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Best way to meter reheat energy for VAV system in EnergyPlus?

asked 2016-02-04 06:54:20 -0500

I've got a VAV system with central water cooling and water heating coils, and terminal units with hot water coils for reheat (AirTerminal:SingleDuct:VAV:Reheat)

I'd like to add some kind of meter that would report the total energy used for all the reheat coils, for example monthly or annually.

Is there a simple way to do so in E+?

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I recently have a same question about getting the reheat energy. I was extracting all heating energy from the coil in air terminal. A friend point it out: not all heating from this terminal is for "reheat". In winter hours these heating energy cannot be called "reheat".

mingo1214@gmail.com's avatar mingo1214@gmail.com  ( 2019-10-16 16:49:14 -0500 )edit

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answered 2016-02-06 09:22:37 -0500

Archmage's avatar

It is not simple, but the example file called HospitalBaselineReheatReportEMS uses EMS to report reheat. It implements a fairly elaborate definition of what portion of heating coil energy should be considered reheat.

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Thanks, I'll make sure to check that out! I guess I wasn't even thinking about what is technically considered reheat, I would have settled for terminal heating coil heating energy.

Julien Marrec's avatar Julien Marrec  ( 2016-02-07 10:29:11 -0500 )edit

I've looked at it and I'm pretty sure it's wrong... The reheat meters, if you output them monthly just keep on increasing. It would be fine if it was just a counter and therefore I would find that the last month (december) would be equal to the number I get if I output at the Annual level, but no: if I sum the 12 months I end up with what the annual frequency gives me.

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Julien Marrec's avatar Julien Marrec  ( 2016-04-15 15:45:23 -0500 )edit
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answered 2016-02-04 08:52:35 -0500

I just recently started to learn the full capability of meters in EnergyPlus, so this might not be quite right, but I believe you can write a custom meter like:

Meter:Custom,
VAV Reheat Energy,  !- Name
Generic,             !- Fuel Type
#{coil_name},        !- Key Name 1
Heating Coil Heating Energy,  !- Output Variable Name 1  
...etc;

and

Output:Meter:MeterFileOnly,VAV Reheat Energy,monthly;
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Yeah I have already started coding that in fact, leveraging OS Api, because 160 coils... Wanted to know if there was a better way to do it ...

Julien Marrec's avatar Julien Marrec  ( 2016-02-04 09:37:11 -0500 )edit

Not that I can figure; it's a pretty specific thing that you want. But hey, at least the api makes it fairly simple.

ericringold's avatar ericringold  ( 2016-02-04 09:46:50 -0500 )edit

I think you must use an E+ measure though, doesn't seem like Meter:Custom is accessible in the OS Api.

Julien Marrec's avatar Julien Marrec  ( 2016-02-04 10:02:08 -0500 )edit

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Asked: 2016-02-04 06:54:20 -0500

Seen: 281 times

Last updated: Feb 06 '16