[esp-r] Re: Calculation of solar gains through complex shading devices

[Geissler Achim]

Hi Germán

some comments below, inline.

Best
Achim


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Von: germolinal at gmail.com [mailto:germolinal at gmail.com] Im Auftrag von Germán Molina Larrain
Gesendet: Dienstag, 7. Mai 2013 15:33
An: Geissler Achim
Cc: esp-r at lists.strath.ac.uk
Betreff: Re: [esp-r] Calculation of solar gains through complex shading devices

Hi Achim,

my original idea of workflow was thought on the basis of a straightforward finide difference simulation (as I have done in Matlab)... so it would be to make the solar simulations (calculation of solar gains and Daylight), and then, to make the thermal simulation; knowing the flows to each node (calculated before).

Now, since you say that ESPr supports BSDF input, maybe the whole thermal simulation should be done in ESPr, leaving Radiance just for lighting. I have been working on the generation of the BSDFs, and I think the problem is practically solved right now, using tools that already exist (I expect I can publish something related to this). How long do those (BSDFed) simulations take? I have heard that in E+ they take considerably more time than the other ones.

I'm afraid I can't tell you, as I have never personally used that particular feature of ESP-r. Also, I am not sure if the format is any "general" BSDF type. How do you generate your BSDFs?

As far as I am aware, the three-phase-method and the "coupling" with EnergyPlus requires two runs? Could you describe the necessary workflow / calculation steps? Where / in which program is the setting of a Venetian type blind set, for example? Based on what?

The direct coupling, I was informed, is complicated. But, just as in ESPr, E+ was provided with the capability of using BSDF information in a very similar way as the Three-phase method does. So everything is actually made on E+.


Anyway, I guess the best should be to make the lighting simulation, calculate the electric lighting consumption and transform it into internal gains for a posterior ESPr simulation, considering BSDFs? Please feel free to comment.

Well, basically ESP-r and Radiance can be used fully coupled. I.e., if you want to have lighting control, you can couple a Radiance model, let that do the lighting calculations and give back which percentage of the pre-set set point are covered by daylight - ESP-r will then add the rest as electric internal gain based on the defined electric light installation. The gain due to daylight is taken into account by the solar gain. This can also be used with the CFCs - there is an experimental feature which generates the Radiance Model with a Venetian type blind during run-time with the slat angle as given by solar needs (e.g. "cut off" control). Computing times are, of course, somewhat longer than usual.


THANKS VERY MUCH

German

2013/5/7 Geissler Achim <achim.geissler at fhnw.ch<mailto:achim.geissler at fhnw.ch>>
Dear German

basically, that is a very interesting idea. However, I would not expect this to be easy and straightforward, as one strength of ESP-r is that it solves all the physics simultaneously. Currently, there are two possible ways to include complex shading: The "CFC" model for multi-layer constructions (to date, this covers venetian type blinds, roller blinds and meshes are "in the works" as far as I am aware) and the input of  bi-directional reflection / transmission input data ("BRTD") - here the problem is basically generating the necessary input data, however this may be possible via Window 7 (LBNL), now.

ESP-r can basically take the solar distribution on the surfaces of the zone behind the window into account. In the mainstream code, the CFCs lack daylighting, however. I am not sure what the situation in this regard for the "BRTD"-type of models is.

As far as I am aware, the three-phase-method and the "coupling" with EnergyPlus requires two runs? Could you describe the necessary workflow / calculation steps? Where / in which program is the setting of a Venetian type blind set, for example? Based on what?

Best
Achim



Von: esp-r-bounces at lists.strath.ac.uk<http://ath.ac.uk> [mailto:esp-r-bounces at lists.strath.ac.uk<mailto:esp-r-bounces at lists.strath.ac.uk>] Im Auftrag von Germán Molina Larrain
Gesendet: Dienstag, 7. Mai 2013 01:07
An: esp-r at lists.strath.ac.uk<mailto:esp-r at lists.strath.ac.uk>
Betreff: [esp-r] Calculation of solar gains through complex shading devices

Hello,

I am German Molina, and I am doing my MSc. on complex shading systems, and how to treat them for simulation purposes (Lighting and Solar Heat Gains). I do not really use ESPr or any other thermal simulation tools, just Radiance for now.

Finished my literature review, I realized that one method used for lighting (the Three-phase method) might be good to be a good estimator of the Solar Heat Gains through complex fenestration systems... later I found out that some people did this, and actually nowadays something very similar can be implemented in EnergyPlus.

Long story short, I think (it is waiting for a validation) that I can accurately calculate the Solar Heat Gains through virtually any complex fenestration system of known BSDF matrices; and not only net solar heat gains, but I think I can also say where the solar radiation is going (calculate the fraction that goes to the ceiling, to the floor, etc.). How difficult would it be to use this output as an input for ESPr? For what I understand, ESPr does not handle very well these kind of systems?

What I am proposing can be actually reduced to just one phrase: Lets use Radiance to what it does best (radiation transport) and ESPr to what I think it does best (Thermal simulation).

THANKS VERY MUCH

German Molina

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