[Greenbuilding] Stale Air

jfstraube jfstraube at gmail.com
Tue Dec 14 12:11:02 CST 2010


We could ventilate less and tolerate it, yes, but the ventilation rates for homes are pretty low already (under 50 cfm for most homes), and yes the irony of ventilating to remove the smell/chemicals of the home is not lost on me.
We do not hermetically seal house.  We try to, but fail (hence all the blower door tests of 4 5 or 8 ACH at 50Pa)
the primary reason we airseal is to IMPROVE air quality, as many pollutants are generated outdoors (radon and soil gases, car pollution) or within the enclosure ( mold in walls, dead animals in out attics, etc).  The first step in air quality should, IMHO, be to provide a known quantity of air with a known quality to each space ( aventilation system with a carefully selected air intake location).  Second step is to stop emissions of dangerous pollutants in the homes (source control). Third step is to not drag pollutants into the home (dirt and dust on our feet is a big one like Mr Lamb described, but pollen and allergens need to be controlled via filters on the air intake).
There is way too much nostalgia and precious little science regarding the air quality of older homes.  Many have quite mediocre air quality, while at the same time having poor comfort and excess energy use.
The worst houses are the ones in between old and good new: these tighten up the house a bit, but dont provide ventilation, and add a fair bit of pollution from the materials and products used.  New houses should have better air quality than 1800s homes if one follows good IAQ practises and ventilates.
The worst air quality I have ever seen was some of the yurts in Mongolian (tremendous particulate loadings from open coal stoves resulting in off the chart incidences of respiratory disease) and Botswana earthen huts (smoldering wood cooking fires inside during rainy season).  So old is not often, or even usually, better.

john

On 2010-12-13, at 9:51 PM, Stephen Collette wrote:

> Interesting. So as a culture, we define stale air and instead of building tolerance to the whole thing, we build an industry to mask it. I suppose in the old days all those powdered wigs and such were the same sort of approach to the odour of the body (as an odour goes) by the powder industry. hmm. What's fascinating though is that we have less issues of body odour, more of chemical odours in our homes, and except for the occasional gym bag left unattended, odours are less and less of an issue within homes, that typically have little actual cooking done in them (clients here, folks, I know we are all die hards here on this list, growing, cooking and preserving food), but as the houses get bigger and the populations in them get smaller, we are ventilating more than ever to resolve this "stale air" which had we not hermetically sealed ourselves into our homes and actually opened windows and aired the place out, may not in fact be as important with respect to the unmeasurable level of staleness.
> 
> Fascinating.
> 
> Stephen
> 
> Stephen Collette BBEC, LEED AP, BSSO
> Your Healthy House - Indoor Environmental Testing & Building Consulting
> http://www.yourhealthyhouse.ca
> stephen at yourhealthyhouse.ca
> 705.652.5159
> 
> 
> 
> 
> 
> 
> 
> 
> On 2010-12-13, at 9:58 AM, greenbuilding-request at lists.bioenergylists.org wrote:
> 
>> From: jfstraube <jfstraube at gmail.com>
>> 
>> ASHRAE standards have historically been set based on early research around odour: it is human smells that set the ventilation rates. Depending on culture and time, these rates have, under ASHRAE's guidelines, varied from about 3 cfm to 30 cfm of fresh air per person.
> 
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John Straube
www.BuildingScience.com



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