[EnergyPlus_Support] Re: Custom Weather Files - Radiation

["hollywas" <hollywas@xxxxxxxxx>]

Hi Linda,
Thank you for both replies.  Could you possibly elaborate on the view factor calculations making E+ crash?  

The complex models will run fine with a standard EPW.  And the homemade EPW will run fine with a simple model.  However combining the two causes fatal errors.

I know that the fatal errors occur when E+ "doesn't like" the radiation data, but I can't figure out what the specific parameter is that makes it crash.  The problem seems to be a large delta in radiation data between timesteps, but it doesn't seem to be consistent.   
Thank you for your time.
Holly


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie <linda@...> wrote:
>
> The weather converter can use the Global horizontal and calculate the 
> direct and diffuse based on the Zhang-Huang correlation.  It also 
> will calculation the Horizontal IR from Sky (using the equation that 
> is in the Auxiliary Programs document).
> 
> The complexity of geometry may have problems in the view factor 
> calculations -- we have worked on that problem for the next release.
> 
> At 03:58 PM 10/4/2010, hollywas wrote:
> >Hello,
> >I am trying to make a custom EPW from an on-site weather 
> >station.  Strangely, the EPW will run successfully when paired with 
> >a simple IDF, such as one of the EnergyPlus example files.  However, 
> >with a more complex model it will fail on certain timesteps.  The 
> >more zones the model contains, the more timesteps will cause fatal 
> >errors... even when modeling the same building.  The error message 
> >says surface temperatures are out of range.  It seems to fail at 
> >timesteps when there is a large change in the direct and/or diffuse 
> >radiation data.  If I manually replace this radiation data, the 
> >simulation will run successfully through this timestep.
> >
> >Do you have any idea why the complexity of the geometry would affect 
> >the success of the EPW?  Do you have any advice on fixing this 
> >besides manually replacing the radiation data at every failing timestep?
> >
> >FYI, The Direct Normal and Diffuse Horiz Radiation are calculated 
> >from measured Global Horiz Radiation.  Horizontal Infrared Radiation 
> >from Sky was not measured so I have tried different values 
> >including:  using TMY3 values and inputting the TMY3 average value 
> >for each timestep.  I also have one reference for how to model it, 
> >but would appreciate any other advice.
> >
> >Thank you in advance for any help!
> >Sincerely,
> >Holly
> >
> >Holly W. Samuelson
>




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