An architecture firm and a developer have a solution to urban blight: build houses cheaply on vacant lots…and build them green.

Philadelphia is half empty.
Its streets resemble a checkerboard; each rowhouse accompanied by an empty lot next door. As Nic Darling, head of public relations and marketing at Postgreen, a newborn development company, says, it “looks like a boxer’s mouth.”
Since the 1960s, the population of this once bustling industrial hub has dropped 26 percent, from a peak of 2 million to less than 1.5 million today. The infrastructure and space could support many more residents.
Although Center City, Philadelphia’s downtown area, is undergoing a bit of a renaissance, half a century of economic decline has left 40,000 abandoned and derelict lots scattered around the various neighborhoods. Roughly 25,000 of these are entirely vacant, the highest per capita rate in the nation.
Those vacant lots attract illegal dumping and arson, as well as drug dealers and other criminals. That is a deadly combination for the nation’s fifth-largest city, as well as for other cities across the country, like Detroit and Cleveland, which are facing similar declines.  
Postgreen and Interface Studio Architects have a solution: build relatively inexpensive, high-quality green houses on those empty lots. And build them one house at a time. If construction costs can be kept under $100,000, then the houses can sell for around $200,000. Although that’s not cheap, it could be a crucial step in revitalizing downtown Philadelphia.

Watch our video interview with the four leading members of the 100K team.

Chad Ludeman, the founder of Postgreen, calls it the 100K House Project. He hopes that it will draw what he calls the “creative class” into the devastated New Kensington neighborhood, a 125-square-block area located northeast of downtown Philadelphia that contains over 1,100 vacant lots.

A 100K World
Just after he was elected in 2007, Mayor Michael Nutter declared in an interview with The Associated Press that Philadelphia was “a filthy mess,” noting all of the trash lying around on the streets. “You really want to say, ‘Yo, who you think’s going to pick that up?’ I mean, your mother’s not walking down the street here.”
The Project is not the first initiative in New Kensington to attempt to clean up the neighborhood one lot at a time.
And it probably won’t be the last.
What makes this plan innovative is the combination of five core elements in the 100K House Project: erasing urban blight, incorporating modern architecture into traditional communities, building green, making it all affordable and keeping within Philadelphia’s dominant architectural style.
Brian Phillips says that Philadelphians expect to live in single-family houses, unlike residents of many big cities. The traditional brick or brownstone rowhouse still dominates neighborhoods, and highrise glass and steel buildings are only now starting to appear.

See the before and after photographs of the (currently) vacant lot where the 100K house will be built in our interactive feature.

Building Green
“It’s an immodest, modest house,” Phillips declares. “And that’s something I get very excited about: modesty can be very cool and have a lot of curb-appeal.”
The boldness is not in the design or the architecture but in the development and marketing. As Phillips says, “it’s about repetition.” The idea is to produce a design that can be replicated easily and cheaply, spreading the availability of green housing with a collection of stock designs.
The Project will hopefully, in Phillips and Ludeman’s vision, become an eco-friendly version of Toll Brothers or Ryan Homes, two of the largest homebuilders in the country. Although there are only two houses slated for construction this September, Ludeman says that they have received requests from readers of their blog nationwide for their own 100k homes.
Buyers can purchase land close to downtown for as little as $20,000 to $30,000, choose a model from the 100K design selection and start building their own home. This marks a radical departure from the traditional suburban and single-family home model, in which developers leverage the economy of scale, buying large tracts of land and building numerous houses at the same time.

Take a visual tour through the 100K house in our slideshow of the current renderings.

The end result of the project will be cookie-cutter urban, LEED platinum-certified dwellings scattered throughout the city. The new homes will feature passive solar heating as well as hi-tech insulation and seals. To the extent possible, they also will be outfitted with recycled materials and equipped with Energy Star appliances, making each 100k house 2.5 times more energy efficient than the average American home.
Across the nation, prefab is emerging as the hot new way to build, and the 100K house can be built in about three months using what Ludeman calls a “hybrid prefab” process. Since the designs employ structurally insulated panels—component wall panels that come precut with windows and doors—even the building of the home will
be efficient.

Smaller is Better
“I think there’s a mentality in America that’s all about big. Big is impressive, and “I think there’s a mentality in America that’s all about big. Big is impressive, and big is better,” says Phillips. “The idea that small can have some real cache, I think, is exciting.”
According to a study (PDF) done by Susan Wachter at the Wharton School at the University of Pennsylvania, the average house sold in New Kensington between 1980 and 2003 weighed in at an average of 1,263 square feet.
The first 100K House that is breaking ground in September, in comparison, will be only 1,035 square feet, including two bedrooms and 1.5 baths, which Ludeman says will go for $215,000 on today’s market. Another model in development, called the 120K house, would be slightly larger and sell for $245,000.
With the average home in America running at over 2,300 square feet last year, the 100K house certainly is small.
But that, too, is part of the plan: the smaller the house, the less resources it will require for heating and cooling.
As Darling says, “we want people to be proud of the size of their house. When they’re comparing their house with somebody, they can look at one of these people living in a McMansion and say ‘my house can fit in your garage.’ And they can feel good about that.”

Green Pieces: Our interactive graphic shows you some of the eco-friendly features of the 100K house and how they each contribute to cutting its energy use drastically.