But insulation also protects from outside heat, so a calculation that only takes into account winter heating could be a bit misleading. In Adelaide for example, it certainly isn't winter when our power stations are under peak load...its summer when we fire up endless AC units. Even Canberra would chew a fair bit of AC power over the three main months of summer.
Embodied energy is one of the reasons I was interested in cellulose potentially instead of batts, for the ceiling. Usually it comes from recycled product. Anyone have any good links on this?
Walls, I think strawbale is probably one of the best options available for insulation in terms of overall eco-friendliness. We produce so much of it in Australia as waste its not funny, and not just from traditional wheat crops, but also from rice too (probably enough to do just about every new house in Australia from rice straw, from what I've heard). Its essentially a carbon sequestration building mode, that's probably even better overall than using wood in this regard; most "sustainable" forestry takes places on land that could be set aside for native woodland that also has biodiversity value. Straw production takes place on land that is set aside for global food demand...we can't really not produce it if we want to eat. Rammed earth, earthbag etc I think definitely have their place, and can be very eco-friendly, low embodied energy, etc, however, I would only consider this if using "waste" earth from on site or nearby. Eg soil that comes from under the actual house build that would be removed anyway. I don't consider taking soil from elsewhere sustainable. It takes a long time to produce soil and its a precious resource for growing food and native vegetation. Its also not always that insulative (apparently rammed earth can be pretty good) though of course has great thermal mass. Similarly, I don't rate "earthship" style building that highly. Sure, tyres are free and recycled, and the soil should be able to come from the hole, but doing a whole house build like that takes a rediculous amount of people hours to construct. I can't get over the number of "workshops" people run where they get stacks of "trainees" (who sometimes pay...a bit wrong in my books) out to shift dirt and tamp it down for them in their earthship walls. I can see its place for sure for some needs, eg you want a good load bearing wall somewhere in the house, or a really good retaining wall for a sloped site. But going out of your way to have to do it...hmmm.
Sorry, didn't mean to rant! Thanks for the good info...its good to see people doing calcs instead of just winging it. That's why since I discovered this ata forum I've fallen in love with it!
Posted Thursday 26 Sep 2013 @ 2:58:12 am from IP
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