Sustainable Building Program and Courses at The Endeavour Centre

More Trent University students may be able to eat locally-grown produce year-round at The Seasoned Spoon cafe, now that their subterranean earthbag root cellar is nearly complete.

This project is very unique, using local low-impact materials to create a food storage structure that will be able to house a range of vegetables at proper temperature and humidity levels year round, without energy intensive cooling or heating equipment.

Here is a complete set of progress photos, showing the building from start to finish:

Endeavour would like to thank the Seasoned Spoon for the chance to be involved with such a great project. Thanks also to Trent University for accommodating the build.

Tim Krahn of Building Alternatives was the adventurous and participatory structural engineer on the project, and Ben Parkes was the lead builder, with lots of help from Justin McKeiver and lots of volunteers.

We’ll post a final look at the root cellar when it’s all complete.

The Sierra Legal Defense Fund’s Sewage Report Card for Canada says “Over one trillion liters of primary or untreated sewage is collectively dumped into our waters every year by cities evaluated in this report (of 21 Canadian cities). This volume would cover the entire 7800 kilometer length of the TransCanada Highway to a depth of nearly 20 meters – six stories high.”

With this in mind (and remembering that this statistic is only counting large cities, not smaller cities, towns and individual homes), it is not possible to think about building a so-called “green” home if that home is contributing to this huge environmental problem.

However, unlike many other environmental issues that are complicated and difficult to address, this one can be handled quite simply: We need to compost our own human excrement. The process is not difficult, and there are solutions that range from the simple and inexpensive (see The Humanure Handbook for the $20 solution) to the more expensive – but still remarkably simple and affordable – chamber-style composting toilet as installed in our Canada’s Greenest Home project.

The bottom of the holding tank for the Clivus Multrum M10 composting toilet.

This is the only time you’ll catch me inside the composting toilet tank!

We started the installation of our Clivus Multrum M10 composting toilet unit today, and we’ll cover that installation in more detail as it progresses. But this is not just a “flashy” green addition to the home… we consider this one of the most important features of the home. Not only does it remove this home’s black waste from the atrocious statistic above, but proper composting of human waste creates useful and nutrient-rich soil amendment. At a time when we can ill afford to pollute more fresh water and when soil depletion is a real and growing problem, the composting of human waste provides a win-win solution.

When asked at workshops and public presentations what the one biggest “green” improvement somebody can make to their home, my response is always to move to composting toilets. It’s not a popular answer. We don’t like to think about our own excrement, let alone contemplate dealing with it.

But it’s not as yucky as most people would think. Dealing with a dog’s waste with your hand in a plastic bag is much more visceral and disturbing than dealing with a well-managed composting toilet system, and millions of people have been “trained” to pick up after their dogs. With that in mind, it’s not hard to imagine a future in which turning our own waste into useful compost is socially acceptable and expected.

This woman picks up her dog’s poo with her hand in a plastic bag! Can we be trained to deal with composting toilets?

Those of you following this blog will know that a lot of time and energy has gone into making Canada’s Greenest Home as air tight and energy efficient as possible. And you probably saw our self-congratulatory post about our great blower door results last week.

This was the first piece of cut barrier we noticed, right above the door.

So imagine our shock and horror when we got to the house this week after the drywall crew had been there to hang board, and saw that they had cut through our air barrier in countless places! And this was after having a talk with the owner of the company stressing the importance of air tightness in the project and receiving his assurance that his crew were aware of this and would be careful!

It doesn’t really matter how well designed a building might be, how much attention each person on the crew puts into their work… if one trade on site is not committed to the idea and the execution, the building will not meet its goals.

In this case, we found these tears and will peel off the board and repair them. That should bring us back to the air tightness we’d achieved prior to the drywall (especially with the Siga tapes).

But if we had stayed off site until the drywall was done, all of this would have been covered up and we would have been surprised to find our final blower test showing much worse results than our initial test.

Is it any wonder the building industry squashed the proposed regulations that would have required a blower door test by code? There just isn’t enough training about high performance building for the trades and not enough buy-in from the guys on the ground to ensure that buildings will perform as well as they can and should.

The roto-zip tool leaves distinctive shred marks…

…While the drywall knife leaves a clean, straight cut. Both require the drywall to be removed in order to repair.

At 0.99 ACH50, we broke the magical (in our minds!) 1.0 barrier. This is a very air tight home!

After our somewhat disappointing blower door test last week, we threw some mud at the walls (well, we placed it carefully around the edges of the wall), did some taping and caulking, and then had Ross and Kat Elliott of HomeSol Building Solutions come by to do our official blower door test.

We went from a code-compliant 3.1 ACH50 (air changes per hour at 50 Pascals) to an almost PassiveHaus compliant 0.99 ACH50! We could feel some small areas of leakage to be addressed (almost all were failures of the Tuck Tape to properly adhere and seal against the air barrier membrane!). After the test, we realized that we hadn’t covered over the sump pit in the basement, and so we think we can do even better on the final test once the house is finished. Ross suggested that it’s common to improve the air tightness by around 20% once all the interior wall and ceiling sheathings are in place.

Even if we end up slightly shy of the 0.6 mark, we are very excited to have built a house that far surpasses the air tightness of conventional building, and to have done that using mostly straw bale walls and even clay plasters. It’s an indication that the use of natural building materials and “alternative” methods can be part of an extremely tight and energy efficient building.

Our thanks to all the students whose constant awareness and vigilance regarding air tightness as we built the house helped to ensure that this result was possible. Way to go, Graham Wise! And our thanks to Matt Caruana for last week’s test… we wouldn’t have achieved this score without a first kick at the can!

As those of you who’ve been reading this blog will know, we’ve worked hard to make Canada’s Greenest Home as air tight as possible. In fact, we’re aiming to try and achieve a PassiveHaus approved 0.6 ac/h (air changes per hour at 50 Pa depressurization). So it was exciting today to have Matt Caruana come by and bring his blower door outfit and his laptop to give the house a first trial run! This is in advance of having Ross Elliot from HomeSol Building Solutions, our official energy rater, come by next week.

Matt Caruana calibrates the blower door and reads the results on his laptop. The blower depressurizes the house, so that outside air tries hard to find its way in. On a cold day like this one, it’s easy to feel the air coming in.

And it’s a good thing we had a first-round test with Matt!…

The first test showed that, despite all our efforts, there were some significant areas of leakage. Fortunately, they are all areas that can be addressed before the next test.

Our result for the first test was 3.15 ACH50, with an equivalent leakage area of 74 square inches (about an 8×9 inch hole in total over the 3,780 square feet of wall area, or 1/7355 of the wall area). What happened? Where were the leaks?

The good news is that we did a really good job of sealing the common areas of leakage. We detected barely any leakage from any of the windows, electrical boxes or seams between foundation and floor or between the two upper floors. All our efforts to make these areas tight definitely paid off.

There was some leakage from our temporarily taped up attic hatch and the cover over the temporary back door. These can be better taped next time around and that will definitely make a noticeable difference in the results.

By far the leakiest area was around the edges of our site-baled north wall. Despite using air fins at all the seams with the prefab walls and the ceiling, the upstairs north wall was leaking significantly all the way around where the plaster had shrunk away from the edges. A quick calculation of this 1/8″-1/4″ gap all the way around the whole north wall says that this could account for almost all the leakage area Matt detected.

This seam leaked like crazy! The air fin that extends behind the plaster was not sufficient to keep air out.

This seam used the exact same style of air fin and in this case no air came through. So our system works, but not reliably!

Surprisingly, the downstairs north wall, which is built in the same manner, using the same detailing, had barely any detectable leakage. Visually, the separation of the plaster is the same thickness, and we used the same plaster mix and plasterers, and the air fins were made in the same way. Our best guess is that the mesh over the air fin may have been better embedded in the plaster downstairs, keeping the plaster tighter to the wall. The takeaway lesson for us is that while this detail can work, it’s definitely not a guaranteed way to seal this seam.

Similarly, there were leaks along the edges of a few of the prefab straw bale wall panels. They were detailed in a similar way to the site baled walls, with an air fin under mesh around the edges of the plaster. And again, some worked very well and others did not. We’ll have to do more thinking about how to make this a more effective and reliable detail on future builds.

As with the site baled walls, a few seams in the prefab walls leaked around the air fins.

The majority of the seams in the prefab bale walls did not leak. But there was no visual indication to say which worked and which didn’t.

Fortunately, these leaky areas can be easily addressed by caulking the gaps between the edge of the plaster and the abutting wall. There is still another layer of finish plaster to go on the walls as well, which will further help to seal and protect the caulking. We’ll take care of these areas before the next blower door test, and then be able to focus in on finding the smaller holes!

A result that sees the house achieve a result somewhere between the 1.5 ACH50 of the R2000 program and the 0.6 of PassiveHaus would make us really happy!

Our results today point to the difficulties involved in making buildings as air tight as possible. We had drawn careful details at the planning stage and spent a lot of time and energy on site making sure those details were well executed, and still didn’t get a great first result. Because we’re taking the time to test at multiple stages, we will find these leaks and fix them. But not every house will get this attention to detail, without which air tightness is a nice idea but unlikely to become a reality. Each and every member of the build team needs to have air tightness in mind as they do their work, and builders need to plan for the time it takes to test and address issues. It would help if such blower door tests were mandatory!