Changing Skyline: An energy-saving milestone planned for Philadelphia's Kelly Drive

A building that runs on half the usual amount of energy? How ho-hum. These days, most new construction in Philadelphia can do that without even trying, simply by adhering to the U.S. Green Building Council's basic LEED standards. What would be really interesting is if someone put up a major building that consumed no energy at all.

Hold onto your electric bills, folks, because the first net-zero apartment house in the United States is coming to a most unlikely spot: a forlorn lot on Kelly Drive in East Falls that has languished for more than a decade. Equally astonishing is that it's being built by a first-rate local design firm, Onion Flats, under the auspices of that most ossified of city agencies, the Philadelphia Redevelopment Authority.

Just 30 American projects have been certified so far by the Passive House Institute, the organization that sets U.S. standards for net-zero buildings - and all but four are single-family homes. To qualify as passive, a building must produce nearly as much energy as it draws from the power grid, relying on a mix of technology that includes solar panels, heat exchangers, and extreme levels of insulation.

The result is net-zero or, more accurately, near-zero consumption. In passive-energy circles, the joke is that you should be able to heat your house with a hair dryer.

It's one thing for a custom-designed private house with a generous budget to accomplish that feat, but not so easy to get the same result with an exponentially larger, profit-driven, multifamily project. Onion Flats' seductive design, which revolves around a lush interior courtyard, promises 130 apartments, a cafe, shops, a covered garage - but no heating furnace. No one in the United States has attempted a passive-energy project this big, although several have been completed in Europe.

"We understand this is not without risk," concedes Ed Covington, who took over the Redevelopment Authority in 2010 with the aim of energizing the city's plodding land bank. He hopes the ambitious project, called Ridge Flats, will work on the agency like a can of Red Bull.