by Tim Shinabarger

The Empire State Building made headlines recently for achieving LEED Gold certification following a major green retrofit project that will reduce the skyscraper's energy consumption by more than 38 percent. The building's electric chiller plant was rebuilt, electric meters were installed at the tenant level, and all 6,514 window units were removed, refurbished to improve their energy efficiency, and reinstalled.

Although its profile may be far lower — both physically and culturally — the Christman Building in Lansing, Michigan, also earned LEED certification at the Platinum level, for measures taken to improve the energy efficiency of the office building's operations. Here, too, the contributing measures included HVAC upgrades, tenant-level metering, and refurbished windows.

Both of these projects exemplify a fast-growing LEED rating system that underscores the critical importance of "greening" the buildings we already have: "LEED for Existing Buildings: Operations & Maintenance."

LEED-EB: O&M evaluates the sustainability of building performance and operations for buildings after they have been built and occupied. First launched by the U.S. Green Building Council in 2003 as a pilot program, LEED-EB complements other LEED rating systems that address the design and construction of new buildings and major renovations.

Although operational improvements might not seem as exciting as shiny new green buildings, LEED-EB is indeed gaining traction as measured by the increasing number of certifications, says Ashley Katz, communications manager for the USGBC.

In fact, in 2010 LEED-EB accounted for nearly half of the 519 million square feet (48.2 million square meters) of space that earned LEED certification (not including LEED for Homes or LEED for Neighborhood Development).

According to data from the USGBC, the number of LEED-EB certifications per year increased from 27 to 277 between 2007 and 2009. In 2011, more than 500 buildings have already been LEED-EB-certified by mid-October.*   >>>

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SUBSCRIPTION SAMPLE The Empire State Building recently received LEED-EB Gold certification after a major green retrofit. Photo: Jiuguang Wang SUBSCRIPTION SAMPLE Serious Windows handled an amazing performance upgrade of the Empire State Building's 6,514 windows — reusing the existing glass. Photo: Courtesy Empire State Building   Click on thumbnail images to view full-size pictures.