RE: [EnergyPlus_Support] Re: How to reduce "not met hours"

Hi, Jean

Xing was using a VAV AHU with setpoint manager referenced to the airloop fan output node. The zones has no VAV damper control. Reheat heater is used for zone heating. Zone temperature values will never be all within tolerance of 0.02°C.

This is why I kept warning them not to mix VAV and non-VAV equipment.

You have a large instalation. VAV will reduce the unitility maximum demand penalty payment. VAV will not reduce your building energy consumption.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Mon, 19 Sep 2011 14:41:50 +0000
Subject: [EnergyPlus_Support] Re: How to reduce "not met hours"

Another place to investigate is the setpoints on the nodes set by setpoint managers, e.g. the cooling and heating coils often work with setpoint managers. You may find coils fighting each other or other errors here. Let us know if and how you solve the problem. Also, there is a way to change the tolerance on setpoint not met, if you can justify it. The default is 0.2.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
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> Hi, Xing Your building entry still hve problems (5 severe errors). It is possible that the exported IDF text is not the same as the IDF in the third party software. You should follow the steps given by Jim Dirkes to display the variables and to trace the program operation. It is not possible to control five zones of a large building and hope to get the correct answer. You may ignore the basement, the EPlus simulation will not. I mentioned to you last time that, if you use templates in the IDF, do not use the IDFeditor to sort or change the expIDF and then send me the IDF. It is quite difficult to un-sort the groups and zones. The temperture control does not work for DesignDay simulation, because you have changed some schedules again.
> Dr. Li
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: xing.shi.2006@...
> Date: Sat, 17 Sep 2011 16:26:38 +0800
> Subject: [EnergyPlus_Support] How to reduce "not met hours"
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> Dear All, We have an ASHRAE 90 system 8 baseline building. The E+ model appears to be correct but the "unmet hours" is a little too high. Cooling and heating unmet both exceed 200. According to ASHRAE 90, we should increase the system capacity incrementally until unmet (cooling + heating) is below 300. We changed the sizing factor in Sizing:Parameters but surprisingly found that it had very little effect on the unmet hours.
> Attached is the IDF file. Why is that? What should we do to reduce the unmet hours. Thank you! XS
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