CHICAGO—In June 2012, Mayor Rahm Emanuel unveiled his Retrofit Chicago's Commercial Buildings Initiative, a voluntary effort by tenants, managers and owners of major commercial buildings to reduce energy use by 20% within the next 5 years. Fifteen months later, some of the participants have begun to report results and draw lessons they hope will make Chicago the most sustainable city in the country.

“The long-term goal of this is to make Chicago number one,” Luke Leung said at this week's BUILDINGChicago and Greening the Heartland Conference. Leung is an architect with Skidmore, Owings & Merrill, LLP, located in the Railway Exchange Building at 224 S. Michigan, an 18-story class A office tower that is part of the initiative.

When the effort began, SOM and other architectural firms in 224 decided to take the lead and start examining how tenants in the building used energy and how they could work together to cut down use. A large proportion of the historic building, best known for its giant atrium, was occupied by architects like Leung, and they felt this deep level of expertise gave them a leg up in the initiative, which at first included a total of 14 buildings, aged 7 to 117 years old, with 14-million-square-feet. Eighteen more buildings joined this March, said Leung.