[EnergyPlus_Support] Re: my input file

[Rahul Chillar <chillarrahul@xxxxxxxxx>]

Hello Teklay

Its true if your model tries to compensate ceiling airspace such as air between trusses by adding air as an additional ceiling material it will not  account for convective heat transfer.

 

One way of getting around this problem is to keep all the actual materials together and increase the Zone height; by the amount you had modeled the thickness of air when air was used as a material.

 

Now you would have a ceiling say 10.3 feet instead of 10 feet.  So an additional 3 inches of air column is added which will account for the additional air gap, which I presume, is due to the ceiling using Trusses for support( from your earlier mails)

 

This should get you closer to the required results and most of all take into account the convective heat transfer.

 

Thanks

Rahul Chillar

Grad Research Assistant

Building Systems Lab

University of Illinois UC

 

 
 


teklay Weldeabzgi <teklay1979@xxxxxxxxx> wrote:

hi Rahul
thanks for your help. i have some confusion in my idf
file, the problem that i have told u is when i run for
the design days only. if i run for the whole year it
gives me a reasonable reasults. so it seems ok as i am
simulating a yearly energy consumption of the
building.
but i have some other problems if u can help me

you gave me last time the property of air to use in
b/n roof and ceiling.
MATERIAL:REGULAR,
AIRONLY, !- Name
VerySmooth, !- Roughness
.3, !- Thickness {m} Give the
Required Thickness 
of air needed here
.0267, !- Conductivity {W/m-K}
1.177, !- Density {kg/m3}
1000, !- Specific Heat {J/kg-K}
0.9, !- Absorptance:Thermal
0.7, !- Absorptance:Solar
0.7; !- Absorptance:Visible
but some body has told me that E+ can't model thick
air spaces. i have used this material in my simulation
and it has a great effect in the yearly cooling load
of the building. and how can i take the effect of
convective heat transfer if i use this material?

thanks 
tek

--- Rahul Chillar wrote:
> teklay
> 
> THere is a slight problem, it holiday season here
> and lot of team members have gone for vacation, so
> there is a delay in your problem. I looked at your
> file but could not find anything wrong, however i
> have send it to other experts in the team and they
> would be seeing it and hopefully reply soon.
> 
> thanks
> Rahul 
> 
> teklay Weldeabzgi wrote:
> 
> here is my input file. 
> 
> 
> 
> __________________________________
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> > ATTACHMENT part 2 application/octet-stream
> name=GodeOffice.idf
> 
> 
> Thanks 
> Rahul Chillar 
> Grad Student 
> Building Systems lab
> Univ Of Illinois Urbana Champaign
> 
> 
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Thanks 
Rahul Chillar 
Grad Student 
Building Systems lab
Univ Of Illinois Urbana Champaign

		
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