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

The intent of this credit is to "Reduce heat islands to minimize impact on micro-climate and human and wildlife habitat." The requirements for the credit call for providing any combination of strategies for 50% of the site hardscape. Our project will implement the strategy of using paving materials with an SRI of at least 29. While some of the asphalt areas are shaded within 5 years of occupancy, our proposal aims to achieve the credit using only the SRI-compliant paving strategy. Our project is a major league ballpark in downtown Minneapolis, MN. The LEED project boundary includes the ballpark, the surrounding concrete plaza/walkway areas and an asphalt surface parking lot with shade vegetation and shade from overhead ramps. The total area of hardscaped parking lot, walkways and plaza is 337,456 SF. To comply with the credit requirements, a minimum of 50% or 168,728 SF must have an SRI of 29 or greater. A CIR dated 6/19/2008 for related credit SSc7.2 Heat Island Effect - Roof allowed the use of a weighted average formula where multiple roofing materials were used, such that the total roof area weighted average SRI exceeded the required SRI. Similarly, our project\'s concrete plaza combines standard gray concrete and multiple concrete paver colors into a pattern. While the majority of the pattern is a concrete color with an SRI of 52, a smaller portion of the pattern is a concrete color with an SRI of 12. The parking lot is asphalt pavement, some of which is shaded, but for the purpose of this calculation, we have considered all asphalt to have an SRI of 0. Using the formula for weighted average per the above CIR, we propose performing a similar calculation for each color of all site hardscape to arrive at a weighted average, as follows: [(Area of Asphalt *(SRI of Asphalt/Required SRI)) + (Area of Std. Concrete*(SRI of Std. Concrete/Required SRI) )+ (Area of Concrete Paver 1*(SRI of Concrete Paver 1/Required SRI)) + (Area of Concrete Paver 2*(SRI of Concrete Paver 2 /Required SRI)) + (Area of Concrete Paver 3*(SRI of Concrete Paver 3 /Required SRI))] >= .50 Site Hardscape Area So our calculation would be [(180,672*0/29) + (31,032*35/29) + (97,869*52/29) + (27,883*12/29) = 224,479 which exceeds the 168,728 SF (or 50%) total hardscape requirement. Will this formula be acceptable for SSc7.1 credit compliance?

The intent of this credit is to reduce heat islands to minimize impact on microclimate and human and wildlife habitat. To meet the requirements of this credit we plan to use light-colored/high-albedo materials for a minimum of 30% of the site\'s non-roof impervious surfaces. We have approximately 62,000 SF of white colored gravel driveways on the site, 80,000 SF of asphalt and 38,000 SF of concrete. We have received documentation from the American Concrete Pavement Association stating that new gray portland cement concrete has a reflectivity between 0.35 and 0.40, which meets the requirements of this credit. Aged gray portland cement has a reflectivity between 0.20 and 0.30. Will we be able to use the documentation from the American Concrete Pavement Association as a sufficient source to show compliance with this credit? Also, will we be able to use the reflectivity ranges for new gray portland cement to fulfill the requirements of this credit? We know that black asphalt will not meet the requirements of this credit. We are unable to obtain documentation from the company supplying the gravel on its reflectivity value. We have tried to borrow or purchase a spectrophotometer to measure the reflectivity of the rocks on our own, but have not found an affordable option. We have also tried to find a federal standard on the reflectivity values of different colors and have been unsuccessful. If the rocks are essentially white, will that be enough of an explanation to factor the rocks into the calculation to comply with the requirements for this credit?

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.