Green building might be little more than a fringe hippie idea if not for certification. The medals and honors now available through rating systems have enabled a good and altruistic effort to become a highly marketable quality. LEED – Leadership in Energy and Environmental Design – is now the most well-known and well-used certification system, claiming nearly 9 billion square feet of space participating in its various certification programs globally. But it’s not alone, and it’s not necessarily the greenest of the green. The relatively new Living Building Challenge has been steadily gathering fans in the green building community for tougher-than-LEED standards such as net-zero energy and net-zero water.