More than 800 U.S. buildings certified as “sustainable” are at extreme risk of flooding — and may have to be abandoned as the planet continues to overheat. That’s because the U.S. Green Building Council — an influential nonprofit that works to make buildings more climate-friendly — has for years largely overlooked the impact of extreme weather. Its point-based Leadership in Energy and Environmental Design certification generally offers new building projects just four points out of a possible 110 for taking steps to protect projects from flooding. LEED certification is a big deal: It’s subsidized or required by more than 350 local and state governments as well as the General Services Administration, which manages the vast federal building stock.