[GSBN] Can bale buildings be air tight?

[Chris Magwood]

Hi Tony,

I share some of your concerns about the quest for air tightness. The 
energy savings side of being air tight is undeniable. In our projects, 
we make sure that there are absolutely no toxic materials going into the 
house (which can take a lot of research and sourcing effort), so try to 
alleviate some of those concerns in that way. You are right though about 
post construction toxins... people love their bathroom sprays and 
cleaning products.

I have a lot of questions about moisture loading in a building that is 
both air tight and vapour permeable. We use a lot of materials that are 
highly moisture absorbent within the house (untreated wood ceilings and 
sometimes walls, permeable plasters, etc), as well as permeable exterior 
wall systems. I don't know that anybody has studied the difference in 
moisture loading between an air tight building with non-permeable 
surfaces and one with very permeable surfaces, but anecdotal evidence 
suggests that there is way less problematic moisture build up in the 
permeable building. Otherwise, every sauna in the world would be rotten 
very quickly.

When I lived off-grid, I was very opposed to mechanical ventilation 
systems due to the constant energy use of the fans. There are much more 
efficient systems now, and they really do a good job. The new ERVs 
exchange the heat and humidity of the outgoing air to the incoming air. 
Definitely keeps things fresh, especially with good filters.

I would love to experiment with some less high-tech solutions, but it's 
difficult to do that under our current codes. Earth tube systems are 
kind of hit and miss, with some performing really well and some being 
the source of major air quality problems. We did a solar hot air system 
once that worked really well... provided great exchange and heated 
incoming air whenever it was sunny in the winter. More than enough to 
keep the building at comfortable moisture/temp levels, but it doesn't 
work at night or when it's not sunny. HVAC design is always about 
control... and maybe we have to give up some of that control to use more 
passive systems.

This is definitely an area for more research. Now that we know our bale 
buildings stand up under loads and don't turn into mush at a problematic 
rate, it would be great to move into some more detailed testing around 
performance, air quality, air exchange, etc. I'd be glad to jump on 
board anybody's efforts to move in this direction!

Chris

On 13-03-10 2:20 PM, Anthony Novelli wrote:
> Just a comment and a correction (sic)....
>
> Comment: Kudos for such great strides in achieving these numbers, and thanks EJ for compiling the data. I always have running questions in my mind about the quest for air-tightness, with off-gassing and such. Perhaps less need for air-change systems if this quest is partnered with close attention to materials in construction, though post-CofO purchasing could load any tight building with noxious vapors it seems.
>
> It also seems useful to show where infiltration occurs, and perhaps adapt systems for the "point loads" of moisture to occur at those points?
>
> Correction: I believe the .88 refers to Patrick Kane, in this wondrous season ;) - at least from my Windy City upbringing!
>
> best to you all,
> Tony
>
>> Chris wrote:
>>
>> Hi ej,
>>
>> Our last test on the house was 0.88 (for hockey fans among you, you may
>> notice that our two scores are the jersey numbers of Wayne Gretzky and
>> Eric Lindros... coincidence?).
> Anthony Novelli
> Assistant Director
> Development Center for
> Appropriate Technology - California Office
> 2101 Wellmar Dr. Ukiah, CA 95482
> (520) 360-8858 • www.dcat.net
> anthony.novelli at gmail.com
>
>
>
>
>
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-- 
Chris Magwood
Director, Endeavour Centre
www.endeavourcentre.org