[Greenbuilding] first certified Passive House in Canada

[John Straube]

Hi Shawna! (sorry I had no time for a visit...)
So how do we answer the question "Why 0.6ACH at 50, not 0.5?"?
Would you agree then that all the homes that you built and tested from 0.61 to 1.0 are not good low-energy houses?  I bet they are.
I would also argue that it is the primary energy use of the home that matters.  I do not understand why a house with 0.2ACH at 50 and one with 1.2 ACH at 50 with the same primary energy use are not considered equal, because the environment will consider them so.
Now if the house is 3.2ACH at 50 we know from experience that comfort, condensation and performance problems result so clearly that is too high for our climate and much warmer climates.
We also know from experience that 1.5 of the R2000 spec is pretty safe on all these levels.
So the limit is somewhere around 1.5.
For energy, the goal should be 0.0
Back to "Why 0.6, not 1.2, or 0.9".

On the PV topic, I agree that one cant make the ROI of PV pay (in Ontario or anywhere) without subsidies.  They dont make sense on ROI. Period.  
I cant make a 0.6ACH at 50 single-family house get its annual heating load down to under 15 kWh/m2/yr (the PH max) in North Bay, or Winnipeg without spending a lot more than 25K. And if any of your ground floor walls is shaded by neighbouring buildings, fences, trees, etc, it becomes darn near impossible. Neither NZE or 15 kWh/m2 heating use makes any ROI sense for single family homes in cold climates.  Rowhouses, apartments OK, duplexes in Halifax and Windsor, maybe.    Note that several houses have shown than solar hotwater systems (SHW) can cost as much to generate hotwater as unsubsidized PV run through a heat pump.  So PV is expensive, but SHW aint cheap either.  PH lets me use SHW to reduce energy, but it wont let me use PV ragardless of cost.

The CMHC Equilibrium NZE homes spent an awful lot of money getting the heating load down to the 25 to 35 range in Calgary, Edmonton, and Ottawa.  Reducing the heating load to half that (when you already have R60-80 in the roof, triple glazed fiberglass windows, etc) is quite expensive.  Those same houses, dropped into Darmstadt Germany, would meet the PH space heating and annual primary energy targets. 

PS (most NZE designs with 200-300 m2 of floor area in Northern US and Southern Canada require 6-8 kW PV arrays, which costs more than 25K, I would estimate closer to 50K).


On 2011-01-26, at 9:31 AM, Shawna Henderson wrote:

> Hey Ross and John,
> 
> Here in NS, we have several small production builders who consistently come in at <1 ACH at 50, Keith Sawlor hit 0.29 (I personally did that test, about 15 years ago!!). On all of our custom design jobs, 0.5ACH @ 50 is the target on our bid documents. While not all builders hit that, they are consistently coming in at less than 1 and some are bang on, because they have long-standing crews who can do the air sealing work. Ross, I'm with you on the NZE house $25,000 PV extravaganza, which might make sense where there is a decent FIT, like ON, but here in NS, where ComFIT comes into play April 1, there is still no real business case for it (ie, ROI sucks). We ensure that the design and planning allows for 3 to 7 kW PV on the roof and with conduit (not wiring) in place and wall space in the mechanical area for inverter and controls, roof mount and any extra bracing etc in place as homeowner dictates. When it's affordable/cost-effective, homeowner can have it installed.
> 
> I agree with John on the issues around the energy modelling, and that a set of dogmatic rules leads us right back to the one-size-fits-all approach, which leads us right back to the problem of large tract builders and 1,000s of spec homes in GTA every year that are not meeting the +20-year-old R2000 standard, but are building to a one-size-fits-all approach, just using a different set of dogmatic rules driven by a different set of requirements ($/sf vs W/sf).
> 
> Cheers from mighty chilly Halifax
> 
> Shawna
>