Re: [EnergyPlus_Support] Window Calculation

[Linda Lawrie <linda@xxxxxxxxxx>]

Some email has gone on behind the scenes, but the answers are included below:

At 02:32 AM 4/29/2003, Alexander Beisteiner wrote:
>1)       In the case of windows, the external film coefficient cannot be
>set with the object "ConvectionCoefficients". This means, if a value is
>defined, the output variable for the window external convection
>coefficient is zero. Is this deliberate?

This was a bug in the program.  It is not (1.1.0.018) doing the user 
supplied convection coefficients (an advanced feature) correctly.  We hope 
to issue an update for this and several other problems that were 
late-breaking soon.

>2)       As defined on page 41 in the Output Details and Examples-
>manual, the calculated conductance does not include film coefficients.
>Comparing this result to the Window5 calculation, values are the same,
>but the Window5 calculation includes film coefficients. Might it be
>possible, that the E+ output for the U-Value includes the film
>coefficient? In that case, can the window U-Value be assumed to be
>constant, independent of the variable external convection coefficient?
>

The documentation was incorrect -- windows are reported WITH film 
coefficients.  However, there is a change request (CR) to have both Window 
Constructions and other Constructions reported with and without film 
coefficients in this report.  (As noted above, the other Constructions are 
already reported WITHOUT film coefficients).  However, note that user 
supplied convection coefficients add a new degree of complexity here -- 
therefore, the nominal film coefficient reporting will be for standard 
conditions -- and will be documented thereof.


Linda

EnergyPlus WebSite: http://www.energyplus.gov
Owner: EnergyPlus_Support list
Member: EnergyPlus Development Team



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