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OpenStudio : Morning Warmup

asked 2020-05-21 17:26:54 -0500

TheEnergyTutor gravatar image

updated 2020-05-23 12:33:49 -0500

Does anyone know where/if there is a setting for morning warmup in open studio? Not pre-starting is causing some unmet occupied hours on the report which would disappear with a proper pre-start in a cold climate. I already searched the forum and didn't see anything covering this.

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answered 2020-05-22 08:42:59 -0500

EnergyPlus has an Air Loop Availability Manager for Optimum Start, so if that fits your needs then you at least won't have to use Energy Management System (EMS) objects to write custom controls. This EnergyPlus feature is available in the OpenStudio GUI (at least in v2.9.1 that I'm using) which you can apply with the following steps:

  1. Click on the HVAC Systems tab on the left.
  2. Select your air and/or plant loops where you want to apply the optimum start in your drop-down at the top.
  3. Click on the Control button at the top.
  4. Drag-and-drop the Availability Manager Optimum Start item from your HVAC Library on the right into the Availability Managers section on the left. The order that you assign availability managers sets their priority from top to bottom (see below for example).

image description

You can also refer to this post for more information, although it's a little dated (gives instructions for making this change via OpenStudio SDK before it was implemented in OpenStudio GUI).

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Awesome Thanks!

TheEnergyTutor gravatar imageTheEnergyTutor ( 2020-05-22 09:42:48 -0500 )edit

The only thing i don't have set for this is the ZoneList. I have 11 ZONES and want to use the MaximumOfZoneList option. The ZoneList selection box is empty. How can i set up my ZoneList in OpenStudio?

TheEnergyTutor gravatar imageTheEnergyTutor ( 2020-05-22 10:06:37 -0500 )edit

I don't think you can create a ZoneList in the OS GUI, you might have to do that through the OS SDK. You can follow this post, since it's asked the same question.

Aaron Boranian gravatar imageAaron Boranian ( 2020-05-22 10:18:15 -0500 )edit

Bummer, this would be really nice. In light of this response, i went ahead and picked a single zone out of the 11 that i thought would be the coldest and trigger the warmup. Should be ok for the modeling.

TheEnergyTutor gravatar imageTheEnergyTutor ( 2020-05-22 10:48:42 -0500 )edit
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answered 2020-05-22 07:07:43 -0500

rafael.alonso gravatar image

Are you referring to the warm up period of your simulation? That only happens before the beginning of your simulation period.

You can adjust the minimum/maximum number of days under simulation settings in OS. image description

Essentially, each zone will be warmed up until the discrepancy in loads/temperature between one timestep and the following is below the convergence tolerance values. All of them will be warmed up at least for the Minimum number of days, independently of whether they reach convergence sooner.

Even if some of them do not converge, at the Maximum number of daysthe warm up period will cease and your simulation period will start.

Rafael

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No, in "morning warmup" the HVAC system prestarts on cold mornings so the space hits the occupied set point at the scheduled occupancy time. In cold country, it can take an hour or so to warm up but we need the building warm when people arrive so there needs to be a optimal prestart algorithm referencing the outdoor air temperate. In DView I noticed all my unmet occ heating hours occur in the first hour of occupancy because the HVAC does not prestart the model.

TheEnergyTutor gravatar imageTheEnergyTutor ( 2020-05-22 07:13:42 -0500 )edit

I see, my answer above completely missed the point.

I have gone around that in a simplified way by tweaking the Setpoint before occupation starts.

One or two hours before the occupation starts the setpoint rises to an intermediatte point between the setback and the occupied set point.

I dont really know if there is any other place to adjust what you are after.

rafael.alonso gravatar imagerafael.alonso ( 2020-05-22 08:01:29 -0500 )edit

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Asked: 2020-05-21 17:26:54 -0500

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Last updated: May 22