Chicago is taking going green in the workplace to a  new level and is now the national leader in office building energy efficiency, according to a recent study.

After placing second to San Francisco in 2016, Chicago claimed the top spot in the 2017 National Green Building Adoption Index. Chicago’s 66 percent green-certified office space—a 6.5 percent increase from last year—drove the city to the lead. The study ranked the nation’s 30 largest real estate markets by measuring the total Energy Star and/or LEED certified office space, which are the green building certifications by the U.S. Environmental Protection Agency and the U.S. Green Building Council respectively.

Chicago was followed by San Francisco, Atlanta, Houston and Minneapolis, according to the report.

“This study underscores the city’s commitment to building a 21st century economy and fostering opportunities to make sustainability part of the Chicago experience,” Mayor Rahm Emanuel said in a July 11 press release in response to the report. “Chicago is a global clean energy leader, and will continue to make strides in establishing new norms by powering our public buildings with renewable energy.”

The report partially attributes Chicago’s growth in green building growth to the city’s 2013 energy benchmarking ordinance. The law is designed to create energy and cost savings opportunities for businesses and residents by raising awareness of energy performance through data transparency. The ordinance obligates all Chicago municipal, commercial, institutional and residential buildings 50,000 square feet and larger to track whole-building energy use, report to the city annually and verify data accuracy every three years.

More than 900 million square feet in Chicago is covered by the ordinance, the second largest total space required to benchmark and publish energy scores in the nation, according to the report.

Tom Jacobs—principal of Krueck + Sexton Architects, a Chicago-based firm in Architects Advocate Action on Climate Change—said he was “positively surprised” to hear the city’s achievement.

“What we see happening is how the whole construction industry, as a community, is pulling in the same direction,” Jacobs said. “There is only so much [AAACC] can do as an advocacy group, but it’s incredibly encouraging how you can see the overall wave of building in more prudent ways has caught on and has momentum.”

AAACC is calling for a bipartisan Climate Solutions Caucus in the U.S. House of Representatives. An open letter to Congress supporting the initiative, which can be found on its website, has 48 representatives and more than 1,000 individual signatures.

Recalling a recent roundtable discussion organized by the U.S. Green Building Council June 19 in Chicago, Jacobs said leaders in development fields are enthusiastic to collaborate on climate change action.

Brian Imus, executive director of the U.S. Green Building Council Illinois’ chapter, said he was not surprised by the news, and the study reflects Chicago’s “robust community” and city officials who advocate for green buildings.

Emanuel signed an executive order formalizing Chicago’s commitment to adopt the Paris Climate Accord guidelines June 7 after President Donald Trump withdrew the U.S. from the 196-nation agreement. The goal is to reduce citywide greenhouse gas emission to the original commitment, 26–28 percent reduction from 2005 levels by 2025, made by former President Barack Obama’s administration.

Chicago, and 12 other cities, also posted research from the EPA Climate Change website June 11 after the Trump administration removed it from the federal website April 29.

Imus added that corporations based in Chicago also played a hand in the city’s success because they see the benefits in energy efficiency.

“Companies like United [Airlines], McDonald’s and Grainger have long wanted to have work environments that are healthy and good for the environment and save them money by being energy efficient,” Imus said.

Cynthia Klein-Banai, associate chancellor for sustainability at the University of Illinois at Chicago, said in a July 11 email that building owners more than likely recognize the cost-savings benefits in energy efficiency.

“Energy, regardless of the federal stance on climate action, costs money and reducing it is attractive to building owners,” Klein-Banai said. “Continuing to provide educational resources to building owners is a key way to encourage better building performance.”

While there has been great success with advancing green buildings in Chicago, Imus said the initiative has been primarily focused downtown. Encouraging surrounding neighborhoods and developers to push beyond the minimum requirements for green-building certification and education on how to make buildings more energy efficient should be the next step.

“A lot of building [owners] want to do the right thing, but they may lack the resources or the time to be able to do what it takes,” Imus said. “Connecting those buildings with the resources and the knowledge that can make it easier for them to take action is important.”

Despite the federal government exiting the Paris Climate Accord, Imus said it is “absolutely” possible to meet the standards the agreement set through policies like those in Chicago.

“The way we’re going to make progress on climate change is going to happen at the state and local level,” Imus said.