Buildings are the source of one half to three-quarters of greenhouse-gas emissions in most American cities. Los Angeles, Boston, Chicago, Houston, and six more large cities have joined forces to tackle the problem by targeting their biggest buildings. “The largest buildings tend to be 3 to 4 percent of the overall number of buildings but account for 40 to 50 percent of the square footage and energy consumption. You have this terrific opportunity to work with a handful of buildings and make a big dent,” says Laurie Kerr, director of the City Energy Project (CEP), which launched in late January.

CEP is, in many ways, an outgrowth of the Greener, Greater Buildings Plan, deployed under New York City’s former mayor Michael Bloomberg, which included a pioneering benchmarking program mandating annual energy and water-use reporting by nonresidential buildings larger than 50,000 square feet. Kerr, who helped write New York’s plan, says the data collected by the city since 2012 show that the least efficient big buildings use four to eight times as much energy as their most efficient counterparts, pointing to “a lot of low-hanging fruit” for boosting energy efficiency.

The CEP is a joint creation of the New York–based Natural Resources Defense Council, where Kerr works, and the Washington,
D.C.–based Institute for Market Transforma­tion, which has strong links to municipalities and real estate developers. Funding of $9
million over the next three years comes from Bloomberg’s personal foundation, Bloomberg Philanthropies, along with the Doris Duke Charitable Foundation and the Kresge Foundation.

The money will help the 10 cities in the program, cash-strapped after five years of recession, by provi­ding a CEP staffer, analytical tools to guide policy development, and networking for the city leaders. Each city is to craft its own tailored action plan this year. In L.A., for example, market-rate multifamily residential units are likely to be a focus since their efficiency investments to date lag behind those of commercial-property owners and affordable-housing managers, according to Ted Bardacke, L.A.’s deputy director of sustainability. Bardacke says CEP fits strategically with L.A.’s effort to phase out coal-fired power—40 percent of its electricity supply—by 2025.

One challenge for all of the CEP cities, says Bardacke, is the stubborn gap between energy-efficiency opportunities and financing. As
his boss Mayor Michael Garcetti told reporters during a CEP launch call last month: “The buildings and the
money are having a hard time connecting.”

Kerr says reporting programs akin to New York’s, already taking shape in CEP member cities Chicago, Boston, and Philadelphia, will help. The reporting is affordable for both cities and building owners, and shows the latter how much less energy they should be paying for. Bloomberg, meanwhile, is taking the energy-efficiency crusade to the world stage. In January, United Nations Secretary-General Ban Ki-moon appointed the former mayor and media tycoon to serve as his Special Envoy for Cities and Climate Change.

Side Note: NYC Data and New Buildings

The New York City energy data that is inspiring an energy efficiency crusade for existing buildings is also raising provocative questions about new building design, such as whether tall buildings are energy hogs.

Luke Leung, director of sustainable engineering services for Chicago-based Skidmore, Owings & Merrill, says that taller buildings are reporting more energy per square foot. Leung says engineering factors such as longer and faster elevator runs are probably at work, but he says differences in occupation may also play a role. Leung says outsized energy use is most pronounced for Manhattan’s tall buildings, where pricey floor space likely drives more dense occupation.

Oberlin College physics professor John Scofield, meanwhile, found that LEED certification had no statistically-significant impact on energy use. While LEED Gold buildings outperformed other NYC office buildings by 20 percent, LEED Silver and Certified buildings underperformed.

Laurie Kerr, director of the City Energy Project at the Natural Resources Defense Council, predicts that such data mining will increasingly guide design, especially as reported data expands to include building equipment. “It’s the beginning of a new field of inquiry,” says Kerr.