Green Building Glossary
Aerated Autoclaved Concrete (AAC)
Precast concrete that is cured by steam pressure inside a kiln called autoclave. The material is lighter weight than conventional concrete and has good insulation properties.
Active Solar Heating
Systems that collect and absorb solar radiation, then transfer the solar heat directly to the interior space or to a storage system, from which the heat is distributed. There are two types of systems: liquid-based systems and air-based systems. If a system cannot provide adequate space heating, an auxiliary or back-up system provides the additional heat. Both air and liquid systems can supplement forced air systems.
Active Solar Power
A solar electric (photovoltaic or "PV") system, not passive solar design, that converts the sun's energy into electricity for the home. It is usually done with PV panels installed on the roof.
Advanced Framing / Concrete Construction
A construction method (also known as "Optimum Value Engineering" or "OVE") that uses less material in the framing of a home and can reduce material costs and improve energy efficiency. Concrete construction involves using insulated concrete forms (ICFs) to create durable, efficient homes. The approach decreases the number of breaks in the thermal barrier of the building envelope. It also can save on construction costs because it is fast, especially compared with "stick built" homes.
ASI / ASHRAE / IESNA Standards
American National Standards Institute (ANSI), American Society of Heating, Refrigerating and Air-Conditioning Engineers Inc. (ASHRAE), Illuminating Engineering Society of North America (IESNA) Energy Standard for Buildings. A nationally-recognized energy standard for commercial buildings.
A structure situated on a lower floor (or even below the first floor) and located on a home's south side can provide passive solar heat to the home. Heat collected by the greenhouse at the lower level rises into the interior of the home by way of convection.
A fan typically mounted on the roof to create positive air-flow through an attic that does not rely on wind or require excessive passive venting. It is connected to a thermostat and operates automatically. Such fans offer several advantages. They:
1. Lower upstairs room temperatures by 10º;
2. Lengthen roof life by keeping shingles cooler;
3. Keep attics dry during the winter if they are installed with a humidistat;
4. Saves up to 30% on air-conditioning costs. (Savings vary by region and roof characteristics.)
A landscape element, often a planted strip along a street or parking lot, for the purpose of capturing surface water runoff and filtering out silt and pollution before the storm water enters the drainage system or groundwater.
Carbon Dioxide (CO2)
The most prevalent of the greenhouse gases. Emitted by burning fossil fuels. Naturally occurring from sources such as human and animal respiration, ocean-atmosphere exchange, and volcanic eruptions.
A system intended to equalize carbon production around the globe by trading greenhouse gas emissions–typically produced through fossil fuel consumption–for environmentally friendly actions, such as planting trees and using clean energy sources.
Cellulose Insulation - Post Consumer Recycled Content
Plant fiber that is used in wall and roof cavities to separate the inside and outside of the building thermally and acoustically. Typical materials used to manufacture the product include old newspapers, and telephone directories and borates and ammonium sulfate are included to retard fire and pests. Four major types of loose-fill cellulose products have been developed under a variety of brand names and are generally characterized as dry cellulose, spray applied cellulose, stabilized cellulose and low dust cellulose.
A test that measures the distribution of heating and cooling systems throughout a building. Measures the overall heat loss factor. The home is alternately heated with the furnace and an array of small heaters (co-heaters) to calculate heat-delivery efficiency.
A quality assurance process intended to confirm that all systems of a building—heat, air conditioning, electrical, plumbing, safety, security—are operating as intended by the building owner and designed by the architect and engineer.
Compact Fluorescent Lamp (CFL)
Small fluorescent light bulbs that can be used in place of incandescent light bulbs. CFLs consume significantly less electricity and last 8–10 times longer than incandescent bulbs.
Demand Limit Controller
The way the demand controller controls loads is called the load control strategy. It is the definition of each load's importance in relation to all other loads being controlled by the system. Generally, there are three load control strategies: priority (fixed), rotating or combination.
Drought Tolerant Plants
Species of plants, shrubs and vines which generally do not require additional watering in order to thrive in their native habitats. Landscapes with drought tolerant plants usually require little or no watering.
Electric Thermostat Timer
Referred to as programmable thermostats. Programmable thermostats save energy by permitting occupants to set temperatures according to whether the house is occupied. These thermostats can automatically store and repeat settings daily with allowance for manual override. By eliminating manual setback, they allow the setting of more comfortable temperatures in the morning before occupants wake. Temperature setback can be adjusted for both heating and cooling seasons. Programmable thermostats can be set to adjust the temperature setting according to a user's schedule. These thermostats typically have a digital interface that allows more precise temperature control and a wider range of options or features.
A system created by the Kyoto Protocol, which allows countries that are under-target on emissions to swap spare emissions with over-target countries with the goal of limiting carbon emissions worldwide.
A written report prepared by a qualified party evaluating energy usage, highlighting weak points in energy efficiency, and identifying cost-savings measures. A less rigorous process than an energy audit.
A special inspection performed to determine where there are energy inefficiencies in a home or building. A qualified tester uses methods and measurements that comply with industry standards and involves collection of detailed data and an engineering analysis. A written report should include recommendations and a detailed cost and savings analysis.
Energy Efficient Appliances
Products that use less energy than conventional models. The ENERGY STAR® label is a credible third-party certification of a product's energy efficiency. Consumers can also refer to the FTC's Energy Guide label, a yellow label affixed to most appliances today. Clothes washers, dishwashers, refrigerators, freezers, water heaters, window air conditioners, central air conditioners, furnaces, boilers, heat pumps, and pool heaters can get the label. Televisions, ranges, ovens, clothes dryers, humidifiers, and dehumidifiers do not receive such labels.
Energy Efficient Light Fixtures
The fixture or the type of bulbs used in a fixture. Compact fluorescent lights (CFLs) and light emitting diodes (LEDs) are becoming more common in homes and buildings and they are more efficient and last longer than incandescent bulbs.
Energy Efficient Mortgage (EEM)
Loan products that take a home's energy efficiency into account when determining the qualifying ratios for a buyer. The rationale is that an efficient home will result in lower monthly bills and potentially make buyers of such homes less risky borrowers than others. EEMs primarily apply to new construction. In some markets, an energy improvement mortgage (EIM) can be used to make energy improvements.
Energy Guide Label
An appliance label that provides an estimate of how much energy the appliance uses, compares energy use of similar products, and lists approximate annual operating costs. Required by the U.S. Department of Energy.
See "Energy Audit" above. An energy rating provides a score for home during energy audits. Energy ratings usually have to be used to determine the ratios for an energy efficient mortgage.
Energy Recover Ventilator
A type of ventilation system wherein the heated (or cooled) air being vented out of the home is used to heat (or cool) the supply air being pulled in from outdoors. The approach decreases the amount of energy needed to heat or cool the supply air.
A certification granted by the Environmental Protection Agency and the US Department of Energy for household appliances and buildings that perform at specified levels of energy efficiency.
Engineered Wood Products
A type of composite wood with superior durability and strength. Thinner or fewer pieces of engineered wood are required to meet the same strength requirements than would be needed with traditional wood.
Enterprise Green Communities
A non-profit organization which provides resources and expertise to enable developers to build and rehabilitate homes that are healthier, more energy efficient and better for the environment, yet still affordable. Green Communities is the first national green building program developed for affordable housing.
A siding that is more durable than wood and is termite resistant, water resistant, non-combustible, and warranted to last 50 years. It is composed of cement, sand, and cellulose fiber that has been autoclaved (cured with pressurized steam) to increase its strength and dimensional stability. The fiber is added as reinforcement to prevent cracking.
Forest Stewardship Council (FSC)
A non-profit organization that encourages the responsible management of the world's forests. FSC sets high standards that ensure forestry is practiced in an environmentally responsible, socially beneficial, and economically viable way. Landowners and companies that sell timber or forest products seek certification as a way to verify to consumers that they have practiced forestry consistent with FSC standards. Independent, certification organizations are accredited by FSC to assess forest management and determine if standards have been met. Certifiers also verify that companies claiming to sell FSC certified products have tracked their supply back to FSC-certified sources.
Geo Thermal Heat System (Closed Loop)
Geothermal heat pumps (GHPs) use the constant temperature of the earth to provide cooling and heating for a home. A loop of piping is buried in the ground and fluid circulates through the loop. In the summer, the fluid uses the cooler temperature of the ground to provide indoor cooling. During colder months, the geothermal heat pump uses the below-ground temperature, which is significantly warmer than the outside air, to warm a home.
A way of living that involves a holistic approach to preservation and conservation of natural resources. It aims to provide a better understanding of the balance between human action and natural environmental resources and improve health and well-being. It also entails creating a better understanding of social responsibility and what effect choices made by people and business have on the environment.
A roof surface covered by a water-proofing membrane, a drainage plane, a water retention medium, and plantings of drought-resistant species. The benefits of a green roof include control of storm water runoff which can reduce urban water pollution; absorption of airborne toxins and an increase in oxygen in the air, and a reduction of surface temperature of the roof (heat island effect). They also can increase the lifespan of the roof system and provide building and noise insulation. Green roofs are most common in multifamily or other large urban buildings.
Grey Water System
Wastewater from bathtubs, shower drains, sinks, washing machines, and dishwashers. Grey water can can be recycled for irrigation, toilets, and exterior washing, and such recycling conserves water. Incorporating plumbing systems that separate grey water from black water (toilet water) can result in water cost savings.
Home Energy Rating System (HERS)
A scoring system established by the Residential Energy Services Network (RESNET). Homes built to the specifications of the HERS Reference Home (based on the 2006 International Energy Conservation Code) scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home. Thus, a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home, and a home with a HERS Index of 80 is 20% more energy efficient.
High Efficiency Furnace
Furnaces that have an Annual Fuel Utilization Efficiency (AFUE) of 85% (oil) and 90% (gas) or higher. In general the higher the AFUE, the more efficient the furnace. The Energy Guide label on the equipment can be consulted to determine whether a furnace is efficient. The label was recently updated by the Federal Trade Commission, and more information on the Energy Guide label is available at http://www.ftc.gov/opa/2007/08/energy.shtm.
A prediction, made by a geologist in the late 1950s, that classified fossil fuels as finite and said that after a peak time access to these resources would rapidly decline, eventually diminishing entirely.
HVAC (16 SEER+)
A rating system, Seasonal Energy Efficiency Ratio (SEER), used to measure the efficiency of central air conditioners and air source heat pumps. The higher the rating, the more energy efficient it is. For reference, air conditioners that are 14 or higher SEER meet ENERGY STAR criteria.
Insulated Concrete Forms (ICF)
Rigid plastic foam forms that hold concrete in place during curing and remain in place afterwards to serve as thermal insulation for concrete walls. The foam sections are lightweight and result in energy-efficient, durable construction.
Insulated Glass Windows
A glass consisting of two panes of glass separated by a space. The perimeter of the glass is sealed, allowing no movement of outside air into the space. The space, itself, can be filled with dehydrated air, or with a special gas. The type of glass, spacer and gas used in the space contribute to the overall insulating efficiency of the glass.
Insulation - Foam in Place
A product that acts as an air barrier and provides insulation and air sealing in one step. Most foam insulation products have a higher R-value per inch than fiberglass batt insulation. Using foam insulation increases energy efficiency because smaller heating and cooling equipment is required.
International Energy Agency (IEA)
An organization committed to energy policies around the world. The goal is to ensure a cost-effective and dependable renewable energy system for a country's citizens through their commitment to energy security, economic development and environmental protection.
A United Nations agreement signed in Kyoto, Japan in the 1990s. The agreement set country-targets for reduction of carbon emissions and created a method for offsetting (trading) carbon emissions.
Leadership in Energy and Environmental Design (LEED)
The green building certification program created by the United States Green Building Council (USGBC). The comprehensive rating system (based on prerequisites and points) takes a whole building approach factoring in community resources & public transit, site characteristics, water efficiency, energy efficiency, materials & resources, indoor environmental quality, awareness & education, and innovation.
Lifestyles of Health and Sustainability (LOHAS)
A marketplace promoting environmentally friendly products and services, social justice, personal development and sustainability for businesses and individuals.
Living Building Challenge
A program launched and operated by the Cascadia Region Green Building Council with standards that go beyond the U.S. Green Building Council's LEED standard. Buildings, neighborhoods, renovations, or infrastructure (non-conditioned space) which meet this rigorous green building standard must achieve all corresponding prerequisites or imperatives.
An outdoor computer installed next to your breaker panel and connected to the 220v appliances like A/C units, clothes dryers, water heaters, electric spa heaters, etc. It measures the usage of power in your home and controls peak demand energy usage by defaulting to a pre-set level. As demand increases, the load controller "sheds" (shuts off) lower priority appliances to maintain a user pre-set demand level.
Low Emittance Doors/Windows
Building materials considered low emittance include window glass manufactured with metal-oxide coatings, housewrap materials, reflective insulation's and other forms of radiant barriers. The Solar Heat Gain Coefficient (SHGC) (http://energy.gov/energysaver/articles/energy-performance-ratings-windows-doors-and-skylights) can be used to measure how well a window blocks heat from sunlight.
Low Flow Toilet
A toilet that combines efficiency and high performance. Design advances enable these toilets to save water with no trade-off in flushing power. Such toilets often have the EPA's WaterSense label.
National Association of Home Builders (NAHB)
A trade association that helps promote the policies that make housing a national priority. Since 1942, NAHB has been serving its members, the housing industry, and the public.
National Green Building Standard (NGBS)
The National Green Building Standard (also known as the ICC-700) is the ANSI-approved, above code rating system for residential green construction. It can be applied to new and existing single and multi-family projects as well as land developments. Certification to the National Green Building Standard is provided by the NAHB Research Center. Further information can be found at www.nahbgreen.org.
A thermostat that allows homeowners to set the temperature at different levels at different times of day. For example, in winter, it could be set to be colder while occupants sleep and warmer as occupants awaken.
A barrier, installed on the underside of roof sheathing in warm or hot climates to reflect some of the sun's radiant heat energy so it does not enter the attic. Radiant barriers can also help prevent winter heat loss from the home.
Radiant Floors - Air
An ineffective choice for residential applications. Although they can be combined with solar air heating systems, the system suffers from the obvious drawback of only being available in the daytime, when heating loads are generally lower. Because of the inefficiency of trying to heat a home with a conventional furnace by pumping air through the floors, the benefits of using solar heat during the day are outweighed by the disadvantages of using the conventional system at night.
Radiant Floors - Electrical
A system that consists of electric cables built into the floor. Systems that feature mats of electrically conductive plastic are also available and are mounted onto the subfloor below a floor covering, such as tile. Because of the relatively high cost of electricity, electric radiant floors are usually only cost-effective if they include a significant thermal mass, such as a thick concrete floor, and if the electric utility company offers time-of-use rates. Time-of-use rates allow homeowners to "charge" the concrete floor with heat during off-peak hours (approximately 9 p.m. to 6 a.m.). If the floor's thermal mass is large enough, the heat stored in it will keep the house comfortable for eight to ten hours, without any further electrical input (particularly when daytime temperatures are significantly warmer than nighttime temperatures). This saves a considerable number of energy dollars compared to heating at peak electric rates during the day.
Radiant Floors - Hydronic
A popular and cost-effective choice that pumps heated water from a boiler through tubing underneath the floor. In some systems, the temperature in each room is controlled by regulating the flow of hot water through each tubing loop. This is done by a system of zoning valves or pumps and thermostats.
Radiant Heated Floors
A way to heat spaces using radiant energy that is emitted from a heat source. There are three types of radiant floor heat: radiant air floors (air is the heat-carrying medium); electric radiant floors; and hot water (hydronic) radiant floors.
A shallow, constructed depression that is planted with deep-rooted native plants and grasses. It is located in the landscaping to receive runoff from hard surfaces, such as a roof, a sidewalk and a driveway. Rain gardens slow the rush of water from these hard surfaces and hold the water for a short period of time, allowing the water to naturally filter into the ground. Rain gardens help control storm water runoff.
Recirculating Hot Water Heater
Systems that use a thermostat or timer to automatically turn on the pump whenever water temperature drops below a set-point, or when the timer reaches a setting. Hot water recirculation systems can be activated by the push of a button or by a thermostat, timer or motion sensor. Such systems ensure that hot water is always available without any waiting time. Hot water recirculation systems generally consist of a pump, an integrated electronic controller, and a zone valve. When the activation button is pushed, or when another type of control turns the system on, the pump starts re-circulating cooled water that has been sitting in the hot water line and sends it back to the water heater through the cold water line. When the water reaches a desired temperature, a control closes the zone valve and turns off the pump. It is much like turning on the hot water faucet and letting the water run until it gets hot, but instead of the water going down the drain, it is simply returned back to the water heater.
Recyled Construction / Household Waste
A strategy in which homeowners, remodeling a house in anticipation of selling it, recycle old materials and demolition waste rather than sending them to a landfill.
Improved or added insulation in the attic or exterior walls to improve the R-value of the building envelope. An R-value indicates an insulation's resistance to heat flow. The higher the R-value, the greater the insulating effectiveness.
Sealed Combustion Fireplace / Woodstove
A sealed combustion fireplace or woodstove that gets its combustion air from outside of the home and exhausts 100 percent of the combustion by-products to the outside. This eliminates the likelihood of "backdrafting," a situation in which combustion gases are pulled back into the home and cause health problems.
Structured Insulated Panels (SIP)
Panels made from a thick layer of foam (polystyrene or polyurethane) sandwiched between two layers of Oriented Strand Board (OSB), plywood or fiber-cement. SIPS are often used in panelized construction. They are an alternative to the foam core and are available with a core of agriculture fibers (such as wheat straw) that provides similar thermal and structural performance. The result is an engineered panel that provides structural framing, insulation, and exterior sheathing in a solid, one-piece component.
Solar Assisted Hot Water
A solar hot water array on the roof that supplements (but does not exclusively supply) the hot water to the home. Water warmed by solar energy is pumped into the hot water heater where less energy is required to get it hot or less cold water needs to be warmed to fill the tank.
Active solar space-heating systems consist of collectors that collect and absorb solar radiation combined with electric fans or pumps to transfer and distribute that solar heat. Active systems also generally have an energy-storage system to provide heat when the sun is not shining. The two basic types of active solar space-heating systems use either liquid or air as the heat-transfer medium in their solar energy collectors.
Solar Pool Equipment
A pool filtration system pumps that pumps pool water through a solar collector so that the collected heat is transferred directly to the pool water. Solar pool-heating collectors operate just slightly warmer than the surrounding air temperature and typically use inexpensive, unglazed, low-temperature collectors made from specially formulated plastic materials. Glazed (glass-covered) solar collectors are not typically used in pool-heating applications, except for indoor pools, hot tubs, or spas in colder climates. In some cases, unglazed copper or copper-aluminum solar collectors are used.
In northern latitudes, a home exposed to the south can take advantage of collecting the sun's energy either for production of electricity (photovoltaic), heating water, or as part of a passive solar design. The approach collects the sun's energy in winter and offers natural lighting during the summer.
Spray Foam Insulation
Insulation that is sprayed into place and then expands to fill cavities. It acts as both an insulator and a sealant and is an alternative to the standard insulation bats. The two types of spray foam are open-cell (isocyanurate) and closed cell (polyurethane). Closed cell foams typically have a higher R-value than open-cell foam.
Single pane windows often installed on the interior of the main windows of home to improve insulation. When window replacement is cost prohibitive, adding storm windows can be an alternative for saving energy.
A construction method that uses waste straw left over from crops, such as wheat, oats, barley, rye, rice and flax, after all the food has been extracted. Straw is gathered, baled, compressed and tied together. Bales are placed over a "stem wall" to protect the straw from the ground soil and the straw bales are stuccoed and plastered over for finishing.
Tankless Water Heater
A system that delivers hot water at a preset temperature when needed, but without requiring the storage of water. The approach reduces or eliminates energy standby losses. Tankless water heaters can be used for supplementary heat, such as a booster to a solar hot water system, or to meet all hot water needs. Tankless water heaters have an electric, gas, or propane heating device that is activated by the flow of water.
Also referred to as a "solar wall", a Trombe wall consists of an 8-to-16-inch-thick masonry wall on the south side of a house. A single or double layer of glass is mounted about 1 inch or less in front of the wall's surface. Solar heat is absorbed by the wall's dark-colored outside surface and stored in the wall's mass, where it radiates into the living space.
An environmental movement that monitors our daily actions and their effects toward the conservation, development, utilization and proper disposal of water in order to maintain safe and effective drainage for the various water systems surrounding us.