In the East Falls neighborhood of Philadelphia is the largest net-zero-capable development in America to date, a 126-unit apartment complex under construction at the intersection of Midvale and Ridge avenues. You might think that such an undertaking would require unorthodox building methods and costly materials. But according to Onion Flats, the developer, it required less of a leap than you would think. In fact, minimally tweaking prefabricated building components is the most economical means to meet Passive House standards.
Not that Ridge Flats lacks excitement. It has on-trend green features and aesthetics. But it’s the simplicity of factory-built modular construction that is due trumpet fanfare. “Factory construction is a very smart way to build,” says Tim McDonald, president of Onion Flats, the co-developer-architect-builder of the $30 million project. (Grasso Holdings, a Philadelphia firm, is a joint venture partner on the project.) “Passive House construction requires a conscious approach to airtightness, which we did by working with our prefabrication company.” McDonald, whose subsidiary architecture firm designed the project, collaborated with manufacturers on door and window placement and high-R-value insulation. The result is a hyper-efficient building envelope.
With 126 units, roofs covered in photovoltaics, and a location overlooking the city’s Schuylkill River, Ridge Flats distinguishes itself from its surrounding buildings.
McDonald believes that, in general, it is smarter to adapt existing methods than to create something new altogether. “To make it simple, we started with the methods manufacturers know,” he says, adding that it is also the best way to achieve a competitive cost-per-square foot. When completed in 2015, the 140,000-square-foot community could easily serve as a model for ultra-sustainable design and construction systems.
No Ordinary Developer
Ridge Flats is Onion Flats’ largest development to date, following a progression of smaller projects—all green—that McDonald, along with brothers Pat McDonald and Johnny McDonald and partner/architect Howard Steinberg (who is also the company’s CFO), has built since the firm was founded in 1997.
In 2012, Onion Flats constructed Pennsylvania’s first certified Passive House development, Belfield Townhomes. The three side-by-side residences were recognized by the Philadelphia chapter of the American Institute of Architects with a Merit Award for design excellence.
With other built homes called E Flats, Rag Flats, Capital Flats, Market Flats, Thin Flats, Margarido, Firehouse, and Number 9, it’s clear that this is no ordinary developer. “Onion Flats was a barroom decision,” says Johnny, who is a partner in the company and its construction, architecture, and green roof and solar subsidiaries, known as JIG, Plumbob, and GRASS, respectively.
Why all the “Flats”? Johnny says it allows the name to relate to the building’s history. Rag Flats, for instance, sits on the site of a former rag factory, its 11 units referencing several classic Philadelphia housing styles: row houses, trinities (three-story, small-footprint houses), industrial lofts, and pavilions.
As is the case with a number of Onion Flats projects, Rag Flats’ name references its history. The 11-unit complex sits atop a site previously occupied by a rag factory.
Thin Flats, in Northern Liberties, is a collection of nine LEED Platinum duplexes and row houses. It employs glass extensively—including on interior walkway “bridges”—and has vegetated roofs. Viewed from the street, Thin Flats reinterprets the row house with staggered vertical columns of glass and steel punctuated with windows, doors, colored panels, and balconies.
Capital Flats is named for a former meatpacking plant (Capital Meats) that operated on site for eight decades. The building’s transformation to an eight-unit apartment building was about turning a derelict eyesore into a community asset while preserving some of its nobler history.
For this family, which builds green as a matter of course, sustainability goes beyond energy conservation. Onion Flats’ project statement for the Capital project asserts that the team “began Capital Flats with the belief that each and every building in a neighborhood, regardless of its state, has the potential to transform a community. The project, therefore, was not about converting a meatpacking plant into apartments. It was about carving out an opportunity within the discipline of architecture to experiment with modes of building, dwelling, and the communities engendered in both.”
For the Love of Philly
Every building constructed by the Onion Flats team of developers, architects, and builders has distinct green features and is often LEED Gold or Platinum certified. But they do this with nuance, striving not to create green buildings, per sé, but to use “intelligent approaches to the way in which buildings manage their own resources and create communities that sustain themselves,” McDonald says. In other words, the company is genuinely focused on how its projects perform over the long term.
Which may have a lot to do with the fact that the Onion Flats team and its employees are mostly native Philadelphians—and the fact that the company houses development, design, and construction in a single enterprise. Pat lives in Rag Flats. Tim lives in Thin Flats. It seems to be a package deal.
The second-level courtyard of Ridge Flats features a variety of native plants irrigated by water collected on site.
Onion Flats was one of three winners of a 2009 competition, “From the Ground Up: Innovative Green Homes,” sponsored by a consortium assembled by Syracuse University that focused on affordable housing schemes (under $150,000 construction) that marry design and sustainable strategies. The firm’s winning entry was a 1,100-square-foot single-family home that employs passive venting to reduce summer cooling costs.
Ridge Flats is being built on land designated for revitalization by the Philadelphia Redevelopment Authority. Onion Flats won the opportunity to develop the project through a competitive RFP—which did not specify Passive House standards. “To make it work, we have to achieve the same costs-per-square-foot as typical construction,” says McDonald, who is a certified Passive House consultant. As Pat told a Philadelphia newspaper, “You should not have to pay more for a house that is LEED certified.”
The Proof is in the Passive
Investors sign on to an Onion Flats project with a pragmatic—some might say skeptical—perspective. “They ask us to prove our claim of lowered operating costs,” McDonald says. “They want to see that we’re developing a type of building that is genuinely more cost effective. That’s why Passive House is so appropriate. Insulation and a tight envelope are ‘cheap as chips,’ as Passive House consultant and certifier Tomas O’Leary of the Passive House Academy puts it. We’re putting the least amount of money into achieving the best outcome.”
Although Ridge Flats will be a market-rate rental apartment complex, charging $1,300 to $2,000 per month for one- and two-bedroom units, future tenants may not all own cars. The building’s location allows for alternative transportation via commuter rail, bus, car-share services, and bicycling (there is a 62-space bike-parking facility on site). In response, the developers have zoning approval for a reduction in the number of parking spaces (less than one car per unit). Ridge Flats also will provide electric charging ports for electric vehicles.
Ridge Flats will feature less car parking than is typically required by zoning law. The developer is targeting a younger demographic more likely to ride a bicycle or take public transportation.
Much of what makes this development green enhances the experience of living in it. It is pedestrian-oriented, at the terminus of a city park system along the Schuylkill River. A second-level courtyard will feature native plants, irrigated with water captured on site. Referencing Philadelphia’s vernacular of front-entrance stoops, residents will enter homes through exterior circulation platforms (i.e. no enclosed hallways). Solar arrays and green roofs top off all tiers of the multibuilding complex.
The fact that this is a rental development also answers housing trends. The number of US households that own their residences has declined in the past eight years, from more than 69 percent in 2006 to 64 percent today, with the highest concentration of renters falling under age 45. Green features such as bike storage and renewable energy are part of the marketing package. “Sustainability matters to at least some of them,” Johnny says. “But most renters are drawn first to aesthetics”—illustrating, perhaps, that marketing energy-efficient housing can be as nuanced as building it.
“Design is as important as energy conservation,” McDonald says. “But it has to be an inspiring place to live. It has to have good light, inviting spaces, with circulation that fosters community interaction.” This, in combination with low- to non-existent energy costs, is what makes this particular Passive House project a game changer in Philadelphia and beyond.
