You could do that, but you will not get into Dwell...
Andrea — June 16, 2012
When Ted and I started this endeavor in 2009, I didn't know the slightest thing about construction. I couldn't have told you how a stud wall is built, or even described with confidence what a 2x4 looks like.
My how things change! Just last night I dreamt I was quizzing a contractor about air barriers and external insulation, while harboring deep suspicions that he hadn't properly managed the vapor barrier on the 2x6 walls of the house he was rehabbing. I was gearing up to explain why polyisosyanurate was a better choice than extruded polystyrene (XPS) for above-grade rigid insulation, since the blowing agent used to produce XPS has a much higher GWP (global warming potential) than the one used for polyiso... but then I woke up.
I honestly never intended to jump into the deep end of residential construction theory! We simply wanted to build a comfortable and energy-efficient house, which led us to Passivhaus, which led us to our energy guru Marc Rosenbaum, who opened my eyes to the rough and tumble world of building science.
I have a problem with the Passivhaus people, because they are building ugly freaking boxes. The only way to get a building to last a long time is if the building is maintained, and people have to want to take care of it. People do not take care of ugly things.
Ouch! That one hurt a bit, probably because I sometimes worry that our house is an example. The exterior is nowhere near as bad as some passive houses I've seen pictures of, but it is not quite as handsome as I would have liked:
I should mention that this is the house's least flattering angle, and it looks particularly odd without the solar collector that will attach to those two white strips on the facade (probably making the house look even odder). I'll post more flattering and accurate photos below, but you can see that we have indeed built a big freaking box.
The house didn't start out like this. We got invaluable advice from our friend Camilo, an architect in New York, and he designed something a lot more stylish:
But reality intervened, and we had to stray far from his plan. Our building site is both sloped and ledgy (i.e. lined with bedrock), so a stem-wall foundation was impractical, and we needed to shorten the house from 58' to 46' to keep the lower piers from rising ludicrously high. This meant lopping off some space (which we probably won't miss at all), and it made it easier for us to reach Passivhaus numbers, but it also made the house more boxy and less "architectural."
We were very sad to have to reverse the roofline, since it drastically reduced the amount of space for solar electric panels. We therefore added the overhang to the top of the south wall, which turned Camilo's dramatic design into a stark-looking quasi-saltbox.
That said, I don't think our house is ugly enough to invite future neglect. In real life, it looks a good deal better than that first photo would suggest. You can't really see the garage in that photo, and the garage's south-facing roofline complements the house nicely:
It looks even better from the road (which of course is how most people will see it):
And the best part, frankly, is the interior. While we mercilessly chucked most of Camilo's exterior design, we consulted him regularly about the floor plan and followed his advice even when it would have been cheaper or easier to ignore it. We refused to replace his vaulted ceiling with a standard attic, which meant we had to find joists that were deep enough for Passivhaus insulation and also strong enough to bridge a 26' clear span. We also sacrificed upstairs floor space to preserve an atrium-like expanse above the dining area. I spent countless hours in SketchUp tweaking and tuning the interior, and now that the house is drywalled I can see that my time was not entirely wasted. It really is a cool space, and it doesn't feel generic or boxlike at all.
Ordinary houses breathe through leaky joints and poor seals, losing heat and wasting energy. But our house won't leak, so we'll use a heat recovery ventilator (HRV) to admit fresh air and expel stale air, transferring heat from one stream to the other.