Wolfe Island Passive House — An Introduction
After planning a more conventional structure, a couple changes gears and decides to build with cross-laminated timber
Editor's note: David and Kayo Murakami Wood are building what they hope will be Ontario's first certified Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. on Wolfe Island, the largest of the Thousand Islands on the St. Lawrence River. They are documenting their work at their blog, Wolfe Island Passive House. This post was originally published on July 2015; it is the first in a blog series that GBAGreenBuildingAdvisor.com will publish about the project.
We have an acre lot in the village of Marysville on Wolfe Island, one lot back from the shore of Lake Ontario. The land slopes gradually down toward the main road and then to the lake shore to the north-west. The existing house sits towards the southern corner of the land. It’s an old military barracks house, one of several that were bought by local farmers from the army and shipped across from the mainland after the War of 1812.
When we moved here five years ago, our original plan was to refurbish this house to make it super-highly insulated and add solar power and so on. The main house is fine, if tiny, but like most houses on the island, the place was originally oriented toward the road, and the windows on the southwest side are small. That makes the house pretty cold at all times of year, and dark in all the downstairs rooms, particularly the kitchen-dining room.
It has been insulated with blown-in cellulose in the framing, and doesn’t score too badly on a blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas., but it’s still very cold in winter. The water, septic, and plumbing systems are all pretty disastrous and not up to any kind of contemporary building code. Finally, the whole thing is finished in some horrible cream-colored vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). siding and the roof is the standard asphalt shingles.
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We explored all kinds of ideas and had two different sets of architects come up with plans, but once they were costed, we realized we would have to spend a lot of money to improve the place, and we’d still end up with a house that had fundamental and unresolvable problems.
We thought about demolition and rebuilding on the same footprint, but the house has a basement, which is just dug into the rock and which sucks heat out of the house, and has water flowing through it much of the time. To build a south-facing house on the same site, we’d have to either fill this in entirely or build the new house diagonally over the basement, which would make the area much bigger than we wanted or needed. In the end, we decided to build completely afresh, but to keep the old house, converting it into a studio and guest space, demolishing the newest addition, and converting the first addition into a single garage. We then plan to refinish the old place in the same white cedar siding and steel roofing we will use for the new place.
Changing plans in midstream
Just when we thought we had everything worked out as well as we could and were happy enough, we got news of a completely different way of building the house that instead of being just good enough would be perfect.
We had a project-transforming meeting with Malcolm Isaacs, one of the founders of the Canadian Passive House Institute. Isaacs taught the Passive House course taken by our architect, Mikaela Hughes. Malcolm has just started to work with some manufacturers in Germany and Austria who make factory-built wooden Passive House components (walls, roofs, windows, etc.). These are built to far higher specifications that anything that's possible to find in Canada, and the materials come from sustainable sources.
Mark Leno CLT panels.
The structure — including all external and internal walls, floors, ceilings, and roof — of our new house will entirely consist of Merk Leno cross-laminated timber (CLT), just about the strongest form of timber there is. The external structure will be clad in Schneiderholz wood fiberboard insulation. All of this comes cut to the millimeter from the factory in Austria and is sent over by sea in shipping containers.
It should take about two months from order to delivery, which gets us into September — way too late to start building, right? But the trick is that once they get here, the components should take no more than two or three days to put together with a crane and a whole lot of long screws, rather like giant Ikea furniture!
Add a water-resistant but breathable layer — absolutely no vapor barrier, which would obstruct the natural qualities of the wood. Add local white cedar claddingMaterials used on the roof and walls to enclose a house, providing protection against weather. over a rainscreenConstruction detail appropriate for all but the driest climates to prevent moisture entry and to extend the life of siding and sheathing materials; most commonly produced by installing thin strapping to hold the siding away from the sheathing by a quarter-inch to three-quarters of an inch. and a basic steel roof, and that’s pretty much it for the structure.
An improvement over earlier plans
This is all good. Not only is this going to be as highly insulated as our previous plans, but it will be a lot more tightly sealed, with far better finishing, far higher quality windows (more about that in a future post) and… believe it or not… will be cheaper than the stick-frame and structural insulated panel(SIP) Building panel usually made of oriented strand board (OSB) skins surrounding a core of expanded polystyrene (EPS) foam insulation. SIPs can be erected very quickly with a crane to create an energy-efficient, sturdy home. combination we had almost settled on.
The lower price is due to several factors: mainly the fact that there will be no framing or trusses, and hardly any drywalling or painting and other finishing, but also the fact that the manufacturers are looking to expand into North America, and we are one of the first willing test subjects. So right now, Mikaela is hard at work redrawing the plans a little to accommodate this pretty fundamental change (which isn’t the only one, but I’ll write more about that later).
One big question here: why isn’t there a Canadian company that can do this? You would think that with Canada’s forestry industry needing new ideas, the cold climate, and the massive home-building market here, a made-to-measure wooden Passive House company would clean up.
It seems to me that most houses will (or should) be built this way in 30 years. There are Canadian producers of CLT, but most of it is vastly inferior to that produced in Europe, and what’s more, they simply don’t have the facilities to custom cut in the same way. No one produces wood-fiber insulation. Canada is still dominated by the belief in cheap fossil fuels and the idea of infinitely expandable land and resources. There are so many reasons why this has to change, but it isn’t changing very fast.
Site plan and orientation
The new house will be part of a group of buildings that include the existing house and the existing barn. It also is oriented to take maximum advantage of the sun for light, passive solar heating, solar thermal water heating, and solar electric generation. This means ignoring all the traditional reasons for house orientation on the island, such as alignment with roads or, more recently, lake views.
The house will be placed where the soil is thinnest — it’s only 10 inches to bedrock in this area, whereas farther down the slope, the soil is deeper and better for growing. That said, we will be making a courtyard kitchen garden in the triangular space created by the lines of the stone wall that runs along the pathway alongside the old house, the west side of the new house and the barn, but this will have deep raised beds.
- David Murakami Wood
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