Philadelphia will join nine other major American cities in a coordinated effort to boost energy efficiency in large commercial buildings, Mayor Nutter announced today.

Details on how the efficiency gains would be achieved were slim -- first, a plan has to be developed -- but officials said that the potential exists for savings of $77 million in energy costs a year.  If that were to happen, it would be the equivalent of reducing the amount of climate change pollution generated by 23,000 households, they said.

"Improving energy performance in Philadelphia's buildings is not just good for the environment, it puts money back in the pockets of building owners, operators, and tenants – and ultimately back into the local economy," Nutter said in a press release about the announcement.

The national effort, dubbed the City Energy Project, is an initiative shepherded by the Natural Resources Defense Council and the Institute for Market Transformation.

The largest source of energy use and climate pollution in cities comes not from transportation, officials said, but from their stationary assets: Their buildings.

According to a Philadelphia analysis, buildings are responsible for 62 percent of the city's carbon emissions, more than either the transportation or industrial sectors. As much as 30 percent of the energy these buildings use, however, is wasted, the analysis found.

Atlanta, Boston, Chicago, Denver, Houston, Kansas City, Los Angeles, Orlando, and Salt Lake City also will be part of the project.

Funds are coming from Bloomberg Philanthropies, the Doris Duke Charitable Foundation, and The Kresge Foundation. The money will go toward helping each of the cities develop plans and policies to boost energy efficiency.

Philadelphia already has a building "benchmarking" program, where building owners measure and compare the energy performance of their buildings.  Think of it as miles per gallon in a car.

"By having more access to data, building owners and managers will be able to compare their building's performance with other like-sized and –aged buildings, and see how much they could be saving on energy costs," the city notes on the program website.

I was talking to a realty trust official about it not long ago, and he felt that energy efficient buildings will be more appealing to tenants, although they might cost more per square foot, too, at the outset. Consider a city block where all the big office buildings basically have the same amenities. "Yet, if I said to you, one building is a D, one is a C, one is a B, one is an A. Where would you rent?" he asked.

Laurie Kerr, Director of the City Energy Project at the Natural Resources Defense Council, said in the press release that the ten mayors "are showing there is the political will to put people to work to build a healthier, more prosperous future for America's cities. In the face of a changing climate and increasingly extreme weather, these city leaders know they cannot wait for the state or federal government to make them more resilient and sustainable – they are taking action now."

The skills and technology are there, said Cliff Majersik, Executive Director of the Institute for Market Transformation, also in the press release. "But we need a coordinated effort by major cities and the private sector to make it happen."