[esp-r] Re: Solar Obstruction unexpected results

[Liam O'Brien]

Jon et al,

Thanks for the response.  I moved my massive block 10cm from the window plane.  The shading analysis seems to have worked properly (direct sun makes it through the gap between the obstruction and the wall in the summer months early and late in the day, but otherwise not at all).  However, the simulation results still don't reflect this.  The peak "solar entering from outside" still occurs midday, which is exactly when the direct sun should be completely blocked out.  Any thoughts?

Thanks.

Liam O'Brien

> Date: Fri, 15 Feb 2008 15:03:47 +0000
> From: jon at esru.strath.ac.uk
> To: obrien_liam at hotmail.com; esp-r at lists.strath.ac.uk
> Subject: [esp-r] Re: Solar Obstruction unexpected results
> 
> 
> A question about shading...
> 
> The important word below is "flush with".  Current versions of the shading analysis
> tool will ignore obstructions which touch the surface or cross over
> the surface.  Leave a gap of several mm.
> 
> Note: the next version of esp-r does not have this limitation.
> 
> If you see messages about crossing the plane then your
> model will have potentially incorrect shading predictions.
> 
> -ESRU
> 
> Hello All,
> 
> I am trying to create an overhang for a window.  After getting unexpected results (a large overhang over a window on the summer solstice at noon reduced "solar entering from outside" by about 15%), I decided to test an extreme case to confirm proper modeling technique.  I created a model with a single window and created an obstruction that is flush against the window and extends beyond it in all directions.  Obviously, this should have yielded zero solar entering from outside.  However, the results were that sunny days experienced peaks of several thousand Watts of solar entering from outside - hardly negligible.  
> 
> My procedure for creating the obstructions is to enter them as a dimensional input, run the ISH module to define a shd file ("calculate shading").  When I "predict insolation", the synopsis says "glazing totally shaded" for all hours that the sun is up, as expected.
> 
> I am using the native Windows version of ESP-r.
> 
> Any thoughts about why I might be getting these results?  Thanks!
> 
> Liam O'Brien
> 
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