Underground Parking

You're on track to earn this credit via Option 2. However, the credit language states taht any roof used to cover parking should have an SRI value higher than 29, or be vegetated or covered in solar panels, and there is space on the LEED Online credit form to enter this information. But—it's marked "optional."If you're purusing SSc7.2, it seems like it would pretty much take care of the documentation needed here.I would suggest you contact USGBC via LEED Online to ask them to clarify what is required documentation in your case.

We have a project in San Francisco where all the parking is underground for the building. Is this acceptable to receive the credit under SS Option 2 Path 4 for Heat Island Effect-Non Roof?

Ron, Yes this approach should work, and their will be no minimum SRI requirement as long as any exposed parking surface area is 50% or less of the total parking surface area, which is usually the case for most underground parking. Also, if 100% of the parking is underground, this will earn the project an exemplary performance point as well.