No, Passive House Doesn't Have to Cost a Lot More

Seattle's largest multifamily Passive House project cost only 5% more.

Solis in the Evening

Via Weber Thompson

One of the standard tropes you hear about Passive House design is that it is too expensive or too hard or not worth the trouble. And then you have Solis, a new multifamily project in Seattle that has received PHIUS certification, uses 50% less energy than a conventional building, and only costs 5% more than conventional construction. And they got a lot for that 5%.

Architect Bronwyn Barry has noted that Passive House is a team sport. It's also been said Passive House has a learning curve. Probably the main reason they could pull this off is because it was such an experienced team. The architects were Weber Thompson, which has been on Treehugger many times with their influential 2008 Terry Thomas Building—it was most definitely not a Passive House design.

The Solis project was conceived and built by Sloan Ritchie, who built the first Passive House residence in Seattle—and I believe lives in it. He also previously built the Pax Futura apartment building, which he also claimed had only a 5% premium.

view of balconies

via Weber Thompson

So why should it cost more at all? According to the Cascade Built website, costs were carefully controlled here. "This was done through the use of conventional materials in innovative ways including pairing an enhanced building enclosure with a top-notch mechanical system for exceptionally comfortable and healthy units."

Passive House designs have more insulation and more expensive triple-glazed windows, so the exterior wall can be significantly more expensive than a regular building. However, because it is multifamily, the exterior wall is a much smaller proportion of the cost of the building, just one or two walls per unit. But it is also a marketing advantage, earning its keep in comfort and quiet. As the developer, SolTerra notes:

Solis Interior

via Weber Thompson

"Triple-pane glazing creates an exceptionally quiet interior away from the bustle of the outside urban environment. Healthy finish materials were selected to meet the EPA’s Airplus standard, and matte surfaces are used to reduce glare in kitchens. Thanks also to the energy efficient systems, residents pay significantly less in heating and cooling bills."
Solis Air Barrier and Ventilation


Passive House designs have strict requirements for air barriers to seal them tight and require fresh air and ventilation, which costs a lot more than the usual apartment building systems that just pump air into the corridors. This is often offset a bit by savings in heating and cooling equipment but still costs more. But again, there are marketing advantages; "Continuously filtered fresh air, healthy materials, zero air-transfer between units and individual unit heat pumps make Solis a powerhouse of health for those who call it home." The Passive Houe and energy consultants ArchEcology provide greater detail, noting that it has "automated solar shading devices, triple pane windows and a centralized HRV system with integral heat pump system."

Sloan Ritchie notes other benefits from the ventilation system:

“Passive House building is our future -- along with reducing the impact of carbon emissions produced by buildings, it meets increasing demands for better air quality, especially prevalent in the wake of continued smoke from regional fires, protection against rising energy costs, and building longevity as materials and labor become challenging to acquire."
Exterior with Jewel Box

Weber Thompson

The design is simple with generous windows, and a big exterior stairway that adds interest to the facade. Note the shadows from the balconies on the end wall; they are doing double duty, reducing being a sunshade to reduce heat gain while adding outdoor space. Sometimes architects think the designs are too simple, and sure enough, there is "a striking, patterned screen 'jewelbox'" to jazz up the corner and act as an entrance.

Solis Jewel Box Entry

Via Weber Thompson

Everyone seems to love this project; it has received piles of awards from PHIUS and the real estate industry. It raises the question once again about why every building isn't designed this way, and why it isn't actually in the building codes. Sloan Richie suggests that it might be: “Very soon, Passive House standards will be codified to meet climate goals and being at the forefront of this movement enables us to ensure everyone is ready to come along.” 

That day can't come too soon. Others, like Invizig in Hamilton, Ontario, have shown that you can build to Passive House standard even in a much colder climate for not much more money than conventional buildings. There is no good reason not to do it.