Making LEED greener

The state of California faces a problem shared by many green builders. It is charged with constructing the greenest buildings possible to save energy and water, but it is struggling to determine which green features will generate the biggest reductions in cost. 

The state’s planners rely upon the world’s dominant green building rating system, the U.S. Green Building Council’s LEED certification, for guidance. LEED, however, doesn’t always determine which features create the biggest green benefits.

To determine which set of building features equal the lowest overall environmental impacts, the state worked with Scientific Certification Systems (SCS), a third party environmental certification body, to evaluate the potential impacts of its planned LEED-NC Gold-rated Inland Empire Transportation Management Center. The 50,000-square-foot building is owned by California’s Department of General Services and operated by Caltrans and the California Highway Patrol to manage area traffic.

SCS based its study on life cycle assessment (LCA), which accounts for the environmental impacts of a building over its entire lifetime. It quantifies environmental impacts of each phase of construction, from the extraction of natural resources through building usage and the eventual disposal of materials.

Builders can use the LCA framework to predict the performance of a building so its owners’ can ensure that a LEED-certified building actually results in the most resource and cost reductions. Once a building is occupied, data collected from occupants can be used to update the LCA and encourage occupants to play a role in reducing impacts over time.

The transportation center’s assessment relied upon the widely accepted ISO 14044 standard. It examined a full spectrum of environmental factors, including occupants’ commutes, energy use and deconstruction, in addition to the factors covered by LEED. Each factor has a distinct impact – greenhouse gas emissions, oceanic acidification and air quality, among others. SCS compared the environmental impacts of the planned LEED Gold building to criteria for the same building built to average specifications.

The state of California has seen some fascinating preliminary results. It is clear that the use phase of a building, which has been ignored by most green building standards, can be responsible for a disproportionately large share of environmental impacts. The study found that longer commutes could potentially outweigh the benefits of other green measures, like using sustainable materials. In other words, a truly green building should be located in a place that minimizes transportation distance. It also found that photovoltaic solar panels, if located on biologically sensitive land, could have a negative impact. The LEED criteria for low water usage can significantly reduce water use, according to the study.

To be fair, LEED-NC focuses on design and construction planning – it wasn’t intended to result in better environmental performance when considering all building and user factors over a building’s lifetime. But a life cycle approach can help green builders pick up where the USGBC left off and look at the building’s operation-related impacts.

LEED is in the middle of a public comment period for its next version, which awards points for tracking energy and water usage. Life cycle assessment could be used in future updates to take the next step in creating a more accurate, weighted scoring system that would optimize for actual building performance.

A common point brought up by LEED critics is that it awards equal credit for building features, like energy-efficient windows or landscaping that uses minimal water, that may have widely differing environmental impacts. This allows for tradeoffs that could result in less-green buildings scoring highly on the LEED scale.  For example, installing bicycle parking, showers and changing rooms earns one LEED credit each, which is the same amount earned for site selection. But what happens if you select a site that is virtually inaccessible for bicycles, like a highway patrol outpost? In this instance, the scoring system misses its goal.  If LCA were used to inform green builders, they would have access to data on the savings for each feature and award points accordingly. 

Results for the transportation center study will be presented in the first environmental building declaration, a report of the building’s environmental data based on the ISO 14040 series of standards for LCA, which provide guidance so assessments can be conducted consistently and reproducibly by different practitioners. Environmental building declarations would also allow the state to report the building’s performance over time.

While critics of LEED may be correct in pointing out some of its limitations, the rating system has been wildly successful in gaining widespread industry acceptance and recognition, as has shown willingness to evolve and improve over time.  As with other public standards, the LEED program will continue to mature as the building industry moves towards more sustainable practices. The green building industry can use LCA to refocus the popular LEED system to emphasize credits with the greatest impact reductions, and live up to its goal of creating truly green buildings.

Nick Kordesch is a Communications Associate and Keith Killpack is a Life Cycle Practitioner at Scientific Certification Systems.  Both authors hold Masters degrees in Environmental Science and Management from the University of California, Santa Barbara.