[Greenbuilding] Stale Air

[JOHN SALMEN]

Sorry Stephen - I know you know all that stuff, I liked the question and was
thinking out loud and still thinking out loud. One of the interesting things
for me is that when someone is cyanotic or hypoxic in a medical situation it
is pretty apparent. Basically co2 drives our breathing as we eliminate it.
Chronic high(er) levels of co2 in our built environment may be an issue. It
would never be the case that there was not sufficient oxygen - more that the
body becomes less able to utilize the oxygen as it becomes less able to
eliminate co2 or other mixtures of gases. So we end up with chronic
problems.

 

That is one thought and then a companion thought is that co2 is used as an
indicator - if it is present at higher levels then other gases are so is a
broad measuring tool for IAQ and these gases interact. I think we are
allowed approximately double the exterior co2 level for indoor environments.
Perhaps that is too high for an aging or health compromised population. 

 

Increasingly I think ventilation rates are too low (and people spend too
much time indoors but ironically not that much time in their houses). Are we
heating and ventilating houses far too much when are unoccupied and then
ventilating sufficiently for when they are? How well is demand controlled
ventilation actually working?

 

Thanks for the question - has me scratching my head as well.

 

John

 

 

JOHN SALMEN ENVIRONMENTAL DESIGN

4465 UPHILL RD,. DUNCAN, B.C.  CANADA, V9L 6M7

PH 250 748 7672 FAX 250 748 7612 CELL 250 246 8541

terrain at shaw.ca

 

  _____  

From: Stephen Collette [mailto:stephen at yourhealthyhouse.ca] 
Sent: December 12, 2010 4:44 PM
To: JOHN SALMEN
Cc: Greenbuilding at bioenergylists.org
Subject: Stale Air

 

Thanks for your thoughts John. I am wondering how useful the measurement of
CO2 in homes is. I have a CO meter and pull it out on occasion and to my
memory have not found anything with it in a home. Typically with a couple of
people or small family in a single family dwelling, I wonder whether they
alone could ever get the levels up to something dangerous? Now blended
families or extended families all living under one roof, I think that may be
possible. 

 

I'm not disagreeing with you at all, what you are saying is what I talk
about too, but again, is it actually valid? I don't know, and hence the head
scratching. 

 

Grateful for your time thinking about this.

 

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

 

 

Hi,

 

There are a lot of adjectives for air - stale, stagnant, dead, fetid.

Air basically means for us oxygen as a requirement - so stale air could
simply be oxygen poor air.

.

With ashrae I guess there is adequate ventilation and inadequate ventilation
and stale would be an excess of unventilated air (stale??). Ashrae uses co2
concentrations as the indicator for adequate ventilation so there definition
is ppm for various uses.

 

In emergency first aid I measure ventilation rates,  blood oxygen levels as
well of level of consciousness - all of which could reveal an emergency
condition in students in a classroom at the end of a day subject to averaged
ventilation and subsequent 'stale' air. Tidal volume (breath) is about 500ml
with about 14% oxygen and 4.4% co2 exhaled - outside air is about 21% oxygen
and .04% co2. 

 

So a significant amount of c02 is released on each breath in comparison to
the intake - so we could say that 'stale air' is any air exhaled.

 

Fun question.

John

 

 




 

 






 

 

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