Exemplary Siting -- Development Density Plus Design Intent: The intent of the proposed innovation in design credit is to utilize best practices in subterranean construction to achieve three measurable benefits: 1) greatly exceed the development density requirements (SSc2), (2) significantly reduce the building footprint (SSc5.2), and (3) reduce energy demand using ground cover. Design Approach: The project is a 13 level healthcare facility located in an urban setting in the northeastern United States. Three floors are below grade, and two of those levels extend under an adjacent street, where the new building will be connected to an existing hospital campus on the opposite side of the street. This unique stacking and extension arrangement results in a design that we believe represents exemplary siting, based on the following three design features: a. The property density of the project is 484,801 ft2/acre (436,321 ft2/ 0.9 acres). This is 8.1 times the minimum density requirement of 60,000 ft2/acre for SSc2 Development Density. b. The site plan drawings confirm a building footprint of 28,200 ft2. The footprint that extends under the adjacent street totals an additional 14,027 ft2. If the extension had been designed at grade, the building footprint would have been 42,227 ft2. Subterranean construction results in a net building footprint reduction of 33%, based only on the extended section under the adjacent street (not including the three basement levels). This design strategy meets and exceeds the modification to SSc5.2 listed under LEED 2.2. c. A third noteworthy feature of subterranean construction is energy savings. The ground cover on east and west faces provides thermal insulation from solar gain in the summer, plus reduced perimeter heat loss in the winter. A comparative analysis of expected energy use was made utilizing DOE2.1E. Calculating the thermal energy needs of the extension above and below grade, we estimate a 15% decrease in energy use due to the below grade portion under the street. Proposed submittals: (1) Development density calculations (2) Site plan with extension area marked with building footprint reduction and supporting calculations, (3) Summary of energy modeling calculations, comparing thermal energy impact of ground cover vs. above-grade construction. Does this strategy meet the requirements for an Innovation in Design credit?
The strategies described do not qualify for an Innovation credit for exemplary performance. They can already contribute to two existing LEED credits - SSc2, and SSc5.2 (in terms of open space). Unfortunately the energy savings are not credited within EAc1. However, based on evidence that higher density locations can achieve substantially and quantifiably higher environmental benefits, the following threshold requirements can be used to qualify a project for an exemplary performance Innovation Credit: A LEED-NC project must first meet either the requirements of SSc2 in LEED-NC v2.1 or Option 1 of SSc2 (density path) in LEED-NC v2.2. Additionally, the project must meet one of the two following requirements: a) The project itself must have a density of at least double that of the average density of the area within a 415\' radius of the project. OR b) The average density of the area within an 830\' radius of the project (twice as large as for the base credit achievement) must be at least 120,000 square feet per acre. These requirements are based on the decision that a project achieving exemplary performance for this credit (1) should not lower the existing average density of the area, (2) should achieve a density of at least twice the threshold of the base credit, and/or (3) should locate within an area of established density that is larger than that required for the base credit, which is why the radius used in the base credit has been doubled.