Understanding LEED Certification: Part I

A project’s location is the groundwork for sustainability, as it has a dramatic impact on the performance of a building over its lifetime, from the way people travel to and from the building to how it coexists with the local ecosystem.

In the LEED for Existing Buildings: Operations & Maintenance rating system, the Sustainable Sites category involves maintenance of a building’s site, including building landscape, hardscape (inanimate landscape elements, such as roadways, sidewalks, and stone walls), and building exterior management practices. The credits foster the creation of a sustainable site maintenance plan geared toward reducing environmental damage to the building site while also promoting sensitivity for flora, fauna, water, and air quality. To achieve these credits, companies must reduce energy use, harmful chemicals, water waste, air and light pollution, solid waste, and chemical runoff.

Environmentally focused site maintenance practices may also reduce site operation and maintenance costs.

Sustainable Sites Credit 1: LEED Certified Design and Construction (4 points)

Intent: To reward environmentally sensitive building design and construction, enabling high-performance building operations to be more easily achieved.

Requirements: This credit can be fulfilled if the project has already achieved certification through LEED for New Construction and Major Renovations or LEED for Schools. Projects certified under LEED for Core & Shell Development also must have at least 75 percent of the floor area certified under LEED for Commercial Interiors.

Potential Strategies: Projects that previously achieved LEED certification easily can earn this credit by meeting one of these criteria.

Sustainable Sites Credit 2: Building Exterior and Hardscape Management Plan –(1 point)

Intent: To encourage environmentally sensitive building exterior and hardscape management practices that provide a clean, well-maintained, and safe building exterior while supporting high-performance building operations.

Requirements: The project must employ a management plan addressing the following five operational elements: (1) maintenance equipment, (2) snow and ice removal, (3) cleaning of the building exterior, (4) cleaning of sidewalks, pavement, and other hardscape, and (5) paints and sealants used on the building exterior.

Potential Strategies:

1. Maintenance, landscaping, cleaning equipment: Minimize use of parking lot sweepers, mowers, pressure washers, and other equipment and plant vehicles that consume fossil fuels, or replace existing equipment with lower-impact alternatives, such as replacing gas-powered machinery with electric-powered equivalents.

2. Snow and ice removal: In cold climates, apply deicer to hardscapes before storms rather than use toxic chemicals to melt ice afterward.

3 and 4. Cleaning of the building exterior and hardscape: Maintain site appearance and safety by using biodegradable cleaning products that have lower environmental impacts on air, waterand ecosystems. Take care that chemicals do not run into the sewer system.

5. Paints and sealants used on the building exterior: Protect the health of workers and improve both outdoor and indoor air quality by using environmentally preferable paints with low volatile organic compound (VOC) emissions.

Sustainable Sites Credit 3: Integrated Pest Management, Erosion Control, and Landscape Management Plan (1 point)

Intent: To preserve ecological integrity, enhance natural diversity, and protect wildlife while supporting high-performance building operations and integration into the surrounding landscape.

Requirements: Sustainable Sites Credit 3 calls for an environmentally sensitive management plan addressing: (1) outdoor integrated pest management and (2) erosion and sedimentation control for ongoing landscape operations and future construction activity.

For building projects with landscaped areas, the site plan must also address the diversion of landscape waste from the waste stream and the reduction of chemical fertilizer.

Potential Strategies:

1. Exterior pest management: Use nontoxic and least toxic methods to keep the site’s animal and insect populations under control, such as by removing landscaping features that might harbor pests and managing pest attractants (such as trash receptacles).

2. Erosion and sedimentation control: Eliminate major causes of erosion related to landscape operations, including foot and vehicle traffic on unpaved slopes and runoff that exceeds vegetation’s holding power on slopes. Erosion related to construction activity is caused by site disturbance and can be counteracted using temporary seeding and mulching, among other techniques.

Sustainable Sites Credit 4: Alternative Commuting Transportation (3 to 15 points)

Intent: To reduce pollution and land development impacts from automobile use for commuting.

Requirements: Reduce the number of commuting round trips made by regular building occupants using single occupant, conventionally powered, and conventionally fueled vehicles. Points are earned based on the percentage reduction in conventional commuting trips, as compared to if all regular occupants were commuting alone in conventional automobiles.

Potential Strategies: For the purposes of this credit, alternative transportation includes telecommuting; compressed workweeks; mass transit; walking; bicycles; other human-power conveyances, carpools; and vanpools, and low-emitting, fuel-efficient, or alternative-fuel vehicles. Infrastructure needed to support these types of transportation includes secure bike storage and shower facilities, preferred parking spaces for carpool or fuel-efficient vehicles, and access to mass transit or alternative-fuel refueling stations.

Sustainable Sites Credit 5: Site Development – Protect or Restore Open Habitat  (1 point)

Intent: To conserve existing natural site areas and restore damaged site areas to provide habitat and promote biodiversity.

Requirements: Have in place native or adapted vegetation covering a minimum of 25 percent of the total site area (excluding the building footprint), or 5 percent of the total site area (including the building footprint), whichever is greater. Off-site areas that incorporate native or adapted plants also can contribute toward earning this credit. Every 2 square feet off-site can be counted as 1 sq. ft. on-site. Other ecologically appropriate features contributing to this credit are water bodies, exposed rock, and unvegetated ground.

Potential Strategies: Establishing new plants, eliminating or controlling invasive species, constructing habitats, and mitigating pollutants are all practices that contribute to this credit. Urban projects with few landscaping opportunities may consider installing a vegetated roof.

Sustainable Sites Credit 6: Stormwater Quantity Control (1 point)

Intent: To limit disruption of natural hydrology by reducing impervious cover, increasing on-site infiltration, reducing or eliminating pollution from stormwater runoff, and eliminating contaminants.

Requirements: Implement a stormwater management plan that infiltrates, collects, and reuses runoff or evapotranspirates runoff from at least 15 percent of the precipitation falling on the whole project.

Potential Strategies: The stormwater management plan may depend on project site conditions, as well as regional differences, and should deal with controlling as well as harvesting stormwater runoff. This can be accomplished by reducing the amount of impervious area and implementing a stormwater harvesting system, which should consider the following features: water budget, drawdown, drainage area, conveyance system, pretreatment, and pressurization.

Sustainable Sites Credit 7.1: Heat Island Reduction – Nonroof (1 point)

Intent: To reduce heat islands (thermal gradient differences between developed and undeveloped area) to minimize impacts on microclimates and human and wildlife habitats.

Requirements: Use any combination of the following five strategies over 50 percent of the site hardscape: (1) provide shade from existing tree canopy; (2) provide shade from structures covered by solar panels; (3) provide shade from architectural devices or structures with a solar reflectance index (SRI) of at least 29; (4) use hardscape materials with an SRI of at least 29, uses an open-grid pavement system.

A secondary option to fulfill Sustainable Sites Credit 7.1 is to place a minimum of 50 percent of parking spaces under cover, with a vegetated roof, solar panels, or shade/covering with an SRI of at least 29.

Potential Strategies: To mitigate heat island effect, use materials with higher solar reflectance properties. For example, replace dark paving materials with light-colored concretes, or apply light-colored coatings over existing surfaces. To employ shading strategies, use native or adapted trees, shrubs, or vines to provide the desired level of shading within five years of being planted. Utilize pervious surfaces and accommodate vegetation within open cells.

Sustainable Sites Credit 7.2: Heat Island Reduction – Roof (1 point)

Intent: To reduce heat islands to minimize impacts on microclimates and human and wildlife habitats.

Requirements: Three options may be employed to fulfill Sustainable Sites Credit 7.2: (1) use roofing materials with adequate SRI value on 75 percent of the roof surface; (2) install a vegetated surface covering at least 50 percent of the roof area; (3) install both high-albedo and vegetated roof surfaces that work in tandem.

Potential Strategies: Applying paints and coatings that meet the SRI threshold is one method of achieving this credit. Note that multiple testing methods are available for measuring emissivity and reflectivity, so special care should be taken when consulting the manufacturer’s literature and making calculations. Another option is to install a vegetated roof, some variations of which require significant plant care, while others are grass-based and require no maintenance.

Sustainable Sites Credit 8: Light Pollution Reduction (1 point)

Intent: To minimize light trespass from the building and site, reduce sky-glow to increase night sky access, improve nighttime visibility through glare reduction, and reduce development impact from lighting on nocturnal environments.

Requirements: Sustainable Sites Credit 8 deals with both interior and exterior lighting. For the interior requirement, a lighting control system must be implemented to ensure that nonemergency built-in luminaries are automatically turned off during after-hours. For the exterior requirement, there are three viable options: (1) for LEED certified projects, showing that Sustainable Sites Credit 8 was already earned is sufficient; (2) projects may partially or fully shield all exterior fixtures 50 watts and over to prevent emitting light to the night sky; (3) educing site lighting levels to applicable standards.

Potential Strategies: An interior lighting control system should eliminate direct lines of sight and feature automatic controls. Exterior lighting should maintain safe lighting levels, but avoid unnecessary lighting of architectural and landscape features to reduce night sky light pollution. Shielding fixtures to cast light down rather than up, as well as installing low-angle spotlights, are two examples.