CHICAGO-O’Hare International Airport, one of the world’s busiest transit areas, is also the location for the largest green roof at a US airport. FedEx Corp. recently opened a new 175,000-square-foot package sorting center at the airport with a total green roof, the largest on a freestanding building in the Chicago area.

This is the company’s first green roof, though it plans more of the structures on at least three new buildings planned in Chicago. A FedEx spokeswoman tells GlobeSt.com that the sedum planting will reduce air pollution, storm water runoff and energy costs by 35% per year, or about $1.4 million, as the life of the roof will also double to 40 years. “We’re already seeing tremendous benefits from the roof,” she says. “The building wins because the roof is more durable, the company wins because of the lower heating bills and the environment wins because of the reduced water runoff and cleaner air.”

A joint venture of Power Construction Company LLC and Ujamaa Construction Inc. built the center. Intrinsic Landscaping Inc. created the roof for FedEx. The Sort Building includes 3.9 acres of pre-vegetated mat, over 2,200 cubic yards of media and 3 miles of edging. It is estimated to have a saturated weight of 4.3 million pounds as well as the ability to retain two million gallons of storm water annually.