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Is it possible to use Energyplus EMS during sizing?

asked 2015-05-27 12:23:27 -0600

updated 2020-03-08 11:29:32 -0600

I am trying to add a load only during sizing calculations through EMS and although I find that something is happening during summer and winter designdays, the sizing results are exactly the same with the EMS load than without it. EMS code is working well during simulation but for sizing it seems not to affect the results despite edd file shows these lines:

PROGRAM CODE, During Warmup, Occurrence info=SUMMER DESIGN DAY IN MADRID JUL, 07/15 00:00 - 00:10 PROGRAM CODE, During Warmup, Occurrence info=SUMMER DESIGN DAY IN MIJAS JUL, 07/15 23:50 - 24:00

And the same for WINTER DESIGN DAY.

I don't understand why those lines seem to be only executed for 00:00 - 00:10 and 23:50 - 24:00 periods. Is that the expected behaviour? I think it would be better if EMS code could be taken into account during sizing calculations.

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Yes, EMS can be used during sizing. See EMS document below for details.

Also look at the program calling points EndOfZoneSizing, EndOfSystemSizing (and/or AfterComponentInputReadIn, UnitarySystemSizing). Thanks.

Chandan Sharma's avatar Chandan Sharma  ( 2015-05-27 20:49:43 -0600 )edit

Thanks, but I am afraid it is not what I mean. I know you can change sizing results after the sizing with EMS but I need to integrate a variable thermal load during the sizing calculation. I have written some EMS code that mimics outdoor air thermal load using 2 OtherEquipment objects (one for sensible and the other for latent load). I want to add this load during sizing. It is the only way I have come to introduce outdoor air load in sizing calculations when you are using AirFlowNetwork but want a simpler outdoor air load calculation for sizing.

ecoeficiente's avatar ecoeficiente  ( 2015-05-28 02:15:16 -0600 )edit

sorry for misunderstanding the question. maybe someone else can offer insight. 'CurrentEnvironment' built in variable may be used to turn on schedules of OtherEquip during sizing but there might be better/more accurate approach to tackle this problem which I am not aware of.

Chandan Sharma's avatar Chandan Sharma  ( 2015-05-28 06:03:00 -0600 )edit

If you are trying to introduce a zone load for sizing only, a simpler approach may be to use the OtherEquipment object with a schedule that activates the load on design days only. I have used this approach before to properly size reheat coils for zones with high ACH ventilation requirements. Sounds like you may be after something similar.

Lyle K's avatar Lyle K  ( 2015-05-29 10:28:48 -0600 )edit

Thanks LyleK. The problem is that I'd like OtherEquipment to reproduce outside air load (variable during the day). I know I could build a schedule with such variation and apply only to Design Days but I wanted something more reusable (without the need to recalculate the schedule if external or internal Design Conditions changed). The reason I cannot do it with ZoneVentilation:DesignFlowRate is because I am using Airflow Network simulation. And I need it is because Zone sizing does not account for outdoor air brought by a mechanical distribution system. I have finally achieved that with EMS.

ecoeficiente's avatar ecoeficiente  ( 2015-05-29 10:57:00 -0600 )edit

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answered 2015-05-29 10:06:26 -0600

The answer is "depending on the EMS Calling Point you use".

I was using as calling point Inside HVAC System Iteration Loop. It gave me more precise results during simulation than Begin Timestep Before Predictor.

However, it seems that ideal load calculation during sizing is not performed as an HVAC System, so the calling point Inside HVAC System Iteration Loop is not valid for sizing. I have changed to Begin Timestep Before Predictor and now the program is working for Sizing too.

Hope this findings are useful to the rest of you.

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Asked: 2015-05-27 12:23:27 -0600

Seen: 617 times

Last updated: May 29 '15