NC-2009 SSc7.1: Heat island effect - nonroof 1 point

The project building maintains 100% of its parking spaces under cover through the use of a multi-level underground parking garage located partially beneath the building and partially beneath the property\'s landscaping and hardscape. In the spirit of SS 7.1, the developer\'s decision to locate 100% of the building\'s parking below grade has resulted in a reduced heat island effect by allowing for surface vegetation where the presence of an above ground garage would have otherwise prohibited vegetation. While it is clear that an uncovered multi-level garage located above ground would have qualified for 1 point under SS 7.1, it is not clear if an underground multi-level garage would qualify for 1 point under SS 7.1 given that it is partially covered by a building with an unknown SRI value. Given that the intent of this point is related to "non-roof" surfaces, is the building required to document SRI criteria for the roof of a building that covers an underground parking garage or is the point otherwise earned automatically since 100% of the parking is located in a multi-level underground garage? Please clarify the intent and required submittals for scenarios involving a multi-level underground parking garage.

This CIR seeks clarification on whether a stabilized grass parking system can be counted in OPTION 1 calculations as open grid pavement. Our project is a cultural institution that receives a surge in visitors during the summer months. The stabilized grass system is proposed for the site\'s overflow parking areas that are required to meet the peak season parking demand. By using this system rather than other types of paving, these areas will be preserved as an open meadow during the remaining 9 months of the year. Town officials have approved the system; as a result we have been able to reduce the amount of paving required for parking by 44%. Designed to hold vehicular traffic while allowing for infiltration, this stabilized grass profile promotes healthy vegetation and prevents soil compaction. The structural base for this system is made up of a twenty inch profile consisting of twelve inches of crushed stone over eight inches of compacted sand and gravel. The strength of the profile arises from the stone on stone contact. The large pore spaces between the stones hold soil to support turf and meadow grasses. Over the crushed stone layer, a two inch veneer of planting soil provides the horticultural medium within which to grow grass. The planting soil is a sandy loam which water percolates through quickly. The water then moves through the crushed stone layer, through the sand and gravel layer, and finally to the subgrade. This system percolates more quickly than the native soils on the site. The stabilized grass parking system has a better hydraulic conductivity and therefore better infiltration rate than open grid paving. We have compared our system to Escofet Checkerblock, which is 77% open. The hydraulic conductivity of the stabilized grass system is 3"/hour. For the Checkerblock, the hydraulic conductivity of the turf soil is 1.5"/hour multiplied by the fraction of the checkerblock that is pervious (77%), the resultant rate for Escofet Checkerblock paving is 1.15"/hour. The hydraulic conductivity of the stabilized grass system will be guaranteed through conformance to the specification which reads, "The final mix shall have a hydraulic conductivity of not less that 3 inches per hour when compacted to a minimum of 94 percent Standard Proctor. Tests shall be by combined hydrometer and wet sieving in compliance with ASTM D422 after destruction of organic matter by ignition." The surface of the stabilized grass parking areas will be 100% vegetated rather than the 50% required for open grid pavement. This system was developed by the project\'s soil scientist and landscape architect. An installation using the same detail, soil profile, and soil blend was installed on an adjacent site and has been proven successful.

We are defining our LEED project as the building plus approximately 26% of a parking deck (and of the landscaped area around it), with the parking deck located in a block diagonally across from the building. We are operationally allocating to the project 407 out of 1550 parking spaces (26.3%), in the 7-level parking deck with 484,500 sq. ft. total. We are planning for the top deck of the parking deck to be a light-colored/ high-albedo site surface (probably regular concrete with a solar reflectance of 0.30, avoiding the darkening fly-ash content for the top floor). Allocating 26.3% of the 69,220 sq. ft. top level, the resulting area - 18,205 sq. ft. - is greater than 30% of the combined area of this plus the other hard site surfaces in the city block of our building. Thus, we exceed the requirement of providing light-colored/ high-albedo material for 30% of the sit? s non-roof impervious surfaces simply with our top parking level. Please confirm that the USGBC agrees with our interpretation. (We may still want to pursue SS Credit 5.1 without being penalized by having to apply the top deck toward the site areas of the main city block, 50% of which we may want to restore to habitat areas. Is this a separate question? SS Credit 7.1 is more important to us.)Also, it is not clear to us if the 50% underground parking option would also apply, as most of the parking is in covered levels in the parking deck; or does the parking deck indeed need to be "underground"? - Further, are the covered levels of the parking deck a non-roof impervious shaded area, qualifying the project for yet another option of meeting the credit requirements? If at all possible, for our education, please address all three options of qualifying for this credit - could we qualify under any of the options? Which one is the best to prove? Should future credit requirements address parking decks?

The intent of this credit is to reduce the heat island effect created by large expanses of pavement. For a building to earn option B of the credit, they must provide shade for at least 50% of the provided parking. This can be underground, under a deck, under a roof, or under the building itself. In addition, a building that provides 100% of its parking under cover is eligible to earn an exemplary performance point. One of our project buildings is located in downtown San Francisco and does not provide any parking for building tenants. We believe that this fulfills the intent of the credit because there are no paved parking areas whatsoever that would contribute to the heat island effect. The net heat island effect is the same as a building that provides 100% of parking underground. However, the building that does not have parking at all gets 0 points where as a building that provides 100% parking underground gets 2 points. An existing building that was designed many years ago to reduce heat island effect should still be rewarded under a rating system that was incepted later on. We would like to petition the USGBC to consider awarding 1 point under Option B to projects that have no parking provided.

Many of the ASTM Standards we reference have been withdrawn, upgraded, or superseded. Provide guidance on which updated standards should be used.

Can sidewalks, roads, and other hardscape areas located above a project building\'s underground parking structure, which are required by the governing municipality to be constructed of non-compliant materials, be excluded from the SSc7.2 and SSc7.1 calculations?

Can this credit point be achieved under the following pavement system scenario. We propose to use a tan-colored clay, open-grid pavement system filled with limestone gravel for the entire driveway and parking lot for our office building consisting of 90% of the site\'s hardscape surfaces (non-roof). You require "an open grid pavement system that is at least 50% pervious". This percentage drastically limits the pavement system choice to a plastic "egg carton-type", thin walled paving system. We have the "egg carton" system in several locations and they do not work for us because the constant traffic compacts the soil so grass will not grow resulting in bare dirt and increased runoff. (Defeating the purpose of using them.) This type of paver also presents a maintenance problem in the winter because they cannot be plowed. The thin-walled pavement systems are designed for occasional, light-duty use, not daily traffic. We are proposing the use of a clay paver for it\'s durability, ease of maintenance, and ability to have it produced in a light color which can meet the SRI requirements. The open grid in this type pavers can achieve 36% pervious openings. You define the open-grid pavement as ".pavement that contains vegetation in the open cells". In our experience, any open-grid pavement systems, even concrete cells, that have day to day traffic will not support vegetation due to soil compaction. This is why we propose that the grid be filled with gravel. This method will also allow evaporation as desired by this credit as well as infiltration and ground water recharge. The use of this system has allowed us to design the site without use of an underground storm sewer system and to infiltrate all site storm water. Philosophically we are suggesting a more sustainable method pavement system. The majority of the "egg carton-type" pavers are made of virgin plastics, require more energy to produce, and can not be recycled in this area. The clay pavers are made from a natural material and are chemically inert which allow it to be crushed and recycled as aggregate. To us this is a more sustainable choice.