LEED Looks Ahead With an Ambitious Overhaul

Rating system revamp provides more grounding in science and promotes those strategies with the greatest environmental benefit
This course is no longer active
[ Page 2 of 5 ]  previous page Page 1 Page 2 Page 3 Page 4 Page 5 next page
From Architectural Record
Joann Gonchar, AIA

 

The LEED point redistribution (below) is based on an inventory of 13 aftereffects of human activity (above)
weighted according to a tool developed by the National Institute for Standards and Technology.
Because of the emphasis placed on controlling carbon emissions in this analysis, energy credits
are the clear point winner in the reallocation effort.

 

The alignment of the individual rating systems, along with the new thresholds and the introduction of the 100-point scale, should simplify the documentation and certification process. In addition, they also help establish a framework that can accommodate more building types and market-specific requirements over time. However, the goals of the overhaul are more ambitious than streamlining and rationalizing the system. The larger aim was to provide incentives for project teams to deploy those strategies with the greatest potential for environmental or human-health-related benefit, with greenhouse-gas reduction at the top of the priority list. "LEED 2009 emphasizes the critical issues of energy, transportation, and water, and makes them the most important," says Rand Ekman, AIA, director of sustainability at OWP/P, Chicago.

This prioritization is achieved by redistributing points among the various LEED credits to emphasize some over others. To formulate this reallocation, USGBC staff, committees, and consultants started with an inventory of 13 aftereffects of human activity created by the U.S. Environmental Protection Agency (EPA) and known as "TRACI." Short for "Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts," TRACI includes categories such as fossil-fuel use, ozone depletion, and global warming.

Next in the reallocation process was prioritization of the TRACI categories. To assign a relative importance to each, the LEED 2009 team relied on a tool developed by the National Institute for Standards and Technology (NIST). Ultimately, the council created a matrix that established the relationship between existing LEED credits and the TRACI categories. The matrix served as the basis of a spreadsheet for calculating the number of points each credit is worth.

Energy and transportation credits came out as big point winners in this analysis, primarily because of the importance assigned to controlling carbon emissions. For example, strategies intended to increase energy efficiency and the reliance on renewable power generated on-site can earn projects up to 26 points, versus 13 when compared to the previous LEED for New Construction. A location close to public transportation, which also has the potential to reduce occupants' energy use, counts for six points, up from only one in the old system.

Some credits with a less direct link to slowing global warming also have heavier emphasis in LEED 2009. For example, ambitious water conservation goals can help garner as many as 10 points, double the number previously available.

The reallocation process also involved some value judgments along with the weighting exercise. Partly because of gaps in the data, strict application of the TRACI-NIST tool would have made some credits worth almost nothing, especially for the categories of indoor air quality and human health. But it was important to the LEED 2009 development team to retain the existing credits, even those associated with relatively small environmental benefit. So all are assigned at least one point in the new system. The approach keeps the structure of the rating system intact and should make it seem familiar to users accustomed to the preceding versions of LEED. "It is an elegant solution," says Scot Horst, the USGBC's senior vice president of LEED. "The scorecard doesn't look that different."

 

[ Page 2 of 5 ]  previous page Page 1 Page 2 Page 3 Page 4 Page 5 next page
Originally published in Architectural Record
Originally published in May 2009

Notice

Academies