<div dir="ltr">Hi Jacob, <div>I don't know if you remember me. I am analyzing the energy needs of a building in an urban setting. I modeled in TRNSYS a canyon through virtual windows adopting the "solution 1" proposed by you. Now I want to analyze the difference between the model with canyon like thermal zone (including multiple reflections) (model A) and the model without canyon (model B) (see figures). The solar radiation absorbed by facades overlooking canyon should be the same in the two models. This does not happen: the solar radiation absorbed in the model A is less than in the model B. Why?</div><div>Thank you</div><div>Best regard</div><div>Chiara Colucci</div><div><br></div><div>(Model A)</div><div><img src="cid:ii_1583efa08cbffb4c" alt="Immagine incorporata 2" width="472" height="275"></div><div><br></div><div>(Model B)<br></div><div><img src="cid:ii_1583ef9c4c84c428" alt="Immagine incorporata 1" width="472" height="352"><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">2016-04-22 13:12 GMT+02:00 hotline <span dir="ltr"><<a href="mailto:hotline@transsolar.com" target="_blank">hotline@transsolar.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">





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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Dear
</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Chiara,</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">A virtual surface isn’t the appropriate approach.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Virtual surfaces should be used  as adjacent surfaces between zones in SketchUp which are merged into one zone with multiple airnodes.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">A virtual surface isn’t a heat transfer surface, it doesn’t exist in the thermal model. Thus, the error
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">message is correct. The volume of the canyon zone  isn’t closed and therefore no view factor matrix
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">could be calculated.  <u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Modelling outdoor space isn’t  a straightforward task.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Solution 1<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">In order to generate a closed volume of the canyon and allow solar radiation to penetrate into the zone
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">you need a window. To do the shortwave solar correct you may use a so-called “no window” which has a transparency of 100 %.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">However, this surface has a temperature and thereby influences the zone air temperature by its inside convections<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">heat transfer coefficient (HTC) and the longwave exchange by its temperature.
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">For reducing the influence on the air temperature you may define the  inside HTC to be small (like 0.01 kJ/k m²).<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">For longwave radiation exchange the window temperature should be approximately the sky temperature.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">However, you can’t fix a temperature of window. You have to try to calculate a surface gain such that the<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Temperature is close and the model is still converging.
<u></u><u></u></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Solution 2<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">You use solution 1 for calculating the incident radiation (total and direct) on the window and use this radiation<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">as input to a model which doesn’t contain a “canyon zone”.  For longwave radiation exchange you have to<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">estimate the “effective ground temperature”.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">All the best<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The Transsolar Software Team<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial","sans-serif";color:black">______________________________<wbr>______________________________<wbr>______________________________<wbr>_______<u></u><u></u></span></p>
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<p class="MsoNormal"><i><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">Jakob Merk<u></u><u></u></span></i></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">TRNSYS Software Team<u></u><u></u></span></p>
<p class="MsoNormal"><i><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black"><br>
</span></i><b><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">Transsolar Energietechnik GmbH<u></u><u></u></span></b></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">Curiestraße 2<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">70563 Stuttgart<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">Fax:        <a href="tel:%2B49%20711%2067976-11" value="+497116797611" target="_blank">+49 711 67976-11</a><br>
Email:    </span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="mailto:hotline@transsolar.com" target="_blank"><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:#0563c1">hotline@transsolar.com</span></a></span><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">Web:      </span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="http://www.trnsys.de/" target="_blank"><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:blue">www.trnsys.de</span></a></span><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black">
</span><span style="font-size:11.0pt;font-family:"Arial","sans-serif";color:#1f497d"><u></u><u></u></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Von:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> TRNSYS-users [mailto:<a href="mailto:trnsys-users-bounces@lists.onebuilding.org" target="_blank">trnsys-users-bounces@<wbr>lists.onebuilding.org</a>]
<b>Im Auftrag von </b>Chiara Colucci<br>
<b>Gesendet:</b> Mittwoch, 6. April 2016 16:49<br>
<b>An:</b> <a href="mailto:trnsys-users@lists.onebuilding.org" target="_blank">trnsys-users@lists.<wbr>onebuilding.org</a><br>
<b>Betreff:</b> [TRNSYS-users] Trnsys17<u></u><u></u></span></p>
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