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Re: [EnergyPlus_Support] COMIS AIR FLOW: Opening




My apologies for the delay in answering this question.  

1.  The current implementation of COMIS in EnergyPlus requires that all COMIS 
AIR FLOW:OPENING Discharge Coefficients be >0.  The Input Output Reference and 
the IDD incorrectly state that zero is a valid value.

2.  When the window is closed, the "Air Mass Flow Coefficient When Window or 
Door Is Closed" and "Air Mass Flow Exponent When Window or Door Is Closed" are 
the primary factors specifying the flow rate at 1Pa along with crack length 
modifiers.

3.  When venting is active, the "Window Open Factor for Ventilation" specified 
in COMIS SURFACE DATA specifies the opening factor to be used when the venting 
controls fully open this window.  So, if this value is 0.5, then the window can 
never have an opening factor greater than 0.5.

4.  If the venting controls modulate, the modulation is for opening fators from 
0 to the value specified in 3 above.

5.  If venting is active and modulating, as the modulation approaches zero, the 
values associated with Opening Factor #1 in the COMIS AIR FLOW:OPENING object 
(Discharge coefficient, Width factor, Height factor, and Start height) control 
the flow.  When the venting controls completely close the window, it reverts to 
using the factors in 2.

I hope this helps clarify how the various inputs interact with each other.

Mike


On 28 Sep 2004, at 16:24, alexandrevarela2000 wrote:

> Hello All,
> 
> I´ve been messing around with COMIS and got this question:
> 
> My windows are either fully opened or fully closed. So I thought that 
> in COMIS AIRFLOW: Opening I would just have to set:
> 
> Number of opening factors: 2
> Opening factor #1: 0
> Discharge. coeff. for opening factor #1: 0
> Width factor for opening factor #1: 0
> Height factor for opening factor #1: 0
> Start height factor for opening factor #1: 0
> Opening factor #2: 1
> Discharge. coeff. for opening factor #2: 1
> Width factor for opening factor #2: 1
> Height factor for opening factor #2: 1
> Start height factor for opening factor #2: 0
> 
> But with this setup I allways get a severe error:
> 
>    ** Severe  ** &-WI:  *WI_0001_1: Cd is zero just in some lines!
>    ************* It has to be zero in every line (Cd will be 
> calculated) or in no line.
>    ** Severe  ** &-NET-LINks:  LinkNr: 
> Srf_000039                                        Room depth
>    ************* has to be input with H/D/W option ! Otherwise Cd can 
> not be calculated!
> 
> When I change Discharge. coeff. for opening factor #1 to, let´s say, 
> 0.1 the error goes away.
> 
> I think that I´m not getting the real meaning for these inputs from 
> InputOutput reference. Can anyone give me a hint?
> 
> Thanks!
> Alexandre
> 
> 
> 
> 
> 
> 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 not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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