Passivhaus

[Bryan Couch]

There really isn't a lot of discussion in this section but I'm wondering if anyone on the site has any first hand experience in Passive House design? This is a very intriguing concept and seems to be very big across the ocean in Europe. I'm curious about any cold weather designs. It seems, comparably, very easy to design and build for areas without freezing temps and and progressiveness more difficult and involved (expensive) the farther north you go.

I've seen a few examples here (http://www.ecohome.net/news/latest/kenogami-house-designed-endure) and another still in construction with a lot of pictures and descriptions here (http://cottonwoodpassivehouse.ca/).

Judging form the amount of hits I get on designers and builders in Ontario and the rest of Canada it seems that this style of construction is just starting to become known. I'm trying to find someone with some practical experience to talk to about the possibilities in my neck of the woods.

[Torry Jackson]

I have been designing and building passive solar homes since the early nineteen eighties.

More recently I began putting together some online interactive lessons on Passive solar design which you can access for a small payment via my website. Otherwise message me and may be able to offer free advice.

http://www.sustainabilitysolutions.net.au/

[Rob Beckers]

Bryan, since your somewhat older thread has surfaced again: I know someone who's building a passivhaus here in the area (http://www.passivehouseontario.ca/index.html). He did the certification course (you need to use their very elaborate spreadsheet to show that the energy use of the house falls within the rules), and is now about to start building last I heard.

The requirements to get certified are pretty extreme: Since energy use per square foot is regardless of climate, here in the northern part of the continent the insulation requirements are massive. For the new office/warehouse (http://www.greenpowertalk.org/showthread.php?t=18748) we're using pretty hefty insulation values (R-50 roof, R-35 walls, R-20 floor, especially for an industrial building those are high), they are nothing to what passivhaus requires. I've heard about R-100+ roofs, R-70 walls etc. We did incorporate some aspects inspired by passivhaus structures: The windows we use are pretty popular for passivhaus construction (triple-pane, two coatings, R-7.1 whole-window value for the northern windows, slightly less for the southern windows), and the ERV that is going in was at the advise of my passivhaus buddy, it is used in those because of its 95% efficiency. I also designed things with a constant eye on thermal bridges and air infiltration.

Talking about air infiltration: Passivhaus requires less than 0.6 ACH50. That is an incredibly tight structure, and very hard to reach (normal building techniques won't get you there, it needs to be very carefully put together with air sealing constantly in mind, and multiple redundant layers sealing in the envelope).

In a larger context, if the legislature mandated this, it would not be all the difficult for regular builders, architects etc. to construct residences (and commercial structures) that are close to passivhaus standards. Right now each one is a one-off, that reinvents the wheel to some extend. If building techniques would standardize on better (existing) materials, such as SIPs, ICFs, spray foam where parts meet, it would make for much better buildings than we currently produce. Stick framing is still the standard here. It makes for leaky structures that are hard to seal (short of using spray foam everywhere, and/or materials like ZIP-sheeting). If the industry standardized on better materials I doubt it would cost any more than today's construction, and let's not forget, there are savings too: Heating/cooling systems end up being much smaller than they are now, and the cost to run such a building is much lower over time.

Given the need to save energy this would be a massive step forward. The bulk of our energy use is space heating...

If you would like to talk to someone about passivhaus design let me know and I'll you in touch with my friend.

-RoB-

[Bryan Couch]

My how I've learned in the last few months! I remember starting this thread, I had seen a few web sites and the ideas had intrigued me. 10 or 12 weeks and who knows how many sites later and my knowledge on the subject has grown exponentially.

I learned a lot from this site http://www.passipedia.org/ and like you've said the standards are high compared to typical built to code housing and even make R2000 look draughty (sp?). A typical house would have R-22 maybe R-30 walls, I'd probably be looking at higher than R-70 and for the ceiling better than 150, at least 3x what a normal "to code" build would have! A typical house has an ACH50 (air changes per hour @ 50kpa) of around 5, R2000 around 1.5 and like you said a passive house is less than 0.6, although I have seen 0.2ish more than once! Like you said high end windows and doors are a must, some of the new passive house windows have a higher whole window R value as good as the walls in my house!!

The passive house certification doesn't state a specific insulation to use or even construction techniques to use. The certification depends on the modeling of the house and more importantly the actual build of the house. Just because you modeled the house to minimize thermal bridging doesn't mean you're certified, the builders need to follow the design exactly or risk not just the certification but more importantly risk the performance of the house! A small mistake in the air sealing not caught before it's covered could make all the work in design and the choice of windows and mechanical systems pointless!

When it comes to materials there are different routes you can take.

In milder climates to our south SIPS work well however the passive house crowd seems to have a large percentage of people who are looking not only to save on future heating and cooling costs but are trying to reduce their impact on the environment. These people actually choose wood framing and mineral or wood/cellulose insulation for most of their project. The main reason for this is the HFC blowing agents used in XPS and spray foams. It's impact is over 1400 times worse than CO2.
In our neck of the woods you won't find a SIP with a high enough R value for a passive house so stick frame is still used although it's not your typical 2x6 wall. They use a double stud wall depending on the local climate maybe around 16" thick sealed air tight on the inside. Then maybe a 2x4 interior wall is used as a service wall and insulated before drywall giving you a 20" wall with an R value over 70.

Construction techniques for passive house are coming along. There are some proven designs that minimize the thermal bridges and help make air sealing easier but as you said Rob there aren't any "standard" techniques or materials. The techniques and materials used are more or less picked because the designer or builder has had success with them before. From what I can tell the price a few years ago was around 20% more than a standard build but I've seen some designers saying 15% and even heard close to 10% recently. As the techniques are learned and materials become more readily available (meaning you don't have to import from Europe where they're easy to find) the price is coming more in line with standard construction. Given the savings on heating a passive house is becoming an attractive option for more people and when utility prices rise the savings are even greater... but natural gas and hydro won't increase in the next 10 years... I promise!! :cool:

I'd never turn away any tips or discussion on the subject, the preliminary economic assessment for the mine came back very positive and every month it looks more and more like we'll be building. If we can a passive house design is what we're aiming for.

Bryan

[Rob Beckers]

Bryan, good to hear a passivhaus is still in the running for you! If you do go ahead, it would be great if you document the process here (with pictures!). I'm pretty sure many would be interested in learning about it as you go along.

It is interesting to see how little price difference there is between a conventional and passivhaus residence. It's not that I think everyone should be building passivhauses, but it makes you wonder why we still build these s$i%!y buildings that perform relatively poorly, when all the knowledge is there to do so much better. There seems no willingness on either the consumer as well as the builder's side to do better if it costs even a penny more. The only change in behavior I've seen over the years is when it is mandated by code changes (such as increases in minimum insulation values). Even then many builders find new and creative ways to screw up the increased performance by doing other things poorly (such as thermal bridging).

Anyway... I'll get off my soap box... :notrust:

Good point regarding the impact of blowing agents in rigid foam. That should be a temporary issue though, that will go away within a few years. Europe has already switched to other blowing agents that have no greater impact than CO2, North America is sure to follow. Right now, it's difficult to do without rigid foams if you want to build something highly insulated. What else is there to put under a slab? Using other insulation materials would be difficult too for the roof.

Let us know how it goes!

-RoB-