Outside the realm of LEED ratings and certifications, there’s another option for the energy-conscious builder: passive homes.
Matt Fine of Frederick-based Zavos Architecture and Design is working to retrofit a trio of 1963 multifamily residential buildings in southeast Washington, D.C.
Weinberg Commons will be the first passive house retrofit in the mid-Atlantic region, according to Bruce Zavos, president of Zavos Architecture and Design.
Zavos thinks more incentives should be provided for “decision makers,” whether they are homeowners or housing organizations, to consider more sustainable design.
The overall goal for the Weinberg Commons project is energy efficiency, which brings down the cost of utilities. But as Fine describes, there’s more to the $10 million project than making sure the brick-faced buildings’ doors and windows are airtight.
To be a passive structure, a building must meet four criteria. The first is, indeed, air-tightness: the building should minimize the amount of heated or cooled air it loses.
In the Weinberg buildings, the firm’s design added insulation under the roof and in the walls, plus triple-paned windows that swing shut to create a tight seal.
The house also must not exceed a certain amount of energy to heat or cool the interior; a passive house cannot use more than 15 kilowatt-hours per square meter of living space per year.
The third requirement is a cap on the peak amount of energy that the heating and cooling system and appliances in the house use. That cannot exceed 120 kilowatt-hours per square meter of living space per year.
Another requirement is a limit on the amount of energy it takes to heat a square foot of living space on the coldest day of the year to 68 degrees Fahrenheit.
“It’s a pretty strict energy standard,” said Blaise Rastello, director of affordable housing at THC Affordable Housing, Inc.
The Weinberg Commons project came from his interests in net-zero homes built for the U.S. Department of Energy’s Solar Decathlon and affordable housing.
Each of the three Weinberg Commons buildings has 12 units at about 720 square feet each.
A dozen units will be affordable for households with incomes at 30 percent or less of the area’s median income, and 24 units will be affordable for households with incomes at 60 percent or less.
“Lower utility costs translate into more affordability for families,” Rastello said.
THC Affordable Housing, a nonprofit organization, is taking a risk on this building, he said, but as the property owner, they may also benefit if energy efficiency improves after the retrofit is complete.
Catonsville resident Michael Hindle, president of the Board of Managers of the Passive House Alliance of the U.S., reviewed the design for Weinberg Commons.
He said passive house design is more accessible than people generally think.
“Retrofits are more complicated, but it doesn’t have to be prohibitively so,” he said. “The trick is to look at the home — or commercial building — holistically as a system, and get your architect and passive house consultant involved early in the process.
“The cost of the energy-related aspects of the construction typically add less to the mortgage than the cost of energy without the improvements,” he said.
Follow Sylvia Carignan on Twitter: @SylviaCarignan.