[GSBN] Air tight bale buildings and ventilation

[Bruce King]

Have I mentioned lately that I love GSBN?  

Many thanks to everyone who has posted recently, but particularly to John and Chris, two of our many wacky hockey-lovin' Canadians.  John for bringing his deep and long perspective from building science, and Chris for pointing out that we have reached a good first understanding of natural structure and insulation, leaving the somewhat more challenging goals of achieving groovy modern comfort -- interior climate control -- with skimpier, more "natural", use of energy and materials.

As Francis Bacon said, "Nature to be controlled must be obeyed".


GSBN.  Ne plus ultra.

from rainy California where the sun is always shining,

Bruce King

(415) 987-7271
Skype: brucekingokok
Twitter: @brucekinggreen 
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On Mar 20, 2013, at 10:44 AM, Chris Magwood <chris at endeavourcentre.org> wrote:

> Thanks John, for your input. I agree wholeheartedly, even more so now that I've built an extremely air tight (final inspection 0.63ACH/50... finish clay plaster over the rough, straw-rich plaster brought us down from 0.88, for those who still think this thread is about air tight bale buildings!) bale home with a full mechanical ventilation system. It is hands-down the freshest, cleanest and healthiest indoor environment I've ever experienced. Even the construction dudes who've come on site have commented on this, including the smokers!
> 
> For me, the question is not whether to build appropriately air-tight and well insulated buildings, or whether to ventilate them. The question is how much ventilation is required and can it be done in a more passive manner.
> 
> I definitely have reservations about having made a building that is so reliant on generated energy (the house has 5kw of solar, but is still grid-tied) in order to function as designed. I certainly understand the hesitation of those who would rather not have the "mechanical lung" running in their homes. I'm not sure I do either.
> 
> What seems to be needed is a look at how much ventilation is required. Right now, this particular home is designed to Ontario Building Code standards for "required" ventilation to each designated room in the house. These standards, I'm assuming, were developed for homes that have little or no moisture storage capacity in the building materials and a certain amount of offgassing from materials in the home. I'm sure that our "vapour-open" home with the large storage capacity of timber subflooring, clay plasters and wood ceilings in the bathrooms, and no impermeable paints even on the drywall sections, does not need the prescribed amount of ventilation to ensure that there is no moisture condensing on the walls or windows. And given that no material in the home contains toxins (or at least identifiable toxins), we probably don't need code levels of ventilation to flush the poisons.
> 
> So the question I have is this: Can we figure out ways to passively (or with gentle mechanical persuasion) ventilate such a home adequately? Solar hot air collectors? Earth tube ventilation? Vent tubing in trombe walls? Solar exhaust fans? Air intake through heated slabs? Gerbil propelled fans in each room?
> 
> Just as we've started to see that there is a reasonable meeting ground between 100% natural (a la cave or mud hut) buildings and those that use lots of assembled natural materials used wisely along with sparing and thoughtful use of manufactured materials (nobody seems to think that good windows are a bad idea), I think our next collective objective is to figure out how to service such buildings with a blend of assembled natural principles and materials and sparing use of manufactured systems (little, hard-wired PV with DC motors).
> 
> It's hard to imagine that the acres of ductwork, wiring, computer chips, blower motors and other equipment used to heat/ventilate our buildings can really be the end point on this continuum. Those systems work very well and meet one key objective of keeping the IAQ way up. In the same way that we've collectively figured out how to make high performance structures with the lowest possible impacts, I think the next frontier for those looking to move forward is high performance mechanical systems with the lowest possible impacts.
> 
> The good news is that our collective knowledge of how to make efficient buildings makes the next task of figuring out high performance, low energy mechanicals so much easier. The bad news is that I don't think we're going to get the infusion of research cash that helped the building industry figure out the air tightness, insulation and mechanical strategies that are now becoming current. The next round of arguments with code officials will not be around straw bale walls, but around passive and low-energy ventilation and heating strategies, use of rainwater in buildings, composting toilets and grey water recycling, etc.
> 
> Here's to hoping that the creative energy that we collectively displayed in learning how to make high performance natural buildings can now be directed toward the operational systems of these buildings. Then we'll have really kicked some ass.
> 
> Chris
> 
> On 13-03-20 11:53 AM, John Straube wrote:
>> The claim that "airtightness = unhealthy" is simply not true.
>> 
>> 
> -- 
> Chris Magwood
> Director, Endeavour Centre
> www.endeavourcentre.org
> 
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