[EnergyPlus_Support] Re: Suspicious daylighting results - please help

["Liam O'Brien" <liambrn@xxxxxxxxx>]

Thanks for the response, Linda.

The thing is, I do want to account for transmitted light through interior windows.  My results suggest that there might be a bug in the detailed daylight model.  Using IgnoreInteriorWindowTransmission pretty much narrows it down to the fact that the light coming through the interior windows is causing higher than expected workplane illuminance.

Put another way, EnergyPlus reports that for a fixed exterior window geometry/properties, the addition of interior windows roughly doubles the mean workplane illuminance.  This obviously defies physics, as the number of lumens entering the building is fixed.  A few points in my 10 by 10 illuminance map could conceivably be higher, but certainly not all of them - and about double, at that.

Thank you.

Liam

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie <linda@...> wrote:
>
> You can try an undocumented object:
> 
> Output:Diagnostics,IgnoreInteriorWindowTransmission;
> 
> and see if that helps.
> 
> At 09:49 AM 1/31/2010, Liam O'Brien wrote:
> >Hi all,
> >
> >In an earlier post, I mentioned that I was trying to subdivide a 
> >large perimeter zone into smaller zones so that I can have finer 
> >control over lighting (since only two sensors are allowed per zone).
> >
> >In the process, I discovered unexpected results.  The presence of 
> >that wall (which is mostly single glazing, to replicate an office 
> >where there is no obstruction to light between zones) nearly DOUBLES 
> >the mean workplane illuminance.  The only conclusion I can come up 
> >with is that EnergyPlus thinks that that interzonal window is 
> >actually outside (despite the fact that I have defined it to be 
> >attached to the neighbouring zone.
> >
> >I've posted two models to demonstrate this phenomenon.
> >1) A 6m wide by 5m deep by 3m high zone.
> >2) Exact same except split into two equal zones with a interzonal 
> >window seperating them.
> >
> >In reality the second case should be marginally darker, since the 
> >glass will absorb some light.  The results are far from what I would 
> >have expected.
> >
> >If anyone has experience with the detailed daylighting model, their 
> >comments would be greatly appreciated.
> >
> >Thanks in advance.
> >
> >Liam O'Brien
> >
> >
> >
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> >
> >
> >
>




------------------------------------

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