It feels like things are starting to pick up and the place is really starting to look and feel like a house. Yeay! Over on stuff.co.nz this week I'm talking about the air tightness system from ProClima that we've installed - another of the Passive Design principles we've chosen to adopt in the build. As I keep saying we are not trying to achieve PassivHaus standard because we simply cannot afford it. To put it in context: getting the right windows on our build to meet the standard, we would have meant adding more than 20K to our bill (that's over and above the double glazing, LowE glass windows we already have, I'm talking ones that are truly air-tight - but that's a whole other post that I'll come to when I talk more about numbers).
We have, however, been able to put in the air tightness system and we're already feeling the big change in warmth in the building - and we haven't even got the real doors in yet! Seriously, while there is white ice all around outside (which doesn't happen often in Auckland) it's pretty warm inside, and like I said, that's without proper doors and the garage still being open.
In case you're not heading over to stuff, the basic principle of the air tightness system is giving our insulation the best possible chance of keeping us warm. It's a Goretex jacket over a woolly jumper - keeping all the warm in but not letting the cold air outside steal it and make us need to heat the house with means we need to pay for.
The process is relatively straight forward: cut Intello pieces to fit, staple them in place and tape the puppy every which way to Christmas. We also need to tape or fill every nook and cranny we can find, so around power points (where there are special boxes to help with the job), doorframes, floors, ceilings, you name it, we're trying to seal it up. It’s another job we’ve done ourselves with staple guns, a sharp pair of scissors and some seriously specialised tape from ProClima.
We’ve had to think hard about plumbing and wiring – keeping as much of that in the internal walls as possible, because every time we make a hole we have to seal it up. Real good. In the ceiling however, we got round that problem by creating a service cavity, fixing the Intello directly to the frame and then using GIB Rondo battens to create the cavity for wiring and light fittings.
We’re not experts, and a few insulation installers do put it in, but it’s a pretty specialised product so it’s not like the yellow pages are crawling with installers yet so it’s hard to gauge how much we might have saved putting it in ourselves, but to put it in perspective it’s taken Mr BuildingBoxes about four and a half days, plus the blower door test (which is definitely outside of our scope). And speaking of blower door test, if you have popped over from stuff, here are the edited highlights with Jon Davies from ProClima New Zealand.
Happily yes, we did manage to crack the rating we were hoping for, less than 2ACH, which wasn't bad considering, as I said, we've still got work to do. The process of course is to do this test now, while we can access the membrane and seal up any obvious leaks. Then when the linings have gone in and we're almost there, we'll test again to see how we're doing and the rating should drop again. So 2ACH at this point is great, compared to anywhere from 5ACH in a great new build house to 10ACH in a pretty standard one. Should save us plenty on powerbills as we manage to use the heat we've gathered in the insulation and the thermal mass in the concrete slab rather than turning on the heater! And just in time, it's been COLD this winter!
A family of four: writer, scientist, lego engineer and destruction specialist. Our previous home is featured in New Zealand Interior Style and this new project promises to provide plenty of great, green, smart and maybe madcap solutions to new building in New Zealand.