Category Archives: energy systems

blower door test

The house envelope is super-insulated and super-sealed. In a passive house, the objective is to seal the home envelope so well that heat energy created by the sun, wood stoves or the back up electrical heaters stays in the house (as long as possible) because there are so few air exchanges or leaks.

The blower door test helps you measure how well your builder/team sealed the envelope: “With a blower door, builders can quantify airflow and the resulting heat
(or cooling) loss, pinpoint specific leaks, and determine when a home needs additional mechanical ventilation.” Energy conservatory has a good article on the testing process.

Rob Gawreletz from Alberta Eco-Visors came the other day to do the blower door test.

blower door test from inside

blower door test from outside

After an initial first reading, Rob depressurized the house so that outside air would try to enter the envelope. Then we walked around and identified a few spots where there were minor leaks around doors and windows that had not yet been caulked for painting etc. We noticed that the plumbing stack, which wasn’t hooked up yet, was not closed off. Oops. And we felt some leaks around where the HRV intake pipe entered the box. Both were easy to fix with duct tape.

The test is helpful. You can correct any minor leaks right away with acoustical sealant or other types of sealants in finished areas.

I’m really glad we went with the spray foam on rim joists and the blown in cellulose walls too. They are sealed nicely.

The results were good: .63 ACH (after we sealed the obvious pipes) – .84 ACH before). Congratulations to Doug the builder and the crew. Excellent job.

An average home today is 1.5 ACH or higher. The net zero homes in the city are at about .7 ACH or so after much hard work. . . so we are in the ballpark.

Doug Hyde (DC Hyde Construction, Athabasca) and his team were meticulous and deserve all the credit. Doug told me that he was trained to always take much care when sealing his homes. But this was the first time in his long career that he ever had one of his buildings assessed with the blower door test. Now that he saw the few small errors and fixes, he is looking forward to the next home and next test. And that’s how your good builders become even greener.

I hope Doug becomes an ambassador of the blower door test for other consumers and other builders up north, where winter is long and cold. If there were more grants to reward smarter building standards, as there are in other countries and provinces like British Columbia, then Alberta would be further ahead.

Tomato Man


a cord of wood

We stacked a cord of wood on the weekend.*
One could say it was our pre-game warm-up. ha.

we will appreciate this at -40C

doesn't this stack look good?

*yes, there have been other changes at the bomo house. But they, like painting and a new! rail! on the stairs, are far less photogenic than a woodstacker and a pile of chopped spruce.


basement wood stove

As the mudding contributes a lot of moisture to the air, and the house has a tight envelope, and the temperature is starting to drop, we have had the basement wood stove installed. It looks great, and for a relatively small woodbox, it burns for a pretty long time. We’re still not sure exactly how long a stoked fire, dampered, will last, but after twelve hours, the coals and stove were still quite warm.

basement woodstove



HRV=Heat Recovery Ventilation. Part of our heating system.
And in general, heating systems are the TMG’s turf.
The Tomato-maker is busy transplanting, though, so the best I can do is a wikipedia description and a picture-y slideshow of ducting and the guts of the HRV system.

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blown cellulose insulation

The walls are now insulated!

The staggered 2×4 construction of the double-stud framing has allowed us to blow in up to 16″ of cellulose insulation in the exterior walls, and get close to R-60.
We have used spray-foam on the rim joists and a few other hard-to-reach spaces like the ceiling of the dining room (you can see it in the “before” picture. The dining room room doubles as the floor of the second-story balcony, so needs some extra protection.


ceiling insulation

In the ceiling, we are using roxul, a mineral wool insulation. Roxul R-value at the ceiling should be 58.

Although we like the look (and dependability of the product), everyone’s favourite grey ultra-tape will not be a finished feature of the system (that is, it’s only holding the ridges in place until the glue sets).


walls are up

Here we have the first floor walls, the exterior of them anyway.

Dining room window

Yes, those are 2x4s. We’ve modeled our exterior walls after those in the Riverdale Net Zero Project. They have an explanation on their FAQ page (Q7) about why they’ve built a dual stud wall. For us, the dual stud construction affords room for extra insulation while avoiding thermal bridging that occurs with a traditional 2×6 construction. A bonus is that 2x4s can be cut from smaller trees, and we like the idea of thick window sills. We are in the process of nailing down (pun intended!) the insulation methods for these exterior walls, and are closest to finalizing a combination of sprayed icynene and blown-in cellulose.
Early on, we had to focus on our top building priorities. While ethical sourcing, low off-gassing, and low “energy-in” are all important to us, our prime directive is to affordably build a house that is efficient to run while considering our northern climate. We have compromised. And of course, capturing the view underscores it all.

south-facing solar wall

This south-facing solar wall is intended to capture the greatest amount of solar heat and light for the space. Our open-concept staircase will be just inside this window-wall.