Category Archives: problems

Reflections After a Year of Living in Our Passive House

Although there is always more to do, at the end of 2017 and after a year of living in our passive house, it’s a good time to reflect on the whole process.

This place was both the product of a shared dream between Kayo and I to create a sustainable and comfortable family house and an experiment for all of those involved. Sitting here on a late December morning after a night when the temperate dropped to an unusually cold -24ºC (yes, and that’s without wind-chill) outside and looking out on the sign shining on half a metre of snow, while feeling totally comfortable inside at 21ºC, we think we’ve achieved our dream and the experiment has been a success! We would even stand by the revised cost estimates we produced back in December 2015.

Wolfe Island Passive House in winter

There are some remaining problems. The first is a building envelope tightness issue that is due to a manufacturing fault. The Optiwin Motura sliding door, which was a prototype, has never sealed as tightly as it should, and last winter and this, we’ve resorted to sealing it up with gasketing and tape to maintain the building envelope. However, this is fixable: Optiwin have been as thorough and responsible as ever, and both issued us with a partial refund for the door and got back to is with a very detailed analysis of the fault and how to remedy it, which we will be putting into place in the spring. I don’t think anyone else considering using Optiwin needs to worry about this – as I said, our door was an early version and the current models are already better.

The second issue was noticed by Malcolm Isaacs, our passive house consultant, in checking the report conducted by Anthony Mach. He reckoned that the passive solar heat gain in winter is not as good as it was in the calculations we made. In other words, the house is not as warm as it could be. It’s not actually something we find uncomfortable, it’s more an optimum performance issue. The reason, we think, is that the downstairs porch roof overhang is not quite the exact height / angle / extension as in the original designs. However this means that to remedy the (small) differences, we’d have to almost completely rebuild the porch. There were at least two points at which things were changed in the design process that could have affected this, and as we were working not only with an architect and builder but also a passive house design consultant and engineer, and a manufacturer (for the pre-fabricated CLT structure), there were even more communication issues to manage than in a normal build. These communication issues can be crucial and really, all calculations need to be checked and recalculated every time there is a change. And of course, when you are working with any kind of pre-fab, there is a point after manufacturing has started that you can’t change anything about that any more and any changes from that point onwards have to be adaptations to what you’ve had manufactured.

Related to the issue of the passive solar heat gain – had we known this was going to be the case, then we probably would have had underfloor heating installed. In fact, we probably should have done anyway as a kind of reserve. Had we done this, we probably wouldn’t have needed the little Thermolec air heating system we have as part of the ventilation. We were just assured that it would be so warm anyway that underfloor heating wouldn’t make any difference. That’s not really true in practice but it’s warm enough so we aren’t complaining! Again, at this point it would mean substantial rebuilding (ripping up and relaying our lovely wooden floors) to do this. The lesson is: lay the underfloor heating even if you end up not using it. It’s better to have the possibility than not.

The other remaining problems are small design issues, that people thinking about building a passive house, or even just any house should note. The first is that although we really like our open-plan downstairs space, and visitors love it, however Kayo would now want a more specific dedicated work area or room. What we did design in was inadequate. It’s difficult to see how we could have done this just by tweaking the design we have. So, it we were starting again, we would include this as one of the essential elements and design around it, as we did with the kitchen.

The second minor element does relate more to passive house design, and it is the way the entrance works. We have an amazing Austrian-manufactured passive-house-certified front door from Tarredo. The only problem is that you still have to open it and once you open it, it doesn’t matter how insulated the door is. Of course, no-one leaves the door open very long in winter in any house but any heat loss is a problem in a passive house in very cold climates. Back when we were still thinking about rebuilding our old house, we had designed what we refered to as an ‘air-lock’ (like in space-ships), which was essentially an insulated porch outside the building shell, which had two insulated doors to outside and inside. Somehow, that element got lost when we moved to designing an entirely new house. I’d really recommend to anyone building a passive house in a cold climate to think about this because, especially around the Holiday season when you have people coming and going, the front door gets opened a lot more than you’d like from a passive house point-of-view! The plus side is that the more parties you have, the more all those people in your house also heat it up substantially. However, whichever way you are thinking about it, you have to factor people and behaviour into your design. The good news is that this particular problem is easily resolved. We think what we will do is create a closed-in porch space outside the front door. We’ve got room. The only question is whether we make it permanent or seasonal and removable.

There is really nothing that has happened in this year of living in our new passive house that has made us regret or rethink the building process or the big decisions we made in the design.

The Zehnder ERV is a minor miracle. The air quality in the house is so good that it almost makes us forget the mould-infested air we used to put up with as normal in practically every other house we’ve ever lived in. It just keeps working in the background with minimal need to maintanance (occasional cleaning or replacement of filters).

We still totally recommend using Cross-Laminated Timber for the structure, however we don’t think it’s necessary to use it for all interior walls, and combining CLT for the main structural walls, with more standard stick-frame and drywall for the other interior walls would make for a more flexible design that would allow you to do things like changing your mind on where electrical sockets etc. go – and even where the walls themselves go.

However, we know that Canadian manufacturers, at least in the East, are still not capable of doing the precise factory-cutting that we had done. Someone needs to make the necessary investment to do so, because CLT should be a standard material in home-building here considering Canada’s timber resources and need to well-insulated homes in a world where we are at the end of the era of limitless oil and gas for heating. Were anyone to use Canadian CLT, however, you wouldn’t be limited, as we were, by the dimensions of shipping containers. You could be more flexible with your design. A lot of things in our design started from this, which meant we went down a certain route.

We would still have the same advice for those considering using CLT as we had in this post back when it seemed that disaster was afflicting our build in January 2016: DON’T start building in the Fall in a climate like this, DO wrap your CLT structure in a breathable, water-proof house-wrap as soon as it’s up.

The roof might also be something I would rethink were we starting again. We designed it to fulfil several functions: to be at a good angle for generating solar power in the shoulder seasons and winter, to provide shade for the upper storey windows in summer and of course to be able to contain enough insulation. Originally, we were not going to use CLT for the roof, but the horror stories we heard about thee practices of truss manufacturers around here convinced us to give it a go. With CLT roof panels, we got added structural strength, which will mean the weight of any number of solar panels is no problem, however we had to have a floating rafter design (and here) in order to retain the overhang. This looks beautiful but it was very complicated to engineer and caused the insulation installation to be much more difficult – and cutting the wood fibre insulation we used into exactly-sized triangular sections was not easy (especially in the depths of winter). Had we started with CLT as our primary material, we might have made different decisions here: we could have gone for entirely different roof designs, and gone for ground-based solar panels, and considered other ways of shading. However, just aesthetically, I really like our roof and I like the fact that it goes against the grain of having roofs finish flush to the walls.

In the end, we have a beautiful, sustainable high-performance passive house, which we love and which works. It was a long journey getting here but it was worth it. We will keep occasionally updating this blog with things that we are doing (we’ve still got a solar PV system to install in 2018 for a start) and performance updates, but in general there probably won’t be more than a post a month in 2018. And we’re always very happy to be contacted with questions from other people considering building sustainably.

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Wolfe Island Passive House Performance – Final Report

We have received a copy of Anthony Mach’s final report on our place, part of a comparative study that also looks at another passive house project in Peterborough, Ontario. We’re not going to comment on the Peterborough project because we know very little about it and it’s very different to ours so, with Anthony’s permission, I will just highlight some parts of the report as it relates to this house.
Anthony’s report compares our Passive House to the new highest Canadian code standards. Bear this in mind, because the average Canadian (or US) house wouldn’t have been built to anything like those latter standards, and as for the average older house on Wolfe Island… well, let’s just say, you could probably punch a hole through the wall of many houses here, our old one included!
I think Anthony has been somewhat conservative with his estimate of the R-value of the walls and ceiling, which based on the whole assembly (including the CLT, which has an R value of 4-5 on its own, and siding) would be nearer 50 in my view. But conservative estimates are better than exaggerated claims for testing efficiency. This leads to some estimates for the house’s performance:
I’m also surprised by how much heat loss there is through the walls in these estimates, but apart from my feelings about R-values, I don’t have any basis for challenging this – it just seems like more than I would have expected. But the important thing is that our energy consumption is reduced dramatically.
I think here there is a little more erring on the side of conservatism here – basically Anthony has estimated the energy consumption of our appliance and lights to be the same as the 2017 Code standard, but we are using all LED lighting now – although we weren’t all the time when the measurements were taken in the winter as the electricians had just used a whole range of conventional bulbs – and we have fewer, smaller and more efficient appliances compared to the average household. We will have to test this empirically through the year via our bills! Anthony’s current estimate for our annual electrical bills has them at almost half the best you would get from a 2017 Code-standard house:
Of course, one of the problems with bills is that you can only reduce them so far: the majority of our bill is not use charges but fixed fees and delivery charges, over which we have no control, unless and until we are totally off-grid, which brings us to…
Green House Gas Emissions
On Green House Gas emissions, I would imagine that once we’ve installed the Solar Thermal and Solar PV panels (probably this summer, although it depends on costs), and possibly some other wind-based generation, this will further reduce our electrical draw draw from the grid and our costs, and therefore also our GHG emissions. Our eventual aim is to have zero energy bills and net zero GHG emissions.
Winter Performance
You can see more detail about the winter temperature and humidity in the preliminary results. While, as Anthony notes, we found the house perfectly comfortable over the winter, I think the house will be a little warmer next time around. Because it was uninhabited until late November and there was no heating for a while after that, the house never really built up the sustained warmth that would thereafter be preserved to a greater degree by the insulation etc. We shall see!
NB: the December average is significantly different because note that we were away for much of the second half of the month, and had the HRV set on its lowest setting and the thermostat at around 13ºC.
Summer Cooling
Anthony’s report doesn’t just cover what actually happened over winter, it also uses PHPP (Passive House software) modelling to estimate what would happen in the rest of the year. Of particular note is that the model predicts mechanical cooling will be necessary in July and August.
The HRV certainly does not function effectively as a cooling system so far as we can tell. But I’m yet to be convinced by the need for mechanical cooling. Although the primary rationale for the orientation of the house and the window size and placement was Fall-Winter-Spring heating, the house was also designed to take advantage of the prevailing wind direction and for both effective stack and cross-ventilation. Simply by opening the windows (and turning off the HRV), we think we will be able to create significant cooling. Indeed that’s how things are working now (late June) even though we are only opening the windows on the tilt setting to minimize the chances of insect entry until we have had the screens manufactured (very soon). So I think we might be able to manage without any mechanical cooling. The PHPP calculations done by Malcolm Isaacs prior to the building had said the same thing – his solution was to have a large fan which we could place temporarily at one of the attic windows in summer, and use occasionally to do an almost full-house air replacement. This may be as far as we go…
The Verdict
There is a lot more in the report, but overall, Anthony characterizes our project as a successful one, and having been here, we know he like the place!
We are really grateful to Anthony for carrying out this research, as we never would have had such a detailed understanding of the house without it.

 

Building waste, reuse and recycling

Now we’ve finished all the basics, we’re back from being away, the snow has gone and the rain has finally stopped, it’s time to think about clearing the site, landscaping and planting. The immediate thing that strikes you is just how much ‘stuff’ there is that’s left over when you build a house. And this is even given all the steps we’ve taken to reduce waste, particularly with the insulation where the Chris and his crew were superb at making use of almost every piece of off-cut wood fibre. And yet… ‘Ecological’ products come wrapped in layers of plastic. Roofers leave inexplicably large pieces of off-cut steel lying around. Siding comes in job lots that always seem to require one more pallet than you thought you would need. And so on. It would be really nice if you could plan the entire house to be precise about the amounts of materials you would need and would fit with commercially-available quantities, but that’s just not feasible.

So after the trials and tribulations of building, the challenges, the fun and the romance, there seems to be a of ‘waste’ to deal with. And there will be more once we start demolishing the old house. Anything that’s unused or reusable, we’re going to store in the barn. Material that could be of use in maintaining the new house (like any uninstalled siding, decking planks etc.), we’ll keep. We also have some plans for greenhouses and chicken coops, and so there’s plenty of stuff we can use for those projects. Other material, we will offer to anyone who thinks they can make use of it. Some, we can recycle, but unfortunately there will be some sent to landfill – as little as we can, but it seems very difficult to do an entirely ‘zero waste’ build within the current system.

But first of all, it all this stuff to be sorted out. So that’s what I’ll be doing over the coming week!