[Greenbuilding] Passivhaus propaganda

[Alan Abrams]

every orthodoxy, including passive house, exposes its fallacies and
contradictions when pushed to the limit.  I'm tripping over one of them on
a current project that is precertified by PHIUS.  Now, in mid construction,
the owners wish to turn what was planned as an unheated 3 season space into
heated space.  In itself, this is neither unreasonable nor unusual.  But
the masonry piers are already in place, and furthermore, this space is
small to begin with, and shoved up against two setbacks, so there is no
reasonable way to develop the 16" wall thickness the rest of the house is
built with.  Connecting it to a meticulously designed mechanical system
would compromise performance elsewhere in the house.

So the certification is probably blown.  What's left is to sort out what
levels of insulation and fenestration make the most sense, and what sort of
independent mechanical system to use.

But even so, there is one important result from this exercise:  that is a
better understanding of heat losses and gains, and the ability to make a
reasonable prediction of  the energy performance of this house.  This is
only possible with a systematic approach.

Whether other systems do it more accurately, or faster, or with fewer
calories than PHPP is a somewhat different question.  In fact, PHPP is
fundamentally obsolete, superceded by WUFI-Passive, which not only analyzes
heat gain and loss on an hourly basis, but also charts the accumulation of
water vapor in envelop assemblies--and does this over the course of many
years.

It goes to ultimate objectives.  If it is accepted that our society should
be carbon neutral by 2030, then we must use a systematic approach  to get
there.

AA


On Thu, Dec 5, 2013 at 10:04 AM, nick pine <nick at early.com> wrote:

> john daglish writes:
>
>  Passivhaus standard with little cost penalty if carefully designed.
>>
>
> With little cost penalty compared to what?
>
>  par ex. Oakmeadow Primary school, Wolverhampton in England built for the
>> same budget as a basic thermal regulation UK standard school.
>>
>
> Why not  build something that costs less than "a basic thermal regulation
> UK standard school" and also needs less than 15 kWh/m^2 of primary heating
> energy in a typical meteorological year?
>
>  Note Passivhaus is just an energy standard, any style will work.
>>
>
> Yes, but every actual Passiv building seems to have too much insulation
> and airtightness and triple-glazed direct gain windows vs air heaters or
> low-mass sunspaces. Is this a prescriptive requirement or a lack of
> imagination? Does the PHPP only allow direct gain solar heat? Is it capable
> of evaluating other designs, with 2 thermal masses at different
> temperatures? Can it even do the equivalent of a single-zone HEED or
> Energy-10 simulation?
>
>  Good video technical presentation
>> https://www.youtube.com/watch?v=MffKNX5qlLw&playnext=1&list=
>> PLAD94D448BBA00BB9&feature=results_main
>>
>
> Jonathan Hines begins by saying the challenge is to build Passiv "at no
> extra cost," then goes on to say that extra Passiv insulation and
> airtightness really do cost more, so they simplified the building design to
> make the total come out the same (as what?) But the final design still has
> about 5 shoeboxes with different roof slopes, vs a simple single shoebox.
> Why not use a single simple shoebox for cost and performance comparison?
> And why all the triple-glazed direct gain windows and their overhangs and
> brises soleils, vs air heaters with natural summertime ventilation instead
> of shading, in this "physics-based" standard? If schools perform better
> without lots of building thermal mass, why not use a solar heat storage
> tank with fan-coils in a lightweight school building? Why daylight, vs
> fluorescent lights? Or prismatic diffusing skylights and complex dimming
> fluorescents, a la Walmart?
>
>
> Topher writes:
>
>  There are a number of Passivhaus houses here in Maine.  If you would like
>> to come see what they are all about, I can arrange for you to be given a
>> tour and a complete explanation.
>>
>
> Thanks for the offer. I'll think about that. I get up to see Rich Komp and
> Elliot Coleman once in a while, preferably in summertime. When Norman
> Saunders and I were at a solar conference at Bates college in February, the
> outdoor temperature got above 0, which the locals called "unseasonably
> waham."
>
> The Passivehaus standard brings out my anti-Nazi sentiments.
>
> Nick
>
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-- 
Alan Abrams

*certified professional building designer, AIBD certified passive house
consultant, PHIUS*
*certified passive house builder, PHIUS*
Abrams Design Build LLC
*sustainable design for intentional living*
cell     202-437-8583
alan at abramsdesignbuild.com
www.abramsdesignbuild.com
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