A small Seattle-area townhome development has set the standard nationwide for high-performance, resource-efficient multifamily construction in more ways than one.
The newly completed 10-unit zHome community, the first multifamily development in the country to earn the WaterSense for New Homes label, goes beyond the 20% water use reduction guidelines of the federal program. Through a variety of water-efficient technologies—including individual rainwater harvesting systems and water-use monitors—project planners are aiming for a net reduction of 70% in potable water use compared with a typical home in the area.
Beyond water conservation, zHome also pushes the limits of sustainable production housing in energy efficiency. It is considered to be the country’s first multifamily project to achieve net-zero energy consumption, thanks to a super-insulated building envelope (R-38 walls, R-65 roof), solar PV systems, and ground-source heating.
Drawing warm air from a communal system of 15 220-foot-deep geothermal wells spread across the site, the dwellings stay comfortable year-round and even in winter require only a bit of hydronic heat—too much, and the units overheat, says project manager Brad Liljequist.
“The ground-source heat pump is amazing,” he says. “I think we’re looking at it being a game-changing product in the next few years.”
Liljequist was also pleasantly surprised by the performance of WaterSense-approved products such as low-flow toilets, 1.5-gpm Kohler showerheads and 0.5-gpm faucets, and Energy Star-rated dishwashers and clothes washers. “Manufacturers have really upped the quality compared to low-flow products from years ago,” he says.
WaterSense certification dictated more than just product selection, such as the location of the hot water runs to minimize the amount of time water flows to showers and faucets before heating to the proper temperature. The program requires that the hot water delivery system store no more than a half gallon of water between the source of the hot water and the farthest fixture in the home. zHome project planners had to move some hot water tanks in order to comply, Liljequist says.
In addition, the project’s rainwater reuse system goes a long way in reducing residents’ reliance on the municipal water supply. Each home’s cistern holds between 1,100 and 1,700 gallons of roof runoff until it is used for clothes washing or toilet flushing.
To help residents track their energy and water usage, the townhomes also include TED energy monitoring systems and Badger water monitors. While the units’ energy-efficient features will help decrease owners’ utility bills, the water-conserving aspects of the dwellings will not yield much of a financial payback, Liljequist says, because water is so inexpensive. “The water-conserving measures were more about being the right thing to do,” he adds.
The project’s Japan-based developer, Ichijo USA, known for its efficient panelized construction techniques, built the zHome’s exterior walls and roofing in its Philippines factory, a move that the project team analyzed extensively. Liljequist spent three days developing an embodied energy carbon footprint analysis of the costs of shipping the panels from Manila to Issaquah.
“It accounted for about six months’ worth of the operating savings the home would save by being zero energy,” he says. “It wasn’t as bad as we thought in terms of the carbon footprint” and helped to provide a cost-effective, ultra-tight building envelope.
Sales prices for the one-, two-, and three-bedroom units range from $365,000 to $599,000. Designed by Seattle-based David Vandervort Architects with a mid-century modern aesthetic, the townhome interiors feel larger than their 800-, 1,350-, and 1,700-square-foot layouts. The architect took a “Sarah Susanka small-home approach” that emphasized a well-thought-out design with no underutilized spaces, Liljequist says.
In a series of open houses last fall, nearly 10,000 visitors toured the project, which is certified 5-Star by regional green building program Built Green. Despite the overwhelming interest in the project’s high-performance features, Liljequist says that today’s buyers are looking for more, especially from an up-market product like zHome.
“You have to be more than deep green in order to sell a home,” he says. “We really tried to combine it with a lot of different layers—most importantly, the radical reduction in the carbon footprint, but also beauty, elegance, a great neighborhood, and a really quality design."
Jennifer Goodman is Senior Editor for EcoHome.