Post Occupancy Results of LEED Buildings in Illinois

Illinois has been an early leader in green building construction, currently ranking sixth in the number of Leadership in Energy and Environmental Design (LEED) buildings built, with the City of Chicago itself having more LEED® certified buildings than any other city in the country. This leadership continues with release of a report from the U.S. Green Building Council – Chicago Chapter (USGBC – Chicago) that provides a first look at post-occupancy performance of LEED buildings on a local scale.

The Regional Green Building Case Study Project: a Post-Occupancy Study of LEED Projects in Illinois report summarizes the first year of a multi-year study to analyze the post-occupancy benefits of 25 LEED certified projects in Illinois related to: energy use, greenhouse gas emissions, water use, construction and operating costs, cost of building green, health and productivity impacts, and occupant comfort. The study was funded by the Grand Victoria Foundation and is a collaborative endeavor between the USGBC-Chicago, U.S. EPA Region 5, the City of Chicago, Delta Institute, and the Center for Neighborhood Technology, which was the lead researcher for the project.

The study found that sustainability does not stop with building design and construction. While a building may be designed to be sustainable, it is often ongoing operational issues that affect the amount of energy, water, and other resources it consumes. Accordingly, ongoing performance evaluation is a key component of long-term sustainability.

“Sustainability must be integrated into ongoing operations and maintenance practices,” says Kathy Tholin, CEO of the Center for Neighborhood Technology, whose Chicago LEED Platinum building was a part of the study. “Constructing to LEED Platinum was a natural choice, given CNT’s long standing commitment to sustainable development,” explains Tholin. “But our job is far from complete. Now that we’re utilizing the space, sustainability means focusing on ongoing operations and maintenance. We’re striving for continuous improvement.”

The USGBC’s LEED Green Building Rating System is the nationally accepted benchmark for the design, construction, and operation of high performance green buildings. LEED provides a roadmap for measuring and documenting success for every building type and phase of a building life cycle.

Doug Widener, executive director of the USGBC-Chicago Chapter emphasizes that “with an understanding of operational issues, tenant behavior, and maintenance practices, building owners and managers can implement ongoing changes that lead to increased building performance and sustainability over time.” Widener adds that “this report is an important step towards achieving our mission of leading the regional transformation of the built environment to become ecologically sustainable, profitable, and healthy.”

The report compliments the USGBC’s recently launched Building Performance Initiative. Beginning this fall, it has analyzed energy and other resource use data from LEED buildings and will provide this data back to building owners to allow for ongoing sustainability improvements over time.

The study also found that resource use varies in LEED buildings. Many participating projects performed better than conventional commercial interiors and buildings, with projects that focused on energy conservation as a part of their LEED strategy performing better in relation to energy use and conservation than projects that focused on other areas of sustainability. Given that LEED is a multifaceted system that rates a building’s sustainability on a variety of factors (including site, water efficiency, energy efficiency, materials and resources, and indoor environmental quality), projects that focused on energy conservation performed better in this area than projects that did not.

All buildings in the first year of the study were certified under older versions of LEED. Newer versions of the rating system mandate, as well as incent, higher levels of energy efficiency.

The results of occupant comfort in surveyed projects were very high, especially related to indoor air quality and lighting. The study also found that construction costs varied greatly, as do construction costs of conventional buildings, and that these are largely driven by programmatic issues. The average premium reported for building green was 3.8%; in line with the national average.

For the second year of the study, 25 additional Illinois LEED projects will be added to its sample for a total of 50. “We are excited by this initial year of the study, but are even more excited for the second year when we will add buildings certified under newer versions of LEED to see if these newer LEED buildings perform better,” notes Widener. “We are also collecting a second year of data for our first year projects. It will be interesting to see if operational changes made as a result of the study will result in improved efficiencies in these buildings.”

For the full report, send an e-mail to with the words “Illinois LEED Report” in the subject line of your e-mail.

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