Karuna House (all photos by Jeremy Bittermann)
BY BRIAN LIBBY
In a recent Gray magazine article, I had the chance to talk with the designers and builders of Karuna House by Holst Architecture. Located on a hillside overlooking the Willamette Valley between Newberg and Sherwood, it is the first project in the world to meet three stringent green building rating systems at the same time: LEED (for which it received the highest rating, Platinum), Passive House, and Switzerland's Minergie.
Although Karuna House had a pretty large budget, and came with some inevitable headaches given its attempt to negotiate three rating systems at once (as documented in a 2013 Wall Street Journal article), I don't think we should necessarily think of those things when we look at the finished building. I see it as a demonstration project, a work of architecture that can help make possible new ideas and methods that will impact other designers' work in the years ahead. What's more, I appreciate the fact that Holst and their client weren't satisfied with just an efficient home. It had to be beautiful, and it had to be full of light.
Only a portion of my conversations with the architects and builders made it into the story, so I've decided to share here remarks from Holst Architecture's Jeff Stuhr and Cory Hawbecker as well as general contractor Hammer & Hand Construction's Sam Hagerman. (Hammer & Hand is a Portland Architecture sponsor, but I felt Hagerman's perspective was relevant in this case. He's been a pioneer in and proponent of Passive House construction in Portland.)
Portland Architecture: Could you talk a little bit about the initial conversations that led to the design?
Jeff Stuhr: The client put a group of people together and we went over to Switzerland to look at Passive Houses and Minergie houses. We saw the gamut from traditional houses to very modern and kind of came back putting everything on the table at that point. What kind of house did he want? How did he want it to feel? Something more rural in nature or a bit more contemporary?
We ran through a number of different schemes and started to come out of the ground with 3D modeling to give Eric [the client] some ideas. We still weren’t sure where he wanted to go. Eric travels widely. He goes to the Himalayas quite a bit. He’d walk in with books on Bhutanese architecture. Then he walked in with a James Cutler book. We finally settled on what I’d say is a modern contemporary almost urban style house in this situation. I think Holst kind of loves of simple volumetric space. Because we’ve often had to work on such tight budgets we’ve said, ‘How can we make the box as good as possible?’
The house sits on a hillside amidst a large parcel of land. How did you go about siting it?
Stuhr: What’s often sad about that landscape is when the houses look plunked down in terms of how they got sited. They look so foreign to the landscape. We wanted this to step down with the landscape and maintain a strong connection between the living spaces and the outdoors. You could have easily done a split-level with main spaces on the upper floor and bedrooms below. But it resonated here to follow the hill down and let the flow go outside. Really the wheat field comes right up to the house and the terraces. The intent is that it sits in this sea of wheat.
How much did the rating systems restrict options for orientation and your use of windows?
Stuhr: The secret to a Passive House is typically to build a compact, rectangular house. Orientation to the sun is beneficial but not necessarily as critical as we used to think. It’s the easiest sun to control in the summer when things are hotter, but because they’re so insulated they can overheat very easily in the summer so you really need to control solar orientation. So exposures to the east and west become critical. In this case our most spectacular view was to the east, so the conundrum was how you build a house that can take advantage of it. The living spaces and Eric’s bedroom and his son’s room are on the east side along the long axis, working out towards the view to the valley and the mountains. So sun control became critical so that’s why we’ve got the solar shades that are on the exterior. Those basically then can mitigate morning sun that comes into the house. Exposure on the south side isn’t a bad thing. It worked in our energy modeling. We always wanted to minimize windows on the north side, and then on the south have some windows that were larger to take advantage in the winter. In Switzerland they said, ‘Don’t even worry about it. You can solve this with robust walls and insulation.’
But as we went through Passive House modeling, we were really tweaking the sizes and shapes of windows. The one theme that came up constantly from Eric was, ‘I want light, and I want it to feel light and bright.’ That started to really drive how we approached the design. On the ground floor it’s like a big open loft: the kitchen, living and dining room spaces are all open to each other.
I love the glass pavilion on the roof. How did that come about?
Stuhr: Up on the third floor, he wanted to go out on the roof any time of the year and sit up and gaze at the stars. They have these little towers with these covered porches to meditate. That became an underlying thing: you do kind of ascend up the house and then you get to this Zen like glass-enclosed room up on the third floor. It’s kind of a spectacular view at this point. You see a view of Mt. Hood. That’s his stargazing, yoga studio. We called it a lot of things. It’s a glass canopy with glass doors that can retract all the way back.
Could you talk a little about negotiating the three systems at once?
Stuhr: We wanted to push the boundaries in terms of design, which you don’t see as often with Passive House, especially in the US. That right off the bat was appealing to us: could we break the code, so to speak? When I was in Switzerland, everybody was like, ‘You guys don’t know what you’re getting into. This is like climbing the Matterhorn.’ The cards were really stacked up. They weren’t being smug. They’ve spent 30 years perfecting Minergie. We are so far behind when it comes to that. We just don’t have the market that demands that. So it was a challenge finding the right windows, finding the proper exterior insulation.
How did going for LEED figure in?
Stuhr: LEED for homes came in late. We said, ‘Why don’t we just get that too?’ Part of the reason for the project was to kind of line them up side by side and see where are the similarities, where are the differences. There are houses with both Passive House and Minergie. I don’t believe anybody in the world has done all three. Not that I would necessarily recommend it.
Could you talk a little bit about some of the issues inherent to preventing thermal bridging and making the house air-tight?
Stuhr: there was quite a bit of complex modeling done with where the materials had to come together, and what we needed to do to hold this stuff without creating huge thermal bridges between inside and outside. In school we learned bout tectonics and expressing the structure. In Passive House it’s not impossible but you have to be much more deliberate, and much more careful about the envelope and what becomes interior versus exterior structure, almost to the point where they never touch. You’ll see in the living room or bedroom where we might have buried the steel on the outside wall within the window wall. We had to keep it completely inside because steel is such a terrible conductor. It’s stuff like that.
How much of a challenge was it negotiating the rating systems at once?
Stuhr: We started off with the Minergie certification and that was what we were going for. Passive House had already come to the US and done the necessary work to translate the calculations. Minergie hadn’t. We were thinking Minergie would expand this way as well. We had to design it in metric and run all the calculations. We ended up hiring a Swiss national out of Minneapolis who works for a Zurich firm. All of our Minergie modeling ran through that. It became clear we weren’t going to get there efficiently because the process was too bogged down.
Hawbecker: all those standards and rules, none of it was in English. Sometimes every hour I’d be calling him with a new question. Even in your native language it can be confusing. Translating it from German to his broken English to some guy in Newberg who hadn’t seen any of it was pretty challenging. We wound up with a house where no stone was unturned. We looked at every material, every adhesive. It was really good. But in terms of the investment of time it was not the most efficient thing in the world. I do want to say about the certifications that I never identified a direct conflict, but they got there in different ways.
Minergie is obviously the system most uncommon in the US. What were its characteristics and challenges?
Hagerman: It’s a progressive standard in that it combines the strengths of the USGBC LEED program with some of the strengths of an energy-focused program like Passive House, AND the Living Building Challenge’s Red List. Minergie has a section that talks about the reusability of the materials, and the accessibility of different parts of the house to be removed and recycled or removed and re-used and replaced over time, generations out. It’s the idea that you wouldn’t build non-resilient materials into the structure at all, and if you did they have to be easily replaceable. Then there’s a section that had to do with the materials in terms of their toxicity and usability, and their workability—specifically focused on worker safety, which I had never seen anyone do before. And then there was the piece that the USGBC and others talk about, the toxicity and the embodied energy of the materials in and of themselves as a component of the building energy budget: how much energy they have, how much energy it took to install them, how much it took to maintain them.
What do you think Minergie’s chances of gaining traction in the US are?
Hagerman: Zero, Just because the Swiss are so spidery about following their protocols. They’re completely non-cooperative, and they will not change to make it more palatable in this marketplace. Particular project questions would take months to get an answer back. ’ If you had a question about it, it’s not like you could go to a manual, or a website, or any base of information. You had to actually call Switzerland and talk to some engineer at the Minergie office. And they would be on vacation. The Europeans take these really long, random vacations. So there were a couple times where we really needed answers, and we couldn’t get an answer for, like, three or four weeks.
And yet Passive House is making inroads in the US.
Hagerman: Yeah, because we broke from Europe. Any building energy standard that you want to make the law of the land in, say, Chicago, that you have to have approved in Germany, is not going to work. The reverse wouldn’t work either. You’ve got to make it native.
Are there things about having gone through the Minergie process that made it a more sustainable house?
Hagerman: I think more sustainable, yeah. Make no mistake: Minergie brought stuff to the table that LEED and Passive House did not. Passive House is pretty clear: ‘We’re just a building energy standard. You could build this thing out of nuclear waste. As long as it has a high R-value and it’s airtight, we love it.’ LEED is like, ‘No, we want recycled pop bottle carpeting, and a bike rack out front.’ There’s a sort of chasm in between those two points of view. I realize that’s a radical oversimplification, but Minergie is basically in the middle. There’s a good story in that these standards all complemented each other on Karuna House. They also served to critique on another as they were applied at the same time. And that critique served as a roadmap. We had to make it through a minefield of certifications overlaid on one another. There was just not a clear path. There was not a straight line through that.
Do you see these certification systems becoming more prevalent in the years ahead?
Hagerman: Certifications are the wave of the future. Buildings are becoming more and more high performance. As they do that they become more airtight and they become more insulated. The mechanical systems change. The glazing changes. All these big components change. So the buildings’ response to the environment changes quite a bit. So the way the buildings are put together with all these new components changes quite a bit. It needs the process not only of certification but of verification. And that’s why we go back to these sorts of certifications that have independent third-party verification as being crucial.
The more efficient you make a building, its window of resilient performance shrinks. The drying potential of the wall assemblies and the whole building assembly decreases. The more airtight and the more insulated you make a building, the less natural ventilation you get through leaky building assemblies. So you need to know how the building performs in terms of its resilience, not just its energy consumption. And that’s what you’re trying to do with the air-tightness standard. That’s like the dirty but noble secret behind the air-tightness standard.
If you’re building a building that’s airtight you control for air, you control for water. If you control for water you control for all kinds of issues. And that’s what you have to do in a building with low-drying potential. Meanwhile you dial-in a balanced fresh air ventilation system through an HRV for great air quality. It’s about energy but it’s really not about the energy. It’s about building resilience and it's about health.
That’s a message that I think needs to get across more clearly. And it’s why the certifications that will ultimately carry the day, hopefully, are going to be the ones that have third-party verification built in.