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Re: [EnergyPlus_Support] Help


I was responding to the original post from someone apparently unfamiliar with EnergyPlus about having "degenerate surfaces" in his model. Under those circumstances, I think it's better to err on the conservative side and suggest that he gets the model physically correct, rather than to suggest shortcuts that seemed to not have adverse effects in your particular case.

Joe

On 2/19/2014 1:06 PM, Niraj Poudel wrote:
>  
The view factor for the roof probably assumes an infinite plane. Hence a 0.5 value. Is what my guess would be.
> Niraj
> 
> On Wed, Feb 19, 2014 at 3:04 PM, Jeremiah Crossett <<mailto:jcrossett@xxxxxxxxxxxxxxx>jcrossett@xxxxxxxxxxxxxxx> wrote:
>>  
Possibly, but the very quick tests I did showed no noticeable difference when adding a zone with walls and a floor, compared to a roof surface and zone area x height. 
The benefit is a quick model of a roof, and it seems alright, but may look further given your opinion..
>> 
>> 
>> Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203 
 | Mobile 503-688-8951
<http://www.phasechange.com/>www.phasechange.com 

>> 
>> 
>> 
>> 
>> On Wed, Feb 19, 2014 at 12:42 PM, Joe Huang <<mailto:YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx>YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>>  
>>> Wouldn't that foul up the zone heat balance that depends on knowing the view factor or at least the area of each surface ?
>>> 
>>> Joe
>>> 
>>> On 2/19/2014 12:37 PM, Jeremiah Crossett wrote:
>>>>  
Depending on what you are doing, you might just as well ignore it-- for example if you want the surface to be fully adiabatic then you could remove it, and would get this warning. 
I have some models that are just roofs with zone area, ceiling height and internal loads per square foot-- and it seems to work as expected, but also produces this warning-  
>>>> 
>>>> 
>>>> Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203 
 | Mobile 503-688-8951
<http://www.phasechange.com/>www.phasechange.com 

>>>> 
>>>> 
>>>> 
>>>> 
>>>> On Wed, Feb 19, 2014 at 12:33 PM, Joe Huang <<mailto:YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx>YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>>>>  
>>>>> "Degenerate surfaces"  sound terrible!  Maybe you should go see a psychologist (just joking :-) )
>>>>> 
>>>>> Seriously, I suggest you search through your IDF, find the  seven surfaces with less than two vertices (which only define a line and not a surface), and add the missing vertices.
>>>>> 
>>>>> Joe
>>>>> 
>>>>> 
>>>>> 
>>>>> On 2/19/2014 11:58 AM, Oswaldo alonso Guzmán villalobos wrote:
>>>>>>  
Hellow, I try to simulate a building, when I simulate it, the energy plus gives the following message,
>>>>>> GetSurfaceData: There are 7 degenerate surfaces; Degenerate surfaces are those with number of sides < 3.
>>>>>> How fix this error?
Thanks.
>>>>>>  
Att. Oswaldo Alonso Guzmán Villalobos
>>>>> 
>>>> 
>>> 
>> 
> 




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