I had posited previously that the increased room temperature due to the placement of a tree could be due to wind-shielding that reduces the wind speed and thus the infiltration rate. However, seeing as how the tree seems to be modeled only as a shading object, then the only possible explanation for the increased room temperature that I can think of is in reducing the SKY-FORM-FACTOR, i.e., the solid angle of sky visible to the wall and window(s) next to the tree, thus reducing the long-wave radiation from those surfaces to the night sky. I don't know if it's possible to extract the long-wave radiative loss from EnergyPlus, but outside of that it would be possible to compare the hourly heat losses from the affected wall and window(s), and see if they are reduced at nighttime when there is a tree.
Having said this, I am skeptical that the reduction in long-wave radiative loss at night would more than compensate the reduced short-wave solar radiation during the day, especially for a deciduous tree that would be bereft of leaves during the winter.
If anyone finds some other explanation for this counter-intuitive
result, please let us all know!
Joe
All,
The example file the OP sent is a Minimal Complete Verifiable Example (MCVE, meaning it has nothing superfluous, only the bare minimum required to reproduce the behavior) which is really good news. Even on my phone I can see what’s in there because it’s sweet and short.
So I would encourage all to take a look at it because it’s quite unusual in our community and1. For once you actually have something workable to reproduce the results and investigate and quickly be able to help2. If it could serve as an example for anyone who may be seeking help in the future here or on similar platforms of the BEM community that would be GREAT.
Anyways/fyi, Koji did use some Shading:Building:Detailed objects with a transmittance schedule which has value of 1 until March and fractional values in July August (in the 0.4 range or so).
���iv>
Koji,Knocking the obvious causes, what weather file are you using? You have design days for Chicago in there, are you using Chicago EPw?Goes without saying that if you were using any epws from the Southern Hemisphere your seasons would be wrong...
Best,Julien
��> Sent from a mobile device, please excuse the brevity.
Julien Marrec, EBCP, BPI MFBA
Owner
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Le 1 juil. 2018 à 22:15, Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> a écrit :
Example:
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 “Solar Modifying Characteristics of Various Species of Trees” in “Landscape architectural graphic standards” By Leonard J. Hopper, 2007. The trees together with component blocks representing neighbouring buildings are modelled for the daylighting simulation.
You can set a transparency schedule for a shading surface.
Vorschau für Anhang "Practical Method to Model Trees for Daylighting Simulation.pdf" ansehen![]()
Practical Method to Model Trees for Daylighting Simulation.pdf385 KB
2018-07-01 21:48 GMT+02:00 Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:
Dear,Have you tried using "Shading:Site:Detailed" with a transmittance schedule that reflects the amount of leaves?
p.s., You are reminding me of some research conducted by Dr. Mojtaba Navvab in the mid-1980s when I was a colleague at the University of Michigan. He took photos of deciduous tress at different times of the year, then digitized the image to determine the amount of transparency and its impact on the indoor environment. This was, in my mind, very innovative in the days when digital images were not the norm.Vorschau für Anhang "Practical Method to Model Trees for Daylighting Simulation.pdf" ansehen![]()
Practical Method to Model Trees for Daylighting Simulation.pdf385 KBOn Sat, Jun 30, 2018 at 8:43 PM, Koji Takemasa koji_takemasa@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com > wrote:
Hi.
I use EnergyPlus to calculate the room temperature when there are
deciduous trees and when there is not.
The strange thing is that those with deciduous trees show higher values
when comparing the room temperature of January when there are deciduous
trees and no deciduous trees.
In this setting, the winter (including January of course) leaves are
falling, so room temperature should be roughly equal.
I do not know the reason.
Since I am not sure whether my setting is correct, I also attached an
idf file.
The attached graph shows annual room temperature fluctuation. The X axis
shows the month and the Y axis shows the time. I think that you can see
the difference when comparing them.
--
Name : Koji Takemasa (Ph.D.)
Mail : koji_takemasa@xxxxxxxxx
http://www.lead-labo....jp/
------------------------------
--
James V Dirkes II, CEO / President
The Building Performance Team Inc...
1631 Acacia Dr, Grand Rapids, MI 49504
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<Practical Method to Model Trees for Daylighting Simulation.pdf>
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