60 decibels in a given space. It is a function of room volume and amount of sound absorption provided by surface finishes in the room. Optimum levels are determined based on room volume and space usage.

rhinitis - Inflammation of nasal mucous membrane. Room cavity

room criteria (rc) - Similar to NC and NR, but from 16 to 8,000 Hertz and more recent. RC also rates noise for rumble or hiss.

r-values - A measure of thermal resistance (the number of watts that will be lost per square meter at a given temperature difference). The inverse of U value (i.e., R=1/U).

seasonal energy efficiency ratio (seer) - Energy performance rating of a whole-house (central) air conditioner or heat pump operating in the cooling mode, calculated as the ratio of the estimated seasonal cooling output divided by the seasonal power consumption in an average climate.

sediment basin - A depression in the soil that is placed to retain sediment and debris on-site.

shallow trench system - A type of drain field used in conjunction with a gray water system that allows for shallow placement of distribution pipes and use of the grey water for irrigation.

shear braces - A bracing system, usually using metal brackets or straps, which eliminates most structural wall sheathing.

sheathing - Material, usually plywood or oriented-strand board (OSB) but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses. Siding or roofing installed on the sheathing, sometimes over strapping to create a rain screen.

sinks - Surfaces that tends to capture volatile compounds from air and release them later. Carpets, gypsum board, ceiling tiles, and upholstery are all sinks.

site - The natural location intended for the Building, altered, modified, and prepared to the point where Construction activities for the Structure can be initiated. (J.A. Tshudy, Part IV, Section C)

site selection and preparation - That complete sequence or series of activities and actions that begins with the natural environment and results in some specific geographic location defined in terms of boundaries, and altered and modified to the point where it has become the building Site ready for Construction to begin.

skylight - A relatively horizontal, glazed roof aperture for the admission of daylight.

slipforms - Concrete forms that are advanced for another pour after the concrete has set.

slow food - The Slow Food movement was founded to counteract fast food and fast life, the disappearance of local food traditions and how our food choices affect the rest of the world.

sludge composting - Process of composting treated municipal sewage waste with organic matter for use as a soil amendment.

sodium silicate - A liquid used in asbestos encapsulation, concrete and mortar waterproofing, and high-temperature insulations (also called water glass). This substance is nontoxic when cured but caustic when wet.

solar altitude - In solar analysis, the vertical angular distance of a point in the sky above the horizon. Altitude is measured positively from the horizon to the zenith, from 0 to 90 degrees.

solar azimuth - In solar analysis, the horizontal angular distance between the vertical plane containing a point in the sky (usually the sun) and true south.

solar collector - Device for capturing solar energy and transferring heat to water or air that circulates through it.

solar energy - energy that is created from sunshine. This is used to either generate solar power or to heat water or buildings. See more solar power terminology.

solar gain - Sunlight entering a building. A passive solar direct-gain system uses solar gain.

solar heat gain coefficient (shgc) - The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.

solar hot water - a term used to describe water that was heated by a solar water heater.

solar radiation - The full spectrum of electromagnetic energy including visible light from the sun. When solar radiation strikes a solid surface or a transparent medium such as air or glass, some of the energy is absorbed and converted into heat energy, some is reflected, and some is transmitted. All three of these effects are important for effective passive solar design.

solar water heater - a system used to harness the energy from the sun to heat water. A typical solar water heater system is made up of a solar collector panel, a circulating pump, and a hot water storage tank.

solar window screens - A mesh screen that is used to block insects as well as light and heat from the sun.

sound power level - Reported in decibels, it is 10 times the logarithm to the base of 10 of the ratio of the total sound power in watts to a reference power of 10- 1 2 watts .

sound pressure level (spl) - Reported in decibels, it is 20 times the logarithm to the base 10 of the ratio of sound pressure to a reference pressure of 20 micropascals.

space planning - Process of converting the needs expressed by the client into the drawings and supporting documentation that outline the plan for the team

spectrophotometer - An instrument for measuring the transmittance and reflectance of surfaces and media as a function of wavelength.

storm water - Runoff from Rain that is either carried off site in storm sewers or allowed to infiltrate the ground; storm water can be reduced through the use of porous paving and other infiltration strategies.

stressed skin - A structural panel with the sheathing permanently bonded to the frame or core to increase its strength.

structure - The completed building envelope on the Site externally and internally complete, including all operating systems ready for its Interior furnishings.

sump - Reservoir or pit in the basement of a house into which water can drain, especially during flooding. A sump pump is used to pump collected water out of this reservoir.

sun tempering - Practice of using a modest area of south facing windows to provide limited passive solar heating to a house.

sun-bearing angle - The solar azimuth angle relative to the horizontal direction a building surface is facing. Often referred to as the relative solar azimuth.

superabsorbent materials - Various artificial materials capable of holding several times their own weight in water. Used in granular form, these are mixed with earth to increase the amount of water held in the soil, the length of time it is held before drying, and its availability to plants. Humus serves this purpose.

super insulate - To insulate extremely well. A house with very efficient windows and tight construction results in very low heating and cooling costs.

super plasticizers - Chemical additives for concrete that increase the fluidity of the mix without excess water.

sustainable - The condition of being able to meet the needs of present generations without compromising those needs for future generations. Achieving a balance among extraction and renewal and environmental inputs and outputs, as to cause no overall net environmental burden or deficit. To be truly sustainable, a human community must not decrease biodiversity, must not consume resources faster than they are renewed, must recycle and reuse virtually all materials, and must rely primarily on resources of its own region.

sustainable yield vs. ecologically sustainable forestry - Sustainable yield forestry dictates that the same number of trees cut down are planted. Clear-cutting with 100 percent replanted is an example of sustainable yield. Ecologically sustainable forestry dictates the management of a productive forest that supports a healthy ecosystem.

swale - Low area of ground used for drainage and often the infiltration of storm water.

synergy - Action of two or more substances to achieve an effect of which each is individually incapable. As applied to toxicology, two exposures together (for example, asbestos and smoking) are far more risky than the combined individual risks.

tankless coil - Heat exchanger used for heating water that is integrated into a boiler. Effective in the winter months when the boiler is operating for space heating, tankless coils waste energy in warmer months, since they require the boiler to fire up every time hot water is drawn.

tankless water heater – Tankless water heaters heat water as it flows through the device. They do not retain any water internally except for what is in the heat exchanger coil. Tankless heaters are often installed throughout a household at more than one point-of-use, or larger models may still be used to provide all the hot water requirements for an entire house. The chief advantages of tankless water heaters are a continuous flow of hot water and energy savings (as compared to a limited flow of continuously heating hot water from conventional tank water heaters).

therm - Unit of heat equal to 100,000 British thermal units (Btus), commonly used to measure natural gas consumption.

thermal bridging - Heat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall because of thermal bridging through the steel.

thermal comfort - The appropriate combination of temperatures, warm or cool, combined with air flow and humidity, which allows one to be comfortable within the confines of a building. This comfort is not usually achieved by the fixed setting of thermostats but through careful design and planning.

thermal envelope - The thermal enclosure created by the building exterior and insulation. Improving the thermal envelope is one of the most important aspects to creating an energy efficient home.

thermal mass - Heavy, high-heat-capacity material that can absorb and store a significant amount of heat; used with a passive solar heating system to keep the house warm at night.

thermosiphon solar water heater - Solar water heater that operates passively (through natural convection), circulating water through a solar collector and into an insulated storage tank situated above the collector. Pumps and controls are not required.

thinset - A modified portland cement and sand mortar used for tile setting. May contain an acrylic additive for strength.

tight buildings - Buildings that are designed to let in minimal infiltration air in order to reduce heating and cooling energy costs. In actuality, buildings typically exhibit leakage that is on the same order as required ventilation; however, this leakage is not well distributed and cannot serve as a substitute for proper ventilation.

top plate - Wood framing member that forms the top of a wall. In advanced framing, a single top plate is often used in place of the more typical double top plate.

top-soil - The uppermost soil horizon (layer), containing the highest amounts of organic material; depth varies greatly from region to region.

transmission - The process by which incident flux leaves a surface, or medium, on a side other than the incident side, without change in frequency.

transmission loss (tl) - Noise reduction corrected for wall area and room absorption.

transmittance - The ratio of transmitted flux to incident flux; measured by a transmissometer.

trombe wall - A south-facing masonry wall that is covered with glass spaced a few inches away. Sunlight passing through the glass is transformed into heat at the wall surface, which either migrates into the building interior or is thermos phoned to interior spaces through vents.

tubular skylight - Round skylight that transmits sunlight down through a tube with internally reflective walls, even through an attic space to deliver day lighting through a ceiling light diffuser. Most tubular skylights are 12 to 16 inches in diameter and deliver daytime lighting comparable to several 100-watt incandescent light bulbs.

ultraviolet radiation (UV) - Any radiant energy within the wavelength range of 0.001 to 0.38 micron; high-energy components of light capable of damaging materials and increasing skin cancer risk.

unit factors - An estimate of the environmental costs (for example, raw materials, energy pollution, and solid waste) associated with a unit of a material, such as a ton of steel or a cubic yard of concrete .

united states green building council (usgbc) – Organization devoted to promoting and certifying green buildings. USGBC created the LEED rating systems.

universal design - Design that makes a building accessible to as many individuals as possible, including older people and those with physical handicaps.

unvented (or vent-free) gas heater - Gas-burning space heater that is not vented to the outdoors. Although unvented gas heaters burn very efficiently, indoor air quality experts strongly recommend against their use because combustion gases, including high levels of water vapor, are released into the house.

urethanes - A family of plastics (polyurethanes) used for varnish coatings, foamed insulations, highly durable paints, and rubber good s .

use and operation - That complete and ongoing sequence and series of activities and actions that are required and occur during the life of a Building from the point where occupancy and operation begin to the point where it becomes obsolete, and as a result, is no longer occupied or used.

uv light treatment - Water treatment system in which water passes through a column where it is exposed to ultraviolet light to kill any pathogens.

vapor diffusion - Movement of water vapor through a material. Water vapor can diffuse through even solid materials if the permeability is high enough.

vapor profile - The relative individual component and total combined vapor permeability of building assemblies. The vapor profile addresses not only how the assembly protects itself from getting wet by vapor diffusion, but also how it dries the assembly gets wet.

vapor retarder - Layer that inhibits vapor diffusion through a building envelope. Examples include polyethylene sheeting, foil facing, Kraft paper facing on bat insulation, and low-permeability paints. Most building codes define a vapor retarder as 1 perm or less, with many common vapor retarders being significantly less than 1 perm. Note that many building scientists prefer a focus on the vapor profile of a building assembly rather than just the individual vapor permeability of the designated vapor retarder.

variable air volume (vav) air handler - System for controlling an HVAC system in which the volume of air provided to conditioned space is varied to control comfort.

variable-air-volume (vav) - A method of modulating the amount of heating or cooling effect that is delivered to a building by the HVAC system. The flow of air is modulated rather than the temperature. VAV systems typically consist of VAV boxes that throttle supply airflow to individual zones, some mechanism to control supply-fan flow to match box demand, and the interconnecting ductwork and components.

vegan - Someone who will not eat products from animals or use material products from animals either.

vegetated roof - A roof partially or fully covered by vegetation. By creating roofs with a vegetated layer, the roof can counter-act the heat island effect as well as provide additional insulation and cooling during the summer.

veiling luminance - Luminance superimposed on the retinal image that reduces its contrast.

veiling reflection - Specular reflection superimposed upon diffuse reflection from an object that partially, or totally, obscures the details to be seen by reducing the contrast. Controlled by distributing

ventilation - Replacement of stale indoor air with fresh outdoor air, usually with fans but sometimes naturally through building design elements. See also heat recovery ventilator.

vermiculite - A naturally occurring silicate mineral that can be expanded by heating into a non-combustible insulating pellet.

visual angle - The angle subtended by an object, or detail, at the point of observation.

visual performance - The quantitative assessment of the performance of a visual task, taking into consideration speed and accuracy.

volatile organic compound (voc) - Chemical compounds based on carbon and hydrogen structures that are vaporized at room temperatures. VOCs are one type of indoor air contaminant. Although thousands have been identified in indoor air, only a few are well understood and regulated.

volatile organic compound (voc) - These substances are indoor air pollutants or chemical compounds that exist as vapor or gases at normal temperatures and are carbon-based molecules typically used as solvents in products such as household cleaners, paints, inks and dyes. Sources of VOCs include formaldehyde (a suspected carcinogen), xylene, toluene, benzene (a known carcinogen) and acetone.

waste management plan - Plan that addresses the collection and disposal of waste generated during construction or renovation, usually including the collection and storage of recyclable materials.

waste reduction - This is a process to reduce or eliminate the amount of waste generated at its source or to reduce the amount of toxicity from waste or the reuse of materials. The best way to reduce waste is not to create it in the first place.

waste stream - The total flow of solid waste from homes, businesses, institutions and manufacturing that is recycled, burned or disposed of in landfills.

waste streams - Waste materials which come from various commercial, industrial or municipal sectors.

water budget - The estimated water use within a facility. Flow rates of fixtures and appliances, occupancy, and landscape needs are calculated.

water harvesting - Collection of both runoff and rainwater for various purposes, such as irrigation or fountains.

water reclamation - Reuse of effluent from wastewater treatment facilities through irrigation, land application, or other recycling methods.

water sense - Program developed and administered by the U.S. Environmental Protection Agency to promote and label water-efficient plumbing fixtures.

watershed - Area of land that, as a result of topography, drains to a single point or area.

weatherization - Cost-effective energy efficiency measures for existing residential and multifamily housing. When weatherization includes the house as a system, it is often called whole-house weatherization.

wetland - In storm water management, a shallow, vegetated, ponded area that serves to improve water quality and provide wildlife habitat.

white noise - Sound that has constant energy per frequency.

wind energy - electricity that is created using a wind turbine.

wind farms - a group of wind turbines that are located together.

window-to-floor ratio - The ratio of total, unobstructed window glass area to total floor area served by the windows, expressed as a percentage. This value can also be further subdivided by solar orientation (such as south-facing window-to-floor ratio).

work plane - The plane at which work is usually done and on which the illuminance is specified and measured. Unless otherwise indicated, this is assumed to be a horizontal plane, 30 inches (0.76 meter) above the floor.

xeriscape - Xeriscaping is derived from the Greek word "xeros", meaning "dry" and combined with "landscape", xeriscape means gardening with less than average water. A trademarked term referring to water-efficient choices in planting and irrigation design. It refers to seven basic principles for conserving water and protecting the environment. These include: (1) planning and design; (2) use of well-adapted plants; (3) soil analysis; (4) practical turf areas; (5) use of mulches; (6) appropriate maintenance; and (7) efficient irrigation .

xeriscaping - Type of landscaping that requires little if any irrigation, is suited to dry and drought-prone climates, and generally relies on regionally adapted native plants.

zenith - The point on the sky dome directly overhead, the 90-degree solar altitude angle .

zero carbon footprint - The goal of carbon neutrality, and the practice of carbon offsetting

3 rs - an abbreviation for "Reduce, Reuse, Recycle", which is a priority list of things to do to reduce waste. Reducing what is used is the first priority and Recycling is the last priority.

3 rs - In the world of green, this standard for Reduce, Reuse, Recycle.