Green / Eco-Friendly

Wall thickness/construction on new construction

  • Last Updated:
  • Oct 25th, 2018 6:52 am
[OP]
Member
Dec 19, 2015
460 posts
231 upvotes
Calgary, AB

Wall thickness/construction on new construction

I’m in the process of deciding whether to knock our old 1950s bungalow down and build a two story house instead. That gives me the option of choosing features with greater “eco” value. Obviously I’ll be talking to designers/architects, but I’m trying to work out whether to spend the extra and go for a specialist in low energy houses, or just a normal designer and a few tweaks.

If you were building from (mostly, basement is stil 2x4 R12 insulation, so no passivhaus) scratch what wall construction would you go for. My one worry is if I went for 12” double stud/ twin layer 2x4 I’ll lose a lot of interior space with the additional 8” of wall which presumably would end up on the interior, not the exterior? Other options would be 2x6 with cellulose and 2” solid on the exterior or just a thinner 8” 2x4 scissored wall.

Anyone done any of this and have an idea of the additional costs involved with these options over just a standard 2x6. I know I’ll never get the money back in energy savings, but I’m happy to pay a little over for comfort and “eco cred”. Alternatively would it be better to just save the money and get better triple glazed windows (I’d probably go triple anyway).
4 replies
Deal Expert
Aug 2, 2001
15111 posts
5379 upvotes
Since you're in Calgary I would talk to fellow Net Zero people to see what their thoughts are. When I have talked to them I believe they said you can get to 80%-90% Net Zero for a very small cost, it's being total Net Zero that drives the price up greatly.

For example, here is an individual in Edmonton that went with extremely thick walls:
http://www.greenedmonton.ca/MillCreekNetZeroHome.html
[OP]
Member
Dec 19, 2015
460 posts
231 upvotes
Calgary, AB
Thanks, do you have any recommendations of who to contact in this regard?
Deal Expert
Aug 2, 2001
15111 posts
5379 upvotes
Andy34 wrote:
Sep 18th, 2018 10:59 am
Thanks, do you have any recommendations of who to contact in this regard?
Here's is the twitter account for the individual with the NetZero home in that article (he's active so message him):
https://twitter.com/conradnobert?lang=en

The link above (in my original post) has many details on his house. I believe it was built by Habitat: http://habitat-studio.com/
Deal Addict
Feb 25, 2007
1089 posts
500 upvotes
Ottawa
Friend of mine in Quebec is building a very energy efficient home. A few relevant observations:

1. As others have said, aiming for the gold ring (net zero, Passivhaus, etc.) tends to be quite challenging/expensive, and from a full lifecycle cost perspective, in the Canadian climate. It's most cost efficient to aim for "nearly there but not quite". Getting the gold ring pays off if and only if you resell fairly quickly to a buyer who values the cachet of the certification, or if you feel that part of your own contribution to society is to support such initiatives as an early adopter.

2. In his case, he's found best bang for the buck in working with an energy efficient specialist at the beginning of the process (to figure out what makes sense at his location), and at the end, to get the details right on the design, but with a "normal" architect in the middle for designing the home to his needs. Of course, this depends on finding the mix of people who are happy to work together, and in his case it was easy to justify in a face-saving way for everyone. (Architect 1 brings in Asian influences and is curious but knows nothing about low-energy design; architect 2 is an energy-efficient design specialist but has a very different aesthetic style.)

3. While the 80-20 principle applies (point #1) to designing to full standard vs nearly-there, this is *not* the case for the actual building. You can lose an awful lot of energy efficiency silently and irreversibly by a builder who cuts corners, or merely doesn't quite take as much care in sealing the building envelope etc. as they should. So ideally go with a *builder* who is experienced building energy-efficient homes, and make absolutely sure there is the oversight on site needed.

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