What Is LEED? – Sustainable Sites
This is the second post in a series on the LEED green building rating system. The first post provided an introduction to LEED.
The first category of LEED prerequisites and credits has to do with the location and piece of land the project is built on. LEED Sustainable Sites credits deal with protecting natural habitat, keeping open spaces, dealing with rainwater, and heat island and light pollution reduction.
Construction Activity Pollution Prevention
This measure is required for LEED certification. It involves executing specific measures designed to limit the effect of construction activities on the surrounding environment, by containing soil erosion, sedimentation of water ways, and airborne dust. A plan must be developed that meets the requirements of the EPA 2012 Construction General Permit or local requirements, whichever is more stringent. This plan must be in effect throughout the project, with photo and inspection evidence to show that the plan was maintained.
This credit is worth 1 point. In order to earn this credit, project teams must perform and document a site assessment of the project location, including the following topics: topography, hydrology, climate, vegetation, soils, human use, and human health effects. The assessment should discuss how the topics above influence the design, as well as any of the topics that were not addressed in the design.
Protect or Restore Habitat
This credit is worth 1-2 points. The project must preserve and protect at least 40% of the greenfield (undeveloped) area on the project site, if such an area exists. In addition, the project must restore 30% of the site to natural habitat using native and adapted plant species (worth 2 credits), or provide financial support to an organization accredited by the Land Trust Alliance (worth 1 credit). The habitat restoration should include both soil and vegetation, and vegetated roofs can be counted in certain circumstances.
This credit is worth 1 point. The project must provide open space equal to 30% of the total site area. At least 25% of that open space must be vegetated or have overhead vegetation. Turf grass areas do not count as vegetated areas. Open spaces must be designed for one or more of the following uses: social gathering, gardening, physical activity, or natural habitat that includes elements for human interaction. Vegetated roofs can be counted in certain circumstances.
This credit is worth 1-3 points. This credit asks the project team to design a rainwater management system that handles the water falling on the site in a way that is similar to the native state of the site. Depending on how much water the system is capable of handling, 1-3 points are possible. The capacity of the system is measured by what percentage of local or regional rain events could be handled by the system. If the system can handle 95% of the events, then it can earn 2 points, and 3 points for handling 98%. Or, as an alternate way of calculating the credit, if the system can handle 100% of the increase in runoff that occurs as the result of the development of the site from its natural state, then the project can earn 3 points.
Heat Island Reduction
This credit is worth 1-2 points. Heat islands occur in areas where hardscape surfaces (such as parking lots and sidewalks) hold heat and reflect it back, raising the temperature of the surrounding environment. This change in temperature can affect weather patterns in the local area. To avoid this, projects receive credit for using roofing materials with a high solar reflectance, reducing the amount of hard surfaces, shading project areas with trees and other foliage, placing parking lots under cover, and using open paver systems.
This credit is worth 1 point. Projects must reduce the amount of up-lighting used for exterior lighting, avoid pollution of light into adjoining sites, and control light levels outside the building to meet certain standards. This requires a photometric plan, which shows the level of light in all areas of the site. The design team must take measurements to confirm that the built condition meets the requirements for this credit.
The next post in this series will provide an overview of the prerequisites and credits available under the Location and Transportation category.