Our question refers to the method of calculation for compliance with Credit SSc5.1- Protect or Restore Habitat of LEED NC 2.2; particularly how to calculate total applicable site area when including a vegetated roof surface. Credit requirements state that on previously developed sites, a project must restore a minimum of 50% of the site area (excluding building footprint) with native or adapted vegetation. It also states that projects in dense urban areas (earning SSc2) may apply vegetated roof surface to this calculation if the plants meet the definition of native/adapted. Our project site, located in Manhattan, New York, is 80,332 square feet and includes a building footprint of 48,090 square feet, leaving an applicable site area of 32,242 square feet excluding building footprint. The project has 16,447 square feet of vegetated roof and 4,000 square feet of plaza planters, all with native/adapted plantings. This totals 20,447 square feet of native/adaptive vegetation within the 32,242 square foot site (excluding building footprint), and restores 63% of the habitat. Please confirm that this calculation methodology is acceptable.
Your inquiry uncovers an omission in the credit requirements regarding the green roof option. This ruling provides clarification regarding credit calculation to address your project as well as those with little or no building setback (i.e. zero-lot-line). When including a green roof in the calculations for this credit, the requirement is 20% of the TOTAL site area (including building footprint). As a result, calculations will have the total native/adapted vegetated area in the numerator and the total project site area in the denominator. In your case, this would be 20,447 sq.ft. / 80,332 sq.ft. = 25%. Applicable Internationally.