Zero Energy Green Glossary


Agricultural Waste:
Materials left over from agricultural processes (e.g., wheat stalks, shell hulls, etc.). Some of these materials are finding new applications as building materials and finishes. Examples include structural sheathing and particleboard alternatives made from wheat, rye and other grain stalks, and panels made from sunflower seed hulls.
Air Changes Per Hour (ACH):
The movement of a volume of air in a given period of time; if a house has one air change per hour, it means that the air in the house will be replaced in a one-hour period.
Air Change Effectiveness:
A measurement of the performance of a ventilation system, by measuring the age of air in a volume. Often accomplished by using a tracer gas decay technique.
Air Cleaning:
Indoor-air quality-control strategy to remove various airborne particulates and/or gases from the air. Most common methods are particulate filtration, electrostatic precipitation, and gas sorption.
Air Exchange Rate:
The rate at which outside air replaces indoor air in a given space.
Airborne Particulates:
Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Sources of airborne particulates include dust, emissions from industrial processes, combustion products from the burning of wood and coal, combustion products associated with motor vehicle or non-road engine exhausts, and reactions to gases in the atmosphere. [2]
Air Handling Unit
Equipment that includes a fan or blower, heating and/or cooling coils, regulator controls, condensate drain pans, and air filters.
Air Plenum:
Any space used to convey air in a building, furnace, or structure. The space above a suspended ceiling is often used as an air plenum.
Air Pollutant:
Any substance in air that could, in high enough concentration, harm man, other animals, vegetation, or material. Pollutants may include almost any natural or artificial composition of airborne matter capable of being airborne. They may be in the form of solid particles, liquid droplets, gases, or in combination thereof. Generally, they fall into two main groups: (1) those emitted directly from identifiable sources, and (2) those produced in the air by interaction between two or more primary pollutants, or by reaction with normal atmospheric constituents, with or without photoactivation. Exclusive of pollen, fog, and dust, which are of natural origin, about 100 contaminants have been identified. Air pollutants are often grouped in categories for ease in classification; some of he categories are: solids, sulfur compounds, volatile organic chemicals, particulate matter, nitrogen compounds, oxygen compounds, halogen compounds, radioactive compound, and odors.
Alternative Energy:
Energy from a source other than the conventional fossil-fuel sources of oil, natural gas and coal (i.e., wind, running water, the sun). Also referred to as "alternative fuel." [2]
Alternative Fuels:
Substitutes for traditional liquid, oil-derived motor vehicle fuels like gasoline and diesel. Includes mixtures of alcohol-based fuels with gasoline, methanol, ethanol, compressed natural gas, and others.
Alternative Refueling Station:
Location that provides the service of refueling an alternative fuel vehicle (e.g., electricity, compressed natural gas). Providing access to alternative fuels with a refueling station is considered a sustainable building strategy in that it encourages the use of alternative fuels and the vehicles that use them.
A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted its use in manufacturing and construction.
American Society of Heating, Refrigeration and Air Conditioning Engineers. [2]


Process by which a building is heated in an attempt to accelerate VOC emissions from furniture and materials. [2]
Benefit/Cost Analysis:
An economic method for assessing the benefits and costs of achieving alternative health-based standards at given levels of health protection. [2]
Refers to the variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequencies. For biological diversity, these items are organized at many levels, ranging from complete ecosystems to the biochemical structures that are the molecular basis of heredity. Thus, the term encompasses different ecosystems, species, and genes.
Biological Contamination:
Contamination of a building environment caused by bacteria, molds and their spores, pollen, viruses, and other biological materials. It is often linked to poorly designed and maintained HVAC systems. People exposed to biologically contaminated environments may display allergic-type responses or physical symptoms such as coughing, muscle aches and respiratory congestion. [2]
All of the living material in a given area; often refers to vegetation.
Entire community of living organisms in a single major ecological area.
A technology that uses plants and soil and/or compost to retain and cleanse runoff from a site, roadway, or other source.
Abandoned, idled, or under used industrial and commercial facilities/sites where expansion or redevelopment is complicated by real or perceived environmental contamination. They can be in urban, suburban, or rural areas. EPA's Brownfields initiative helps communities mitigate potential health risks and restore the economic viability of such areas or properties.
Building Cooling Load:
The hourly amount of heat that must be removed from a building to maintain indoor comfort (measured in British thermal units [Btu]).
Building Envelope:
The exterior surface of a building's construction--the walls, windows, floors, roof, and floor. Also called building shell.
Building Related Illness:
Diagnosable illness whose cause and symptoms can be directly attributed to a specific pollutant source within a building (e.g., Legionnaire's disease, hypersensitivity, pneumonitis). (See: sick building syndrome; biological contamination).


Carbon Dioxide Monitoring:
A method for determining indoor air quality by using the concentration of carbon dioxide as an indicator. Although the level of CO2  is a good general indicator of air quality, it is reliant on the presence of certain conditions and must be applied accordingly.
Carbon Dioxide Sensor:
Device for monitoring the amount of carbon dioxide in an air volume.
Carbon Monoxide (CO):
A colorless, odorless, poisonous gas produced by incomplete fossil fuel combustion.
Any substance that can cause or aggravate cancer.
Cellulose Insulation:
Insulation alternative to glass fiber insulation. Cellulose insulation is most often a mixture of waste paper and fire retardant, and has thermal properties often superior to glass fiber. Glass fiber batt insulation often contains formaldehyde, which can adversely affect indoor air quality and human health, and the glass fibers themselves are hazardous if inhaled and irritating to the skin and eyes. Specify cellulose insulation with high recycled content for maximum environmental benefit.
Certified Lumber:
General shorthand term for lumber that has been certified sustainable harvest by an independent certification authority.
A device that generates a cold liquid that is circulated through an air-handling unit's cooling coil to cool the air supplied to the building.
Chlorofluorocarbons (CFCs):
A family of inert, nontoxic, and easily liquefied chemicals used in refrigeration, air conditioning, packaging, insulation, or as solvents and aerosol propellants. Because CFCs are not destroyed in the lower atmosphere they drift into the upper atmosphere where their chlorine components destroy ozone.
Small tank or storage facility used to store water for a home or farm; often used to store rainwater.
An important design objective in sustainable building. Designing for comfort aims to create a space where people enjoy being; such qualitative, performance-based objectives are a hallmark of sustainable building.
Compact Fluorescent Lamp (CFL):
Small fluorescent lamps used as more efficient alternatives to incandescent lighting. Also called PL, CFL, Twin-Tube, or BIAX lamps.
The relatively stable humus material that is produced from a composting process in which bacteria in soil mixed with degradable materials break down the mixture into organic fertilizer.
Controlled biological decomposition of organic material in the presence of air to form a humus-like material. Controlled methods of composting include mechanical mixing and aerating, ventilating the materials by dropping them through a vertical series of aerated chambers, or placing the compost in piles out in the open air and mixing it or turning it periodically.
Compressed Natural Gas (CNG):
An alternative fuel for motor vehicles; considered one of the cleanest because of low hydrocarbon emissions and its vapors are relatively non-ozone producing. However, vehicles fueled with CNG do emit a significant quantity of nitrogen oxides.
Conservation Easement:
Easement restricting a landowner to land uses that are compatible with long-term conservation and environmental values.
Construction and Demolition Waste:
Waste building materials, dredging materials, tree stumps, and rubble resulting from construction, remodeling, repair, and demolition of homes, commercial buildings and other structures and pavements. May contain lead, asbestos, or other hazardous substances.
Construction Site Recycling:
(See: Construction Waste Management)
A term used in life-cycle analysis to describe a material or product that is recycled into a new product at the end of its defined life. [2]
A term used in life-cycle analysis to describe the entire life of a material or product up to the point of disposal. Also refers to a system that handles a product from creation through disposal.
Cubic Feet Per Minute (CFM):
A measure of the volume of a substance flowing through air within a fixed period of time. With regard to indoor air, refers to the amount of air, in cubic feet, that is exchanged with outdoor air in a minute's time; i.e., the air exchange rate.


Using natural light in an interior space to substitute for artificial light. Daylighting is considered a sustainable building strategy in that it can reduce reliance on artificial light (and reduce energy use in the process) and when well designed, contributes to occupant comfort and performance.
A rough measure used to estimate the amount of heating required in a given area; is defined as the difference between the mean daily temperature and 65 degrees Fahrenheit. Degree-days are also calculated to estimate cooling requirements.
Demand Hot Water System:
Hot water heaters designed to provide instantaneous hot water, rather than storing preheated hot water in a tank. Such devices can serve an entire home, or be "point-of-use", serving an individual water use. Benefits include elimination of "standby losses", or energy wasted keeping stored water warm, and with point of use devices, reduction or elimination of water wasted waiting for water to get warm, as well as conductive losses as water travels through pipes. Electric demand systems tend to use a large amount of energy; gas-fired units with standing pilot lights lose much of their efficiency due to the ongoing pilot light.
Any of a family of compounds known chemically as dibenzo-p-dioxins. Concern about them arises from their potential toxicity as contaminants in commercial products. Tests on laboratory animals indicate that it is one of the more toxic anthropogenic (man-made) compounds.
Drought Tolerance:
The capacity of a landscape plant to function well in drought conditions.
A factor that affects the life cycle performance of a material or assembly. All other factors being equal, the more durable item is environmentally preferable, as it means less frequent replacement. However, durability is rendered moot as a factor if the material is replaced for aesthetic reasons prior to it actually wearing out.


Embodied Energy:
The total amount of energy used to create a product, including energy expended in raw materials extraction, processing, manufacturing and transportation. Embodied energy is often used as a rough measure of the environmental impact of a product.
The treatment of asbestos-containing material with a liquid that covers the surface with a protective coating or embeds fibers in an adhesive matrix to prevent their release into the air.
Energy Analysis:
Analysis of the energy use of a structure.
Energy Management System:
A control system capable of monitoring environmental and system loads and adjusting HVAC operations accordingly in order to conserve energy while maintaining comfort.
Energy Modeling:
Process to determine the energy use of a building based on software analysis. Also called building energy simulation. Common simulation software are DOE-2 and Energy Plus.
Energy Star:
Program administered by the Environmental Protection Agency that evaluates products based on energy efficiency. Zero Energy is an Energy Star Partner.
Engineered Lumber/Wood:
Composite wood products made from lumber, fiber or veneer, and glue. Engineered wood 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. Engineered wood products distribute the natural imperfections in wood fiber over the product, making them stronger than dimensional lumber. This allows for less material to be used in each piece, another environmental benefit. Potential environmental drawbacks with engineered wood include impacts on indoor environmental quality due to offgassing of chemicals present in binders and glues, and air and water pollution related to production.
Environmental Footprint:
For an industrial setting, this is a company's environmental impact determined by the amount of depletable raw materials and nonrenewable resources it consumes to make its products, and the quantity of wastes and emissions that are generated in the process. Traditionally, for a company to grow, the footprint had to get larger. Today, finding ways to reduce the environmental footprint is a priority for leading companies. [2]  An environmental footprint can be determined for a building, city, or nation as well, and gives an indication of the sustainability of the unit.
The wearing away of land surface by wind or water, intensified by land-clearing practices related to farming, residential or industrial development, road building, or logging.  


Fluorocarbons (FCs):
Any of a number of organic compounds analogous to hydrocarbons in which one or more hydrogen atoms are replaced by fluorine. Once used in the United States as a propellant for domestic aerosols, they are now found mainly in coolants and some industrial processes. FCs containing chlorine are called chlorofluorocarbons (CFCs). They are believed to be modifying the ozone layer in the stratosphere, thereby allowing more harmful solar radiation to reach the Earth's surface.
Fly Ash:
A fine, glass-powder recovered from the gases of burning coal during the production of electricity. These micron-sized earth elements consist primarily of silica, alumina and iron. When mixed with lime and water the fly ash forms a cementitious compound with properties very similar to that of portland cement. Because of this similarity, fly ash can be used to replace a portion of cement in the concrete, providing some distinct quality advantages. The concrete is denser resulting in a tighter, smoother surface with less bleeding. Fly ash concrete offers a distinct architectural benefit with improved textural consistency and sharper detail.
Fly ash with a low LOI (carbon content) is used as a substitute for portland cement in concrete. Regulations vary from state to state, however, ASTM suggests that fly ash must not contain more than 6% unburned carbon to be used for its cementitious qualities. Otherwise, concrete companies use it as a fine aggregate in concrete block. Others use it for filling old coal mines, seaside docking areas and as a lining for hazardous waste dumps. [2]
Substitution of fly ash for portland cement in concrete is considered a sustainable building strategy, as it reduces the amount of energy-intensive (and CO2-producing) cement in the mix, as well as providing the performance enhancements described above.
Footprint (Building):
The area of a building formed by the perimeter of the foundation. Shrinking the footprint of a building allows for more open space and pervious surface on a site.
A colorless, pungent, and irritating gas, CH20, used chiefly as a disinfectant and preservative and in synthesizing other compounds like resins.
Fungus (Fungi):
Molds, mildews, yeasts, mushrooms, and puffballs, a group of organisms lacking in chlorophyll (i.e., are not photosynthetic) and which are usually non-mobile, filamentous, and multicellular. Some grow in soil, others attach themselves to decaying trees and other plants whence they obtain nutrients. Some are pathogens; others stabilize sewage and digest composted waste.


Geothermal/Ground Source Heat Pump:
These heat pumps are underground coils to transfer heat from the ground to the inside of a building. (See: heat pump; water source heat pump)[1]  This type of heat pump can realize substantial energy savings over conventional heat pumps, by using the naturally more stable temperature of the earth as its heat source.
Global Warming:
An increase in the near surface temperature of the earth. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases. Scientists generally agree that the earth's surface has warmed by about 1 degree Fahrenheit in the past 140 years. The Intergovernmental Panel on Climate Change (IPCC) recently concluded that increased concentrations of greenhouse gases are causing an increase in the earth's surface temperature and that increased concentrations of sulfate aerosols have led to relative cooling in some regions, generally over and downwind of heavily industrialized areas.
Translucent or transparent element of a window assembly. Glazing can have properties that increase its thermal performance, including Low-Emissivity coatings, multiple panes, thermally broken spacers, etc.
Gray Water:
Domestic wastewater composed of wash water from kitchen, bathroom, and laundry sinks, tubs, and washers.
Gray Water Reuse:
A strategy for reducing wastewater outputs from a building, by diverting the gray water into productive uses such as subsurface irrigation, or on-site treatment and use for non-potable functions such as toilet flushing. Gray water reuse is restricted in many jurisdictions; check with local health and building officials.
Green Design:
A design, usually architectural, conforming to environmentally sound principles of building, material and energy use. A green building, for example, might make use of solar panels, skylights and recycled building materials. [2]
Green Label:
A certification program by the Carpet and Rug Institute for carpet and adhesives meeting specified criteria for release of volatile compounds.
Green Roof:
Contained green space on, or integrated with, a building 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, they modulate temperatures in and around the building, have thermal insulating properties, can provide habitat for wildlife and open space for humans, and other benefits.
Greenhouse Effect:
The warming of the Earth's atmosphere attributed to a buildup of carbon dioxide or other gases; some scientists think that this build-up allows the sun's rays to heat the Earth, while making the infra-red radiation atmosphere opaque to infra-red radiation, thereby preventing a counterbalancing loss of heat.
Greenhouse Gas:
A gas, such as carbon dioxide or methane, which contributes to potential climate change.
Ground Cover:
Low-growing plants often grown to keep soil from eroding and to discourage weeds.


The place where a population (e.g., human, animal, plant, microorganism) lives and its surroundings, both living and non-living.
A type of incandescent lamp with higher energy-efficiency that standard ones.
Bromine-containing compounds with long atmospheric lifetimes whose breakdown in the stratosphere causes depletion of ozone. Halons are used in firefighting.
Heat Exchanger:
Device for exchanging heat present in wastewater or stale air to preheat incoming water or air. (See: Heat Recovery Ventilator)
Heat Island Effect:
A "dome" of elevated temperatures over an urban area caused by structural and pavement heat fluxes, and pollutant emissions.
Heat Pump:
An electric device with both heating and cooling capabilities. It extracts heat from one medium at a lower (the heat source) temperature and transfers it to another at a higher temperature (the heat sink), thereby cooling the first and warming the second. (See: geothermal, water source heat pump)
Heat Recovery Unit/Ventilator:
An air-to-air heat exchanger with balanced exhaust and supply fans that meet all necessary ventilation needs without producing drafts or air pressure imbalance on a heating or cooling system. (Definition: Washington State University Cooperative Extension Energy Program)
High Efficiency:
General term for technologies and processes that require less energy, water, or other inputs to operate. A goal in sustainable building is to achieve high efficiency in resource use when compared to conventional practice. Setting specific targets in efficiency for systems (e.g., using only EPA Energy Star certified equipment, furnaces with an AFUE rating above 90%, etc.) and designs (e.g., watts per square foot targets for lighting) help put this general goal of efficiency into practice.
High-Heeled Truss:
Roof truss design that allows space for insulation near the eaves. Conventional truss design limits the amount of insulation that can be applied in this area.
High Intensity Discharge:
A generic term for mercury vapor, metal halide, and high-pressure sodium lamps and fixtures.
High Performance Glazing:
Generic term for glazing materials with increased thermal efficiency.
Household Hazardous Waste:
Hazardous products used and disposed of by residential as opposed to industrial consumers. Includes paints, stains, varnishes, solvents, pesticides, and other materials or products containing volatile chemicals that can catch fire, react or explode, or that are corrosive or toxic.
Human Health Risk:
The likelihood that a given exposure or series of exposures may have damaged or will damage the health of individuals.
HVAC (Heating, Ventilation, and Air Conditioning):
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.
Hydrocarbons (HC):
Chemical compounds that consist entirely of carbon and hydrogen.
Hydrologic Cycle:
Movement or exchange of water between the atmosphere and earth.
The science dealing with the properties, distribution, and circulation of water.
The decomposition of organic compounds by interaction with water.
Hydronic Heating (Hydronic System):
A space heating system that uses water circulated through a radiant floor or baseboard system or a convection or fan coil system.


Impervious Surface:
A surface that sheds the precipitation falling on it, rather than infiltrating. Impervious surfaces can lead to excessive stormwater runoff and limit the amount of stormwater that remains onsite or recharges local aquifers.
Indigenous Planting:
Landscaping strategy that uses native plants. Provided the natives are placed in the proper growing conditions; such plantings can have low, or zero supplemental water needs.
Indoor Air Pollution:
Chemical, physical, or biological contaminants in indoor air.
Indoor Air Quality (IAQ):
ASHRAE defines acceptable indoor air quality as air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which 80% or more people exposed do not express dissatisfaction. [2]
a. The penetration of water through the ground surface into sub-surface soil or the penetration of water from the soil into sewer or other pipes through defective joints, connections, or manhole walls. b. The technique of applying large volumes of waste water to land to penetrate the surface and percolate through the underlying soil.
Infiltration Rate:
The quantity of water that can enter the soil in a specified time interval.
Insulated Concrete Form:
Expanded polystyrene forms that are left in place after the concrete is poured for a foundation or wall. The foam increases the thermal performance of the structure over non-insulated concrete.


Lead (Pb):
A heavy metal that is hazardous to health if breathed or swallowed. Its use in gasoline, paints, and plumbing compounds has been sharply restricted or eliminated by federal laws and regulations.
A self-assessing green building rating system developed by the U.S. Green Building Council. LEED™ stands for Leadership in Energy and Environmental Design, and evaluates a building from a systems perspective. By achieving points in different areas of environmental performance, a building achieves a level of "certification" under the system.
Light-Emitting Diode (LED):
A long-lasting illumination technology used for exit signs which requires very little power.
Light Shelf:
A horizontal shelf positioned (usually above eye level) to reflect daylight onto the ceiling and to shield direct flare from the sky.
A resilient flooring product developed in the 1800s, manufactured from cork flour, linseed oil, oak dust, and jute. Linoleum's durability, renewable inputs, anti-static properties, and easy-to-clean surface often make it classified as a "green" building material.
Local/Regional Materials:
Building products manufactured and/or extracted within a defined radius of the building site. For example, the US Green Building Council defines local materials as those that are manufactured, processed and/or extracted within a 500-mile radius of the site. Use of regional materials is considered a sustainable building strategy due to the fact that these materials require less transport, reducing transportation-related environmental impacts. Additionally, regional materials support local economies, supporting the community goal of sustainable building.
Low Emissivity (low-E) Windows:
Window technology that lowers the amount of energy loss through windows by inhibiting the transmission of radiant heat while still allowing sufficient light to pass through.
Low Toxic:
Generic term for products with lower levels of hazard than conventional products. Specific criteria need to be applied to this term to make it meaningful in the selection of sustainable building materials.
Low VOC:
Building materials and finishes that exhibit low levels of "offgassing," the process by which VOCs (Volatile Organic Compounds) are released from the material, impacting health and comfort indoors and producing smog outdoors. Low (or zero) VOC is an attribute to look for in an environmentally preferable building material or finish. (See: Volatile Organic Compound (VOC))


An overlooked element of a product, system, or design strategy that impacts cost over the life cycle. Selecting products and designing for easy maintenance enhances durability and lessens the likelihood that maintenance is overlooked. Establishing and adhering to a maintenance protocol ensures that materials and systems function to specifications.
Material Safety Data Sheet (MSDS):
A compilation of information required under the OSHA Communication Standard on the identity of hazardous chemicals, health, and physical hazards, exposure limits, and precautions. Section 311 of SARA requires facilities to submit MSDSs under certain circumstances.
MDF (Medium Density Fiberboard):
A composite wood fiberboard, used for cabinetry and other interior applications. MDF containing urea formaldehyde can contribute to poor indoor air quality.
A metal that is an odorless silver liquid at room temperature, converting to an odorless, colorless gas when heated. Mercury readily combines with other elements, and accumulates in the environment. Mercury is toxic, and causes a range of neurological, organ, and developmental problems. Fluorescent lights and old thermostats are two building related products that can contain significant amounts of mercury. Newer fluorescent lights are available with substantially reduced amounts of mercury.
A colorless, nonpoisonous, flammable gas created by anaerobic decomposition of organic compounds. A major component of natural gas used in the home. [1]  Methane has also been found to be a potent greenhouse gas. Methane from landfills, livestock, and composting operations can be captured and used as a fuel source for alternative energy production.
Modular Building:
Building technique using modular, or pre-constructed components. Building on a "module" also refers to the concept of using standardized dimensions that reduce the amount of construction waste. Building in four-foot increments is one strategy.
A layer of material (wood chips, straw, leaves, etc.) placed around plants to hold moisture, prevent weed growth, and enrich or sterilize the soil.


Natural Ventilation:
Ventilation design that uses existing air currents on a site and natural convection to move and distribute air through a structure or space. Strategies include placement and operability of windows and doors, thermal chimneys, landscape berms to direct airflow on a site, and operable skylights.
Night Flushing:
The process of removing hot air from a building during the cool evening hours, to cool elements with thermal mass within the building and flush stale air.
Nonrenewable Energy:
Energy derived from depletable fuels (oil, gas, coal) created through lengthy geological processes and existing in limited quantities on the earth. [2]
Nonrenewable Resource:
A resource that cannot be replaced in the environment (e.g., fossil fuels) because it forms at a rate far slower than its consumption. [2]


Occupancy Sensor:
A sensing device, commonly connected to a room's lighting but also occasionally to heating or ventilation, that shuts down these services when the space is unoccupied.
Release of volatile chemicals from a product or assembly. Many chemicals released from materials impact indoor air quality and occupant health and comfort. Offgassing can be reduced by specifying materials that are low- or no-VOC and by avoiding certain chemicals (e.g., urea formaldehyde) entirely. Controlling indoor moisture, and specifying pre-finished materials, can also reduce offgas potential.
On-Demand Hot Water:
See Demand Hot Water Systems
On-Site Stormwater Management:
Building and landscape strategies to control and limit stormwater pollution and runoff. Usually an integrated package of strategies, elements can include vegetated roofs, compost-amended soils, pervious paving, tree planting, drainage swales, and more.
Operations Manual (O&M Manual):
Manual developed to assist building occupants in maintaining and operating a green building and its features. Many features' effectiveness can be reduced or eliminated by the actions (or inaction) of occupants and maintenance crews. An operations manual usually includes product and system information and warranties, contact information, and other information required for effective operations and maintenance.
Organic Compound:
Vast array of substances typically characterized as principally carbon and hydrogen, but that may also contain oxygen, nitrogen and a variety of other elements as structural building blocks.
Orientation (Solar):
Orientation of a structure for controlled solar gain is essential to the success of passive and active solar design elements. Sun charts and software assist in orienting a building for maximum solar benefit. Designing for solar considerations can substantially reduce both heating and cooling.
Oriented Strand Board. A high strength, structural wood panel formed by binding wood strands with resin in opposing orientations. OSB is environmentally beneficial in that it uses small dimension and waste wood for its fiber; however, resin type should be considered for human health impact, and the production process monitored for air pollutant emissions.
Occupational Safety and Health Administration. [2]  Federal agency created in 1971 with the mission of preventing work-related injury, illness and death.
Outdoor Air Supply:
Air brought into a building from outside.
Architectural elements on roofs and above windows that function to protect the structure from the elements or to assist in daylighting and control of unwanted solar gain. Sizing of overhangs should consider their purpose, especially related to solar control.
Ozone Depletion:
Destruction of the earth's ozone layer, which can be caused by the photolytic breakdown of certain chlorine- and/or bromine-containing compounds (e.g., chlorofluorocarbons), which catalytically decompose ozone molecules. [2]
Ozone Hole:
A thinning break in the ozone layer. Designation of amount of such depletion as an "ozone hole" is made when the detected amount of depletion exceeds 50 percent. Seasonal ozone holes have been observed over the Antarctic and arctic regions, part of Canada, and the extreme northeastern United States. [2]
Ozone Layer:
The protective layer in the atmosphere, about 12-15 miles above sea level, that absorbs some of the sun's ultraviolet rays, thereby reducing the amount of potentially harmful radiation that reaches the earth's surface. [2]
Ozone (O3):
A naturally occurring, highly reactive, irritating gas comprising triatomic oxygen formed by recombination of oxygen in the presence of ultraviolet radiation. This gas builds up in the lower atmosphere as smog pollution, while in the upper atmosphere it forms a protective layer that shields the earth and its inhabitants from excessive exposure to damaging ultraviolet radiation. [2]


Particulate Pollution:
Pollution made up of small liquid or solid particles suspended in the atmosphere or water supply. [2]
a. Fine dust or particles (e.g., smoke). b. Of or relating to minute discrete particles. c. A particulate substance. [2]
Passive Solar:
Strategies for using the sun's energy to heat (or cool) a space, mass, or liquid. Passive solar strategies use no pumps or controls to function. A window, oriented for solar gain and coupled with massing for thermal storage (e.g., a Trombe wall) is an example of a passive solar technique.
An expression of the intensity of the basic or acid condition of a liquid; may range from 0 to 14, where 0 is the most acid and 7 is neutral. Natural waters usually have a pH between 6.5 and 8.5.
A device that measures the amount of incident light present in a space. [4]
Photovoltaic (PV) Cell:
An electronic device consisting of layers of semiconductor materials fabricated to form a junction (adjacent layers of materials with different electronic characteristics) and electrical contacts and being capable of converting incident light directly into electricity (direct current). [3]
Photovoltaic (PV) Module:
An integrated assembly of interconnected photovoltaic cells designed to deliver a selected level of working voltage and current at its output terminals, packaged for protection against environment degradation, and suited for incorporation in photovoltaic power systems. [3]
Generally, the presence of a substance in the environment that, because of its chemical composition or quantity, prevents the functioning of natural processes and produces undesirable environmental and health effects. Under the Clean Water Act, for example, the term has been defined as the man-made or man-induced alteration of the physical, biological, chemical and radiological integrity of water and other media. [2]
Pollution Prevention:
Techniques that eliminate waste prior to treatment, such as changing ingredients in a chemical reaction. Identifying areas, processes and activities that create excessive waste products or pollutants in order to reduce or prevent them through alteration or elimination of a process. The EPA has initiated a number of voluntary programs in which industrial or commercial "partners" join with the EPA in promoting activities that conserve energy, conserve and protect the water supply, reduce emissions or find ways of utilizing them as energy resources, and reduce the waste stream. [2]
Porous Paving:
Paving surfaces designed to allow stormwater infiltration and reduce runoff.


Radiant Heat:
Heat transferred in the form of light energy (including non-visible spectra). Distinct from conductive heat, occurring with the direct contact between two materials.
A colorless naturally occurring, radioactive, inert gas formed by radioactive decay of radium atoms in soil or rocks. Design strategies help reduce the amount of radon infiltration into a building and remove the gas that does infiltrate.
Rainwater Catchment/Harvest:
On-site rainwater harvest and storage systems used to offset potable water needs for a building and/or landscape. Systems can take a variety of forms, but usually consist of a surface for collecting precipitation (roof or other impervious surface) and a storage system. Depending on the end use, a variety of filtration and purification systems may also be employed.
Restoration of materials found in the waste stream to a beneficial use that may be other than the original use. [2]
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 or an industrial/agricultural source ("pre-consumer" or "post-industrial").
Process by which materials that would otherwise become solid waste are collected, separated or processed and returned to the economic mainstream to be reused in the form of raw materials or finished goods. [2]
Recycling Areas:
Space dedicated to recycling activities is essential to a successful recycling program, both on the construction site and in the building after occupation. For strategies related to determining recycling area configuration and placement, see the Business and Industry Resource Venture site.
Recycling Bins:
Containers to temporarily hold recyclable materials until transferred to a larger holding facility of pick-up by a recycling service. Conveniently located bins increase recycling rates by allowing occupants to recycle more easily. Designing space for recycling bins is a physical reminder of a commitment to recycling.
Products that have been upgraded to be returned to active use in their original form. Refurbishing is considered a form of reuse, and is preferable to recycling as it requires less processing and inputs to return a product to useful service.
Regional Manufacture:
Goods produced within a certain radius of the project site. Using regionally produced goods is considered a sustainable building strategy in that it reduces the transportation impacts associated with the product, it often allows for a better understanding of the production process and increases the likelihood that the product was manufactured in accordance with environmental laws, and it supports regional economies.
Relative Humidity:
Ratio of the amount of water vapor in air at a specific temperature to the maximum capacity of the air at that temperature. [2]
Renewable Resources:
A resource that can be replenished at a rate equal to or greater than its rate of depletion; e.g., solar, wind, geothermal and biomass resources. [2]
Upgrade of an existing building or space that maintains the original structure of a building.
Resource Conservation:
Practices that protect, preserve or renew natural resources in a manner that will ensure their highest economic or social benefits. [2]
Using a product or component of municipal solid waste in its original form more than once; e.g., refilling a glass bottle that has been returned or using a coffee can to hold nuts and bolts. [1]  Reuse is a sustainable building strategy in that it reduces the strain on both renewable and nonrenewable resources, and when materials are reused on or near the site of salvage, they reduce transportation-related environmental impacts.
Route of Exposure:
The avenue by which a chemical comes into contact with an organism, e.g., inhalation, ingestion, dermal contact, injection.


Building materials diverted from the waste stream intended for reuse.
Sick Building Syndrome:
Building whose occupants experience acute health and/or comfort effects that appear to be linked to time spent therein, but where no specific illness or cause can be identified. Complaints may be localized in a particular room or zone, or may spread throughout the building.
All else being equal, smaller is usually preferable in sustainable building. Larger buildings and spaces require more materials and energy to construct and use more resources to heat, cool and maintain.
Solar Collector:
Any device used to capture or concentrate the sun's energy. The leaves on a tree can be considered a solar collector, as can a window, solar panel, or dark surfaced thermal mass.
Solar Orientation:
(See: Orientation (solar))
Solar Panels:
General term for an assembly of photovoltaic modules. (See: photovoltaic) Use of solar panels is a sustainable building strategy in that it lessens a building's reliance on nonrenewable sources of power distributed through the grid system.
Source Reduction:
The design, manufacture, purchase or use of materials to reduce the amount or toxicity of waste in an effort to reduce pollution and conserve resources (i.e., reusing items, minimizing the use of products containing hazardous compounds, extending the useful life of a product and reducing unneeded packaging).
Practices that reduce the amount of any hazardous substance, pollutant or contaminant entering any waste stream or otherwise being released into the environment. Such practices also reduce the risk to public health and the environment associated with such releases. Term includes equipment or technology modifications, substitution of raw materials, and improvements in housekeeping, maintenance, training or inventory control. [2]
The sequencing and physical positioning of building materials on a construction site. Sustainable building pays particular attention to staging in order to minimize the impact to the construction site and protect materials from damage.
Straw-Bale Construction:
Alternative building method using bales of straw for wall systems. The method uses an agricultural waste product in place of diminishing dimensional lumber, and achieves high insulation values. It is a building method most appropriate for regions with relatively little precipitation.
Structural Insulated Panel (SIP):
Manufactured panels consisting of a sandwich of polystyrene between two layers of engineered wood paneling. Can be used for walls, roof, or flooring, and result in a structure very resistant to air infiltration.
Economic incentives to engage in an activity or purchase a product. Subsidies can work for or against environmental protection. Governments and utilities will sometimes offer subsidies for technologies that decrease energy or water use.
Sulfur Dioxide (SO2):
A heavy, smelly gas that can be condensed into a clear liquid; used to make sulfuric acid, bleaching agents, preservatives and refrigerants; a major source of air pollution in industrial areas. [2]
Devices for blocking unwanted solar gain.
Practices that would ensure the continued viability of a product or practice well into the future. [2]
Sustainable Development:
An approach to progress that meets the needs of the present without compromising the ability of future generations to meet their needs. [2]


Thermal Break:
Method of increasing the thermal performance of a material or assembly by reducing conductive heat loss. By inserting a less thermally conductive material in a material or assembly that bridges conditioned and unconditioned space, the conductive path is reduced or broken. An example is the thermal break featured in aluminum-framed windows.
Thermal Bridging:
Unwanted heat loss or gain due to conduction through a material. An example of thermal bridging is heat loss that occurs with structural steel framing that is insufficiently insulated between conditioned and unconditioned space.
Thermal Mass:
A mass (often stone, concrete, or brick) used to store heat and reduce temperature fluctuation in a space, by releasing heat slowly over time.
Trombe Wall:
Thermal storage system used in passive solar design. A high-mass wall that stores heat from solar gain during the day and slowly radiates the heat back into the living space at night.
U (U-Value):
A measure of the amount of heat that flows in or out of a substance under constant conditions when there is a one degree difference between the air within and outside a building. U-values are used in determining the performance of a glazing system or window assembly.


Process by which outside air is conveyed to an indoor space. [2]
Ventilation Control (by Occupants):
The ability of building occupants to control ventilation rates. A strategy for giving control of comfort back to occupants, this can be achieved through access to individual electronic controls or by operable windows in workspaces. Studies show that giving increased control to occupants over their environment results in greater occupant tolerance for variability in the indoor environment.
Ventilation Rate:
The rate at which indoor air enters and leaves a building. Expressed as the number of changes of outdoor air per unit of time: air changes per hour (ACH), or the rate at which a volume of outdoor air enters in cubic feet per minute (CFM).
Volatile Organic Compound (VOC):
Organic substances capable of entering the gas phase from either a liquid or solid form. [2]


The spent or used water from a home, community, farm, or industry that contains dissolved or suspended matter.
Water-Source Heat Pump:
Heat pump that uses wells or heat exchangers to transfer heat from water to the inside of a building. Most such units use ground water. (See: groundsource heat pump; heat pump)
Waterless Urinal:
Urinal with no water line. Most designs use a specialized material that allows fluid to drain one-way into the sewer system.
Watts per Square Foot:
A shorthand measure of the energy use of a building, often applied to indoor lighting. Energy codes often limit the watts per square foot based on building type and function.
An area that is saturated by surface or ground water with vegetation adapted for life under those soil conditions, as swamps, bogs, fens, marshes, and estuaries.
Wind Turbine:
Device for generating electricity from wind; windmill.
Window Shading:
Any device for reducing unwanted heat gain from a window.

The main goal with a Zero Energy Home is to become energy independent, producing all that you will consume and consuming only what you need.

The initial cost is typically more compared to conventional construction but your investment will pay off in the long run. Also, many state and federal rebates and grants are available to homeowners who want to build a Zero Energy Home – the time to act is now