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best way to evaluate plant sizing results in optimization process

asked 2020-11-01 03:21:35 -0500

Babak's avatar

updated 2020-11-09 09:45:39 -0500

I want to optimize chilled water loop sizing and configuration to meet the cooling load of a building. I have a detailed model that includes thermal zones and AHUs but I don't want to change them during the optimization process.

My concern is choosing a variable as the constraint for thermal comfort. I need this to evaluated whether my plant loop can meet the demand or not. I tried Unmet hours but I got weird results and I cannot work with that.

Is there any variable in energyplus that I can ensure it can evaluate my plant sizing results?


Update: I'm using "Time Setpoint Not Met During Occupied Cooling" with 1 C tolerance. I get about 52 hours of unmet cooling hours. I don't the standard value but it seems a lot to me:

image description

By the way in this case I'm using two chillers with a sizing factor of 0.55 for each one.

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You need to provide more information. First, which "unmet hours" you have tried, and where? Then, why did you find the results "weird"?

Yi Zhang's avatar Yi Zhang  ( 2020-11-01 03:58:09 -0500 )edit

@Yi Zhang I provided some details. thanks.

Babak's avatar Babak  ( 2020-11-01 05:04:19 -0500 )edit

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answered 2020-11-03 09:50:31 -0500

Yi Zhang's avatar

It seems to me that either the system is under-sized, or there is too much inertia in the system/building and the cooling is not starting early enough. If you plot the hourly temperature profile, and the cooling schedule, you will be able to see when these unmet hours are, which will tell you what the problem is.

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Asked: 2020-11-01 03:21:35 -0500

Seen: 214 times

Last updated: Nov 03 '20