Anyone who has spent even an hour or so thinking about sustainability has heard of LEED building certification and other green building standards. These are building systems that are meant to significantly decrease the amount of energy a building consumes while also making the building more accommodating for its inhabitants. But do these systems really work? Here are a few opposing views on the effectiveness of the LEED system. First, we have a LEED critic, Henry Gifford recorded at the Westford Symposium on Building Science. Gifford maintains that LEED is skewing its data and misrepresenting the effectiveness of its system. Instead of saving 30% on energy in a typical LEED building, Gifford maintains LEED buildings underperform by 30%. Harsh criticism, but is he correct? The second video advocates LEED.