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Don’t Forget the Site in LEED Certification

You are considering making the commitment to make your next project a LEED certified project. What does it really mean for you, for the contractor and for the design team? Beyond the obvious, widely marketed bragging-rights, is a very stringent list of prerequisites that will have major impact on how your project is designed and developed.

Each site is very different with regard to location, size, access routes, construction material storage areas, and topography. All of these influence how the project will be developed. A recent project of Ecos’ that met the criteria for LEED certification is a good example of the unique characteristics that might exist on a site. The Klaus Advanced Computing Building, located in the heart of the Georgia Institute of Technology’s campus, was an extremely challenging site for both the designers and the general contractor to work with, due to the compact site envelope and extreme grade change. To further complicate matters, it involved working within an active college campus.

If you have the luxury of selecting your project site, the following LEED prerequisites will limit your search to sites that

• Are not considered prime farmland (as defined by the US Department of Agriculture).
• Have an elevation that is 5 feet above the 100-year FEMA flood limit.
• Have not been identified as a habitat for any species on Federal or State threatened or endangered lists.
• Are not within 100 feet of any water (including wetlands).
• Were not formerly public parkland.
• Are on or near public transportation.

The overall intent of these requirements is to discourage development of sites that will suffer undue environmental impact.

Once the site has been selected, the key to the next level of prerequisites is achieved through solid environmental and sustainable design principles. To achieve compliance with the reduced site disturbance credit, the overall project design must reflect the credit requirements in the concept stage, since an option of this credit requires 50% of the site to be restored as open space. Having spatial design requirements will certainly influence the approach used by the design team. The Klaus project used a multi-story approach, which included three levels of parking within the building’s footprint. This permitted the project to achieve the owner’s goals while providing the necessary open space to achieve 50% restored.

This same credit provides the compliance option of limiting the amount of site disturbance to 40 feet beyond the building perimeter, 5 feet beyond primary roadway curbs, walkways and main utility branch trenches and 25 feet beyond constructed areas with permeable surfaces. The pursuit of this option will significantly change the complexity of the construction for the general contractor. A general contractor’s LEED experience will be advantageous in providing clear insight into how best to stage the project—a critical element in limiting the amount of disturbance on the project site. For example, the extremely limited area of the Klaus project required the general contractor to use off-site locations for material storage and even employee parking.

As the design concept is further developed, the impact of the reduced site disturbance credit will continue to influence other design elements such as stormwater management. LEED provides an opportunity to achieve compliance through rate and quantity as well as treatment. Depending on the amount of existing imperviousness of the site, compliance could require as much as a 25% reduction in both the rate and quantity of stormwater runoff. The possible footprint for this amount of reduction could be significant, especially if the project is trying to limit the amount of site disturbance. Careful planning and design will be important to ensure compliance for each of the credits.

This creative design approach is reflected in the Klaus Building’s stormwater management system, which includes 170,000 gallons of below-grade cistern storage, skillfully integrated within the site, just adjacent to the building’s face, to limit the amount of site disturbance.

Additional levels of coordination with the general contractor were required since the same real estate needed to permit construction equipment, scaffolding, and utilities, needed to remain permeable for stormwater infiltration. The Klaus project achieved this balance through a multi-stage design approach that permitted the contractor to “back out” of the area.

Complex designs as well as high expectations for site construction techniques are only achievable through experience and good communications. Employing LEED-experienced design professionals, as well as general contractors, and initiating the dialog between the two groups during the design process can save the project not only money, but could ultimately be the critical step in achieving design elements as well as LEED credits.