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[EnergyPlus_Support] Re: Possible causes



Hi Dr. Li,
Thanks for the feedback. I've been following other posts you've made regarding groud temperature, and fully agree. In my case though, the slab is not in contact with the ground and the cavity under it is open to the outdoor air which is quite cold in winter. Because the slab is very thick, I have assumed an slab temperature on the outside surface equal to the yearly average temperature. I've checked the U-value of the slab which is very low and can therefore can assume heat transfere across the slab to be so minimal that it probably doesn't matter what "ground" temperature I use.

I'll try to report the surface temperatures to narrow the problem surfaces down.

Kind regards,

Jean

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
>
> 
> Regarding the error message, it is possible that you were asking the system to cool the building and it is already too cold in Summer.
> 
> 
>  Dr. Li   
> 
> 
>  
> 
> 
> 
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: jeannieboef@...
> Date: Fri, 1 Apr 2011 20:46:25 +0000
> Subject: [EnergyPlus_Support] Possible causes
> 
> 
>   
> 
> 
> 
> I'm simulation a summer week and have cooling set point not met problems. As far as I can tell there's something wrong with my building materials?
> 
> ** Warning ** Inside surface heat balance did not converge with Max Temp Difference [C] =2.301E-003 vs Max Allowed Temp Diff [C] =2.000E-003
> ** ~~~ ** During Sizing, Environment=SUMMER DESIGN DAY IN KITA, at Simulation time=.....................
> .
> time=04/01 06:40 - 06:45
> time=04/01 06:50 - 07:00
> time=04/01 07:00 - 07:10
> time=04/01 07:10 - 07:15
> time=04/01 07:20 - 07:25
> .
> .
> .
> etc. last reported error is at 09:00-09:05
> 
> This causes slightly incorrect sizing and later
> 
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118420 AHU, at KITA, 07/03 16:00 - 16:02
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118434 AHU, at KITA, 07/04 11:56 - 11:58
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118145 AHU, at KITA, 07/04 12:32 - 12:34
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118340 AHU, at KITA, 07/04 14:20 - 14:22
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118145 AHU, at KITA, 07/04 14:22 - 14:24
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118288 AHU, at KITA, 07/04 14:34 - 14:36
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118371 AHU, at KITA, 07/04 14:34 - 14:36
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118145 AHU, at KITA, 07/04 14:36 - 14:38
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118348 AHU, at KITA, 07/04 14:36 - 14:38
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118371 AHU, at KITA, 07/04 14:50 - 14:55
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118145 AHU, at KITA, 07/04 15:03 - 15:07
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118145 AHU, at KITA, 07/04 15:20 - 15:22
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118443 AHU, at KITA, 07/04 15:26 - 15:28
> ** Warning ** SolveAirLoopControllers: Maximum iterations (50) exceeded for 118371 AHU, at KITA, 07/04 15:28 - 15:30
> 
> What should I be looking for? Can I tell on which surface this is happening and how?
> 
> I have set the ground temperature to 14 degrees, because by building slab is the roof of a large underground parking (no contact to ground), but this is not changing during the summer months. Is there a way to change this for the summer months...EMS maybe?
>




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