The precipitation of dilute solutions of strong mineral acids, formed by the mixing in the atmosphere of various industrial pollutants (primarily sulfur dioxide and nitrogen oxides) with naturally occurring oxygen and water vapour.
Alternative Fuel Vehicles
Vehicles that use low-polluting, nongasoline fuels, such as electricity, hydrogen, propane or compressed natural gas, liquid natural gas, methanol and ethanol. In LEED, efficient gas-electric hybrid vehicles are included in this group.
The variety of life in all forms, levels and combinations, including ecosystem diversity, species diversity and genetic diversity.
Plant material from trees, grasses or crops that can be converted to heat energy to produce electricity.
A stormwater control feature that uses a combination of an engineered basin, soils and vegetation to slow and detain stormwater, increase groundwater recharge and reduce peak stormwater runoff.
Previously used or developed land that may be contaminated with hazardous waste or pollution. Once any environmental damage has been remediated, the land can be reused. Redevelopment on brownfields provides an important opportunity to restore degraded urban land while promoting infill and reducing sprawl.
The floor area of the building divided by the total area of the site (square feet per acre).
The area on a project that is used by the building structure, defined by the perimeter of the building plan. Parking lots, landscapes and other non-building facilities are not included in the building footprint.
The amount of connection between a site and the surrounding community, measured by proximity of the site to homes, schools, parks, stores, restaurants, medical facilities and other services and amenities.
The total square footage of all building within a particular area, measured in square feet per acre or units per acre.
Diversity of Uses or Housing Types
The number of types of spaces or housing types per acre. A neighbourhood that includes a diversity of uses--offices, homes, schools, parks, stores--encourages walking and its residents and visitors are less dependent on personal vehicles. A diversity of housing types allows households of different types, sizes ages and incomes to live in the same neighbourhood.
Excavated areas that detain stormwater and slow runoff but are dry between rain events. Wet ponds serve a similar function but are designed to hold water all the time.
Land that is likely to be flooded by a storm of a given size (e.g., A 100-year storm).
The relationship between the total building floor area and the allowable land area the building can cover. In green building, the objective is to build up rather than out because a smaller footprint means less disruption of the existing or created landscape.
A measure of the amount of illumination falling on a surface. A footcandle is equal to one lumen per square foot. Minimizing the number of footcandles of site lighting helps reduce light pollution and protect dark skies and nocturnal animals.
Heat Island Effect
The absorption of heat by hardscapes, such as dark, nonreflective pavement and buildings and its radiation to surrounding areas. Particularly in urban areas, other sources may include vehicle exhaust, air-conditioners and street equipment; reduced airflow from tall buildings and narrow streets exacerbates the effect.
The resistance of a material to penetration by a liquid. The total imperviousness of a surface, such as paving, is expressed as a percentage of total land area that does not allow moisture penetration. Impervious surfaces prevent rainwater from infiltrating into the ground, thereby increasing runoff, reducing groundwater recharge and degrading surface water quality.
Native and Adapted Plants
Native plants occur naturally in a given location and ecosystem. Adapted plants are not native to a location but grow reliably with minimal attention from humans. Using native and adapted plants can reduce the amount of water required for irrigation as well as the need for pesticides or fertilizers and may provide benefits for local wildlife. Native plants are considered low maintenance and not invasive.
The percentage of the surface area of a paving material that is open and allows moisture to pass through the material and soak into the ground below
Previously undeveloped land with soil suitable for cultivation. Avoiding development on prime farmland helps protect agriculture lands, which are needed for food production.
A stormwater management feature consisting of an excavated depression and vegetation that collects and filters runoff and reduces peak discharge rates.
The amount of a site that is disturbed by construction activity. On undeveloped sites, limiting the amount and boundary of site disturbance can protect the surrounding habitat.
Solar Reflectance Index (SRI)
A measure of how well a material rejects solar heat; the index ranges from 0 (least reflective) to 100 (most reflective). Using "cooler" materials helps prevent the urban heat island effect (the absorption of heat by roofs and pavement and its radiation to the ambient air) and minimizes demand for cooling of nearby buildings.
Water from precipitation that flows over surfaces into sewer systems or receiving water bodies. All precipitation that leaves project site boundaries on the surface is considered stormwater runoff.
Street Grid Density
An indicator of neighborhood density, calculated as the number of centerline miles per square mile. Centerline miles are the length of a road down its center. A community with high street grid density and narrow, interconnected streets is more likely to be pedestrian friendly than one with a low street density and wide streets.
Transportation Demand Management
The process of reducing peak-period vehicle trips.
Vehicle Miles Traveled (VMT)
A measure of transportation demand that estimates the travel miles associated with a project, most often for single-passenger cars. LEED sometimes uses a complementary metric for alternative-mode miles (e.g., In high-occupancy autos).
Plants that require saturated soilds to survive or can tolerate prolonged wet soil conditions.
A landscaping method that makes routine irrigation unnecessary by using drought-adapatable and low-water plants, as well as soil amendments such as compost and mulches to reduce evaporation.