<div dir="ltr">David,<br><br>I am not familiar with TRNBuild. Does it have a built-in CAD interface that one can draw a building? Can one define building surfaces by coordinates? Can one import a 2-D or 3-D CAD drawing? As I recall in Type56, one needs to pre-calculate the wall and window areas by orientation for each zone and input the area value into TRNSYS. I am not sure if this is still the case. <br>
<br>Thanks,<br>Chaoqin<br><br><br><div class="gmail_quote">On Fri, Aug 1, 2008 at 9:43 AM, David Bradley <span dir="ltr"><<a href="mailto:bradley@tess-inc.com">bradley@tess-inc.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Chaoqin,<br>
There are three parts to the geometry issue.<br>
<br>
For internal radiation exchange, you are correct that TRNSYS is a<br>
non-geometrical model and that two surfaces do not have any knowledge of<br>
their mutual view factor. Like many of the other building models out<br>
there, TRNSYS uses a star-network in which each surface "radiates" to<br>
the air node and vice versa.<br>
<br>
For external geometry, one defines orientations in the building<br>
processor (TRNBuild) and then defines corresponding surfaces (slope and<br>
azimuth) in the weather data reader. Solar radiation from a particular<br>
weather data reader surface is then linked to the appropriate Type56<br>
inputs for each orientation defined in TRNBuild.<br>
<br>
For external shading (including building self-shading), one places a<br>
series of wingwall and overhang components between the unshaded solar<br>
radiation calculated by the weather data reader and the building, in<br>
effect cutting down on the amount of radiation incident on the building.<br>
It is a flexible methodology but a bit of a cumbersome one. One of the<br>
main pushes in the current development of TRNSYS 17 is a much more<br>
automated methodology for doing building self-shading. The Type56<br>
developers are also working on a true view-factor methodology for<br>
internal radiation exchange within a zone.<br>
<br>
Kind regards,<br>
David<br>
<br>
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</blockquote></div><br></div>