Ah, modeling trees in building energy simulations.
What I've done (with DOE-2, but it's equally doable in EnergyPlus) is to model them as five BUILDING-SHADES making up a box, and give the shades a transmittance schedule depending on when the leaves fall. The second slide in the attached PPT is from an ASHRAE presentation I gave in Dallas two weeks ago that happened to have some trees modeled around a house. The only thing to watch out for, in my case at least, was to set the transmissivity at the square root of the intended value, since the solar radiation always passed through two building shades. If building-shades in EnergyPlus are one-way, then I guess even this detail is unnecessary.
If you're not satisfied with how clunky a square tree looks, you can also input polygons to make a sphere. About ten years ago, I wrote some awk scripts to do that for modeling building domes in Egypt, that I reported in DOE-2 User News Sept-Oct 2002 (see second slide attached). Of course the script just does the top hemisphere, but extending it below shouldn't be a problem. The article is available at www.whiteboxtechnologies.com/downloads/02_09_Usr_News_YJH_modeling_domes.pdf , which contains the awk script. If anyone tries to modify it, like putting it in another language, outputting the vertices in E+ IDF format, doing the lower hemisphere, etc., let me know how it turns out.
Joe
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga CA 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx www.whiteboxtechnologies.com (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
On 2/14/2013 2:51 AM, Fabiano Domingues Ferreira wrote:
Thanks Jean!
Fabiano Ferreira
De: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] Em nome de Geert Bellens
Enviada em: Thursday, February 14, 2013 7:53 AM
Para: EnergyPlus_Support@xxxxxxxxxxxxxxx
Assunto: RE: [EnergyPlus_Support] Re: The best way to represent the trees
Jean,
very helpfull ! I was looking for such a reference.
Geert
Van: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] Namens Jean marais
Verzonden: 14 February 2013 08:09
Aan: EnergyPlus_Support@xxxxxxxxxxxxxxx
Onderwerp: [EnergyPlus_Support] Re: The best way to represent the trees
Remember that a shading surface only shades in one direction, unless the newer versions of eplus changed that. So you'll need an opposite face.
I did this once:
The 3 large horse chestnut trees (Aesculus hippocastanum) onsite are also modelled having 17,5% transmission during summer and 73% transmission in winter. Transmissions are based on the table â��Solar Modifying Characteristics of Various Species of Treesâ� in â��Landscape architectural graphic standardsâ� By Leonard J. Hopper, 2007. The trees are modelled for the daylighting simulation and in the energy simulation for both design and baseline case models together with component blocks representing neighbouring buildings.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Fabiano Domingues Ferreira wrote:
>
> Hi,
>
>
> I'm working in a project that I'm trying to model the trees. Follow attached the geometry in 3D showing the way that I represent and bellow the transmittance schedule that I have adopt.
> Does anyone know the best way to represent the trees?
>
> Schedule:Compact
>
> Transmittance schedule for Building 1 - Trees
>
> Any Number
>
> Through: 03/21
>
> For: Alldays
>
> Until: 24:00
>
> 0.3
>
> Through: 06/21
>
> For: Alldays
>
> Until:24:00
>
> 0.6
>
> Through: 09/23
>
> For: Alldays
>
> Until:24:00
>
> 0.8
>
> Through: 12/21
>
> For: Alldays
>
> Until:24:00
>
> 0.2
>
> Through: 12/31
>
> For: Alldays
>
> Until:24:00
>
> 0.3
>
>
>
>
>
> Thanks,
>
> Fabiano Ferreira
>
>
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