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<div class="moz-cite-prefix">On 11/11/2013 11:13 AM, conservation
architect wrote:<br>
</div>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"> </span>Absolute humidity
and dew point are directly proportional.</font></font></span></div>
</div>
</blockquote>
I would phrase this as they are measuring the same quantity with
different units.<br>
<br>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"></span></font></font></span><span
style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font face="Times
New Roman"><font style="FONT-SIZE: 14pt">This was
alarming, so I decided to heat the house above comfort
in order to dry it out.<span style="mso-spacerun: yes">
<br>
</span></font></font></span></div>
</div>
</blockquote>
<font face="Times New Roman"></font>I find this a generally
confusing way to talk about this process. People often talk about
'drying out the air' with heat, and this is just wrong. 'Drying out
the air' requires *cold*. I try to say things like, increase the
temperature to evaporate more water (which can then be flushed from
the house). <br>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"> </span><span
style="mso-spacerun: yes"></span>I got the house to
104F.<span style="mso-spacerun: yes"> </span>I found
that the absolute humidity went way up over what would
be expected if no moisture was added to the air.<span
style="mso-spacerun: yes"> </span>This was the
moisture being evaporated from house contents inside
thermal envelope.</font></font></span></div>
</div>
</blockquote>
<font face="Helvetica, Arial, sans-serif">Right.</font><br>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"> </span>Since the house
was closed up, I would assume minimal infiltration.<span
style="mso-spacerun: yes"> <br>
</span></font></font></span></div>
</div>
</blockquote>
Ha. Good luck with that. Did the pressure in the house go up with
that temperature increase? No? Then the house has leaks. Even the
best sealed houses would exchange 1/2 their volume of air over an
afternoon.<br>
<br>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"> </span>After a few hours
of this, I opened up the house to vent out the heat and
moisture.<span style="mso-spacerun: yes"> </span>Returning
to night flushing I was able to return house to low 70s
and 10% lower RH by morning.</font><span
style="mso-spacerun: yes"><font style="FONT-SIZE: 14pt">
This returned my house to an earlier time in the humid
season. </font></span></font></span>
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"></span> </p>
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt">I
would propose that intermittently heating a house that
has humidity build up is a way to manage the humidity.<span
style="mso-spacerun: yes"> </span>The mold is
dried and must start all over. Yes, control humidity
at the source where possible.<span
style="mso-spacerun: yes"> </span>However, when
the ambient conditions are humid that strategy is
incomplete.</font></font></span></p>
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</blockquote>
<font face="Helvetica, Arial, sans-serif"><br>
The problem with this is that most things which retain moisture,
exchange it fairly slowly in response to changing conditions (as
you observed). I wouldn't expect a change made over the course of
a day to last more than a day when conditions are returned to what
they were. It might be useful if you had a sudden influx of
moisture, or if it was done at one of the transition points into a
drying regime (to speed up change that was going to happen anyway).<br>
</font>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000">
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"> </span><span
style="mso-spacerun: yes"></span>This heating is a
is appropriate where the house has low mass, allowing
the temperature to be easily raised and returned to
normal.<span style="mso-spacerun: yes"> </span>I
would also propose that we take steps to build up the
desiccant capacity of the house such that fewer cycles
such as this would be needed.<span
style="mso-spacerun: yes"> <br>
</span></font></font></span></p>
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</blockquote>
<br>
The higher the desiccant capacity, the less well this is going to
work.<br>
<br>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000">
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"> </span>Because we are
taking away the humidity in the humid seasons, it may
result in the house being dryer in the early heating
season.<span style="mso-spacerun: yes"> </span>A
strategy of humidification might be considered.<span
style="mso-spacerun: yes"> </span>I am aware that
there is risk if air is flowing through the thermal
envelope and cooling to dew point as a result of
higher indoor humidity.<span style="mso-spacerun: yes">
</span>However, if a well designed and built thermal
envelope with a thick layer of foam that is high
enough proportion of the total R value such that
humidified air that would penetrate to the warm side
will be above dew point in the expected coldest
conditions, this could work.</font></font></span></p>
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</div>
</blockquote>
<br>
<font face="Helvetica, Arial, sans-serif">Maybe. On a day like you
were discussing, 80's and high humidity outside, the dew point is
going to be in the high 70s, With a temperature inside of 104 and
evaporating moisture that would otherwise have been accumulating,
the dew point of any intra-wall surface is ALREADY going to be
below the dewpoint, no cold conditions required. Nor is that
surface going to have had time to adjust to the suddenly increased
temperature. In other words, you might potentially be driving
moisture into the walls from both inside AND outside. Not good.</font><br>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000">
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt"><span
style="mso-spacerun: yes"> </span>With those risk
managed, humidification is much lower energy
consumption and environmental risk than the
refrigerant driven dehumidification. </font></font></span></p>
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</blockquote>
<font face="Helvetica, Arial, sans-serif"><br>
Got numbers for that?</font> Do you not have any cheap sources of
cold?<br>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000">
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"></span> </p>
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt">Perhaps
leaving the windows open during the day and not
pulling cold moist air into the house at night is
another way to reduce humidity risk.<span
style="mso-spacerun: yes"> </span>Though the
absolute humidity would be about the same, the higher
relative humidity resulting from the higher
temperature would be less vulnerable to humidity
problems.<span style="mso-spacerun: yes"> </span>Although,
I contend it is less comfortable.</font><span
style="mso-spacerun: yes"><font style="FONT-SIZE:
14pt"> </font></span></font></span></p>
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</blockquote>
<font face="Helvetica, Arial, sans-serif">If you assume a set
temperature inside, you are better off letting in night air than
day air (at least in my climate). Check out a weather graph which
shows temperature and dew point (I use weatherspark). You may see
that a warm day in a shoulder season starts with the temperature
at the dewpoint, and as the day warms the temperature rises
significantly, and the dewpoint follows it but at a much lesser
magnitude. So the time of lowest *absolute* humidity is at
night. Pulling in colder, less absolute humidity air in at night
is better than pulling in warmer, higher absolute humidity air in
the day, particularly if that air is warmer than the inside.<br>
</font>
<blockquote cite="mid:282E527F8E1B42DC8E31051F6948B7AA@userHP"
type="cite">
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<div style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial'; COLOR:
#000000"><font face="Helvetica, Arial, sans-serif">
</font>
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><font face="Helvetica, Arial, sans-serif"><span
style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"></span></font> </p>
<p class="MsoNormal" style="MARGIN: 0in 0in 0pt; LINE-HEIGHT:
13pt"><span style="FONT-FAMILY: ; LINE-HEIGHT: 16pt"><font
face="Times New Roman"><font style="FONT-SIZE: 14pt">Very
interesting subject.<span style="mso-spacerun: yes"></span></font></font></span><br>
</p>
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<br>
<font face="Helvetica, Arial, sans-serif">Yup.</font> I explained
dew point to my 6 year old niece, and I told her once she got it
internalized, she would be halfway to being able to replace me.<br>
<br>
Thank You Kindly,<br>
<br>
Corwyn / Topher Belknap<br>
<pre class="moz-signature" cols="72">--
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
<a class="moz-txt-link-freetext" href="http://www.GreenFret.com/">http://www.GreenFret.com/</a>
<a class="moz-txt-link-abbreviated" href="mailto:topher@greenfret.com">topher@greenfret.com</a>
</pre>
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