Location Chattanooga, TN
Size 25,000 ft²
Program Affordable housing, with 2- and 3-bedroom unit townhouses
Only thirty-six projects from across the United States were selected to receive grants for building sustainable and affordable homes from the 2009 American Economic Recovery and Reinvestment Act. The Fairmount Avenue Development in Tennessee was one of them—and it’s an attention-getter. Designed by local firm Hefferlin + Kronenberg Architects, the 18-unit townhouse project is built in the saltbox vernacular common to the American South—with long, sloping roofs perfectly angled for photovoltaic panels. Principal Craig Kronenberg walked gb&d through the special circumstances of the development.
This project drew together three organizations with complementary goals. The Chattanooga Housing Authority (CHA) provides affordable housing to families, the elderly, and the disabled. The Department of Housing and Urban Development (HUD) was the conduit for the stimulus-act funding, which was awarded according to criteria written by Enterprise Community Partners (ECP), a 30-year-old national nonprofit. Since 2004, ECP has partnered with HUD to channel $1 billion in public and private funding toward building 20,000 homes. The organization says that green, affordable homes in vibrant communities can be a springboard to a good life, and the Chattanooga project met that criteria.
Architect Hefferlin + Kronenberg Architects
Client Chattanooga Housing Authority
Landscape Architect Sara Hedstrom Design
Engineer March Adams Consulting Engineers
General Contractor Lee Adcock Construction Company
Fitting the Neighborhood
An initial design for two three-story buildings met community opposition because they would’ve comprised nearly 50 units, so Hefferlin + Kronenberg redrew the project as an 18-unit development of two- and three-bedroom townhouses, one of which is handicap-accessible and one usable by the audio or visually impaired. The topography of the project location, in North Chattanooga, enabled the buildings to both make use of sunlight and provide shade where needed, even as they’re situated on a steep, curving hilltop road.
These homes have an enviable perch in a panoramic setting of hills and trees. The city is nicknamed ‘Scenic City’ for its position between the Appalachian Mountains and the Cumberland Plateau, yet the general location ranks a relatively low walkability score—a 40 out of 100 from Walkscore.com. So the designers incorporated stepped pathways, some on segmental retaining walls, that enable pedestrian access to two bus stops, three churches, two schools, a park, a daycare center, a convenience store, and medical offices all within a half-mile radius of the site. “The project had to comply with HUD’s Green Communities Criteria for connectivity—that’s the reason for the pathways,” says Kronenberg, noting that the community is just a few miles from downtown. “I foresee the site … becoming a destination for the athletes at Normal Park School next door and children and parents walking to school, church, and the store.”
Certification LEED Platinum (expected)
Topography Stepped walkways encourage pedestrian/recreational use of hilly terrain
Siting Buildings oriented to capture sunlight actively and passively
Materials Reflective roofing, polished concrete floors, pervious paving
Energy Photovoltaic array, Energy Star appliances, natural daylighting
Water Storm-water retention via cisterns for irrigation
Landscape Native plantings, natural rocks for character and play
All units use sealed concrete floors on the first level and linoleum upstairs. “Concrete is just trowelled well and sealed, about $1 per square foot,” says Kronenberg, comparing it to the cost of carpet ($2 per square foot, plus “forbidden” by HUD), wood or bamboo (starting at $5.50), and linoleum ($4.50). Enterprise Green Communities has studied the impact of sustainable housing on such things as childhood asthma and found that children’s symptoms in a test program in Seattle improved dramatically with the installation of eco-friendly materials; children living in healthful, green public housing had 60 percent more symptom-free days and a 67 percent reduction in the use of urgent clinical care.
Perhaps the material with the greatest impact is the development’s exterior paving, most of which is pervious to allow the capture and infiltration of storm water on-site, minimizing runoff and subsequently used for irrigation. “It was a big deal to get this progressive design feature approved by the city engineer,” Kronenberg says. The coated, standing-seam metal roof was selected for its high-albedo emissivity, or reflectivity, and carries a 40-year warranty, though Kronenberg says it will probably last a century.
Passive for Platinum
The project is registered for LEED certification and will probably reach the Platinum level under the LEED for Homes rating as well as comply with ECP criteria. Many of the green strategies are passive ones. “We used techniques such as smart framing, [which] led to savings,” Kronenberg says. “The roof form naturally provides attic insulation, and the design maximizes access to natural light.” And the roof’s slope is perfect for the 189 photovoltaic panels that convert the Tennessee sunshine into electricity.
This region of Tennessee is prone to heavy rainfalls as well as hot summers. Fairmount’s Kynar-coated, standing-seam metal roofs direct runoff to a cistern that feeds an automatic sprinkler system, which waters the native landscaping—plants that can tolerate both wet and dry conditions. Natural rocks above the buildings were intentionally kept for children’s recreation, which adults can supervise from each of two porches that accompany their homes. “The rock outcroppings rival the rocks in New York’s Central Park,” Kronenberg says. “It will be a fun place to play.”