[esp-r] Re: solar problem

[Achim Geissler]

Dear Hua

I am not quite sure that I can follow your points below, but again some comments inline.

Best
Achim

On Oct 21, 2012, at 1:50 PM, HUA SUO <surano1505 at hotmail.com> wrote:

> Dear Achim,
>   Thanks for your great help. 
>   Could you also help me with the following questions?
> 1.why the output for each surface , "SW radiation(inside)" equals to "SW rad abs(other fc)", except that the information in the floor does not exit in "SW rad abs(other fc)" ?
Sorry, I don't know. I haven't looked at the "other face" thing in a while. Isn't "other face" the one facing outside of the zone under consideration? The value will depend on what boundary condition you defined. If you defined "similar" for internal walls, then "other face" will have the same values as "inside face".
> 2.I preset the absorbitivity 15% for the glazing in optical database, for each surface, should the "SW rad abs( other fc)"/global irradiance of this surface =15%?but it is only around 4%.The transmissivity is 10%.Why?
Careful with "global irradiance". What are you using, here? You should look at the radiation hitting the surface, not global (possibly horizontal?) radiation.
> 3.I tried to set the absorbability 99% for the grazing in optical database, for each surface, "SW rad abs( other fc)"/global irradiance of this surface=25%?
Strange values for a glazing. Typical values would be (double glazing unit) trans=60 - 70%, abs=8-15% refl=1-abs-trans
> 4. Where I can get the absorbed solar energy by floor?
For any given surface, I find it easiest to add a small surface with an opaque material I called "sensor". This is totally black (absorption = 0.999). Thus, "solar absorbed" on this "sensor surface" is the amount that hits the surface (everything is absorbed).
> 
> Regards,
> 
> Hua
> 
> 
> From: achim.geissler at intergga.ch
> Date: Sat, 20 Oct 2012 19:38:49 +0200
> To: surano1505 at hotmail.com
> CC: esp-r at lists.strath.ac.uk
> Subject: [esp-r] Re: solar problem
> 
> Dear Suo Hua
> 
> see some comments / answers below, inline.
> 
> Best
> Achim
> 
> On Oct 19, 2012, at 12:03 AM, HUA SUO <surano1505 at hotmail.com> wrote:
> 
> Hello, ESP-r experts.
>  
> I made a model that the all the façade is totally single grazing( material newly created by me) and the floor is opaque. After several test , I have some questions and hope that I can get help from you.
> 1. I found that if I change the properties in the material database for the single grazing, namely ” the solar direct tran” ,  “solar reflec out”, “solar reflect in”, nothing changes for the simulation result. Only if I change properties in the optical database ,namely”direct trn” “reflct” “abs” that can affect the simulation result. Am I right?
> Yes, the properties "trans" and "abs" ("refl") for transparent materials are taken from the optics database. The property "eps" (long wave emissivity), the geometry (i.e. the layer dimensions) and the thermal properties (thermal capacity and thermal conductivity) are taken from the materials database entry.
> 2. For the RES file, “solar entering the zone” is the summation of transmissivity (the parameter  in optical database) multiplies the global irradiance for each glazing surface. What is “solar absorbed in zone” ? I checked that it is not the summation of absorptivity (the parameter in optical database) multiplies the global irraiance for each glazing. It also can be noticed that “ solar absorbed in zone” is less than “solar entering the zone” in all the test I did.
> "solar absorbed" is that part of entering solar radiation that is not re-reflected directly back out of the zone.
> 3. When I try to get the solar energy that passes through the glazing and then absorbed by the floor , I extracted the information from ” SW radiation(inside)” , it seems that this parameter is very large and obviously not equal to the absorptivity of the floor multiplies the global irradiance to the floor(how to get this parameter ?). And for the glazing "SW radiation(inside)" divided by the irradiance is not the absorptivity I gave .What is “SW radiation(inside)” means exactly?
> Are you writing out the values "per m2"? SW (short wave) radiation inside should be closely correlated to radiation hitting the given surface and transmission of the transparent material (not absorption).
>  
> Regards,
> 
> 
> 
> Suo Hua
>  
> Ph.D Student in Tecnologia e Progetto per l'Ambiente Costruito/Technology and Design for Environment and Building
>  
> Il Dipartimento B.E.S.T.Dipartimento di Scienza e Tecnologie dell’Ambiente Costruito/ The Department of Building Environment Science & Technology
>  
> Politecnico Di Milano
> 
> Email:hua.suo at mail.polimi.it
> 
>  
>  
>  
>  
>  
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achim.geissler at intergga.ch




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