If you keep your budget tight, get the best equipment, and have a clear mental idea of what you want, you can find yourself a wonderful Philadelphia home. Chad’s wariness is twofold: It’s that of an entrepreneur anxious to keep hold of his end of the market in a neighborhood Postgreen has laid claim to, and that of a Philadelphian who values small, green homes within reach of the young professionals (like him) otherwise priced out of owning in Center City. Thanks in part to the Ludemans, East Kensington might be the next frontier in the sprucing up of Philadelphia—but as the early construction across the street suggests, not everyone thinks as they do.

“In this recession, I think we’ve learned that housing values have very little to do with housing,” Chad observes. And though new development across the street and speckled across the surrounding blocks may bode well for Postgreen’s fortunes, Chad sets higher store by a house’s Home Energy Rating System (HERS) rating than its resale value.

Though affordability and sustainability are Postgreen’s clear aims, the developers’ understanding of value extends beyond the property line. But to achieve what they imagine people like themselves want—small, sustainable houses for reasonable prices—Chad and Courtney first had to prove they could make one for themselves. By setting a tight budget, building only as much as they could afford, and making the house’s shape conform to the budget’s limitations (“The box comes first!” was both a rallying cry during the design phase and a fact of life during construction), Postgreen and Interface Studio Architects successfully built the first installment in what Interface principal Brian Phillips calls “a little design ghetto over here.”The Ludemans moved into their debut creation, the 100K House, in 2009, using it as both a domicile and a test case. The project comprises a pair of adjacent, two-story homes clad in durable HardiePanel vertical siding that announces them as defiantly modern. What’s not visible from the street, though, is the 100K House’s LEED Platinum certification—
or its 2010 LEED for Homes Project of the Year award from the U.S. Green Building Council.

The novelty, and the success, of the Ludemans’ two-unit building (the 100K House is just one of the houses; the adjacent 120K cost a bit more to build) is due to its small size and devotion to green building practices, but the real selling point is that their 1,296-square-foot residence came in at just $81 per square foot in construction costs. The “100K” moniker comes from the house’s hard materials and construction costs (they actually ran closer to $105,000: $45,000 in materials and $60,000 more in labor), though the remaining soft costs like permits and architect’s fees brought the small residence in for around $200,000. The lot cost a mere $37,500 per unit, with $3,000 more in closing fees. East Kensington’s cache of cheap, vacant lots, proximity to the hip Fishtown neighborhood, and nearby public transit make it an ideal laboratory for inexpensive urbanity.

Keeping costs down meant building in a rougher neighborhood as well as sticking to a limited palette of materials: The space is defined by exposed concrete and birch plywood, an Ikea kitchen, and the HardiePanel vertical exterior. “We had to hit the budget to prove that the concept could work,” says Phillips, noting that he treated his design process “more like industrial design than architecture.”

“As an architect you often collect information from your client and then imagine what kind of a house might meet those aspirations,” Phillips continues. “In this case we knew exactly what the aspirations were: $100 per square foot, LEED Silver [they hit Platinum as a “happy accident”], and a provocative design. Then we asked ourselves, Can a house really do that?”

Doing less also meant consuming less. The 100K House is close to 70 percent more energy efficient than the older properties next door, thanks to heavy-duty insulation, tight-fitting windows, and serious attention paid to the home’s R rating. It’s a common theme in Postgreen’s projects: The Skinny Project down the block has a HERS rating of 23—Chad claims it’s the lowest in the city for a residence—and the Passive Project a few streets down is built to Germany’s highly efficient Passive House standards.