[EnergyPlus_Support] Re: Suspicious daylighting results - please help

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

It is V4.  Thank you, Linda.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie <linda@...> wrote:
>
> I will take your input file and file it with our "daylighting" expert 
> to see if it is a problem or not.
> 
> I hope you are using V4 as some of the earlier versions did have 
> problems that were fixed (as we continue to try to fix defects every release).
> 
> At 02:04 PM 1/31/2010, Liam O'Brien wrote:
> >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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> > > >
> > >
> >
> >
> >
> >
> >------------------------------------
> >
> >The primary EnergyPlus web site is found at:
> >http://www.energyplus.gov
> >
> >The group web site is:
> >http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> >Attachments are currently allowed but be mindful that not everyone 
> >has a high speed connection.  Limit attachments to small files.
> >
> >EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf 
> >under the Documentation link and press the "search" button.
> >Yahoo! Groups Links
> >
> >
> >
>




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