[EnergyPlus_Support] Re: U value input

["eric_zhou1223" <eric_zhou1223@xxxxxxxxx>]

Many thanks Brent. 

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Griffith, Brent" 
<brent_griffith@...> wrote:
>
> I don't quite follow you, I ran your files and they seem to be 
reporting
> similarly.  If you are looking at the Envelope Summary in the html
> report, there does seem to be a problem with reporting of "U 
Factor with
> Film".  
> 
>  
> 
> But in general, the best approach is to use the E+ report for U-
values
> without the film coefficients and then apply the film coefficients
> yourself so that they agree with what the Standard is expecting.
> Internally E+ doesn't use crude combined convection/radiation film
> coefficients so reporting with the film coefficients is somewhat
> arbitrary.  E+ is neutral with respect to specific Standards and 
it may
> be that there are different film coefficients that need to be used
> depending on the Standard.  
> 
>  
> 
> It is important to understand that film coefficients, and hence U-
values
> with film coefficients, depend on orientation (vertical, 
horizontal heat
> flow up, horizontal heat flow down, etc) and are not uniquely 
defined
> for just constructions.  So the reporting of these is by surface, 
not by
> construction.  To get a report in eio file with film coefficients 
you
> would need to add a "Report, surfaces, details;" input object to 
the idf
> file.  See page 23 (or 29 absolute) in 
OutputDetailsAndExamples.pdf for
> more information.
> 
>  
> 
> ________________________________
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of 
eric_zhou1223
> Sent: Tuesday, January 22, 2008 10:55 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: U value input
> 
>  
> 
> Thanks a lot, Brent. I used the tool to output two files, the only 
> difference between them being location and perhaps system type. 
Yet 
> one of them can report "U-Factor with Film " and "U-Factor no 
Film", 
> another can only report "U-Factor no Film". Would you please give 
> me hint on this? Thanks again. I uploaded two files package 
named "U 
> factor".
> 
> Eric
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> , "Griffith, Brent" 
> <brent_griffith@> wrote:
> >
> > Not directly. E+ uses layer-by-layer descriptions and targeting a
> > specific U-value often requires iteration. Tune the material 
> properties
> > of an insulation layer inside the construction. Be careful about 
> the
> > surface film coefficients when setting targets... (E+ can report 
> them
> > with or without, but Standards aren't always so clear). If the 
> Standard
> > is 90.1, you could try constructions out of an input file from 
the
> > EnergyPlus Example File Generator. 
> > 
> > 
> > 
> > ________________________________
> > 
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of 
> eric_zhou1223
> > Sent: Thursday, January 17, 2008 12:27 AM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > Subject: [EnergyPlus_Support] U value input
> > 
> > 
> > 
> > Hi all,
> > 
> > Is there a simple way to define an U value for a wall,which is 
> made of 
> > several layers, like in eQuest? Given that I need to set the 
wall 
> U-
> > value to a standard value.
> > 
> > Eric
> > 
> > 
> > 
> > 
> > 
> > [Non-text portions of this message have been removed]
> >
> 
>  
> 
> 
> 
> [Non-text portions of this message have been removed]
>




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