How to design curve walls

answered 2015-10-02 07:35:40 -0500

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Since E+ calculates heat transfer in only one direction, the wall surfaces must be planar and cannot be curved. As such, if you try to use the Arc or Circle tool in the SketchUp plugin and create a zone, it will divide the curved surface into multiple planar surfaces.

There was recently a great talk about result accuracy depending upon number of planar surfaces used to create a circular zone at the ASHRAE Energy Modeling Conference in Atlanta given by Cheryl Saldanha. In her talk, she showed that using four surfaces was too simplistic, but using 24 surfaces yielded very similar results to using 72 surfaces.

I hope this helps!

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Thanks,

This is the type of answer that I'm looking for.

J Monteiro ( 2015-10-02 11:44:04 -0500 )edit

24 surfaces might be too much anyways, you have to use your judgment for this. In any case, make sure you get the zone volume and exterior surface areas accurately. A square that fits in a circle definitely does not satisfy any of these two, and therefore you'll be underestimating everything.

Julien Marrec ( 2015-10-02 18:47:17 -0500 )edit

You could do a rough sensitivity analysis by staring with say an 8 surface approximation, then increasing to 12, then 16, etc. until the difference between successive simulations is less than some amount you are happy with accepting as an error. Not too scientific, but if you're just gonna use your judgement this may help inform it in a "smart" way.

alexmead ( 2015-10-04 23:02:28 -0500 )edit

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