Hi, Liem
I picked up your IDF file ( two_zone_free_float.idf ) and ran it.
I noticed that the temperature values for the two zones are about equal at midnight. The South zone is warmer at noon. This may be normal for Chicago.
When I looked at the table for constructions, I noticed that
N_West and S_West walls are different. N_West wall used Exterior Floor, while all the other surfaces were Exterior Wall.
After I change the construction of the N_West wall to Exterior Wall, the simulation failed to converge and generated the error file attached.
Hope this may help you to investigate further, and solve the sever error problem. One of the experts did suggest that mass may cause problem. Maximum 25 warm-up days were also exceeded during the simulation.
The DesignDay sizing warning was because the DesignDay Data object was not present.
Dr. Li
To: energyplus_support@xxxxxxxxxxxxxxx
From: yli006@xxxxxxxxxxx
Date: Sat, 24 Oct 2009 18:57:37 -0400
Subject: RE: [EnergyPlus_Support] Re: Finite difference method error
Hi, Liam
I do not know exactly what you are calculating.
To me, it seem impossible to make a building complely no sun, no wind.
0.02°C with CTF is small compared with 3°C, but may mean that there are some differences in external conditions.
What about calculating the two zones one at a time at thier respective coordinate location, or changing the zone ordering in calculation?
Or repeat the calculation more than once to check for the steady state as suggested by Candanedo?
To: EnergyPlus_Support@yahoogroups.com
From: liambrn@yahoo.com
Date: Sat, 24 Oct 2009 13:10:58 +0000
Subject: [EnergyPlus_Support] Re: Finite difference method error
Save up to 84% on Windows 7 until Jan 3-eligible CDN College or University students only. Hurry-buy it now for $39.99!
I do not know exactly what you are calculating.
To me, it seem impossible to make a building complely no sun, no wind.
0.02°C with CTF is small compared with 3°C, but may mean that there are some differences in external conditions.
What about calculating the two zones one at a time at thier respective coordinate location, or changing the zone ordering in calculation?
Or repeat the calculation more than once to check for the steady state as suggested by Candanedo?
Dr. Li
To: EnergyPlus_Support@
From: liambrn@yahoo.
Date: Sat, 24 Oct 2009 13:10:58 +0000
Subject: [EnergyPlus_
Dr. Li,
Good thought, but the Conduction Transfer Function method yields results within 0.02C, as expected. I did rotate the building and get the exact same results. This shouldn't make a difference though, because wind and sun exposure were turned off.
Liam
--- In EnergyPlus_Support@yahoogroups.com , YuanLu Li <yli006@...> wrote:
>
>
> Is the longer axis of the building, North-South, or East West?
>
>
>
> Are the two zones joined with a partition or separate?
>
>
> The sun and wind are turned off. What do you think would be the external conditions? DesignDay, sizing and normal run period may give different answers.
>
>
>
> Turn the building around at different orientation angles and see how the values changes.
>
>
> Dr. Li
>
>
>
>
>
>
> To: EnergyPlus_Support@yahoogroups.com
> From: tincandanedo@...
> Date: Thu, 22 Oct 2009 23:03:48 +0000
> Subject: [EnergyPlus_Support] Re: Finite difference method error
>
>
>
>
>
> This is interesting... Have you tried changing the time step? Another possibility is that the system hasn't reached steady state. Finally, is it possible to change the size of the control volume?
>
> José Candanedo
>
> --- In EnergyPlus_Support@yahoogroups.com , "liambrn" <liambrn@> wrote:
> >
> > I have created two adjacent zones with identical wall constructions, geometry and boundary conditions. I turned sun and wind exposure off. The temperatures are free floating. However, I'm seeing a difference of about 3C between the two zones throughout the day. The zones remain within ~0.2C using the ConductionTransferFunction method. Thoughts?
> >
> > Thanks.
> >
> > Liam O'Brien
> >
>
>
>
>
>
>
>
>
>
> __________________________________________________________
> Ready for a deal-of-a-lifetime? See fantastic offers on Windows 7, in one convenient place.
> http://go.microsoft.com/?linkid=9691634
>
Good thought, but the Conduction Transfer Function method yields results within 0.02C, as expected. I did rotate the building and get the exact same results. This shouldn't make a difference though, because wind and sun exposure were turned off.
Liam
--- In EnergyPlus_Support@
>
>
> Is the longer axis of the building, North-South, or East West?
>
>
>
> Are the two zones joined with a partition or separate?
>
>
> The sun and wind are turned off. What do you think would be the external conditions? DesignDay, sizing and normal run period may give different answers.
>
>
>
> Turn the building around at different orientation angles and see how the values changes.
>
>
> Dr. Li
>
>
>
>
>
>
> To: EnergyPlus_Support@
> From: tincandanedo@
> Date: Thu, 22 Oct 2009 23:03:48 +0000
> Subject: [EnergyPlus_
>
>
>
>
>
> This is interesting.
>
> José Candanedo
>
> --- In EnergyPlus_Support@
> >
> > I have created two adjacent zones with identical wall constructions, geometry and boundary conditions. I turned sun and wind exposure off. The temperatures are free floating. However, I'm seeing a difference of about 3C between the two zones throughout the day. The zones remain within ~0.2C using the ConductionTransferF
> >
> > Thanks.
> >
> > Liam O'Brien
> >
>
>
>
>
>
>
>
>
>
> ____________
> Ready for a deal-of-a-lifetime? See fantastic offers on Windows 7, in one convenient place.
> http://go.microsoft
>
Save up to 84% on Windows 7 until Jan 3-eligible CDN College or University students only. Hurry-buy it now for $39.99!
Save up to 84% on Windows 7 until Jan 3-eligible CDN College or University students only. Hurry-buy it now for $39.99!
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