[Greenbuilding] Aggressively Passive: Building Homes to the Passive House Standard

John Straube jfstraube at gmail.com
Sun Jan 9 12:21:43 CST 2011


All Net Zero Energy houses use some renewable energy on site to get to zero.
There is no doubt that there are stupid NZE homes out there.  I know one in Texas that use a 16 kW array to get there. Insane. And I know several that use less than 4 kW to get there.  
I also know that PH does not reward small and simple  homes. There are PH houses of over 4000 square feet, which, because of the area based energy metric (120 kWh/m2/yr) means that it uses more energy than a code-built 2000 sf home.  That is insane too.
All systems can be gamed. Which is why none should be approached as religion or dogma, all need to be understood.

I dont believe large numbers of NZE homes are sensible or a likely future for things like load shifting, peaks, paying for the grid, etc. Both PH and NZE can easily result in a misallocation of resources without careful thought.   I also dont think that the PH will be any more successful for the same reasons.  Until they adjust for the Canadian and US market, they wont be able to make much more of a difference.

Small, simple, well insulated is a dam fine rule by me. But you wont get a label or ceritification for that.

Check out Martin Holliday's recent blog on this topic at greenbuildingadvisor for some good thoughts.

http://www.greenbuildingadvisor.com/blogs/dept/musings/net-zero-energy-versus-passivhaus




On 2011-01-09, at 11:54 AM, Reuben Deumling wrote:

> Thanks for that tidy summary, John. 
> 
> But I have one question. You write:
> 
> On Sun, Jan 9, 2011 at 7:53 AM, John Straube <jfstraube at gmail.com> wrote:
>   A higher standard than the PH one is a NetZero energy house.  This takes things further and sets a numerical energy target of Zero, considerably less than the PH standard.
> 
> While I like both the Passivhaus approach--in so far as I understand it--and all its antecedents, my understanding of the piece that the netzero house adds to the mix is some onsite renewable supply, usually PV. To me this approach suffers from its own hyperbole and, at least in my limited understanding of how it works in practice, does a medium job of actually reducing the loads since the PV system can in principle and is often in practice ramped up to some pretty big systems. The implications for the grid, for peak, for load shifting are another piece of this that doesn't make much sense to me. Or am I missing something?
> 
> Small, simple, & well insulated tend to win out for me, but I'm not always up on the newest definitions of these certification systems. 
> 
> Reuben Deumling
> 
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Dr John Straube, P.Eng.
Associate Professor
University of Waterloo
Dept of Civil Eng. & School of Architecture
www.buildingscience.com

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