[Greenbuilding] Relative humidity in heated houses

[JOHN SALMEN]

I was just going to reference that article as well. It is from the 80's but
I wasn't aware it was 'widely debunked'?? Are the 24 studies it references
also debunked? I have an article in front of me 2008 that references it as
well as the humidity/influenza studies. And what about the stuff from Oregon
a couple of years ago that retested data and did establish low absolute
humidity as the control.

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


-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of John
Straube
Sent: October 27, 2010 11:48 AM
To: Michael O'Brien; greenbuilding-bounces at lists.bioenergylists.org;
Berletts Straube
Cc: Greenbuilding
Subject: Re: [Greenbuilding] Relative humidity in heated houses

That's the one by Theodor Sterling. Widely quoted long debunked. 

John Straube
519 741 7920
Sent via BlackBerry
  

-----Original Message-----
From: "Michael O'Brien" <obrien at hevanet.com>
Sender: greenbuilding-bounces at lists.bioenergylists.org
Date: Wed, 27 Oct 2010 11:40:42 
To: John Straube<jfstraube at gmail.com>
Cc: Greenbuilding<greenbuilding at lists.bioenergylists.org>
Subject: Re: [Greenbuilding] Relative humidity in heated houses

Hi, John--

See ASHRAE Transactions 1985, Volume 91, Part 1B, pp. 611-622 for a summary
of general health effects of low and high humidities. It includes a
widely-used chart.

Best,

Mike O'Brien

On Oct 27, 2010, at 11:29 AM, John Straube wrote:

> Corwyn, can you please share with us the references to the health studies
of lower RH exacerbating colds?
> I have never seen this evidence.  Ranges like "40-60" or "35-55" are
bandied about, and there is graphs floating everywhere show that low RH is
good for one thing or another (the most famous one is by Sterling, and has
been widely debunked), but I, and others, have never seen the research
although we have looked pretty hard.  ASHRAE does not, with all of its
resources, have anything to offer to show this.  Currently I believe they
say there is no lower limit to RH (because there is no data supporting
that), but recommend over 25% (because that feels right, but also has no
data).
> As far as I know, "low RH" starts to be noticeable to people, and possibly
connected to health, when it is really low, like under 20%RH, perhaps even
10 or 15% and I surmise it is these types of "low" RHs that are a problem
for people.   Eyes and noses and upper throat do evaporate lots of moisture
at these low RH levels, and so people begin to feel itchy eyes, scratchy
throats.
>
> I regularly run into MDs who suggest people with respiratory problems add
humidifiers to their homes (and I get involved because of the disasterous
results on the home) and challenge them for the data that supports this
recommendation. Never ever got it.
> I do know that people with respiratory illness were often sent to
sanatoriums in places like Arizona and New Mexico, which have very low RH's.
But that is anecdotal.
>
> On 2010-10-27, at 1:56 PM, Corwyn wrote:
>>>
>>
>> What constitutes high relative humidity is subject more to preference and
other conditions than a hard number.  Lower humidity exacerbates colds while
higher encourages more mold.  So, whichever of these you are more
susceptible to will drive you opinion on humidity.  The best I could find in
the medical literature is somewhere between 40% and 60% is most healthy (and
that is probably for average persons).  Additionally, a tight house with a
weakness in the insulation envelope somewhere (say, bad windows) will be
more prone to condensation while one without such a weakness will allow a
higher humidity with no problems.
>>
>
>
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