by Kristin C. and Troy H.
At Habitat Philadelphia, we build homes that are not only affordable, but sustainable. The five North Philadelphia Complete Blocks homes that we’re working on right now (or have planned) are no different. Thinking about green building practice, we might divide our techniques into two broad categories: using more earth-friendly materials to build the house, and creating a durable, sustainable structure that will require less energy once occupied. By building within the urban fabric of Philadelphia and utilizing recent developments in materials technology, we can achieve both.
The energy-efficient design of Philadelphia’s iconic rowhome allows us to build to high efficiency standards in both our rehabbed homes and our new-construction homes. Rowhomes share their “party walls”—the side walls—with the houses on either side, which means that their exterior surface area is close to half that of a stand-alone house (which thus means far less exposure to the elements). In addition, we rehab existing rowhouses whenever we can, so that their inherent efficiency, beauty, and architectural design are preserved. Utilizing the current housing stock also keeps valuable construction materials out of landfills. Older houses were built to last—think of all of those thick old joists and studs in old houses, which are still very much structurally sound and will continue to hold up the house for countless years to come. And when we do build new projects on vacant lots, we maintain the city’s urban fabric by utilizing the time-tested precedent of the rowhome.
Our focus on serious efficiency took off in 2009, when we completed seven homes on Stiles Street in West Philadelphia that were certified as LEED Silver. “LEED” stands for Leadership in Energy and Environmental Design, and is a national program providing independent, third-party verification that a building, home or community was designed and built using strategies aimed at achieving high performance in key areas of human and environmental health. The program examines things like sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality. To learn more about LEED for Homes, you can visit the United States Green Building Council’s website at www.usgbc.org/LEEDforhomes
But we didn’t stop there. Since finishing our first LEED-certified homes, Habitat Philadelphia has made a commitment to energy efficiency and green design, because building with these goals in mind means that our homes are not only affordable to purchase, but also affordable to maintain. Efficiency is built into every aspect of a Habitat house, from the ground up (literally!). We use extra rigid foam insulation on the outside of our homes, beginning in the basement and extending all the way up to the top floor. The joist bays in attics are coated with a thick layer of spray-in cellulose insulation. And the windows that we install in every home are “low-e, argon-filled”—fancy words that essentially mean the window glass itself is insulated and prevents excess heat transfer between the inside and the outside of the house. All three of these insulating materials were developed relatively recently, and together they’re a huge improvement over the older, more widespread fiberglass insulation, giving us much more flexibility in the way that we keep houses warm in winter and cool in summer.
In some cases, using less building material actually results in additional energy efficiency (sounds crazy, right?). Think of the 2×4” studs used to frame walls in just about every single-family house you’ve ever seen. Up until recently, building standards dictated that studs should be spaced exactly 16 inches apart, and never more than that (the thinking was that a greater distance would mean that the wall wouldn’t be as strong). But recent research shows that studs can actually be placed a full 24 inches apart, and the resulting structure won’t lose any rigidity or durability whatsoever. More distance between studs means fewer of them—one third fewer, to be exact—which means far less wood is needed for each house. The upshot? We also know that wooden studs allow some heat to flow through them, but that insulation (like rigid foam or fiberglass) doesn’t. So, the fewer studs are in a wall, the more insulation we can have, and the less heat is lost from inside a house. With our increased understanding of building materials, we can achieve greater efficiency both during building and long into the life of the home.
But we’re not doing it for the science and fancy terms; green design has real-world consequences for the low-income families that purchase houses from Habitat Philadelphia. Energy-efficient building techniques translate into far lower utility costs, which—taken together with our zero-interest mortgage—allow Habitat homeowners to save a greater percentage of their income every month, or redirect their hard-earned money towards the other costs of raising a family successfully.
There is a unity of tradition and technology in all of our green building practices. We use the centuries-old idea of the rowhome, a structure whose popularity in cities around the world testifies to its intelligent, practical design. We combine this with an ever-greater understanding of building materials—choosing those that are kinder to the earth, and to the family purchasing a home, as much as possible.
This is green building at its best: a consideration of environmental, economic and social concerns and a practice that takes the best ideas from both the old and the new—combining them to create a safe, sustainable and affordable home.
More news and information about Habitat’s green building:
We are excited to announce that we will be pursuing LEED Certification on the two new homes on Wilt Street!
LEED Certification on these two homes is being made possible through a partnership with BOULD, LLC and their program, EverbuildPRO [link: www.everbuildpro.com], a comprehensive training program providing hands-on LEED experience for professionals and students seeking to launch green careers! Participation includes:
- Qualification for ALL LEED Professional exams.
- 50 hours of LEED participation, over a four-month building project.
- Flexible access to all phases of LEED Design, Construction, and Documentation processes.
- Construction of an awesome LEED-certified home for a local low-income family!
Stay Tuned for more updates as we progress through the LEED Certification process on 1905 & 1909 W Wilt Street.