Planning October 2017
Multiple Efficiencies for Multifamily
There’s a growing movement to bring Passive House standards to apartments and condos.
By Jeffrey Spivak
When a nonprofit developer and designer conceived a new senior-living complex in Milton, Vermont, they knew they wanted a sustainable green building. But not just any type of green building would do. They wanted a superior shade of green, one that would use significantly less energy than standard construction and one that would result in exceptionally low utility bills for the residents.
They chose a little-known but fast-growing green building standard called Passive House, which is popular in Europe and now emerging across North America. Passive House relies on building materials and methods, like better insulation and thicker windows, to maintain a fixed temperature inside a living area while using very little energy — no matter what the conditions are outside.
So at the new Vermont senior apartments called Elm Place, the three-story, 42,000-square-foot building is expected to consume just 20 percent of the power for utilities like heating, cooling, and lighting that a similarly sized conventional building would use. And the heating bill for all 30 one-bedroom units is likely to total the same amount as one of the town's older single-family homes.
"It's pretty amazing," says Michael Wisniewiski, Elm Place's architect.
Passive House is considered the next step forward in green building's continuously evolving progress. The name comes from taking a more "passive" approach to thermal comfort — as opposed to standard or "active" construction, where mechanical systems provide constant supplies of conditioned air for heating and cooling. The passive approach means dramatically less energy is used than in typical buildings: Studies show reduced heating requirements ranging from 60 percent to 90 percent.
In Europe, Passive House is so accepted that cities like Antwerp, Brussels, Cologne, and Frankfurt have made it part of their building code requirements. In North America, however, Passive House is still in its infancy, overshadowed by other better-known green building rating programs such as Leadership in Energy and Environmental Design and Green Globes — but that's starting to change.
"What people find intriguing is it's incredibly different than LEED and the majority of other green building programs in how it reduces greenhouse gas emissions. It's a way of building that we haven't been doing," says Stuart Kaplow, a Maryland-based green building attorney whose blog, the Green Building Law Update, called Passive House "in" for 2017. "But it's still relatively new in the U.S. It's still a niche."
Elm Place was certified by the Passive House Institute U.S. in July, making it Vermont's first official multifamily construction to meet Passive House standards. Located in Milton, the building offers 30 affordable — and energy-efficient — units for seniors. Photo courtesy Jeffrey Spivak.
Exponential growth
From just a handful of North American projects at the dawn of this decade, certified Passive House construction through either U.S. or international governing bodies has been doubling virtually every year to total some 1,200 overall housing units with more than one million cumulative square feet last year, according to the Pembina Institute, a Canadian-based energy policy advocacy group that tracks the Passive House movement.
In the U.S., Passive House designs have mostly focused on single-family residences but are now increasingly applied to multifamily and high-rise projects. In New York City, the first residential high rise built to Passive House standards, a 26-story student housing complex, is set to open this year on Cornell University's technology campus. The building's facade, constructed of a prefabricated metal panel system, acts as a thermally insulated blanket wrapping the structure.
Hotbeds of Passive House activity are occurring in places with supportive public policies, like New York and Pennsylvania. But apartment projects have been popping up in a variety of locales, from cities such as Kansas City, Missouri, and Portland, Oregon to smaller towns like Gilford, New Hampshire, and Muir Beach, California. In Kansas City, developer Jonathan Arnold is constructing North America's largest mid-rise Passive House apartment project, the 276-unit Second and Delaware development on the edge of downtown. The Arnold Development Group is a B Corporation, dedicated to social and environmental issues; his cause is scaling up Passive House to attract future funding interest from institutional investors for additional large-scale housing projects.
"If we want to change the marketplace and prove the value of Passive House, then we need to show Passive House works at this scale," Arnold says.
Growth of Passive House in North America
In 2009, just a few residential projects (multifamily and single family) had been certified by the Passive House Institute and the Passive House Institute US. That number had grown to more than 250 by last year.
Source: Pembina Institute.
It seems to be working.
"We're at a tipping point now [with Passive House], where it's growing into bigger buildings," says Ilana Judah, principal of FXFOWLE Architects in New York, who coauthored a study earlier this year on the feasibility of Passive House for tall residential buildings. The Pembina Institute says the 2,000 Passive House multifamily units in development are double the number of finished units.
Katrin Klingenberg, cofounder and executive director of Passive House Institute U.S., the industry's governing body, agrees. "Multifamily is the next frontier, and it's here," Klingenberg says. "We've seen exponential growth."
That's particularly apparent in the affordable housing sector. Beginning with Pennsylvania in 2014, more than 10 states now have incentives for affordable housing developers to meet Passive House standards, such as by earning points in state Low- Income Housing Tax Credit applications, according to a compilation by Philadelphia-based architecture firm Onion Flats.
Affordable housing developers are attracted to Passive House because the buildings are so well insulated and airtight, they can offer significant savings on utility bills. In Portland, Maine, for instance, the Portland Housing Authority's newly opened, 45-unit Bayside Anchor project is expected to cost $111 per unit per year for heating on average — less than $10 per month.
Lower costs help tenants in some scenarios, but in affordable housing, utilities are often included in a fixed rent. That benefits the owner and helps keep rents low while reducing building costs. "In the affordable housing world, developers and nonprofits are looking for an edge when competing for land or financing," says Chris Benedict, a New York Citybased architect who has designed several Passive House affordable multifamily projects in the city and received the New York Passive House's Pioneer Award in 2015. "Passive House provides that edge."
The Guiding Practices and Principles
Passive House construction is all about the enclosure: thicker windows, extra installation, and exterior air sealing.
Broader benefits
In addition to the direct reduction of energy use, a big selling point of Passive House for communities is its ability to contribute to larger community goals. "If any communities have carbon emission reduction goals or climate plans, this is the way we're going to get there, by building like this," says Alisa Kane, the green building manager for the Bureau of Planning and Sustainability in Portland, Oregon, where private developers erected some of the first Passive House apartments on the West Coast. "It's next-generation building."
Residential, commercial, and institutional buildings are responsible for almost 40 percent of carbon pollution in the U.S., according to industry studies. So architects and developers interested in energy efficiency are drawn to Passive House because of its expected performance; buildings following the latest U.S. standard (adopted in 2015) will, based on modeling, use only 10 percent to 25 percent of the energy that a similar-sized structure built to code would use.
But how does Passive House do it? Common design factors to multifamily projects include:
- Extra-thick exterior wall insulation, often including several inches of rigid foam board
- Exterior air sealing, such as with a fluid-applied silicone air barrier over the plywood sheathing. This can minimize thermal bridges, or tiny gaps around windows, doors and roof lines where, for instance, heat can be lost in winter
- Triple-paned windows in triple-glazed PVC casements, to minimize heat loss and gains
- High-efficiency heat-recovery ventilators in each unit to supply fresh air by continuously exchanging stale indoor air with fresh outdoor air
With its entire focus on energy usage, Passive House differs considerably from most other green building certification systems. Those typically award points for an assortment of eco-friendly attributes such as use of renewable energy and rainwater management systems, but also on some factors not related to building performance, such as bicycle facilities or transit access. As a result, studies have consistently found wide variations in energy usage among certified green buildings of a similar size.
Passive House, on the other hand, simply sets a series of specific energy-related targets and lets designers decide how to achieve them.
"The Passive House concept is really only concerned with the energy balance and performance of a building," says Andreas Benzing, a New York City architect who is LEED accredited and president of the board of New York Passive House, a regional affiliate. "It doesn't tell you what you have to do. It gives you the freedom of designing to achieve the holistic goal."
Another plus for residents of these buildings: comfort and noise reduction from the exterior and surrounding units. One of the first residents to move into Elm Place was retired widow Karen Trombley. She came from an old brick house she "loved," but was so dry inside she had to run a humidifier every night. At Elm Place, she put away her humidifier.
"I can wake up in the morning, and my mouth isn't dry and my skin isn't dry. I can just breathe better," Trombley says. "I am just thrilled to death." As far as noise from her apartment neighbors or from the downtown streets goes, Trombley says she hardly notices any.
Breaking barriers
Still, for all its benefits, the Passive House program is not without conflict. For one thing, Passive House construction typically costs around six percent more than conventional construction for multifamily dwellings because of additional design consulting, energy modeling, and high-performance equipment — although that premium can vary. For example, costs at Vermont's Elm Place senior apartments were only two percent higher than comparable traditionally built complexes.
Passive House's innovative designs sometimes require zoning adjustments and building code variances as well, but a growing body of policy decisions in places like New York City and Vancouver, British Columbia, have shown how these challenges can be overcome.
In New York City, for instance, the planning department's Zone Green initiative added an amendment that exempted up to eight inches of exterior wall thickness in calculations of floor area, thus giving some Passive House multifamily projects extra usable space. For Chris Benedict's 34-unit PERCH Harlem apartment building, that variance gave the project an additional 750 square feet, or enough for one more unit.
Another Passive House code issue concerns energy recovery ventilation systems in apartment units. Such systems, which typically replace central heating and cooling systems, use separate air ducts to bring in fresh outside air and expel indoor conditioned air. Building codes generally mandate that such air ducts must be far apart, around 10 feet, to avoid mixing intake and exhaust air. But Passive House designs want them closer to take advantage of the energy they provide. In winter, for instance, warmer exhausted air can pass over the cold fresh intake air and help heat it. New York City is one place that has allowed this variance.
"The promise New York City sees with Passive House is low-energy buildings with low greenhouse- gas emissions leading to happier and healthy homes," says John Lee, deputy director for buildings and energy efficiency in the mayor's sustainable planning office. "If planners understand these social benefits, then they'll be willing to work through the policy issues. They can look to New York and other cities for guidance on how to handle them. There's an applicability across city boundaries," he adds.
Indeed, a growing number of North American cities and states are now beginning to include Passive House or its energy-use targets in their building policies. Vancouver, which has a goal to become the greenest city in the world by 2020, introduced policies in 2015 to encourage Passive House multifamily construction, including relaxing lot-line restrictions to account for the room needed for extra levels of exterior insulation. The city's Green Buildings Policy for Rezoning also requires multiunit residential projects to meet stringent thermal and greenhouse gas targets, or to achieve Passive House certification. These changes led to a wave of interest in Passive House there, with building permit approvals for 240 units at one point last summer.
"The policies signaled to the industry that the city would like to see more of Passive House," says Chris Higgins, a green building planner in Vancouver's planning and sustainability department. "There's been far more interest than we imagined."
Going forward, though, Passive House will likely need greater brand awareness and more educational outreach to become one of the go-to standards for green building.
Jeffrey Spivak, a market research director in suburban Kansas City, Missouri, is an award-winning writer specializing in real estate planning, development, and demographic trends.
Resources
Passive House Institute U.S., the organization developing and promoting Passive House standards, practices, and certification in the U.S.: phius.org.
Pembina Institute's market study of the Passive House movement: www.pembina.org/pub/passive-house-report.
International Passive House Association: passivehouse-international.org/index.php?page_id=65.