Glossary | U.S. Green Building Council
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The terms below are applicable to LEEDv4: BD+C (except Homes and Multifamily Midrise), ID+C, and O+M


abandoned property

property left behind intentionally and permanently when it appears that the former owner does not intend to come back, pick it up, or use it. One may have abandoned the property of contract rights by not doing what is required by the contract. However, an easement and other land rights are not abandoned property just because of nonuse. Abandoned land is defined as land not being used at the present time but that may have utilities and infrastructure in place.

adapted plant 

vegetation that is not native to a particular region but that has characteristics that allow it to live in the area. Adapted plants do not pose the same problems as invasive species.

added antimicrobial treatment

a substance added to a product (e.g., paint, flooring) to kill or inhibit the growth of microorganisms. Some products, such as linoleum, exhibit natural antimicrobial properties. Despite current practice, science has not proven that antimicrobial treatments reduce infection transfer in building finishes more effectively than standard cleaning procedures. Also known as added microbial agent. See U.S. EPA factsheet, Consumer Products Treated with Pesticides ( factsheets/treatart.htm).

adjacent site

a site having at least a continuous 25% of its boundary bordering parcels that are previously developed sites. Only consider bordering parcels, not intervening rights-of-way. Any fraction of the boundary that borders a water body is excluded from the calculation.

alternative daily cover (ADC)

material other than earthen material placed on the surface of the active face of a municipal solid waste landfill at the end of each operating day to control vectors, fires, odors, blowing litter, and scavenging. Generally these materials must be processed so they do not allow gaps in the exposed landfill face. (CalRecycle)

alternative fuel

low-polluting, nongasoline fuels such as electricity, hydrogen, propane, compressed natural gas, liquid natural gas, methanol, and ethanol

alternative water source

nonpotable water from other than public utilities, on-site surface sources, and subsurface natural freshwater sources. Examples include graywater, on-site reclaimed water, collected rainwater, captured condensate, and rejected water from reverse osmosis systems (IgCC).

annual sunlight exposure (ASE)

a metric that describes the potential for visual discomfort in interior work environments. It is defined as the percentage of an analysis area that exceeds a specified direct sunlight illuminance level more than a specified number of hours per year.


a built-in, nonstructural portion of a roof system. Examples include skylights, ventilators, mechanical equipment, partitions, and solar energy panels.

area median income

midpoint in the family-income range for a metropolitan statistical area, the non-metro parts of a region, or local equivalent to either. The figure often is used as a basis to stratify incomes into low, moderate and upper ranges.


reports the percentage of sensors in the analysis area, using a maximum 2-foot spacing between points, that are found to be exposed to more than 1000 lux of direct sunlight for more than 250 hours per year, before any operable blinds or shades are deployed to block sunlight, considering the same 10 hour/day analysis period as sDA and using comparable simulation methods


a product formulated from multiple materials (e.g., concrete) or a product made up of subcomponents (e.g., a workstation)

attendance boundary

the limits used by school districts to determine what school students attend based on where they live

average LED intensity (ALI)

the illumination output for light-emitting diode lamps, as specified in the International Commission on Illumination Standard 127–2007


base building

materials and products that make up the building or are permanently and semi-permanently installed in the project (e.g., flooring, casework, wall coverings)

baseline building performance

the annual energy cost for a building design, used as a baseline for comparison with above-standard design

baseline condition

before the LEED project was initiated, but not necessarily before any development or disturbance took place. Baseline conditions describe the state of the project site on the date the developer acquired rights to a majority of its buildable land through purchase or option to purchase.

baseline water consumption

a calculated projection of building water use assuming code-compliant fixtures and fittings with no additional savings compared with the design case or actual water meter data

basis of design (BOD)

the information necessary to accomplish the owner’s project requirements, including system descriptions, indoor environmental quality criteria, design assumptions, and references to applicable codes, standards, regulations, and guidelines

bicycle network

a continuous network consisting of any combination of the following 1) off street bicycle paths or trails at least 8 feet (2.5 meters) wide for a two-way path and at least 5 feet (1.5 meters) wide for a one-way path 2) physically designated on-street bicycle lanes at least 5 feet (1.5 meters) wide 3) streets designed for a target speed of 25 mph (40 km/h) or less

bicycling distance

the distance that a bicyclist must travel between origins and destinations, the entirety of which must be on a bicycle network.

bio-based material

commercial or industrial products (other than food or feed) that are composed in whole, or in significant part, of biological products, renewable agricultural materials (including plant, animal, and marine materials), or forestry materials. For the purposes of LEED, this excludes leather and other animal hides.


wastewater containing urine or fecal matter that should be discharged to the sanitary drainage system of the building or premises in accordance with the International Plumbing Code. Wastewater from kitchen sinks (sometimes differentiated by the use of a garbage disposal), showers, or bathtubs is considered blackwater under some state or local codes.

block length

the distance along a block face; specifically, the distance from an intersecting Right-of-Way(ROW) edge along a block face, when that face is adjacent to a qualifying circulation network segment, to the next ROW edge intersecting that block face, except for intersecting alley ROWs.


the removal of makeup water from a cooling tower or evaporative condenser recirculation system to reduce concentrations of dissolved solids


real property or the expansion, redevelopment, or reuse of which may be complicated by the presence or possible presence of a hazardous substance, pollutant, or contaminant.

BUG rating

a luminaire classification system that classifies luminaires in terms of backlight (B), uplight (U), and glare (G) (taken from IES/IDA Model Lighting Ordinance). BUG ratings supersede the former cutoff ratings.

buildable land

the portion of the site where construction can occur, including land voluntarily set aside and not constructed on. When used in density calculations, buildable land excludes public rights-of-way and land excluded from development by codified law.

the portion of the site where construction can occur, including land voluntarily set aside and not constructed on. When used in density calculations, buildable land excludes public rights-of-way and land excluded from development by codified law or LEED for Neighborhood Development prerequisites.

building exterior

a structure’s primary and secondary weatherproofing system, including waterproofing membranes and air- and water-resistant barrier materials, and all building elements outside that system

building interior

everything inside a structure’s weatherproofing membrane

bus rapid transit

an enhanced bus system that operates on exclusive bus lanes or other transit rights-of-way. The system is designed to combine the flexibility of buses with the efficiency of rail.


carbon offset

a unit of carbon dioxide equivalent that is reduced, avoided, or sequestered to compensate for emissions occurring elsewhere (World Resources Institute)

chain of custody (CoC)

a procedure that tracks a product from the point of harvest or extraction to its end use, including all successive stages of processing, transformation, manufacturing, and distribution


an intensive, multiparty workshop that brings people from different disciplines and backgrounds together to explore, generate, and collaboratively produce design options

chlorofluorocarbon (CFC)-based refrigerant

a fluid, containing hydrocarbons, that absorbs heat from a reservoir at low temperatures and rejects heat at higher temperatures. When emitted into the atmosphere, CFCs cause depletion of the stratospheric ozone layer.

circulation network

all motorized, nonmotorized, and mixed-mode travel ways permanently accessible to the public, not including driveways, parking lots, highway access ramps, and rights-of-way exclusively dedicated to rail. It is measured in linear feet.

civil twilight

the point in time in the morning (dawn) or evening (dusk) when the center of the sun is geometrically 6 degrees below the horizon. Under good weather conditions, civil twilight is the best time to distinguish terrestrial objects clearly. Before civil twilight in the morning and after civil twilight in the evening, artificial illumination normally is required to carry on ordinary outdoor activities.

classroom or core learning space

a space that is regularly occupied and used for educational activities. In such space, the primary functions are teaching and learning, and good speech communication is critical to students’ academic achievement. (Adapted from ANSI S12.60)

clean waste

nonhazardous materials left over from construction and demolition. Clean waste excludes lead and asbestos.

clear glazing

glass that is transparent and allows a view through the fenestration. Diffused glazing allows only daylighting.

closed-loop cooling

a system that acts as a heat sink for heat-rejecting building and medical equipment by recirculating water. Because the water is sealed within the system, some closed-loop cooling systems use nonpotable water (such as recycled process water harvested from an air handler's cooling coil condensate).

color rendering index

a measurement from 0 to 100 that indictes how accurately an artificial light source, as compared with an incandescent light, displays hues. The higher the index number, the more accurately the light is rendering colors. Incandescent lighting has a color rendering index above 95; standard high-pressure sodium lighting (such as orange-hued roadway lights) measures approximately 25; many fluorescent sources using rare earth phosphors have a color rendering index of 80 and above. (Adapted from U.S. ENERGY STAR)

combination oven discharge

water released from an oven that includes a steam cycle or option

combined heat and power

an integrated system that captures the heat, otherwise unused, generated by a single fuel source in the production of electrical power. Also known as cogeneration. (Adapted from U.S. Environmental Protection Agency)

commingled waste

building waste streams that are combined on the project site and hauled away for sorting into recyclable streams. Also known as single-stream recycling.

commissioning (Cx)

the process of verifying and documenting that a building and all of its systems and assemblies are planned, designed, installed, tested, operated, and maintained to meet the owner’s project requirements

commissioning authority (CxA)

the individual designated to organize, lead, and review the completion of commissioning process activities. The CxA facilitates communication among the owner, designer, and contractor to ensure that complex systems are installed and function in accordance with the owner’s project requirements.


the measurement of the level of dissolved solids in water, using the ability of an electric current to pass through water. Because it is affected by temperature, conductivity is measured at 25°C for standardization.

construction impact zone

the project’s development footprint plus the areas around the improvement where construction crews, equipment, and/or materials are staged and moved during construction

conventional irrigation

a region’s most common system for providing water to plants by nonnatural means. A conventional irrigation system commonly uses pressure to deliver water and distributes it through sprinkler heads above the ground.

cooling tower blowdown

the water discharged from a cooling tower typically because increased salinity or alkalinity has caused scaling. Cooling tower blowdown may be too saline for use in landscape irrigation.

covenants, conditions, and restrictions (CC&R)

limitations that may be placed on a property and its use and are made a condition of holding title or lease

cradle-to-gate assessment

analysis of a product’s partial life cycle, from resource extraction (cradle) to the factory gate (before it is transported for distribution and sale). It omits the use and the disposal phases of the product.


a segment of the circulation network that terminates without intersecting another segment of the circulation network

cultural landscape

an officially designated geographic area that includes both cultural and natural resources associated with a historic event, activity, or person or that exhibits other significant cultural or aesthetic values

current facilities requirements (CFR)

the implementation of the owner’s project requirements, developed to confirm the owner’s current operational needs and requirements


For the purposes of PEER, this refers to the consumer served by the grid operator. For city projects, this includes customers of all classes billed by the utility, municipality or third-party supplier. For campuses, this includes business and groups of individuals (i.e., building tenants, or university departments) that are served by the grid operator. In the case where the building owner is the grid operator, “customer” refers to the individuals or groups of individuals on the consumer side of the meter, regardless of billing practices.

Synonyms: customer

dedicated storage

a designated area in a building space or a central facility that is sized and allocated for a specific task, such as the collection of recyclable waste. Signage often indicates the type of recyclable waste stored there. Some waste streams, such as mercury-based light bulbs, sensitive paper documents, biomedical waste, or batteries, may require particular handling or disposal methods. Consult the municipality’s safe storage and disposal procedures or use guidelines posted on the U.S. Environmental Protection Agency website, at

demand response (DR)

a change in electricity use by demand-side resources from their normal consumption patterns in response to changes in the price of electricity or to incentive payments designed to induce lower electricity use at times of high wholesale market prices or when system reliability is jeopardized

demand response (DR) event

a specific period of time when the utility or independent service operator calls for a change in the pattern or level of use in grid-based electricity from its program participants. Also known as a curtailment event.

demountable partition

a temporary interior wall that can be easily reconfigured. In a health care facility, acoustical concerns and embedded equipment, as in a surgery suite, may prevent demountable partitions from being used

densely occupied space

an area with a design occupant density of 25 people or more per 1,000 square feet (93 square meters)


a measure of the total building floor area or dwelling units on a parcel of land relative to the buildable land of that parcel. Units for measuring density may differ according to credit requirements. Does not include structured parking.

departmental gross area (DGA)

– the floor area of a diagnostic and treatment of clinical department, calculated from the centerline of the walls separating the department from adjacent spaces. Walls and circulations space within the department are included in the calculation. This calculation excludes inpatient units.

development footprint

the total land area of a project site covered by buildings, streets, parking areas, and other typically impermeable surfaces constructed as part of the project

differential durability

a state in which two materials with different life spans make up one complete component. If one material wears out and cannot be separated and replaced, the entire product must be thrown away.

direct access

a means of entering a space without having to leave the floor or pass through another patient’s room, dedicated staff space, service or utility space, or major public space. Patients’ and public circulation corridors, common sitting areas, and waiting and day space may be part of a direct access route.

direct sunlight

an interior horizontal measurement of 1,000 lux or more of direct beam sunlight that accounts for window transmittance and angular effects, and excludes the effect of any operable blinds, with no contribution from reflected light (i.e., a zero bounce analysis) and no contribution from the diffuse sky component (Adapted from IES)

district energy system (DES)

a central energy conversion plant and transmission and distribution system that provides thermal energy to a group of buildings (e.g., a central cooling plant on a university campus). It does not include central energy systems that provide only electricity.

diverse use

a distinct business or organization that provides goods or services intended to meet daily needs and is publicly available. Automated facilities such as ATMs or vending machines are not included. For a full list, see the Appendix."

downstream equipment

the heating and cooling systems, equipment, and controls located in the project building or on the project site and associated with transporting the thermal energy of the district energy system (DES) into heated and cooled spaces. Downstream equipment includes the thermal connection or interface with the DES, secondary distribution systems in the building, and terminal units. drift water droplets carried from a cooling tower or evaporative condenser by a stream of air passing through the system. Drift eliminators capture these droplets and return them to the reservoir at the bottom of the cooling tower or evaporative condenser for recirculation.


water droplets carried from a cooling tower or evaporative condenser by a stream of air passing through the system. Drift eliminators capture these droplets and return them to the reservoir at the bottom of the cooling tower or evaporative condenser for recirculation.

durable goods

products with a useful life of approximately two or more years and that are replaced infrequently. Examples include furniture, office equipment, appliances, external power adapters, televisions, and audiovisual equipment.

durable goods waste stream

the flow of long-lasting products from the project building after they are fully depreciated and have reached the end of their useful life for normal business operations. It includes leased durable goods returned to their owner but does not include durable goods that remain functional and are moved to another floor or building.


electric vehicle supply equipment

the conductors, including the ungrounded, grounded, and equipment grounding conductors, the electric vehicle connectors, attachment plugs, and all other fittings, devices, power outlets or apparatuses installed specifically for the purpose of delivering energy from the premises wiring to the electric vehicle. (National Electric Codes and California Article 625)

electronic waste

discarded office equipment (computers, monitors, copiers, printers, scanners, fax machines), appliances (refrigerators, dishwashers, water coolers), external power adapters, and televisions and other audiovisual equipment

elemental mercury

mercury in its purest form (rather than a mercury-containing compound), the vapor of which is commonly used in fluorescent and other bulb types

emergency lighting

a luminaire that operates only during emergency conditions and is always off during normal building operation

employment center

a nonresidential area of at least 5 acres (2 hectares) with a job density of at least 50 employees per net acre (at least 125 employees per hectare net)


the exterior plus semi-exterior portions of the building. Exterior consists of the elements of a building that separate conditioned spaces from the outside (i.e., the wall assembly). Semiexterior consists of the elements of a building that separate conditioned space from unconditioned space or that encloses semi-heated space through which thermal energy may be transferred to or from the exterior or conditioned or unconditioned spaces (e.g., attic, crawl space, basement).

energy service provider

a designation that allows an outside entity, such as USGBC, to access water and energy usage information that a building management team maintains with ENERGY STAR Portfolio Manager or a similar tool

engineered nanomaterial

a substance designed at the molecular (nanometer) level. Because of its small size, it has novel properties generally not seen in its conventional bulk counterpart. See the Australian National Industrial Chemicals Notification and Assessment Scheme,

environmental product declaration

a statement that the item meets the environmental requirements of ISO 14021–1999, ISO 14025–2006 and EN 15804, or ISO 21930–2007


the combination of evaporation and plant transpiration into the atmosphere. Evaporation occurs when liquid water from soil, plant surfaces, or water bodies becomes vapor. Transpiration is the movement of water through a plant and the subsequent loss of water vapor.

extended producer responsibility

measures undertaken by the maker of a product to accept its own and sometimes other manufacturers’ products as postconsumer waste at the end of the products’ useful life. Producers recover and recycle the materials for use in new products of the same type. To count toward credit compliance, a program must be widely available. For carpet, extended producer responsibility must be consistent with NSF/ANSI 140–2007. Also known as closed-loop program or product take-back.

extensive vegetated roof

a roof that is covered with plants and typically not designed for general access. Usually an extensive system is a rugged green roof that requires little maintenance once established. The planting medium in extensive vegetated roofs ranges from 1 to 6 inches in depth. (Adapted from U.S. EPA) exterior vegetated surface area the total area of vegetation on the project site, including vegetated roofs and turf grass

exterior vegetated surface area

the total area of vegetation on the project site, including vegetated roofs and turf grass

external meter

a device installed on the outside of a water pipe to record the volume of water passing through it. Also known as a clamp-on meter.


floor-area ratio (FAR)

the density of nonresidential land use, exclusive of parking, measured as the total nonresidential building floor area divided by the total buildable land area available for nonresidential structures. For example, on a site with 10,000 square feet (930 square meters) of buildable land area, an FAR of 1.0 would be 10,000 square feet (930 square meters) of building floor area. On the same site, an FAR of 1.5 would be 15,000 square feet (1395 square meters), an FAR of 2.0 would be 20,000 square feet (1860 square meters), and an FAR of 0.5 would be 5,000 square feet (465 square meters).

foundation drain

the water discharged from a subsurface drainage system. If a building foundation is below the water table, a sump pump may be required. Discharge from the sump may be stored and used for irrigation.

freight village

a cluster of freight-related businesses that include intermodal transfer operations. Freight villages may offer logistics services, integrated distribution, warehousing capabilities, showrooms, and support services. Such support services may include security, maintenance, mail, banking, customs and import management assistance, cafeterias, restaurants, office space, conference rooms, hotels, and public or activity center transportation.

functional entry

a building opening designed to be used by pedestrians and open during regular business hours. It does not include any door exclusively designated as an emergency exit, or a garage door not designed as a pedestrian entrance.

furniture and furnishings

the stand-alone furniture items purchased for the project, including individual and group seating; open-plan and private-office workstations; desks and tables; storage units, credenzas, bookshelves, filing cabinets, and other case goods; wall-mounted visual-display products (e.g., marker boards and tack boards, excluding electronic displays); and miscellaneous items, such as easels, mobile carts, freestanding screens, installed fabrics, and movable partitions. Hospitality furniture is included as applicable to the project. Office accessories, such as desktop blotters, trays, tape dispensers, waste baskets, and all electrical items, such as lighting and small appliances, are excluded.


grams per brake horsepower hour

metric used to communicate how many grams of emissions (e.g., nitrogen oxide or particulate matter) are emitted by an engine of a specific horsepower rating over a one-hour period


“untreated household waste water which has not come into contact with toilet waste. Graywater includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washers and laundry tubs. It must not include waste water from kitchen sinks or dishwashers” (Uniform Plumbing Code, Appendix G, Gray Water Systems for Single-Family Dwellings); “waste water discharged from lavatories, bathtubs, showers, clothes washers and laundry sinks” (International Plumbing Code, Appendix C, Gray Water Recycling Systems). Some states and local authorities allow kitchen sink wastewater to be included in graywater. Other differences can likely be found in state and local codes. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area.

green infrastructure

a soil- and vegetation-based approach to wet weather management that is cost-effective, sustainable, and environmentally friendly. Green infrastructure management approaches and technologies infiltrate, evapotranspire, capture and reuse stormwater to maintain or restore natural hydrologies. (Adapted from U.S. Environmental Protection Agency)

green power

a subset of renewable energy composed of grid-based electricity produced from renewable energy sources

green vehicles

vehicles achieving a minimum green score of 45 on the American Council for an Energy Efficient Economy (ACEEE) annual vehicle rating guide (or a local equivalent for projects outside the U.S.).


area that has not been graded, compacted, cleared, or disturbed and that supports (or could support) open space, habitat, or natural hydrology.

See also: previously disturbed

gross bulk generation

The sum of bulk purchased electricity delivered to the site. Bulk generation delivered to the site should be adjusted for transmission and distribution losses to the site.

Synonyms: Gross bulk generation

gross local generation

The sum of electric power generated at the generator terminals of local generators. This does not include any hotel loads producing electric power in the plant.

Synonyms: Gross local generation


the inanimate elements of the building landscaping. It includes pavement, roadways, stonewalls, wood and synthetic decking, concrete paths and sidewalks, and concrete, brick, and tile patios.

hazardous material

any item or agent (biological, chemical, physical) that has the potential to cause harm to humans, animals, or the environment, either by itself or through interaction with other factors

heat island effect

the thermal absorption by hardscape, such as dark, nonreflective pavement and buildings, and its subsequent radiation to surrounding areas. Other contributing factors may include vehicle exhaust, air-conditioners, and street equipment. Tall buildings and narrow streets reduce airflow and exacerbate the effect.


a transportation thoroughfare intended for motor vehicles with limited access points, prohibitions on human-powered vehicles, and higher speeds than local roads. A highway generally connects cities and towns.

historic building

a building or structure with historic, architectural, engineering, archeological, or cultural significance that is listed or determined to be eligible as a historic structure or building, or as a contributing building or structure in a designated historic district. The historic designation must be made by a local historic preservation review board or similar body, and the structure must be listed in a state register of historic places, be listed in the National Register of Historic Places (or a local equivalent outside the U.S.), or have been determined eligible for listing.

historic district

a group of buildings, structures, objects, and sites that have been designated or determined to be eligible as historically and architecturally significant, and categorized as either contributing or noncontributing to the historic nature of the district

homogeneous material

an item that consists of only one material throughout or a combination of multiple materials that cannot be mechanically disjointed, excluding surface coatings


a group of plantings with similar water needs



the incident luminous flux density on a differential element of surface located at a point and oriented in a particular direction, expressed in lumens per unit area. Since the area involved is differential, it is customary to refer to this as illuminance at a point. The unit name depends on the unit of measurement for area: footcandles if square feet are used for area, and lux if square meters are used. (Adapted from IES) In lay terms, illuminance is a measurement of light striking a surface. It is expressed in footcandles in the U.S. (based on square feet) and in lux in most other countries (based on square meters).

impervious surface

an area of ground that development and building have modified in such a way that precipitation cannot infiltrate downward through the soil. Examples of impervious surfaces include roofs, paved roads and parking areas, sidewalks, and soils that have been compacted either by design or by use.

individual occupant space

an area where an occupant performs distinct tasks. Individual occupant spaces may be within multioccupant spaces and should be treated separately where possible.

industrial process water

any water discharged from a factory setting. Before this water can be used for irrigation, its quality needs to be checked. Saline or corrosive water should not be used for irrigation.

infill site

a site where at least 75% of the land area, exclusive of rights-of-way, within ½ mile (800 meters) of the project boundary is previously developed. A street or other right-of-way does not constitute previously developed land; it is the status of property on the other side of right-of-way or the street that matters.

LEED ND only:

a site that meets any of the following four conditions:
a. At least 75% of its boundary borders parcels that individually are at least 50% previously developed, and that in aggregate are at least 75% previously developed
b. The site, in combination with bordering parcels, forms an aggregate parcel whose boundary is 75% bounded by parcels that individually are at least 50% previously developed, and that in aggregate are at least 75% previously developed
c. At least 75% of the land area, exclusive of rights-of-way, within ½ mile (800 meters) of the project boundary is previously developed
d. The lands within ½ mile (800 meters) of the project boundary have a preproject connectivity of at least 140 intersections per square mile (54 intersections per square kilometer)
The circulation network itself does not constitute previously developed land; it is the status of property on the other side of the segment of circulation network that matters. For conditions (a) and (b) above, any fraction of the perimeter that borders a water body is excluded from the calculation. "


(HVAC) uncontrolled inward air leakage to conditioned spaces through unintentional openings in ceilings, floors, and walls from unconditioned spaces or the outdoors caused by the same pressure differences that induce exfiltration. (ASHRAE 62.1–2010)

informal transit

a transit service in which individuals travel together in a passenger car or small van that seats at least four people. It can include human-powered conveyances, which must accommodate at least two people. It must include an enclosed passenger seating area, fixed route service, fixed fare structure, regular operation, and the ability to pick up multiple riders.

infrared (thermal) emittance 

a value between 0 and 1 (or 0% and 100%) that indicates the ability of a material to shed infrared radiation (heat). A cool roof should have a high thermal emittance. The wavelength range for radiant energy is roughly 5 to 40 micrometers. Most building materials (including glass) are opaque in this part of the spectrum and have an emittance of roughly 0.9, or 90%. Clean, bare metals, such as untarnished galvanized steel, have a low emittance and are the most important exceptions to the 0.9 rule. In contrast, aluminum roof coatings have intermediate emittance levels. (Adapted from Lawrence Berkeley National Laboratory)


an individual admitted to a medical, surgical, maternity, specialty, or intensive-care unit for a length of stay exceeding 23 hours

inpatient unit

any medical, surgical, maternity, specialty, or intensive-care unit where an individual receives care for more than 23 hours

integral labeling

an information conveyance system that cannot be easily removed. For furniture, such labeling may include radio frequency identification, engraving, embossing, or other permanent marking containing information on material origin, properties, and date of manufacture.

integrated pest management

a method of pest management that protects human health and the surrounding environment, and improves economic returns through the most effective, least-risk option

integrated project delivery

an approach that involves people, systems, and business structures (contractual and legal agreements) and practices. The process harnesses the talents and insights of all participants to improve results, increase value to the owner, reduce waste, and maximize efficiency through all phases of design, fabrication, and construction. (Adapted from American Institute of Architects)

intensive vegetated roof

a roof that, compared with an extensive vegetated roof, has greater soil volume, supports a wider variety of plants (including shrubs and trees), and allows a wider variety of uses (including human access). The depth of the growing medium is an important factor in determining habitat value. The native or adapted plants selected for the roof should support the site’s endemic wildlife populations. (Adapted from Green Roofs for Healthy Cities)

interior floor finish

all the layers applied over a finished subfloor or stairs, including stair treads and risers, ramps, and other walking surfaces. Interior finish excludes building structural members, such as beams, trusses, studs, or subfloors, or similar items. Interior finish also excludes nonfull spread wet coatings or adhesives.

interior wall and ceiling finish

all the layers comprising the exposed interior surfaces of buildings, including fixed walls, fixed partitions, columns, exposed ceilings, and interior wainscoting, paneling, interior trim or other finish applied mechanically or for decoration, acoustical correction, surface fire resistance, or similar purposes

intermodal facility

a venue for the movement of goods in a single loading unit or road vehicle that uses successively two or more modes of transportation without the need to handle the goods themselves

interstitial space

an intermediate space located between floors with a walk-on deck, often used to run the majority of the utility distribution and terminal equipment, thus permitting convenient installation, maintenance, and future modifications

invasive plant

nonnative vegetation that has been introduced to an area and that aggressively adapts and reproduces. The plant’s vigor combined with a lack of natural enemies often leads to outbreak populations. (Adapted from U.S. Department of Agriculture)

IT annual energy

electricity consumption by information technology and telecom equipment which includes servers, networking, and storage equipment over the course of a year



a device emitting light in a fixture, excluding lamp housing and ballasts. Light-emitting diodes packaged as traditional lamps also meet this definition.

lamp life

the useful span of operation of a source of artificial light, such as bulbs. Lamp life for fluorescent lights is determined by testing three hours on for every 20 minutes off. For high-density discharge lamps, the test is based on 11 hours on for every 20 minutes off. Lamp life depends on whether the start ballast is program or instant. This information is published in manufacturers’ information. Also known as rated average life.

land trust

a private, nonprofit organization that, as all or part of its mission, actively works to conserve land by undertaking or assisting in conservation easement or land acquisition, or by its stewardship of such land or easements (Adapted from Land Trust Alliance)

land-clearing debris and soil

materials that are natural (e.g., rock, soil, stone, vegetation). Materials that are man-made (e.g., concrete, brick, cement) are considered construction waste even if they were on site.

landscape water requirement (LWR)

the amount of water that the site landscape area(s) requires for the site’s peak watering month


a label, defined by U.S. EPA regulations under the Safe Drinking Water Act, that allows small amounts of lead in solders, flux, pipes, pipe fittings, and well pumps

least-risk pesticide

a registered pesticide in the Tier III (lowest toxicity) category, using the San Francisco Hazard Ranking system, or a pesticide that meets the requirements in the San Francisco Pesticide Hazard Screening Protocol and is sold as a self-contained bait or as a crack-and-crevice treatment used in areas inaccessible to building occupants. Rodenticides are never considered least-risk pesticides.

length of stay

the amount of time a person remains in a health care facility as an admitted patient

life-cycle assessment

an evaluation of the environmental effects of a product from cradle to grave, as defined by ISO 14040–2006 and ISO 14044–2006

life-cycle inventory

a database that defines the environmental effects (inputs and outputs) for each step in a material’s or assembly’s life cycle. The database is specific to countries and regions within countries.

light pollution

waste light from building sites that produces glare, is directed upward to the sky, or is directed off the site. Waste light does not increase nighttime safety, utility, or security and needlessly consumes energy.

light rail

transit service using two- or three-car trains in a right-of-way that is often separated from other traffic modes. Spacing between stations tends to be ½ mileor more, and maximum operating speeds are typically 40–55 mph (65–90 kmh). Light-rail corridors typically extend 10 or more miles (16 kilometers).

light trespass

obtrusive illumination that is unwanted because of quantitative, directional, or spectral attributes. Light trespass can cause annoyance, discomfort, distraction, or loss of visibility.

load shedding

an intentional action by a utility to reduce the load on the system. Load shedding is usually conducted during emergency periods, such as capacity shortages, system instability, or voltage control.

long-term bicycle storage

bicycle parking that is easily accessible to residents and employees and covered to protect bicycles from rain and snow

low-cost improvement

an operational improvement, such as a repair, upgrade, or staff training or retraining. In LEED, the project team determines the reasonable upper limit for low-cost improvements based on facility resources and operating budgets.

low-impact development (LID)

an approach to managing rainwater runoff that emphasizes on-site natural features to protect water quality, by replicating the natural land cover hydrologic regime of watersheds, and addressing runoff close to its source. Examples include better site design principles (e.g., minimizing land disturbance, preserving vegetation, minimizing impervious cover), and design practices (e.g., rain gardens, vegetated swales and buffers, permeable pavement, rainwater harvesting, soil amendments). These are engineered practices that may require specialized design assistance.


major renovation

LEED ND: extensive alteration work in addition to work on the exterior shell of the building and/or primary structural components and/or the core and peripheral MEP and service systems and/or site work. Typically, the extent and nature of the work is such that the primary function space cannot be used for its intended purpose while the work is in progress and where a new certificate of occupancy is required before the work area can be reoccupied.

makeup water

water that is fed into a cooling tower system or evaporative condenser to replace water lost through evaporation, drift, bleed-off, or other causes

manage (rainwater) on site

to capture and retain a specified volume of rainfall to mimic natural hydrologic function. Examples of rainwater management include strategies that involve evapotranspiration, infiltration, and capture and reuse.

master plan boundary

the limits of a site master plan. The master plan boundary includes the project area and may include all associated buildings and sites outside of the LEED project boundary. The master plan boundary considers future sustainable use, expansion, and contraction.

mean lumen output

a measurement of a source’s emitted light derived from industry standards, taken with an instant-start ballast that has a ballast factor of 1.0 as measured at 40% of lamp life (except for T-5 lamps, which use a program-start ballast)

medical furnishing

an item of furniture designed for use in health care. Examples include surgical tables; procedure, supply, and mobile technology carts; lifting and transfer aids; supply closet carts and shelving; and overbed tables.

metering control

a regulator that limits the flow time of water, generally a manual-on and automatic-off device, most commonly installed on lavatory faucets and showers

mixed paper

white and colored paper, envelopes, forms, file folders, tablets, flyers, cereal boxes, wrapping paper, catalogs, magazines, phone books, and photos

modular and movable casework

shelving and cabinetry designed to be easily installed, moved, or reconfigured. In a retail setting, items that are movable but semipermanently attached using mechanical fastening systems for operational use are considered furniture and not base building elements (e.g., a table or display bolted to the floor, or shelving attached to a wall).

mounting height

the distance between ground level (or the workplane) and the center of the luminaire (light fixture); the height at which a luminaire is installed.

movable furniture and partitions

items that can be moved by the users without the need of tools or assistance from special trades and facilities management

multitenant complex

a site that was master-planned for the development of stores, restaurants and other businesses. Retailers may share some services and common areas.


NAED code

a unique five- or six-digit number used to identify specific lamps, used by the National Association of Electrical Distributors

native vegetation

a species that originates in, and is characteristic of, a particular region and ecosystem without direct or indirect human actions. Native species have evolved together with other species within the geography, hydrology, and climate of that region.

natural refrigerant

a compound that is not manmade and is used for cooling. Such substances generally have much lower potential for atmospheric damage than manufactured chemical refrigerants. Examples include water, carbon dioxide, and ammonia.

Natural Resources Conservation Service (NRCS) soils delineation

a U.S.-based soil survey that shows the boundaries of different soil types and special soil features on the site

natural site hydrology

the natural land cover function of water occurrence, distribution, movement, and balance

net usable program area

the sum of all interior areas in the project available to house the project’s program. It does not include areas for building equipment, vertical circulation, or structural components.

non-inpatient area

a public space, diagnostic or treatment area, ambulatory unit, or any other space in a health care facility that is not for individuals who have been admitted for care

non-regularly occupied space

an area that people pass through or an area used for focused activities an average of less than one hour per person per day. The one-hour timeframe is continuous and should be based on the time a typical occupant uses the space. For spaces that are not used daily, the one-hour timeframe should be based on the time a typical occupant spends in the space when it is in use. 

nonpotable water

water that does not meet drinking water standards

nonwater toilet systems

dry plumbing fixtures and fittings that contain and treat human waste via microbiological processes

nonwater urinal

a plumbing fixture having a water flush with a trap that contains a layer of buoyant liquid that floats above the urine, blocking sewer gas and odors


occupant control

a system or switch that a person in the space can directly access and use. Examples include a task light, an open switch, and blinds. A temperature sensor, photo sensor, or centrally controlled system is not occupant controlled.

occupiable space

an enclosed space intended for human activities, excluding those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are occupied only occasionally and for short periods of time (ASHRAE 62.1–2010)

occupied space

enclosed space intended for human activities, excluding those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are only occupied occasionally and for short periods of time. Occupied spaces are further classified as regularly occupied or nonregularly occupied spaces based on the duration of the occupancy, individual or multioccupant based on the quantity of occupants, and densely or nondensely occupied spaces based on the concentration of occupants in the space.

on-site wastewater treatment

the transport, storage, treatment, and disposal of wastewater generated on the project site

ongoing consumable

a product that has a low cost per unit and is regularly used and replaced in the course of business. Examples include paper, toner cartridges, binders, batteries, and desk accessories. Also known as ongoing purchases.

open-grid pavement system

pavements that consist of loose substrates supported by a grid of a more structurally sound grid or webbing. Pervious concrete and porous asphalt are not considered open grid as they are considered bounded materials. Unbounded, loose substrates do not transfer and store heat like bound and compacted materials do.

operations and maintenance (O&M) plan

a plan that specifies major system operating parameters and limits, maintenance procedures and schedules, and documentation methods necessary to demonstrate proper operation and maintenance of an approved emissions control device or system

ornamental luminaire

a luminaire intended for illuminating portions of the circulation network that also serves an ornamental function, in addition to providing optics that effectively deliver street lighting, and has a decorative or historical period appearance


a patient who is not hospitalized for 24 hours or more but who visits a hospital, clinic, or associated healthcare facility for diagnosis or treatment

owner’s project requirements (OPR)

a written document that details the ideas, concepts, and criteria determined by the owner to be important to the success of the project


patient position

a patient bed, infusion chair, recovery room bay, or other location where a patient receives clinical care

peak demand

the maximum electricity load at a specific point in time or over a period of time

peak watering month

the month with the greatest deficit between evapotranspiration and rainfall. This is the month when the plants in the site’s region potentially require the most supplemental water typically a mid-summer month. (Sustainable Sites Initiative)

permanent interior obstruction

a structure that cannot be moved by the user without tools or assistance from special trades and facilities management. Examples include lab hoods, fixed partitions, demountable opaque full- or partial-height partitions, some displays, and equipment.

permanent peak load shifting

the transfer of energy consumption to off-peak hours, when demand for power is lower and energy is therefore less expensive

permeable pavement

a paved surface that allows water runoff to infiltrate into the ground

persistent bioaccumulative toxic chemical

a substance that poses a long-term risk to both humans and the environment because it remains in the environment for long periods, increases in concentration as it moves up the food chain, and can travel far from the source of contamination. Often these substances can become more potent and harmful to ecosystems the longer they persist. See U.S. EPA’s website on persistent bioaccumulative toxic chemicals,

place of respite

an area that connects healthcare patients, visitors, and staff to health benefits of the natural environment. (Adapted from Green Guide for Health Care Places of Respite Technical Brief)

plug load or receptacle load

the electrical current drawn by all equipment that is connected to the electrical system via a wall outlet.

postconsumer recycled content

waste generated by households or commercial, industrial and institutional facilities in their role as end users of a product that can no longer be used for its intended purpose

potable water

water that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems

power distribution unit output

the electrical power from a device that allocates power to and serves information technology (IT) equipment. Power distribution unit (PDU) output does not include efficiency losses of any transformation that occurs within the PDU, but it can include downstream non-IT ancillary devices installed in IT racks, such as fans. If the PDU system supports non-IT equipment (e.g., computer room air-conditioning units, computer room air handlers, in-row coolers), this equipment must be metered and subtracted from the PDU output reading. The metering approach should be consistent with the metering required for the power usage efficiency (PUE) category (e.g., continuous consumption metering for PUE categories 1, 2, and 3).

power utilization effectiveness (PUE)

a measure of how efficiently a data center uses its power; specifically, how much power is used by computing equipment rather than for cooling and other overhead

powered floor maintenance equipment

electric and battery-powered floor buffers and burnishers. It does not include equipment used in wet applications

preconsumer recycled content

matter diverted from the waste stream during the manufacturing process, determined as the percentage of material, by weight. Examples include planer shavings, sawdust, bagasse, walnut shells, culls, trimmed materials, overissue publications, and obsolete inventories. The designation excludes rework, regrind, or scrap materials capable of being reclaimed within the same process that generated them (ISO 14021). Formerly known as postindustrial content.

preferred parking

the parking spots closest to the main entrance of a building (exclusive of spaces designated for handicapped persons). For employee parking, it refers to the spots that are closest to the entrance used by employees.

premature obsolescence

the wearing out or disuse of components or materials whose service life exceeds their design life. For example, a material with a potential life of 30 years is intentionally designed to last only 15 years, such that its remaining 15 years of service is potentially wasted. In contrast, components whose service life is the same as their expected use are utilized to their maximum potential.

previously developed

altered by paving, construction, and/or land use that would typically have required regulatory permitting to have been initiated (alterations may exist now or in the past). Land that is not previously developed and landscapes altered by current or historical clearing or filling, agricultural or forestry use, or preserved natural area use are considered undeveloped land. The date of previous development permit issuance constitutes the date of previous development, but permit issuance in itself does not constitute previous development.

previously developed site

a site that, prior to the project, consisted of at least 75% previously developed land

previously disturbed

areas that have been graded, compacted, cleared, previously developed, or disturbed in any way. These are areas that do not qualify as 'greenfield.’

See also: greenfield

prime farmland

land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber, and oilseed crops and that is available for these uses, as determined by the U.S. Department of Agriculture’s Natural Resources Conservation Service (a U.S.-based methodology that sets criteria for highly productive soil). For a complete description of what qualifies as prime farmland, see U.S. Code of Federal Regulations, Title 7, Volume 6, Parts 400 to 699, Section 657.5.

private meter

a device that measures water flow and is installed downstream from the public water supply meter or as part of an on-site water system maintained by the building management team

process energy

power resources consumed in support of a manufacturing, industrial, or commercial process other than conditioning spaces and maintaining comfort and amenities for building occupants of a building. It may include refrigeration equipment, cooking and food preparation, clothes washing, and other major support appliances. (ASHRAE)

process load or unregulated load

the load on a building resulting from the consumption or release of process energy (ASHRAE)

process water

water that is used for industrial processes and building systems, such as cooling towers, boilers, and chillers. It can also refer to water used in operational processes, such as dishwashing, clothes washing, and ice making.

product (permanently installed building product)

an item that arrives on the project site either as a finished element ready for installation or as a component to another item assembled on-site. The product unit is defined by the functional requirement for use in the project; this includes the physical components and services needed to serve the intended function of the permanently installed building product. In addition, similar product within a specification, each contributes as a separate product.

project electrical load

The project load includes electric power delivered to metered customers, buildings, or loads within the project boundary, including the electric power required to centrally produce other energy delivered to customers, buildings, or loads within the project boundary such as chiller loads. This does not include parasitic loads such as transmission and distribution losses or reactive power compensation.

Synonyms: Project electrical load

public water supply (PWS)

a system for the provision to the public of water for human consumption through pipes or other constructed conveyances. To be considered public, such system must have at least 15 service connections or regularly serve at least 25 individuals. (Adapted from U.S. Environmental Protection Agency)


rainwater harvesting

the capture, diversion, and storage of rain for future beneficial use. Typically, a rain barrel or cistern stores the water; other components include the catchment surface and conveyance system. The harvested rainwater can be used for irrigation.

raw material

the basic substance from which products are made, such as concrete, glass, gypsum, masonry, metals, recycled materials (e.g., plastics and metals), oil (petroleum, polylactic acid), stone, agrifiber, bamboo, and wood

reclaimed water

wastewater that has been treated and purified for reuse

recycled content

defined in accordance with the International Organization of Standards document ISO 14021 – Environmental labels and declarations – Self-declared environmental claims (Type II environmental labeling)

reference evapotranspiration rate

the amount of water lost from a specific vegetated surface with no moisture limitation. Turf grass with height of 120 mm is the reference vegetation.

reference soil

a soil native to the project site, as described in Natural Resources Conservation Service soil surveys (or a local equivalent survey outside the United States), or undisturbed native soils within the project’s region that have native vegetation, topography, and soil textures similar to the project site. For project sites with no existing soil, reference soils are defined as undisturbed native soils within the project’s region that support appropriate native plant species similar to those intended for the new project.

refurbished material

an item that has completed its life cycle and is prepared for reuse without substantial alteration of its form. Refurbishing involves renovating, repairing, restoring, or generally improving the appearance, performance, quality, functionality, or value of a product.

regularly occupied space

an area where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. The one-hour timeframe is continuous and should be based on the time a typical occupant uses the space. For spaces that are not used daily, the one-hour timeframe should be based on the time a typical occupant spends in the space when it is in use. 

regularly used exterior entrance

a frequently used means of gaining access to a building. Examples include the main building entrance as well as any building entryways attached to parking structures, underground parking garages, underground pathways, or outside spaces. Atypical entrances, emergency exits, atriums, connections between concourses, and interior spaces are not included.

regulated load

any building end use that has either a mandatory or a prescriptive requirement in ANSI/ASHRAE/IES Standard 90.1–2010

remanufactured product

an item that has been repaired or adjusted and returned to service. A remanufactured product can be expected to perform as if it were new.

renewable energy

energy sources that are not depleted by use. Examples include energy from the sun, wind, and small (low-impact) hydropower, plus geothermal energy and wave and tidal systems.

renewable energy credit (REC)

a tradable commodity representing proof that a unit of electricity was generated from a renewable resource. RECs are sold separately from electricity itself and thus allow the purchase of green power by a user of conventionally generated electricity.


the reemployment of materials in the same or a related capacity as their original application, thus extending the lifetime of materials that would otherwise be discarded. Reuse includes the recovery and reemployment of materials recovered from existing building or construction sites. Also known as salvage.

reused area

the total area of the building structure, core, and envelope that existed in the prior condition and remains in the completed design

revenue-grade meter

a measurement tool designed to meet strict accuracy standards required by code or law. Utility meters are often called revenue grade because their measurement directly results in a charge to the customer.


salvaged material

a construction component recovered from existing buildings or construction sites and reused. Common salvaged materials include structural beams and posts, flooring, doors, cabinetry, brick, and decorative items.

school authority

the authority responsible for decision making about school operations, districts, personnel, financing, and future development. Examples include school boards, local governments, and religious institutions.

Scope 1 emissions

direct greenhouse gas emissions from sources owned or controlled by the entity, such as emissions from fossil fuels burned on site. Electricity produced on site through the burning of fossil fuels is measured by the Scope 1 emissions associated with that fossil fuel.

Scope 2 emissions

indirect greenhouse gas emissions associated with the generation of purchased electricity, heating/cooling, or steam off site, through a utility provider for the entity’s consumption


the percentage of analysis points across the analysis area that meet or exceed this 300 lux value for at least 50% of the analysis period 

server input

the information technology (IT) load as measured at the point of connection (e.g., power receptacle) of the IT device to the electrical power system. Server input captures the actual power load of the IT device exclusive of any power distribution losses and non-IT loads (e.g., rack-mounted fans).

service life

the assumed length of time that a building, product, or assembly will be operational for the purposes of a life-cycle assessment

shared multioccupant space

a place of congregation, or where occupants pursue overlapping or collaborative tasks

shell space

an area designed to be fitted out for future expansion. Shell space is enclosed by the building envelope but otherwise left unfinished.

short-term bicycle storage

non-enclosed bicycle parking typically used by visitors for a period of two hours or less.

simple box energy modeling analysis

(also known as “building-massing model energy analysis”) a simple base-case energy analysis that informs the team about the building’s likely distribution of energy consumption and is used to evaluate potential project energy strategies. A simple box analysis uses a basic, schematic building form.

site assessment

an evaluation of an area’s aboveground and subsurface characteristics, including its structures, geology, and hydrology. Site assessments typically help determine whether contamination has occurred and the extent and concentration of any release of pollutants. Remediation decisions rely on information generated during site assessments.

site master plan

an overall design or development concept for the project and associated (or potentially associated) buildings and sites. The plan considers future sustainable use, expansion, and contraction. The site master plan is typically illustrated, with building plans (if applicable), site drawings of planned phased development, and narrative descriptions.

soft space

an area whose functions can be easily changed. For example, hospital administrative offices could be moved so that this soft space could be converted to a laboratory. In contrast, a lab with specialized equipment and infrastructure would be difficult to relocate.


the elements of a landscape that consist of live, horticultural elements

solar garden/community renewable energy system

shared solar array or other renewable energy system with grid-connected subscribers who receive credit for the use of renewables using virtual net metering (Adapted from

solar reflectance (SR)

the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. Determine the SR of a material by using the Cool Roof Rating Council Standard (CRRC-1).

solar reflectance index (SRI)

a measure of the constructed surface’s ability to stay cool in the sun by reflecting solar radiation and emitting thermal radiation. It is defined such that a standard black surface (initial solar reflectance 0.05, initial thermal emittance 0.90) has an initial SRI of 0, and a standard white surface (initial solar reflectance 0.80, initial thermal emittance 0.90) has an initial SRI of 100. To calculate the SRI for a given material, obtain its solar reflectance and thermal emittance via the Cool Roof Rating Council Standard (CRRC-1). SRI is calculated according to ASTM E 1980. Calculation of the aged SRI is based on the aged tested values of solar reflectance and thermal emittance.

sound-level coverage

a set of uniformity criteria that ensure consistent intelligibility and directionality of audible frequencies for all occupants within a space

source reduction

a decrease in the amount of unnecessary material brought into a building in order to produce less waste. For example, purchasing products with less packaging is a source reduction strategy.

spatial daylight autonomy (sDA)

a metric describing annual sufficiency of ambient daylight levels in interior environments. It is defined as the percentage of an analysis area (the area where calculations are performed, typically across an entire space) that meets a minimum daylight illuminance level for a specified fraction of the operating hours per year (i.e., the Daylight Autonomy value following Reinhart & Walkenhorst, 2001). The illluminance level and time fraction are included as subscripts, as in sDA300,50%. The sDA value is expressed as a percentage of area.

speech privacy

a condition in which speech is unintelligible to casual listeners (ANSI T1.523–2001)

speech spectra

the distribution of acoustic energy as a function of frequency for human speech 


a transit service with small, individual rail cars. Spacing between stations is uniformly short and ranges from every block to ¼ mile, and operating speeds are primarily 10–30 mph (15–50 kmh). Streetcar routes typically extend 2–5 miles (3-8 kilometers).


elements carrying either vertical or horizontal loads (e.g., walls, roofs, and floors) that are considered structurally sound and nonhazardous

systems manual

provides the information needed to understand, operate, and maintain the systems and assemblies within a building. It expands the scope of the traditional operating and maintenance documentation and is compiled of multiple documents developed during the commissioning process, such as the owner’s project requirements, operation and maintenance manuals, and sequences of operation. 


Technical Release (TR) 55

an approach to hydrology in which watersheds are modeled to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes, developed by the former USDA Soil Conservation Service

thermal emittance

the ratio of the radiant heat flux emitted by a specimen to that emitted by a blackbody radiator at the same temperature (adapted from Cool Roof Rating Council)

three-year aged SR

or SRI value a solar reflectance or solar reflectance index rating that is measured after three years of weather exposure

time-of-use pricing

an arrangement in which customers pay higher fees to use utilities during peak time periods and lower fees during off-peak time periods


undercover parking

vehicle storage that is underground, under deck, under roof, or under a building

uninterruptible power supply (UPS) output

the electricity provided by a unit that keeps information technology (IT) equipment functioning during a power outage. UPS output does not include efficiency losses from the unit itself but does include losses from downstream electrical distribution components, such as power distribution units, and it may include non-IT ancillary devices installed in IT racks, such as fans. If the UPS system supports non-IT equipment (e.g., computer room air-conditioning units, computer room air handlers, in-row coolers), this usage must be metered and subtracted from the UPS output reading. The metering approach should be consistent with the metering required for the power usage efficiency (PUE) category (e.g., continuous consumption metering for PUE categories 1, 2 and 3).

universal waste

hazardous items that are easily purchased and commonly used. Examples include batteries, pesticides, mercury-containing equipment, and light bulbs. See

unoccupied space

an area designed for equipment, machinery, or storage rather than for human activities. An equipment area is considered unoccupied only if retrieval of equipment is occasional.

upstream equipment

a heating or cooling system or control associated with the district energy system (DES) but not part of the thermal connection or interface with the DES. Upstream equipment includes the thermal energy conversion plant and all the transmission and distribution equipment associated with transporting the thermal energy to the project building or site.

USDA Organic

the U.S. Department of Agriculture’s certification for products that contain at least 95% ingredients (excluding water and salt) produced without synthetic chemicals, antibiotics, or hormones. Any remaining ingredients must consist of USDA-approved nonagricultural substances or agricultural products that are not commercially available in organic form.


vertical illuminance

illuminance levels calculated at a point on a vertical surface, or that occur on a vertical plane

vision glazing

the glass portion of an exterior window that permits views to the exterior or interior. Vision glazing must allow a clear image of the exterior and must not be obstructed by frits, fibers, patterned glazing, or added tints that distort color balance.


walking distance

the distance that a pedestrian must travel between origins and destinations without obstruction, in a safe and comfortable environment on a continuous network of sidewalks, all weather-surface footpaths, crosswalks, or equivalent pedestrian facilities. The walking distance must be drawn from an entrance that is accessible to all building users.

waste diversion

a management activity that disposes of waste through methods other than incineration or landfilling. Examples include reuse and recycling.


the conversion of nonrecyclable waste materials into usable heat, electricity, or fuel through a variety of processes, including combustion, gasification, pyrolization, anaerobic digestion, and landfill gas (LFG) recovery


water that has been used for a purpose and conveyed by building plumbing systems toward a point of treatment and disposal. Wastewater from buildings can be classified as graywater, blackwater, or process wastewater.

water body

the surface water of a stream (first-order and higher, including intermittent streams), arroyo, river, canal, lake, estuary, bay, or ocean. It does not include irrigation ditches.

water budget

a project-specific method of calculating the amount of water required by the building and associated grounds. The budget takes into account indoor, outdoor, process, and makeup water demands and any on site supply including estimated rainfall. Water budgets must be associated with a specified amount of time, such as a week, month, or year and a quantity of water such as kGal, or liters.

wet meter

a device installed inside a water pipe to record the volume of passing water


an area that is inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances does support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas, but exclude irrigation ditches unless delineated as part of an adjacent wetland.


plant-based materials that are eligible for certification under the Forest Stewardship Council. Examples include bamboo and palm (monocots) as well as hardwoods (angiosperms) and softwoods (gymnosperms)



landscaping that does not require routine irrigation


yard tractor

a vehicle used primarily to facilitate the movement of truck trailers and other types of large shipping containers from one area of a site to another. It does not include forklift trucks. Also known as terminal tractor, yard truck, utility tractor rig, yard goat, or yard hustler.


zero lot line project

a plot whose building footprint typically aligns or nearly aligns with the site limits