Green-building glossary

Advanced Framing: Framing techniques that use less lumber, thereby reducing material cost and use of natural resources, and increasing the level of insulation as a result. Also known as Optimum Value Engineering. (9) 
Air Barrier: A rigid material installed around a building frame to prevent or reduce the infiltration of air into the interior of a structure. To improve energy efficiency by maintaining conditioned air inside the home and improving the efficacy of insulation, an air barrier is installed. Air barriers are not vapor barriers. (1) 
Air Infiltration: Uncontrolled inward air leakage to conditioned spaces through unintentional openings in ceilings, floors and walls from unconditioned spaces or the outdoors. (2)  
Batt Insulation: The most common and widely available type of insulation. It comes in the form of pre-cut blankets or rolls and consists of flexible fibers, most commonly fiberglass, but is also available in cotton. It’s held together with a binder. (10)  
Building Envelope: The exterior surface of a building’s construction: the walls, windows, floors, roof and floor. Also called building shell. (2) 
Cellulose Insulation: A blown-in insulation material that is a mixture of waste paper and fire retardant. It high in recycled content, has no added formaldehyde and is blown in for easy installation around obstacles in the wall cavity. (2)  
Combustion Safety: For health and safety, locate combustion appliances outside of the conditioned envelope or use sealed or direct combustion appliances. Provide carbon-monoxide monitoring. (3) 
Daylighting: The controlled admission of natural light into a space through glazing with the intent of reducing or eliminating electric lighting. Daylighting creates a stimulating and productive environment for building occupants. (2) 
Energy Modeling: Process to determine the energy use of a building based on software analysis. Can be used to provide a cost-benefit analysis with upgrades for energy efficiency. (2) 
Engineered Lumber: Composite wood products made from lumber, fiber or veneer, and glue. These products can be environmentally preferable to dimensional lumber, as they allow the use of waste wood and small-diameter trees to produce structural building materials, but can also increase off-gassing into the home. (2) 
Fly Ash: A fine, glass powder recovered from the gases of burning coal during the production of electricity. Fly ash can be used to replace a portion of cement in the concrete, providing some distinct quality advantages. (2) 
Forest Stewardship Council (FSC): A third-party certification organization, evaluating the sustainability of forest products. FSC-certified wood products have met specific criteria in areas such as forest management, labor conditions and fair trade. (2) 
Formaldehyde: A colorless, pungent and irritating gas. H2C0 is used chiefly as a disinfectant, preservative and in synthesizing other compounds like resins. It is the component of many types of glue in wood products and may cause respiratory problems. (2, 3) 
Graywater Reuse: A strategy for reducing wastewater outputs from a building by diverting the graywater into productive uses such as subsurface irrigation, or on-site treatment and use for nonpotable functions such as toilet flushing. Graywater includes water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs. (2) 
Greenguard: Certification that a product meets emission thresholds for formaldehyde, total aldehydes, total volatile organic compounds (TVOCs), and one-tenth of the threshold limit value (TLV) — a regulatory standard — for many other compounds. The program also assesses emissions of other chemicals of concern. (7) 
Green Label: A certification program by the Carpet and Rug Institute for carpet and adhesives meeting specified criteria for release of volatile compounds. (2) 
Green Seal: A nonprofit that has certified products to an environmental standard since 1992. Green Seal now provides third-party certification for a wide range of products, including paints, adhesives, lamps, chillers, windows, cleaners and occupancy sensors. (7) 
Green Roof: Green roofs maintain living plants in a growing medium on top of a membrane and drainage system. Green roofs are considered a sustainable building strategy in that they have the capacity to reduce stormwater runoff from a site, modulate temperatures in and around the building, have thermal insulating properties, can provide habitat for wildlife and open space for humans, and provide other benefits. (2) 
Ground Source Heat Pump: A heat pump that uses the ground temperature instead of air temperature to cool or heat a home. Usually this is accomplished with underground water pipes that transfer the ground temperature into the heat pump. (3) 
Heating, Ventilation and Air Conditioning (HVAC): General term for the heating, ventilation and air-conditioning system in a building. System efficiency and design impact the overall energy performance of a home and its indoor environmental quality. (2) 
Heat Recovery Ventilator: An air-to-air heat exchanger with balanced exhaust and supply fans that is an energy-efficient way to meet necessary ventilation needs without producing drafts or air pressure imbalance on a heating or cooling system. (2) 
Indoor Air Quality (IAQ): The nature of the air inside the space that affects the health and well-being of building occupants. IAQ is heavily influenced by both choice of building materials (and cleaning procedures) and ventilation rates. (1, 2) 
Infill: Developing on empty lots of land within an urban area rather than on new undeveloped land outside the city. Infill development helps prevent urban sprawl and can help with economic revitalization. (1) 
Insulated Concrete Forms (ICF): This wall structural system provides a strong and well-insulated wall system by using blocks fabricated from rigid insulation to create permanent forms for a poured concrete core. (3) 
Kilowatt-hour (kWh): A measure of energy equal to the amount of power multiplied by the amount of time the power is used. It is most often used to describe amounts of electrical energy. A 100-watt light bulb burning for 10 hours uses one kilowatt-hour of power. (3) 
Load Calculation: A heat-gain-and-loss calculation necessary to properly size the heating and cooling equipment to adequately and efficiently provide comfort and dehumidification for a particular building. Room-by-room load calculations should be performed, taking into account actual insulation levels, windows, building orientation, number of occupants, system location, air tightness, etc. 
Low VOC: See “Volatile Organic Compound” for more information. (2) 
Minimum Efficiency Reporting Value (MERV): A number from 1 to 16 that is relative to an air filter’s efficiency. For the cleanest air, a user should select the highest MERV filter that their unit is capable of forcing air through, based on the limit of the unit’s fan power. (4) 
Mixed-Use Development: A development that includes diverse use types, including elements of housing, retail and office space. (1) 
Net Metering: A metering and billing arrangement that allows on-site energy generators to send excess electricity flows to the regional power grid. (2) 
Passive-Solar Homes: Homes optimally designed to take advantage of the sun for heating in the winter and are shaded with an overhang, trellis etc. in the summer and swing months. These homes have calculated amounts of thermal mass (concrete, tile, stone etc.) and glass, insulation for the window “collectors,” and their solar features are oriented to the south. A passive-solar home is one in which the building itself is the solar collector and heat-storage system. (3) 
Payback Period: The time estimated for a capital investment to pay for itself, calculated by relating the cost of the investment to the profit it will earn or savings it will incur. (1) 
Performance Contracting: A contracting service that provides customers with a comprehensive set of energy-efficiency, renewable-energy and distributed-generation measures and often comes with guarantees that the savings produced by a project will be sufficient to finance the full cost of the project. (11) 
Pervious Paving: Paving surfaces designed to allow water infiltration and reduce stormwater runoff. (2) 
Photovoltaics (PVs): Solid-state cells (typically made from silicon) that directly convert sunlight into electricity. (1) 
R-value: A unit of thermal resistance used for comparing insulating values of different materials; the higher the R-value, the greater it’s insulating properties. (2) 
Radiant Barrier: A material (typically an aluminum foil) that is good at blocking the transfer of radiant heat across a space because it has a low emissivity. In a hot climate, it is often installed in attics under the roof decking to keep the attic cooler. (1) 
Radiant Floor Heat: A thermal mass floor with pipes laid underneath to transfer heat generated either by a solar collector or other type of liquid heating system. (3) 
Radon: A colorless, naturally occurring, radioactive, inert gas formed by radioactive decay of radium atoms in soil or rocks. When trapped in buildings, concentrations build up, and can cause health hazards. (1, 2) 
Rainwater Catchment/Harvest: On-site rainwater harvest and storage systems used to offset potable water needs for a building and/or landscape. (2) 
Rain Garden (Bioretention): A landscape feature that incorporates deep porous soils and specially designed plantings to gather, store and treat stormwater. (3) 
Rapidly Renewable Materials: Material that is considered to be an agricultural product that takes 10 years or less to grow or raise and to harvest in an ongoing and sustainable fashion. Examples include bamboo flooring, biocomposite veneers, fiber-based finishes, wool and cotton insulation. (2, 3) 
Recycled Content: The content in a material or product derived from recycled materials versus virgin materials. Recycled content can be materials from recycling programs (post-consumer) or waste materials from the production process of an industrial/agricultural source (post-industrial). (2, 3) 
Retrofit: The replacement, upgrade or improvement of a piece of equipment or structure in an existing building or facility. (1) 
Salvage: Building materials diverted from the waste stream intended for reuse. Commonly salvaged materials include structural beams and posts, flooring, doors, cabinetry, brick and decorative items. (2) 
Scientific Certification Systems (SCS): A third-party assessment body that offers evaluation and certification services to a broad range of manufacturing sectors. Their Eco Product Certifications include: Environmentally Preferable Products, Sustainable Choice, four Indoor Air Quality Certifications and Material Content. (8) 
Seasonal Energy Efficiency Ratio (SEER): The measure of the energy efficiency for air conditioners and the cooling side of heat pumps. The higher this number, the better, with code being 14 SEER. (1)  
Solar Electric Systems: Electricity-producing systems that directly convert the sun’s energy into electricity. Photovoltaic systems consist of solar panels, an inverter and controller, and are either off grid or grid tied. (1) 
Solar Heat Gain Coefficient (SHGC): The fraction of solar radiation admitted through a window or screen, both directly transmitted and absorbed, and subsequently released into the living space. (1)  
Solar Thermal Systems: Energy-producing systems that gather the sun’s radiant energy to heat air or water for use as domestic hot water or space heating. 
Spray Foam Insulation: The insulation is applied as a liquid that is sprayed through a nozzle into wall, ceiling and floor cavities, where it expands to fill every nook and cranny. Spray foam insulation makes it easy to completely fill wall cavities with insulation and to perform air sealing in the same step. (9) 
Stormwater Management: To protect the local ecology and hydrology, limit and control stormwater runoff by providing for on-site storage and filtration. Pervious pavement systems, reduced amounts of impervious pavement (concrete, asphalt), rainwater collection, green roofs, rain gardens (bioretention) and constructed wetlands are methods to accomplish this. (3) 
Straw-Bale Construction: Alternative building method using bales of straw for wall systems in place of standard construction materials. (2) 
Structural Insulated Panel (SIP): Manufactured panels consisting of a sandwich of polystyrene between two layers of engineered wood paneling. SIPs can be used for walls, roof or flooring, and result in a structure very resistant to air infiltration. (2) 
Thermal Mass: A mass (often stone, tile, concrete or brick) used to store heat and reduce temperature fluctuation in a space by releasing heat slowly over time. Used in passive-solar design. (2, 3) 
Universal Design: The design of products and environments that are usable by all people, regardless of age or physical ability, to the greatest extent possible, without adaptation or specialized design. (6) 
Ventilation: The process by which outside air is conveyed to an indoor space. Energy-efficient homes must be air tight, but to maintain healthy indoor air it is necessary to provide controlled fresh air to the building interior at recommended rates. (2, 3) 
Volatile Organic Compound (VOC): Carbon compounds that become a gas at normal room temperatures. This class of chemical compounds can cause nausea, tremors, headaches and, some doctors believe, long-lasting harm. VOCs can be emitted by oil-based paints, solvent-based finishes, formaldehyde-laden products and other products on or in construction materials. (2, 3)  
WaterSense: Modeled after Energy Star, the EPA’s new water-efficiency program seeks to educate consumers about water efficiency through an easily identifiable logo. Products include fixtures, faucets, showerheads, irrigation systems and toilets. WaterSense differs from Energy Star in that a product’s conformance to EPA standards must be independently tested before qualifying for the label. (7) 
Wind Power: Systems that convert air movement into mechanical or electrical energy. Driven by the wind, turbine blades turn a generator or power a mechanical pump. Wind generators include a tower and wind turbine, and can be off-grid or grid-tied. (2, 3) 
Xeriscaping: Landscaping design for conserving water that uses drought-resistant or drought-tolerant plants. (2)

(1) Sourcebook Glossary, Efficiency/Programs/Green Building/Sourcebook/sourcebookGlossary.pdf  
(2) City of Seattle,
(3) 2007 N.C. Sustainable Energy Association’s Tour Book 
 Environmental Building News, “Defining Recycled Content,” December 2008,  
 Environmental Building News, “Behind the Logos: Understanding Green Product Certifications,” January 2008,