OK, so it’s been about 3 years since we moved OUT of our wonderful “almost passivhaus” house in Stow, MA… a few comments (now that I have a little distance) about things I would do differently.
1. Building a passivhaus in very cold climates is important but not *that* important. Our’s was REALLY close but even getting as close as we did was VERY expensive because it’s such an unusual thing but also because the climate is so extreme that the insulation needed (to do it right and not have condensation problems) is expensive. Condensation… see book: Builder’s Guide: Cold Climates
2. Building a cube is… not that important.
3. A custom design is… not that important.
4. Building the house so the roof points EXACTLY solar south (or whatever your designer tells you is absolute best for PV solar panels or passive-solar) is…. not that important
5. Small windows on the North is… not that important. It’s important, but not at the expense of views and connection to nature.
What to do instead:
1. Instead of passivhaus, do something more along the lines of the “pretty good house” (google it) with 10-20-40-60 insulation. Why? You can get 90% of the way there for $100k or more less money which would be more efficiently spent on saving the planet with solar panels. The house will be just as comfortable.
Read more:
http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/pretty-good-house
Good example: Bick Corsa’s house, but you can obviously make a fancier design.
http://www.builditsolar.com/Projects/SolarHomes/MAZeroEnergy/MAZeroEnergy.htm
2. There are lots of energy efficient houses in recent years that are tall little cubes with footprints on the scale of 26×26, and sure that is a LITTLE more energy efficient and uses less concrete for the foundation or basement, but it also is less ideal for 1) entertaining since you have a small 1st floor 2) little kids … stairs to get to bedrooms and playrooms means more separation… they want to be closer to the action which is in the living room and kitchen. Sure there will be a time as they get old where being farther away is good too, but there are ways to do both.
So… instead?
They get knocked a lot, but the classic split-level ranch we have found to be the ideal compromise. Everything is a half-flight away and there are long views that are right out of A PATTERN LANGUAGE. It’s a popular design for a reason. And number 3) a wider foot print means more space on the roof for solar panels.
Book info: A Pattern Language
3. Since you are interested in this stuff, you will most likely be perfectly happy with a stock plan … just build it with slightly thicker walls for more insulation — either a double wall or with crosshatched studs. Your interior rooms will be at most 6″ smaller and the only details to have worked out is how to frame the doors and windows a little differently and just be careful to pick a plan with a simple roof line so that air-sealing is straightforward. This doesn’t have to be so difficult.
4. Getting close to solar south is good, but even a full 45-degrees off will work quite well. Solar panels are MUCH cheaper than they were just a few years ago so you will still get huge savings, especially if your electric company allows net-metering. But even without this, it’s still worth it — we didn’t have net metering in Stow at the time and it will worked out $$-wise. You’ll see by changing the orientation at PVWatts that it doesn’t matter that much.
5. Do some windows you want on the North. Not worth sweating it. It’s worth the extra $100 a year in energy costs (because this is literally how little we are probably talking) to have the view and house design you want. If you fell guilt get the *even fancier* windows with even more panes of glass and better insulation in the frames. If it’s the environmental damage that concerns you… buy some more carbon offsets or PV panels for your neighbors house, ride your bike more, or cut down on your meat eating. Lots of other things to do.
6. I would probably do “rafters” instead of trusses (“parallel-chord scissor trusses” to be exact). I assume (perhaps naively) that rafters would be easier to modify, say if you later wanted to add dormers to a third-floor unfinished attic. Some in green building maybe see this as EXACTLY the reason to do trusses — you don’t want to make it too easy for someone to ruin the very-energy efficient envelope in the future! But I think that’s a wrong and dogmatic view of things. Do rafters if you’re on the fence. I know there are other trade-offs, like you’ll need a place to transfer the load downward at each end of the main beam, and that can restrict placement of windows, etc. but ¯\_(ツ)_/¯
What does matter instead:
1. Location location location. Our solar panels in Stow generated as much energy as we used doing extra driving vs living closer to our work and schools in a less ideal house. And living in a walkable neighborhood close to friends, shops, nature, etc. Our Stow house was in a dream location in terms of nature… amazing quiet and nature and trails and water. But the driving was a bit much for us.
2. Connection with the site. Views. The yard you want. We had that in Stow, but just be careful to not let the tail wag the dog. Sometimes a certain house design will just not work with certain sloped lots. That’s OK, do something that makes sense for the location and site you love!
3. A garage. OK, build it separate or not (it can be designed to visually loot connected, but all the air-barriers can keep it separate). But build it! 2 reasons: 1) even more room for solar panels. 2) Could allow you to build a smaller house, but leave some unfinished space for bonus room for later, or for storage space (if you are not building a basement or attic) We are an active family and need room for 1) bicycles, scooters, skateboards, ramps, ski equipment, camping equipment, kayak, canoe, etc, etc. It’s very difficult to fit this amount of active gear into a small shed. That was our experience at least! Just build the garage. They also work very well as a mudroom. (Also a must have but a section of garage can do pretty well double duty as a mudroom. I’ve also seen a screen porch work very well as a mudroom….)
See also:
My further comments about A PATTERN LANGUAGE
Book Review: A Pattern Language
Erik's Blog 