Wall Insullation

Combined with the decision on the type of structure, we needed an idea of how to insulate the walls. Conventional insulation would assume 6" walls with 'pink' fiberglass insulation in between. This provides too little insulation and too much thermal bridging. A netzero house in Edmonton is using a nice double wall design that utilizes two 2x4 walls with a 6" gap in between. We also looked into blow-in cellulose, straw bale (but the climate is too wet), structured insulated pannel (SIP) walls (our walls aren't structural), and put a lot of thought into where the air/vapour barier should be located in the entire system (most people but the air barrier on the inside of the stud wall, a big mistake in my opinion as this makes the house much more difficult to seal). We really liked what the energy nerd had to say about external insulation techniques and we've decided to go with the REMOTE technique with two layers of 3" rigid insulation on the outside of the studs and air barrier. The same goes for the ceiling and should make it a lot easier to seal the envelope.

Once the technique was determined we sourced out the insulation. Purcell Timber Frame orders R22, 3.3" thick isoboard for their roof structure (I hope to post a blog on roof structures). We decided to get them to order some extra for the walls too. I first got confused with R values but I have learned (thanks to wikipedia) that there is the R value (ft²·°F·h/Btu Imperial Units) and the RSI value (m²·K/W - SI Units). The commercially available insulation uses the imperial units but the Canadian CSA standards use the SI units.

Here's some photos of the final result.




As a side note, I have to poke fun of the BC Hydro power smart team, who recently set up a mini power-smart demo 'house' as part of the 2010 Olympics. Going inside you got to see some fancy energy saving electronics and a washing machine and radiant heaters (which I believe are bogus), but when you asked them 'what is the insulation?' they naivly proclaim that the walls are R12 and the roof is R20. For an energy efficient design that is ridiculously low. I think it's even lower than the Vancouver building standard... I've looked into this a bit more and it turns out the 'Power smart' group don't know much about insulation or energy efficient construction, just electronics.