Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.0

Inquiry

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?