Going for Passivhaus! (plus new ugly rendering)
Andrea — July 11, 2011
After much waffling, Ted and I decided to bite the bullet and go for Passivhaus certification. More on this soon, but in the meantime we're busily weighing envelope upgrades in search of the best (read: cheapest) path to 4.75 kBTU/(f2year).
I am superstitious and have no immediate plans to change the website name. The web address, of course, will not change. I am now grateful that I was unable to get http://www.almostpassive.com, which is boldly carrying out its mission to tell visitors "All You Need To Earn Almost Passive Income Online! "
In other news I made a new house rendering, but don't get too attached because I'm likely to change it again in a few days. The new rendering places the solar panels on the top awning, which will be almost entirely unshaded and can fit 4.76 kW of DC goodness.
Things that will change in the next rendering are:
- The colors, which are currently quite ugly. We may also change the ratio of cedar shingle and reverse board and batten siding.
- The terrain and foundation, since our building site is a wooded rocky hillside and not an eerie CAD plain.
- Awnings will appear over the lower windows, though they might be removable in some way to allow full winter heat gains.
- A solar collector for hot water might appear in the gap between the two groups of windows, assuming we can afford it.
More to come!
Edited to correct Passivhaus heating requirement units
Random Bits
Before installing solar panels, get a home energy audit to find out where you're wasting the most energy. Your house will be more comfortable if you seal leaks and add more insulation, so don't just slap solar panels on the roof without curbing energy use.
Solar thermal
Ed Davies — September 25, 2011Hi, recently found your blog and enjoying catching up...
If you can afford PV how can you not afford solar thermal? Seriously, both the financial and ecological payback on solar hot water is much quicker than on PV. If you're messing with the roof and with the plumbing (which you are, of course, on a new build) then there really have to be very special reasons why it's not sensible to put in solar DHW. Even if you're going for a tankless system solar pre-heating makes a lot of sense.
Re: Solar thermal
Andrea — September 25, 2011Hi Ed,
We are doing solar hot water. I haven't added it to the drawing yet, but it'll be there.
Cheers,
Andrea
Re: Going for Passivhaus! (plus new ugly rendering)
John' O'Brien — July 19, 2011Have you guys considered going with exterior shades instead of the awnings.... They'd be far more effective in blocking the sun when you don't need it, while not blocking any sun when you need it.
Re: Going for Passivhaus! (plus new ugly rendering)
Andrea — July 19, 2011Yes, that's exactly what I've been thinking of late. We need to connect with Camilo, our consulting architect and overall aesthetic guru, but I'm currently envisioning removable exterior louvers.
Re: Going for Passivhaus! (plus new rendering)
Nick Barnes — July 11, 2011I'm confused. I thought the Passivhaus rating was 10kWh per square metre per year, i.e. 3.6e7 joules per square metre per year (about 1 watt per square metre), 3.3e6 joules per square foot per year, which is about 3000 BTU per square foot per year.
Re: Going for Passivhaus! (plus new rendering)
Andrea — July 11, 2011Nick, don't you know that everything is bigger in America? ;-)
Actually, I have no clue what the answer is — math class is hard! Have a look at the details on the Passive House Institute US site.
Re: Going for Passivhaus! (plus new rendering)
Nick Barnes — July 11, 2011Ah, 15kWh/m^2/year, which is 4.75 *k*BTU/sf/year.
So there's a factor of a thousand in there somewhere. :-)