[Greenbuilding] first certified Passive House in Canada

[jfstraube]

I like 0.6 at 50 too, but it takes a lot of effort to achieve, and this may not always be justified.  If I can get it, in cold Canada, I will take it every time. But if I only get to 0.9, then the house can still use the same energy as a PH with some other modifications.

I also hear that the reason for the 0.6 is to limit condensation (would it not be nice to have this documented somewhere other than in interviews with Herr Feist?).  
However, if I design a wall properly, say placing half the insulation value outside of the wood framing, and use a ventilated space behind the cladding, it is essentially impossible to get condensation, even with, say, 2 ACH at 50.  So if condensation control is the goal, we have the science and experience to support alternate methods of achieving that goal.  The frost balls on the outside are not harming anything and we have many years of experience to show that R2000 airtightness has licked the condensation problems in climates much more severe than Germany.

If energy saving is the issue of air tightness, then trade-offs between other components of the building should be allowed: it should be rolled into the energy target.  There needs to be a limit to avoid comfort problems and IAQ problems: likely this is in the 1.5 to 2.5 range depending on climate.  But the energy and condensation reasons are not technically supportable.
R-2000 air leakage limit is 1.5 at 50.  Thousands have been built.    We can do it.  Thousands of homes have been built to 0.6.  We can do this.  The question is, how much work and how worth it is it?  

This is the type of conversation that is needed.  0.0 ACH at 50 is nice and good, 0.5 is better than 0.6.  Why 0.6 and not 0.7 or 1.0.  If people are to follow the standard, there should be a good reason for the number or it should not be a hard requirement.

Can you point me to more information on how HOT2K does not handle high performance homes? It was developed based on careful comparisons with real houses in the Canadian climate with Canadian occupants, and has worked well in my experience.  I would like to see more of the problems you or others hace identified (and I bet NRCan would like to have some real info on this too) since I dont know of them.  Many are using HOT3000 to get more accurate solar DHW and thermal mass feedback, although I would use WUFI PLUS (a German program with very good detail) to truly capture thermal mass.   My retrofit house has an ERS rating of 86, which I achieved without a ground source heat pump, and with some changes I made this last year, I bet I would get 88 now.

I like the open-source PHPP, but to make it this open they made a lot of simplifications and assumptions that limit its accuracy.  It is fine in my books (I have my own set of spreadsheets I use, but they are based on hourly weather data, not monthly), but it is not correct to say it is more sophisticated, or more accurate, or more advanced (I have all claimed) than many other programs out there being used to design high performance houses.  Check out the CEPHEUS 100 house study: predictions varied around measured by +/-50% like most prediction programs.

The Net Zero homes should not use "exorbitantly expensive renewable energy systems" to reach zero.  Please look into them in some more detail.  For example, some of them have R100 roofs and R70 walls and ACH around 0.5.  They compared the cost of insulation or the cost of heat pumps or the cost of renewable energy systems and tried to choose the least cost path to optimization.  Adding R20 of foam to an R20 foam slab (which seems common to some PH designs) is more expensive than using PV at market prices to save the same amount of energy that could be generated by the PV.  Adding $10000 of insulation to say $250   PV can be wastefully deployed.  Insulation and airtigtness and windows can be wastefully deployed.  Todays PV systems will likely have the same lifespan or more than the glazing in the windows so I dont get the "obsolete" comment.
  
 I dont think PH's sole emphasis on insulation and airtightness is necessarily the right philosophy: nor do I believe Net Zero is the best way.  I am sure that PH is not perfect and should be open to explaining its reasoning better than it does, and be more flexible to local climate and practise.    You, Ross, are one of the level headed PH advocates who is willing to admit "PH is not the answer to everything", which makes this an enjoyable exchange.

John

On 2011-01-25, at 7:12 PM, Ross Elliott wrote:
> 
> John, maybe I’ve been brainwashed by the Germans, but I kinda like that 0.6 ACH50. According to the good Dr. Feist at that level of air tightness you won’t get any hidden condensation problems (don’t ask me why, I just believe everything I hear). My own place meets R-2000’s 1.5 ACH50, yet in the last cold snap I discovered several frost balls on the outside of the foamboard (which would soon be hidden behind siding) where I’ve got some small air leaks. We’ve got a tract builder here in Ottawa who has built hundreds of homes in a row below 1.5 ACH50, so I don’t think it’s unreasonable to shoot for better on a custom green home.
>  
> The “sophisticated computer program” we’ve been using for R-2000 since 1983 actually doesn’t work that well for high performance houses beyond the current R-2000 / ERS 80, there’s going to be real problems getting them to NRCan’s magical ERS 86 or 87 in the next version of R-2000 without using heat pumps everywhere. HOT2K just isn’t that good at modeling great envelopes right now. It’s also a “black box” where we just have to accept the results are accurately calculated, whereas the PHPP Excel spreadsheet allows you to see what’s going on – not that it does a guy like me any good to know the formulas, but at least it’s there for smarter people than me to quibble over.
>  
> The Net Zero homes use exorbitantly expensive renewable energy systems to push them to zero, whereas in my humble opinion if they’re not up around Passive House for their building envelope before they go for renewable then they’re just buying energy to waste, at a lot higher cost than from the grid or pipeline. Talk about a science experiment… And if your total annual energy bill is under $1000 because you built a true energy efficient home, then putting $25,000 worth of PV on the roof seems like just a political statement, since those PV panels will be obsolete long before they pay for themselves (notwithstanding taxpayers covering the cost through incentive programs). But I really do appreciate your insights into where the tradeoffs should be in terms of cost, energy savings and carbon emissions, it’s a conversation well worth continuing. Passive House may not be the answer to everything, but I think it’s better than any of the alternatives currently available.
>  
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