[EnergyPlus_Support] Re: Bias in Direct Solar Report ?

["ancarrillo2001" <ancarrillo@xxxxxxxxxxx>]

Dear Linda:

I made my tests with a SummerDesignDay, (I have not used a weather
file), and I reported on my 1 minute time step. I have been reading
the documents you mentioned, and I have made a few more tests and I
have found that the unexpected results do not depend on the reporting
time step:It is just that the DirectSolar and Diffuse Solar reported 
from the DesignDay are clearly asymmetrical with respect to the noon.

This is not the case with the Solar Altitude Angle and the Surface Ext
Solar Beam Incident over an horizontal surface, which are symmetrical
with respect to the noon as expected in a generated DesignDay. 

So I guess that the solar calculations over the building are well made
(because the solar beam incident over exterior surfaces is OK) but
there may be a problem with the reporting of the DirectSolar and
DiffuseSolar from a DesignDay.

Thank you for your answers

Antonio Carrillo
ETS Ingenieros Industriales
University Of Malaga
Spain
tlf: +34-953132409





--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie <linda@...> wrote:
>
> Are you reporting hourly or on your 1 minute time step?
> 
> What you might be seeing is the interpolation done on hourly weather, 
> described in the IOReference on page 1528, PDF page number 1569.
> 
> Do you see the same reporting on the Design Day solar models?  The 
> writeup for the solar modeling did not make it in the 2.1 documentation.
> 
> Linda
> 
> At 09:21 AM 2/1/2008, ancarrillo2001 wrote:
> 
> >Both the Solar Altitude Angle and the Surface Ext Solar Beam Incident
> >over an horizontal surface peak at 13:00h,just as expected.
> >
> >But the Direct Solar peaks at 13:29 aprox, and so does the Diffuse
> >Solar. This is very strange to me, is there any known problem with the
> >Direct and Diffuse Solar reports?
> >
> >On the other hand, I have tried to look for the ASHRAE ClearSky model,
> >  that is used in the DesignDays calculation. In the Input-Output
> >Reference say that there is more information in the Engineering
> >Reference but I couldn't find anything. Is it there?
> 
> 
> [Non-text portions of this message have been removed]
>




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