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HVAC Doubts - My model

asked 2015-11-04 15:43:46 -0500

Gabi.ms gravatar image

updated 2015-11-04 16:10:47 -0500

Again I'm here with some doubts. I want to model a real building (in E+), simulate a green roof on it and see the amount of kWh that I can reduce in my consumption. The problem is: I have a lot of zones (each zone is a room or a piece of a room) and in some of them I have like 20 Split ACs. I tried to model the zones with more than one AC (I used an Window AC to test it) but I always have to say that they are staged...when they actually aren't, so....

  1. Is there a way to model the same type of equipment inside the same zone but working at the same time, not staged?
  2. If there is not and I need to model as one HUGE AC, how can I do it? Can I still evaluate the kWh when I do this?
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Gabi, our convention is to not include greetings (hi, thanks, etc).

Julien Marrec gravatar imageJulien Marrec ( 2015-11-04 16:10:29 -0500 )edit

You French are so unfriendly!

__AmirRoth__ gravatar image__AmirRoth__ ( 2015-11-04 16:12:35 -0500 )edit

@Julien Marrec I did not know that, I'm sorry! Maybe I skipped that part when I was reading the rules. I'll remember from now on.

Gabi.ms gravatar imageGabi.ms ( 2015-11-05 05:50:56 -0500 )edit

That's perfectly ok and understandable.

Have you tried assigning the same sequence number for all of your zone equipment on ZoneHVAC:EquipmentList?

Julien Marrec gravatar imageJulien Marrec ( 2015-11-05 07:06:05 -0500 )edit

Yes, I tried @Julien Marrec. It doesn't simulate, a fatal error appears :/

" * Severe * GetZoneEquipmentData1: ZoneHVAC:EquipmentList = ZONE EQUIPMENT * ~~~ * ...multiple assignments for Zone Equipment Cooling Sequence=1, must be 1-1 correspondence between sequence assignments and number of equipments."

Gabi.ms gravatar imageGabi.ms ( 2015-11-05 08:09:18 -0500 )edit

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answered 2015-11-05 07:00:12 -0500

1) The zone equipment is simulated in priority order. This means that each equipment component will add or subtract from the zone load and the next equipment will try to meet the new load. This means that each equipment will meet a different load. The only way I can think of to operate 2 components identically is to use the EMS programming language.

ZoneHVAC:EquipmentList,
  Corner_Class_1_Pod_1 Equipment,  !- Name
  ZoneHVAC:AirDistributionUnit,  !- Zone Equipment 1 Object Type
  Corner_Class_1_Pod_1 Dual Duct Box,  !- Zone Equipment 1 Name
  1,                       !- Zone Equipment 1 Cooling Sequence
  1,                       !- Zone Equipment 1 Heating or No-Load Sequence
  ZoneHVAC:WaterToAirHeatPump,  !- Zone Equipment 2 Object Type
  Corner_Class_1_Pod_1 Heat Pump,  !- Zone Equipment 2 Name
  2,                       !- Zone Equipment 2 Cooling Sequence
  2;                       !- Zone Equipment 2 Heating or No-Load Sequence

2) Using a larger piece of equipment should not introduce significant differences in the results. I admit I have not tested this theory to determine the magnitude of the difference but I assume them to be small. DX cycling equipment would have more losses if there were 2 components, but then again, if there are 2 and they are always running, there would not be cycling losses now would there.

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Asked: 2015-11-04 15:43:46 -0500

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Last updated: Nov 05 '15