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.

 

Preliminary winter performance data

We have had temperature and humidity data recorded in the house over the last 4 months as part of a project conducted by Anthony Mach, a passive house designer and Building Science research student at Algonquin College. The preliminary data is now available, courtesy of Anthony. What we have here is essentially the raw temperature and humidity records in two locations: one in the middle of the open-plan downstairs space (1st Floor), and the other upstairs on the landing (2nd Floor). There is a lot of analysis to be done with this data combined with other data on external temperatures, energy use and so on.

A few things to note when looking at these charts:

1. We were only half-moved in for most of November – we started using the kitchen sometime in the second week.
2. When we moved in (around the 21st November), the HRV (which actually turned out to have an ERV core – for more on the differences, see here) had still not been properly balanced and we were still only using the system on its lowest setting.
3. After the HRV had been balanced properly on the 4th December, we started using it on the middle setting, with boosts after baths and during cooking.
4. We only had the 2kW Thermolec heating element, that works with the HRV, installed on December 14th. Up until that point we had only been using a single 1kW space heater. If it was cloudy in the morning after this point we used both, but if it was sunny we didn’t need the later.
5. However, that installation coincided with a serious cold spell where external temperatures dropped to -25ºC or lower.
6. We were away from the 20th to the 30th of December, and had the HRV just ticking over, which means that the house would have had almost no internal heating. You can see the drop, but what’s remarkable is that the place still never got below 13ºC.
7. Once everything was back to normal and functioning properly, from early January, the temperatures in the house were generally between 17ºC (average night-time low) and 19ºC (average day time high) upstairs, with the extremes being 15.5ºC and 21ºC; and 18ºC (average night-time low) and 20.5ºC (average day time high) upstairs, with extremes of 16.5ºC and 22ºC. The difference is probably explained by a combination of the use of the extra heating downstairs, the passive solar effect from the larger windows, and generally that there is more activity downstairs for more of the time.
8. The humidity has generally been where you’d want it, between 40 and 50%, gradually drying out as winter goes on. Our HRV having an ERV core helps in stopping the place getting too dry.

February 2017 Round-up

The house and the frozen lake beyond

We’ve not been posting recently because not much is happening. We’ve had and passed the electrical inspection, which means we can actually start to put in the light fittings we intend to live with (which are mainly European and Japanese and while perfectly safe, have not been submitted to Canadian inspection). Chris and Anne from New Leaf Custom Homes came round to discuss the few small things we need to do to get through the final inspection and get our official occupancy permit, which should get done over the next couple of weeks. Beyond that, we don’t have the money at this point to do anything else for a few months. So, the Japanese room, built-in shelving will have to wait, as will the solar array and home battery system.

We’ve had a few interesting and critical comments on aspects of the design from the edited reposts of earlier blog entries that are being published on the excellent Green Building Advisor site, and I’ve responded to those in the site, but the simple observable truth is that the house works. We’ve been in it since December now and even though this has been a grayer and cloudier winter than usual, which means the solar gain is less than normal, the house has still been maintaining an even interior temperature of between about 15ºC (nighttime low) and 21ºC (daytime high) without the wood or pellet stove that so many people insisted that we would need. Rainwater / snow-melt harvesting has also provided for all our water needs without any sign of getting low, although this winter we may have benefitted from the unusually uneven temperatures. Short version: whatever, we could have done differently, and indeed would do differently were we starting again, it’s all good. We already published some reflections on why we did things the way we did, last year, but I will do a more detailed post on exactly what we would change were we starting again, because that’s really what everyone else who might be considering this kind of house wants to know…

Now here are some more pictures…

Looking along the south-facing porch

Icicles forming as snow melts off the porch roof

Morning sun on the south face

West face in the snow