Energy Answers

Editor’s Note: I’ve written about Rob Dumont in the past. He is one of the fathers of the green building movement, and I’m very pleased to have permission to reprint one of his columns here.

By Rob Dumont

Have there been any recent advances in the area of passive solar heating for residences?

Passive solar heating has been known since the time of Socrates. However, it is only slowly catching on in Canada. Improved windows have made the recent advances possible.

In the 1970s there developed two schools of thought regarding how best to reduce space heating bills in residences using passive means. One school was called the “mass and glass” school. With this approach, large south facing windows would be used along with concrete slabs and heavy construction such as adobe. This school had a lot of proponents coming out of the south-western United States. New Mexico was a hotbed. New Mexico has an especially favourable solar energy climate and relatively mild outdoor temperatures compared with most of Canada. A photo of the David Wright Home in Santa Fe, New Mexico, is shown in Figure 1. In Figure 2 a cross section of the house is shown.



Figure 1. South exposure of the David Wright House in Santa Fe, New Mexico

(Photo Credit: Design for a Limited Planet, Skurka and Naar, 1976)



Figure 2. Cross Section of the David Wright Mass and Glass House

( Credit: Design for a Limited Planet, Skurka and Naar, 1976)  read more... »

Making water line connections in the attic

I have to make connections in my attic for the 3/4" copper pipes that do the supply and return runs for my solar thermal collectors.  I'm NOT looking forward to soldering amoung the blown-in insulation.  Someone recommended SharkBite non-soldering connectors (  The appear to have a high enough ratings (certified to 200 PSI and 93 degrees C) but I'm concerned about how they will stand up given the extreme temperature changes in the attic.  Has anyone used these connectors?  Does anyone have any experience with SharkBite fittings and solar thermal systems?



The importance of air tightness in building construction cannot be overstated. Very few factors affect energy performance in a cold climate more than air moving in and out of a building.

The Mill Creek Net Zero Home (MCNZ) has achieved an air tightness test result of 0.36 air changes per hour (ACH) at a pressure of 50 Pascal. In other words, when it’s really cold out, which creates a big pressure difference between the inside and the outside of a house, the 0.36 of the air in the MCNZH would leak out and be replaced with cold air over the course of an hour. It has the equivalent of a 13.8 square inch hole in it leaking air all of the time.

To put the number (0.36 ACH @ 50 Pa) into perspective, here are some average numbers:


Source: Biggs et. al. 1987

The 0.36 number is extremely small. In fact, the MCNZH is probably one of the most air tight wooden buildings in the world.  read more... »

Alberta Home Gardening Blog


An article in the Edmonton Journal yesterday led me to a website by a local gardener. There is no greener activity than producing food in your own backyard, and there is much room for innovation in our northern corner of the world. I’m constantly delighted by what you can grow here, and how many different types of wonderful food can be produced in a few short months of summer.

Of note is the post “17 Hardy Fruits That You Can Grow On The Prairies”.  I’ve put a link to under “100 foot diet” to the left of your screen.