RE: [EnergyPlus_Support] For help:room air models

Hi, Maize

I have a look at the IDF building entries. I think that the warnings, on average ceiling height of 42 m, was generated by your using auto-calculate for the Atrium ceiling height and 4 m for the EL1-Atrium (roof) height.

If you change the ceiling height of EL1 Atrium from 4 to 80 m, the roof of the Atrium will be move up to the top of the building. The warning should disappear.

I have not found the infutration of the atrium of 0.4ACH, and the cause for warnings:-

** Warning ** Inside surface heat balance did not converge with Max Temp Difference [C] =3.872E-003 vs Max Allowed Temp Diff [C] =2.000E-003
** ~~~ ** During Sizing, Occurrence info=SUMMER DESIGN DAY IN SHANGHAI, 07/15 07:30 - 07:31

You may try increasing the timestep from 4 to 6 or 12. The difference is very small and could ignored.

I would like to know how you entered the building information. Did you use another software, such as AUTOCAD? I ask about this, because there are a number of zero coordinates entered as a very small exponential number.

EPlus allows you to define a partition (surface of another zone) so that you do not have to define a wall and a reverse wall construction. The ceiling air space can be declared as a plenum and acts as a mixer. In this way, the ceiling and floor are separate, and there is no need for a reverse floor or roof as construction.

Because the ceiling height is low, you may not need to do the non-dimentional calculation for the room air temperature.

I have not found the roof-glazed atrium yet.

By dimention in my mail, I was referring the building coordinates.

Non-dimentional height calculation, I think, can be done for both controlled and un-controlled periods, as it is trying to take into account of the variation of temperature in a zone. You may need to provide two patterns.

I am still learning. Comments from other users are welcome.

Dr. Li.

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: liyuming1123@xxxxxxx
Date: Sat, 20 Dec 2008 05:22:05 +0000
Subject: [EnergyPlus_Support] For help:room air models

Thank you!

I have another problem of this model.
The result shows that the cooling load of roof-glazed atrium is
zero. I have set the infiltration of the atrium 0.4ACH,so it
shouldn't have no cooling load.
last time,I calculated the model with version2.2.the result is zero.
today, I translate the model to version 3.0, but the result is still
zero.

I have upload the IDF file to the group, please help me see what is
the problem of the model. Thank you very much!

By the way, the input of dimentional room air model is the
temperature gradient of conditioned period or unconditioned period?

--- In EnergyPlus_Support@yahoogroups.com, Yuen Liu <yli006@...>
wrote:
>
>
>
> I think, you should up load the IDF file to the group so that some
one can see how the dimensions are entered. Without the IDF, I
cannot tell how the warning is generated. These are diffeent from
your last posting.
>
> Dr. LI.
>
>
>
> To: EnergyPlus_Support@...: liyuming1123@...: Fri, 19 Dec 2008
08:18:43 +0000Subject: [EnergyPlus_Support] For help:room air models
>
>
>
>
> Hello,I simulated an roof-glazed atrium with nondimentional
pattern of the roomair model, but some warning are appeared and the
results seemed there was no cooling load in the atrium.there are
many warnings like this:Warning ** Problem in non-dimensional height
calculation, too high surface:REVERSE_EL11_CORRIDOR1-ATRIUM WALL in
zone: 1F_ATRIUM** ~~~ ** **** Average Ceiling height of zone is:
42.000** ~~~ ** **** Surface Maximum height is: 44.000** Warning **
Problem in non-dimensional height calculation, too high
surface:REVERSE_EL11_CORRIDOR2-ATRIUM WALL in zone: 1F_ATRIUM** ~~~
** **** Average Ceiling height of zone is: 42.000** ~~~ ** ****
Surface Maximum height is: 44.000** Warning ** Problem in non-
dimensional height calculation, too high surface:REVERSE_EL11 EAST
WALL (G.C6.I20) in zone: 1F_ATRIUM** ~~~ ** **** Average Ceiling
height of zone is: 42.000** ~~~ ** **** Surface Maximum height is:
44.000So can anyone tell me what the warnings mean? And when using
nondimentional roomair models, how does the model calculate the
cooling load of the Atrium?Thank you!
>
>
>
>
>
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