The 2009 version of LEED was crafted to increase the rating system's emphasis on a building's environmental, economic, and social impact. As Ted Smalley Bowen of the Architectural Record writes, the new version “consolidates the many LEED variants, such as the versions for new construction and commercial interiors, into a core set of requirements.” Smalley continues:
Other key changes include the addition of bonus points (eventually core points) for addressing regional environmental conditions, and a methodology for reallocating points within the scoring system to give greater weight to human health and the environment.
The new version also shifts the scale of credits to 100 points, up from the current 69, and places greater emphasis on limiting greenhouse gas emissions. An interesting exploration (and a slightly more critical and humorous one) of the changes can be found at the blog Real Life LEED.
The new release comes on the heels of a study by The American Institute of Architects (AIA) of the three green building rating systems, LEED, Green Globes, and SBTool 07, which asses how the programs “resonate in various dimensions with the goals of the AIA position statements on sustainability.” The statements, part of a larger AIA goal to achieve carbon neutrality in construction by 2030, can be found here.
The study seems to find LEED the most complete system, noting that Green Globes needed more “stringent and specific requirements in the areas of energy reduction and operational performance” since they have a direct relationship with carbon emissions. Similarly, the study looked for SBTool 07 to be more rigorous in their standards, preferring “‘required’ items vs. those that are simply ‘encouraged.’"