p77 BD&C userguide 2009
CASE 2. Previously Developed Areas or Graded Sites
"Projects earning SS Credit 2: Development Density and Community
Connectivity may include vegetated roof surface in this calculation"
does this mean that if I don't earn any points under SSc2, then I can't count intensive (and consisting of native/adaptive species) green roof areas towards calculated area? Why is this? What does it have to do with SSc2?
David Posada
Integrated Design & LEED SpecialistSERA Architects
LEEDuser Expert
1980 thumbs up
August 11, 2010 - 12:30 pm
This case evolved from dense urban projects with zero lot-line development (building footprint covering 100% of the site), where the only place for creating any sort of habitat was the roof. While intensive roofs tend to have lower species diversity than plantings at grade, this is still better than nothing.
On sites with lower density there would be areas outside of the building footprint with an opportunity to restore more habitat. This is seen as having potentially a greater ecological benefit than an intensive green roof - pervious soil for infiltration, possible connection to adjacent green space or vegetated corridors, and direct view & access by humans.
Achieving the SSc2 credit makes a simple and logical way to divide dense from less-dense sites.
Imagine a site with a one-story building covering 50% of the site, and the majority of the remaining site is covered by surface parking lot. Installing an intensive green roof on this building does have significant benefits, and thus contributes to earning credits SSc6.1, 6.2, and 7.2.
Should this project also earn SSc5 without creating any habitat at grade in a low density development? Should that credit be reserved for a project that makes the greater effort to reduce impervious areas and create viable habitat outside the building footprint?