By Ashley Katz, Communications Coordinator, U.S. Green Building Council
With its introduction in 2000, the U.S. Green Building Council’s (USGBC) LEED Green Building Rating System helped to spark a revolution, articulating a new set of integrated, measurable goals that changed how the building industry approaches the design, construction and operation of our offices, schools, hospitals and homes. Over the past eight years, USGBC has moved LEED steadily forward, evolving the way building performance is measured and rated, and doing so against a backdrop of increasing urgency to find solutions to climate change and energy dependence.
Buildings are responsible for 39% of CO2 emissions in the U.S., which made the issue of dramatically improving building performance to the top of the USGBC agenda paramount in 2006. However, this wasn’t enough. USGBC decided that it was time to reframe the focus towards driving greater outcomes in total building performance while, at the same time, incorporating technical advancements such as bioregional credits that would enable LEED to continue to evolve as a better, more refined tool for green building.
In mid-May, the USGBC Board of Directors sent out for public comment a new version of the LEED rating system: LEED 2009. To date, more than 100,000 individuals have accessed the comment version of the rating system online. USBGC anticipates broad-based and rigorous participation in the public comment period.
The LEED Steering Committee, the elected volunteer leaders who steward the ongoing technical evolution of the rating system, have worked tirelessly for more than a year to advance both the structure and content of LEED.
“The work that has gone into LEED 2009 incorporates new science and reflects a new understanding of the priorities of our world,’ said Scot Horst, Chair of the LEED Steering Committee. “Countless days and nights of conversations are represented, thoughts and ideas that have been exchanged since the inception of LEED and the bold action steps around them.”
LEED 2009 includes four major areas of innovation: the alignment and harmonization of prerequisites and credits across all LEED rating systems for commercial buildings; new, transparent credit weightings based on environmental and human health impacts; a methodology for incorporating bioregionally-specific credits; and a 2-year development cycle.
Transparent Environmental/Human Impact Credit Weighting
The biggest proposed change to LEED is the re-weighting/point re-allocation of LEED credits. The process used to evaluate the environmental and human benefit of each LEED credit was complex due to the research and sophisticated analysis involved, but the general philosophy, explained below, is relatively straightforward.
The term ‘weightings,’ as it is used in LEED 2009, refers to the process of redistributing the available points in LEED so that a given credit’s point value more accurately reflects its potential to either mitigate the negative or promote positive environmental impacts of a building. Until now, the LEED Green Building Rating System has not used an overarching, consistent framework for allotting point values to credits. Though ample anecdotal explanation for those choices is available — i.e., consensus of a large pool of talented and experienced individuals in the buildings industry — LEED 2009 goes a step further by weighting LEED according to a logical, transparent framework that incorporates the best available science.
The explicit weightings in the revised LEED Rating System scorecards represent the culmination of a weightings exercise that utilized two existing tools, including the TRACI tool from the U.S. Environmental Protection Agency (EPA), modified for application to buildings by USGBC in conjunction with exhaustive research, policy guidance from the LEED Steering Committee and a new tool developed to synthesize large quantities of relevant information.
Regionalization
The ability to recognize regional environmental priorities in LEED has been and remains a clear priority of LEED users. In response, the LEED Steering Committee created a structure that allows for regional innovation credits in LEED.
As a first step, incentives will be provided through LEED Innovation & Design (ID)-modeled points that will add value to those credits that are considered to be the most important for defined regions. These points will be counted in the same way as LEED ID points and are not included in the certification threshold calculations (ID and regional points count towards a project’s certification tally but they are not ‘base’ points on which Certified, Silver, Gold and Platinum thresholds are established).
Project teams may select bonus points from a list of eligible credits based on the project’s location. The LEED Steering Committee is currently collaborating with USGBC Regional Councils and Chapters to create the list of eligible credits. As defined by these Regional Councils and Chapters, select credits from the available list will be eligible for bonus points in appropriate sub-regions.
LEED Prerequisite/Credit Alignment and Harmonization
In an effort to synchronize the development and deployment of LEED rating systems while creating capacity to respond to previously underserved markets, the LEED Steering Committee undertook a reorganization of the existing LEED Rating Systems. The resultant prerequisite/credit structure is a consolidation, alignment and update of all existing LEED Rating Systems into their “most effective common denominator’. Prerequisite/credit alignment across applicable rating systems now provides a pool of prerequisites/credits for all LEED Rating Systems, and multiple versions of prerequisites/credits have been retained where different approaches were needed to address differing market situations. In some instances, the threshold of performance required by a credit was raised. In addition, a “scrub’ of the existing Credit Interpretation Rulings (CIRs) was conducted and necessary precedent-setting and clarifying language was incorporated into the prerequisites/credits.
Predictable Development Cycle
LEED alignment provides a continuous improvement structure that will enable USGBC to advance LEED on a regular schedule so that LEED users can predict when USGBC will be raising the bar. Using a cycle that is principally based on the familiar method by which building codes are developed, LEED will evolve on a set time. It’s important to hold in mind, however, that LEED is not a building code, and as such, policy mechanisms will be retained to allow for LEED to react to the rapidly changing green building industry. These mechanisms for nimbly incorporating important new ideas into the rating system include, but not limited to, administrative credit interpretations and the establishment of performance/intent equivalent alternative compliance paths to existing LEED prerequisites/credits.
Exemplary Performance
Currently in LEED, projects can earn up to four points for exemplary performance under ID credit 1: Innovation in Design. Exemplary Performance points are granted to projects that can demonstrate a doubling and/or attainment of the next incremental percentage threshold beyond the requirements of a LEED credit. Credit can also be earned under IDc1 for employing innovative strategies in building design, construction or operation. In an effort to encourage more innovation in LEED projects, the LEED Steering Committee voted to grant a maximum of three points for exemplary performance. This step was taken in order to return to the original intent of the credit, to encourage projects to pursue innovation in green building.
Specifics about the LEED changes will be forthcoming over the next few months, which will include the fruition of an initiative to integrate LCA (Life Cycle Assessment) into LEED credits. Official announcements will take place this November in Boston at the Greenbuild Conference & Expo on November 17-19, 2008. For more information on the next version of the LEED certification system: http://www.usgbc.org/DisplayPage.aspx?CMSPageID=1849
