More than a year after the Trump Administration withdrew from the Paris climate agreement, cities and states are continuing efforts to meet U.S. climate goals to reduce carbon emissions 26% by 2025. In a recent move, the U.S. Conference of Mayors unanimously approved a resolution during its annual meeting in support of the latest International Energy Conservation Code.

“The U.S. Conference of Mayors recognizes the unique opportunity for cities to work together [to] meet the lion’s share of Paris Accord targets,” it says. This month, a new report will quantify how much impact such measures are having. The analysis, from the group America’s Pledge—led by California Gov. Jerry Brown (D) and former New York City mayor Michael Bloomberg (R)—is set to be released at the Sept. 12-14 Global Climate Action Summit in San Francisco.

The report, a “bottom-up climate action quantitative analysis,” will examine reductions achieved outside of federal action. Among other things, the report will focus on building energy efficiency and the impact of building retrofits.

Commercial and residential buildings currently account for 28% of U.S. emissions, according to the group. “States control many of the most powerful climate policy levers, from renewable portfolio standards to air pollution regulations,” according to America’s Pledge.

To reduce emissions, cities are first tackling energy usage. The latest version of the International Energy Conservation Code (IECC), adopted by the mayors in June, largely maintains similar efficiency standards as the previous code, according to the Natural Resources Defense Council. Still, overall, the IECC has cut CO2 emissions by 36 million metric tons and cut costs by $44 billion over its 20-year existence, according to the Energy Dept. The code is expected to reduce CO2 emissions by 841 million metric tons from 2010 through 2040.

So far, the only jurisdiction that has adopted the 2018 code update is the U.S. Virgin Islands.

Cities may choose to stick with the earlier versions of the code. Zach Baumer, climate program manager for Austin, Texas, says the city uses the 2015 IECC with amendments that make it tougher. “I think a lot of the focus has been on the new code because we have so many new buildings, there’s so much growth and construction happening in our city,” he says.

But cities are using other tools as well to tackle emissions, with a focus on buildings. “If you break down the way we look at reducing carbon emissions, we’re going to look at the biggest chunk first, and about 70-72% of our emissions come from buildings,” says Sandra Henry, Chicago’s chief sustainability officer.

Next year, Chicago will expand on a 2014 benchmarking ordinance with a ratings system for buildings. Each building will be assigned an energy performance rating that will be shared when a building is sold or leased, says Amy Jewel, senior city advisor, City Energy Project. A similar program will launch in New York City in 2020. 

For cities that set benchmarks or track consumption, “we’ve seen a trend of year-over-year reductions in energy use from 1% to 3% and often even more for carbon emissions,” says Kimi Narita, acting director, City Energy Project at NRDC.

Chicago has taken on retrofits as well, and its voluntary Retrofit Chicago program has 89 participating properties covering more than 56 million sq ft. The program and benchmarking projects together have produced a 1-2% average annual reduction in energy consumption, and the city has reduced emissions in the buildings sector by 17%.