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In mid-November 2015, just before we moved into our new house, we were asked to be part of the Passive House Days tour (a worldwide weekend of awareness of Passive House and energy-efficient building). Well, not “officially” — we were asked to be a part of the tour by the event organizer in Saskatchewan, who was the Passive House (PH) consultant on what should become the first certified PH in Saskatchewan. Even though we did not build a PH, we did follow the standards as closely as I could justify. From the beginning we were not pursuing certification.
Although all of the visitors on the PH tour were very interested in our house, our process, and why we did the things we did, one question we got a lot was, “If you were following the Passive House standard, why not go all the way for certification?”
First, let’s back up a little bit. Indeed, the principles of a PH are second to none. From Passipedia: “Passivhaus is a building standard that is truly energy efficient, comfortable and affordable at the same time.” So simple. Brilliant even. I wanted to build a Passive House. Who wouldn’t?
BLOGS BY KENT EARLE
Adding It All Up, Part 1Blower-Door TestingInsulation, Air-Sealing, and a Solar ArraySoffits and Siding at the Blue Heron EcoHausPlacing the Concrete FloorsAdding Walls and RoofDealing With Really Bad WaterMaking an ICF FoundationLet Construction BeginPicking High-Performance WindowsHow Small Can We Go?Choosing a Superinsulated Wall SystemHeating a Superinsulated House in a Cold ClimateIs Passivhaus Right for a Cold Canadian Climate?
Strangely, if you visit the Canadian Passive House Institute (CanPHI) website, you’ll find that there are total of five projects that have received Canadian PH certification. If you look up the Passivhaus Institut’s Project Database, you’ll find that there are a grand total of 23 houses in all of Canada that have received PHI certification.
Why the discrepancy, you may ask? Why so few certified projects?
A standard designed for the German climate
This is a bit complicated, and took me a while to figure out. But here are the basics as I understand it: the Passivhaus standard was developed in Germany for German buildings in the German climate (obviously). However, when other builders in other countries tried to build a “Passivhaus” — in, say, the U.S., England, or Canada — they realized something profound: Hey… wait a second… I don’t live in Germany!
Maybe trying to build to the German Passivhaus standard in Minnesota or Saskatchewan is going to be really difficult? Maybe impossible? Or maybe possible but really expensive? Or maybe possible but only to produce a really uncomfortable building to actually live in?
Still, PH satellites started to spring up in most countries around the world. Slowly, Passive Houses, built to the German requirements, started to be built in other countries, with the first certified Canadian building being built in 2009. The uptake, however, was certainly neither rapid nor widespread. Why? Was it not as the Passivhaus Institut of Germany said — that these buildings are “truly energy-efficient, comfortable, and affordable”? Or is it just that we are too cheap or lazy or complacent to meet those strict German requirements elsewhere?
It seems like this is something that these PH satellites were struggling with. These issues are discussed here, here, and here.
A few years ago, though, some people started to say, this is silly. Why are we following German standards and requirements for our buildings when we don’t actually live in Germany?
The German Passivhaus standard is as follows:
Space heat demand: Maximum of 15 kWh/m2 annually OR a peak demand of 10 w/m2.
Blower-door test result @ 50 Pa: Maximum of 0.6 ach.
Total primary energy demand: Maximum 120 kWh/m2 annually.
Simple enough, right? Hit these numbers using the PH planning software and your building can be certified as a PH. Where’s the problem?
The airtightness standard of 0.6 ach50 is strict but not impossible. There had been many houses built to this level of airtightness before PH came around. Rob Dumont’s own home in Saskatoon in 1992 tested at an awe-inspiring 0.47 ach50.
Jumping to the third requirement, the total primary energy demand of 120 kWh/m2∙yr ensures essentially that you are not wasting energy or are at least using it wisely. It forces you to use energy-efficient lighting, appliances, and mechanical system components. I don’t think anyone can argue with that as being important to green building.
The space heating demand is the sticking point
The real problem, in my opinion, is the space heating demand of 15 kWh/m2∙yr or a peak load of 10 W/m2. These numbers dictate the maximum amount of space heating allowed for each square meter of a building. Remember — this is based on a German climate.
In Germany, the number of heating degree days (HDD) is around 3,100 annually compared to more than 10,000 in Saskatoon. That means that the heating requirement in Saskatoon is three times that in Germany. Besides that, who really cares what your heating demand is? With the maximum energy demand of 120 kWh/m2∙yr already stated, what difference does it make whether you use 50% of that to heat your house or 10% in terms of your overall efficiency? This is my real beef with PH and the one that most others working towards PH in countries that have climates other than a German one tend to struggle with, too.
Recently, the Passive House Institute U.S. (PHIUS) split off (or was banished — depending on what you read) from the German Passivhaus Institut. This allowed PHIUS to develop its own standard and specific requirements for climate zones in the U.S., and also allowed it to use North American calculation values instead of European. As a result, it is now easier — OK, let’s say, more attainable — to hit the PH targets for your Minneapolis house using a Minneapolis climate to calculate your requirements. Now that makes sense to me.
Sadly, the Canadian PH Institute has resisted following its American counterparts and has continued to align itself with the German requirements. Thus, it’s darn near impossible (practically) to meet the PH standard and become certified by the Canadian PH Institute.
There is a small loophole of sorts, though. A Canadian house can pursue certification via PHIUS, which has climate-specific standards for the northern states, where the climate is somewhat closer to our climate. Although the conversion is not exact, the space heating demand requirement for the northern U.S. is about 30 kWh/m2 annually (or double that allowed in the German standard). That’s better — but still, the maximum heating degree days in Saskatoon are more than any other place in the continental U.S. Nonetheless, there have been a few Passive Houses in Canada that have used the U.S. system to become certified (maybe 10 or 12).
I told you this was complicated…
Canada needs its own standard
Anyway, let’s try to bring this full circle, back to my original question: Why don’t we just build all new houses in Canada to the PH standard?
I hope that I have presented the argument that it may not be realistic to build a certified PH in Canada and follow the original edicts of the German Passivhaus Institut of “energy-efficient, comfortable, and affordable.”
From Part 1 of this series (see the first entry in the “Blogs by Kent Earle” sidebar), you may be able to see that there is a huge chasm between how most new homes in Canada are currently built (as a result of our pathetic building code allowing inefficient homes to be perpetuated) and the extremely difficult PH standards currently set in Canada.
Unfortunately, I think the CanPHI has done itself a disservice in not distancing itself from the German Passivhaus Institut. By not developing its own Canadian climate-specific standard for the unique climate zones of our country, which maybe (just maybe) one day could be adopted on a large nationwide scale.
Until such time that the CanPHI recognizes this and modifies its requirements appropriately and regionally, I doubt that PH will ever gain much more than a very small handful of faithful followers willing to spend, at all costs, to meet an arbitrary set of values developed on the other side of the world.
That being said, I do know that you can in fact build a house in Canada that is energy-efficient, comfortable, and affordable. Because that’s what we’ve done.
But it isn’t a Passive House.
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19 Comments
Should we be surprised at German stubborness?
Back in the mid 2000's when I discovered PH the first thing I thought of was whether it fits within the humid climate of the S.E. US. At that point I discovered the Koppen Climate Scale and behold if I lived in Vancouver BC I could easily build to German PH standards since that was the only area in NA that basically had a climate similar to Germany.
It's only logical to have PH standards that are climate specific.
They said the same thing about Colorado's climate
This argument comes up often as the excuse for there not being more certified buildings. We took a sample of of certified Passive House projects from west Slovakia (similar climate to central Germany) and changed the climate data to Denver. Low and behold the building performed much better in Colorado. My own certified project which is at 7000 heating degree days is 1/2 the 4.75kbtu/sqr/ft year threshold and an architecture firm I work with are having similar results with other certified projects at similar climate conditions. Canada has colder days and less solar gain but is very doable- ie size, use, form factor, glazing can be further optimized. So from my point of view Passive House is better suited for my climate than Germany's. Perhaps the issue is one of perspective?
I believe the biggest misnomer which is unfortunately perpetuated by the author is "the Passivhaus standard was developed in Germany for German buildings in the German climate (obviously)". Of course it was developed in Germany (it has to start somewhere) based on principles developed all over the world but has always been targeted for global implementation. PHI asserts this all the time and we are seeing very high quality and cost effective and projects from Antarctica to the desert being built. Canada (and the US) is not an outlayer.
The lack of certified projects seems to be not so much the thresholds but the lack of experience and optimization processes in North America. That in fact is the entire point, to push our capacity improve the quality and cost of a very good envelope. I would ask CanPHI more questions about how they can successfully implement projects.
As a side, I originally was certifying under PHIUS but the climate data was so erroneous that the project nearly failed during modeling. Two other projects in my region did give up on certification due to the bad "local" climate data so you have the very grave issue of garbage in garbage out.
Response to Andrew Michler
Andrew,
I doubt if we are going to resolve this debate on these pages, but I'll just state briefly that I disagree with your argument, which I've heard before: "If you can't create a cost-effective Passivhaus envelope in your climate zone, it's your fault. You haven't optimized the design! Go back to the drawing board and optimize some more! After all, it's obvious that 15 kWh per square meter per year is the correct target for every climate on the planet."
Those who adopt this argument are taking a religious position rather than an engineering position.
Targets
I have to assume that when any of the PH targets were set, each represented a compromise between achieving energy efficiency and feasibility. Otherwise, why not .01ach50? Why not 5 kWh per square meter per year?
Given that, shouldn't the same tradeoffs be considered in the context of climate? It's silly to say the standard for Denver should be the same as for Saskatoon. If that's the case, either Denver's is too easy to meet or Saskatoon's is too hard.
I would think the point is to save the planet, not get the wall plaque. Using the same standard for everyone means PH will always occupy an insignificant niche in many places.
Finally, doesn't rooftop solar make targets irrelevant?
Optimizing athiest
It's most certainly reasonable to say set a target then find the best way to get there. Imagine if you trained for a marathon thinking well it's a little too hilly so let's make it two miles shorter? To bring up the idea that we are religious in proposing a standard is simply ludicrous and not much of an argument, and for the record I am card carrying atheist. Having a robust target makes for better design with the right tools and training, that's my point, not exactly controversial in most design circles.
Addendum: The reason optimization is such a critical task in Passive House is that we also tend to overshoot as well as miss it. That's why my own project is 50% over the standard. I didn't find the sweet spot so on my next projects it will get closer, faster and cheaper. It's a life long skill to develop and something sorely missing in our industry is that lack fundamental feedback loops based on the building physics.
OK show me! (@ Andrew Michler)
"PHI asserts this all the time and we are seeing very high quality and cost effective and projects from Antarctica to the desert being built."
I'm dying to see the cost effective PHI house located in Antarctica! (Seriously, if it exists, I want details!)
If not Antarctica, any Passivhaus located more than 100 miles north of the Arctic Circle would be interesting enough. The financial analysis assumptions matter too (as in "...cost effective..."), and need to be explicit.
Andrew,
Wouldn't a more accurate marathon analogy be if the organizers said everyone had to finish the course in under 2:30 regardless of the difficulty?
The de-optimized approach
Here is an example of deoptimizing performance. I was just at the new RMI offices in Balsat, Colorado. They claim to be as energy efficient as you can get but after a conversation with the envelope consultant (an International Passive House certifier) and a quick look at the windows showed how much they left on the table. First it is overglazed for 10000hdd. They tried to make up for it with quad pane windows and outside shades but that cuts solar heat gain.
Further the windows use stainless steel spacers rather than super spacers. Given the window geometry its possible a triple pane window would with super spacers would have had a simular psi value installed but better SHG. That could have saved money as well, but this project has cash to burn. They could have easily have used quad superspacer glass and raised the opaque factor to the point where they get 4.75kbtu sqr foot. If they wanted more glass increase the insulation a little or not rely just on SIPs (which are another longevity concern but I digress).
http://www.antarcticstation.org/station/passive_building Passive House Antarctica- the Dutch did it because its cost effective and predictable. Its really a story book in designing envelopes for such radical environments and the water vapor issues.
Cost-effectiveness of envelope improvements in Antarctica
Dana,
The issue of cost-effectiveness in Antarctica is a special case, since heating fuel at the South Pole Station costs about $35 to $40 a gallon (delivered cost). Envelope requirements for a building are different when heating fuel costs are that high than they would be (for example) in Minneapolis or Fairbanks, where heating fuel can be purchased for $4 a gallon or less.
Let's revisit the "Pretty Good House"
I'll bet payback time on the envelope gymnastics required to shoehorn PH standards onto homes in severe climates runs into centuries, not years or decades.
That begs the question of whether investment to meet PH standards is ethical or moral.
Build a pretty good house rather than a Passive House. It might use $50 more in annual energy cost while costing $50,000 less to construct in some climate zones.
Then invest the saved $50k in your community's local weatherization program for a 10 - 100 x increase in bang for the buck.
PH is a ridiculous boutique design algorithm. While I respect people's freedom to choose to construct a PH home, it is delusional to suggest that doing so in any way benefits the environment or the rest of mankind.
PHIUS + Standard
We really don’t need another standard. The PHIUS+ Climate specific Standard works well in Canada. In spite of its substantial virtues, the original PHI will probably to remain aspirational in very cold climates. The very high marginal cost of that last increment of conservation needed to reach the heating demand target is too far out on the flat part of the curve. I think of the PHIUS+ standard as Passive House 2.0. The PHIUS + standard has made Passive house compliance achievable almost anywhere without sacrificing the number that really counts –total annual primary energy use per person.
The team developing the PHIUS+ climate specific standard included northern Canadian and Alaskan climate conditions when they developed and tested the new standard. It works well in Edmonton, Alberta (just slightly warmer than Saskatoon) where I build.
Interestingly, the annual heating demand limit is pretty close to that needed to meet the new Canadian R2000 standard. It is also very close to the sweet spot we’ve arrived at for achieving net zero energy on the Canadian Prairies.
Thanks for the reference! (kewl house!)
Other online pics of that house gives is a bit of remote-planet-base kind of look, but appears to have a fairly substantial airfoil form factor. Is it in a particularly low wind area? I would imagine even with the major anchoring to the rock it might have a lot a shake, rattle & roll in a high wind!
There appears to be a 9 turbine low hub-height wind farm next to it in some of the pictures which would indicate that it's not entirely net-zero with PV that fits on the house. eg:
http://www.educapoles.org/assets/uploads/news_images/belare_2011_digging_out_002.jpg
It's a well thought out building design, to say the least.
(Also note, it's a Belgian project, not Dutch- the young princess Elisabeth is Belgian: https://nl.wikipedia.org/wiki/Elisabeth_van_Belgi%C3%AB Despite the strong linguistic & cultural connections, the Dutch sometimes take offense at being conflated with Flemish, and conversely. )
Martin: Princess Elisabeth Station is less than 100 miles from the shore and at a very modest altitude. I'm sure fuel costs would be cheaper there than at Amundsen-Scott South Pole Station which is pretty high (more than 2x the elevation than at Prinses Elisabeth) and located on the remote interior plateau. I'm sure it's quite a bit more expensive than the fuel pricing in Minneapolis or Fairbanks, but probably not 10x.
According to other sources most diesel fuel is brought to Antarctica in 55 gallon drums by ice-breaker, but transport to the stations from there varies. In South Pole Station it can only get there via C-130 aircraft, which which has to be at least half the cost of getting it there.
This document estimates the average fuel costs to Princess Elisabeth Station (and other Antarctic stations) at $900 per barrel (/55 gallons = $16.36/gallon), which is quite a discount from $35-40/gallon, and enough to move the present-value numbers quite a bit in the financial analysis:
http://polarpower.org/PTC/2013_pdf/PTC_2013_Rempel.pdf
I couldn't open the link provided on South Pole Station fuel costs. The details on the error message read:
"The client and server don't support a common SSL protocol version or cipher suite. This is likely to be caused when the server needs RC4, which is no longer considered secure."
Curt Kinder
What are the PGH standards? How are they enforced?
$50k in insulation?
I sense a lot of hyperbole
Heating via HRV/ERV ducts
I'm no Passivhaus or PHIUS expert or convert, but admire their "gold standard" approach.
I believe I read somewhere that the original idea for the Passivhaus limitation on peak space heat demand (and resulting high levels of insulation) had to do with how much heat could be delivered via HRV or ERV air ducts comfortably. The Passivhaus idea was to eliminate the (hydronic) central heating system, and an HRV or ERV inline electrical resistance air-heating element wasn't considered a central heating system. (The purpose of an HRV/ERV is efficiently delivering fresh air, not heating.) Eliminating the central heating system helps pay for the additional (foam) insulation, pricey windows and (practically necessary but not mandated) HRV/ERV.
Eliminating an expensive (central) heating system is worth pursuing IMHO. That's central to naming it "passive" house. The home's natural balance point (heat gains=heat losses) in wintertime is near the interior temperature comfortable for home occupants.
I haven't designed any Passivhaus or PHIUS passive house, and don't represent their approach. Just my limited understanding of their concept.
PHIUS+ 2015
Hello, I would like to mention that the full name of PHIUS’ standard is in fact “PHIUS+ 2015 Passive Building Standard - North America”, that is, the intended scope is not just the US but includes Canada. The Technical Committee that developed it included two Canadians and an Alaskan, so the cold-climate perspective was well represented. You can see on the climate-specific standards map
http://www.phius.org/phius-2015-new-passive-building-standard-summary
there are performance targets for a number of Canadian cities. OP mentions Saskatoon, we have not done that one but for Edmonton the space conditioning targets are:
Annual heating demand kBtu/sf-iCFA.yr <= 8.4
Annual cooling demand kBtu/sf-iCFA.yr <= 1
Peak heating load Btu/sf-iCFA.h <= 5.8
Peak cooling load Btu/sf-iCFA.h <= 3.3
All of those must be met, no either-or. (There are other requirements for air-tightness, total source energy use, quality assurance, and modeling protocol - the details are spelled out in the Certification Guidebook.) We welcome applications from our neighbors to the north.
As to the the question “what difference does it make whether you use 50% of the energy to heat your house or 10%”, note that PHI’s and PHIUS’ standards share the general feature of separate limits on energy for space conditioning, in addition to a limit on total energy.
This is the distinguishing feature of a passive performance standard. The connection comes about because reducing heating and cooling loads is what passive measures are good for, thus, limiting the heating and cooling loads forces investment in passive measures like insulation, air-sealing, windows, overhangs, heat recovery, etc.
A particular benefit of the concept is passive survivability, the resilience to utility outages.
Heating and cooling performance requirements drive the investment in passive measures, “how much to invest in passive measures” is an important question.
In the development of PHIUS+ 2015, this was the approach taken: the heating and cooling limits are based on life-cycle cost-effectiveness calculations in various climates. The limit-setting is not based on the unconstrained cost-minimum, but targets a higher performance level predicated on very good windows. That is, the targeted performance level is higher than cost-optimal, with a first-cost premium, but still cost-competitive on an annualized basis.
Mr. Earle is correct to make the connection between heating degree days and annual heat demand and note that it does not make sense to keep the annual demand target the same when the heating degree days vary. At this point, advocates of the PHI standard usually bring up the alternate 10 W/m2 peak heating load criterion. The thing is, in most of Canada, especially places like Saskatoon, this is no help because it is probably going to be even harder (less cost-competitive) to meet.
At PHIUS, we chose to base our heating and cooling criteria on economic analysis. The PHIUS+ 2015 targets are the result. The parameters of the analysis are disclosed in development report, and as noted there, they are quite conventional with respect to analysis period, interest rates, discount rate, etc.
Therefore, the PHIUS+ 2015 Standard is equipped to deliver “energy-efficient, comfortable, and affordable” in Canada as well as in the US, and is already showing viability with Canadian projects beginning to certify under the new standard. Please take this into consideration before embarking on another standard development.
Graham S. Wright
Senior Scientist, PHIUS
dual citizen US/Canada
Not knowing what one doesn't know
I applaud the effort that has been going into targeting various climates throughout the US and Canada. You are brave souls! It seems to me that cataloging those facts and statistics may be a bigger undertaking than may be first imagined and the possibility for error immense. I agree that Germany and much of Europe has a much more homogeneous climate than we have. We need to adjust for that, but the opposite extreme of cataloging all those differences and ironing out prescriptive errors will be no small job and likely will take decades to do.
Just as an example I noticed that much of the Hawaiian islands show an average annual cooling load of between about 13 kbtu/sf. and 17 kbtu/sf. Peak loads in an hour average about 4.5 kbtu/sf. I live in an area (not the Hawaiian islands) where it gets up to about 105 degrees at least a few times a summer. Yet its rated at an annual cooling load of 2.6 kbtu/sf and a peak cooling load of 4.7 kbtu/sf in an hour. That seems wrong. Hawaii is a much more temperate area than any other place. Few people who live there would probably object to just opening a window and letting the breezes blow. Or maybe a ceiling fan in every room.
There are also other areas in the United States mainland that are good candidates for time shifting of extreme temperatures around an "average" nice outside temperature. A whole house fan would work remarkably well in those areas as long as there is sufficient air sealing and insulation in the house. I live in such an area. In those areas just let the "artificial" night time breezes blow.
In other words, there's bound to be errors in the prescriptive requirements for homes throughout such a vast area when there are so many variables to account for. Translating it strictly from numbers such as annual heating or cooling loads, or peak cooling or heating loads has its own problems. PHIUS has it's work cut out for them.
Eric
That's an interesting point. The climate shifts dramatically about 15kms down the road from me. Even the marine life is different. I wonder how specific we need to be though? Surely generalizing about a few climate zones in a country is still better than generalizing about the whole planet.
Interesting take
Malcolm, that's an interesting take on my take. All I was advocating for is that PHIUS not be overconfident in the adequacy of their prescriptive advice based on individual climate analysis. I think you may have misread me if you think I think theirs' is not a worthy goal. I was advocating for realism in their own self assessments in attaining that goal. From my non-professional vantage point it seems like a long road to get where they want to be..
Eric
No I think you are spot on. I just wonder where they will draw the line.
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