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Marko,<br>
The reason that the "airlayer" material in the TRNBuild libraries
is massless and has no thickness is that narrow air gaps (i.e.
airgaps with little or no convection in them) can be assumed to
provide thermal resistance in the wall. When you have a wide air gap
then the convection within that airgap becomes important and you
cannot correctly account for it as though it were part of the wall.
What I would recommend you do is to treat that 70cm air gap as
though it were one or more airnodes separated from the ambient and
the conditioned space by "walls" that consist only of your polyester
foil (treated as massless layers offering only a thermal
resistance). You can set the convection coefficients on the inside
of those two layers as computed internally by Type56. This is
probably still not an ideal treatment of the situation either but in
my opinion it is more correct than lumping the air gap into the
wall.<br>
kind regards,<br>
David<br>
<br>
<br>
<div class="moz-cite-prefix">On 4/29/2015 1:58 PM, Marko Mancic
wrote:<br>
</div>
<blockquote
cite="mid:1120083704.359120.1430333883099.JavaMail.yahoo@mail.yahoo.com"
type="cite">
<div style="color:#000; background-color:#fff;
font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif;font-size:16px">
<div id="yui_3_16_0_1_1430325183282_59393"> Hi Trnsys users,</div>
<div id="yui_3_16_0_1_1430325183282_59392"><br>
</div>
<div id="yui_3_16_0_1_1430325183282_59377" dir="ltr">I am trying
to create a model of a lightweight contruction sport hall,
which consists of two leyers of special Polyester foils, and a
70cm air layer between. In reality, the construction is
streched and held in place by a wood sceleton.</div>
<div id="yui_3_16_0_1_1430325183282_59466"><br>
</div>
<div id="yui_3_16_0_1_1430325183282_59467" dir="ltr">I have
noticed, that whichever air layer is chosen from the library,
it is modelled as massless, and the tickness is 0. </div>
<div id="yui_3_16_0_1_1430325183282_59469"><br>
</div>
<div id="yui_3_16_0_1_1430325183282_59484">How can I change the
tickness of the Air layer?</div>
<div id="yui_3_16_0_1_1430325183282_59451" dir="ltr"><br>
</div>
<div id="yui_3_16_0_1_1430325183282_59434" dir="ltr">In
addition, I get the following error messages when I try to
save the project "error when trying to create wall transfer
coefficients"</div>
<div id="yui_3_16_0_1_1430325183282_59450">" unable to find
root, after indication that root exists"</div>
<div id="yui_3_16_0_1_1430325183282_59449">"Maybe time base is
to small"</div>
<div id="yui_3_16_0_1_1430325183282_59469"><br>
</div>
<div id="yui_3_16_0_1_1430325183282_59485">What could be the
couse of the error I am getting?</div>
<div id="yui_3_16_0_1_1430325183282_59486"><br>
</div>
<div id="yui_3_16_0_1_1430325183282_59494"><br>
</div>
<div id="yui_3_16_0_1_1430325183282_59495">Thank you for
helping!</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
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<br>
<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
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