Help needed: CheckingEnergyPlus model for major setup errors in one-zone VRF

asked 2026-03-30 09:29:07 -0500

u_bela
1 ●1

Hi everyone,

I am currently trying to set up a simple one-zone IDF in Munich, Germany, using a VRF system similar to the EnergyPlus example file VariableRefrigerantFlow_5Zone.idf.

I do not have much experience creating IDF files from scratch, so I would appreciate feedback on whether there are any major failure modes or conceptual mistakes in my current setup that I should fix before going further.

My main goal is to generate simulation data for training a model that predicts indoor air temperature and HVAC energy consumption.

Since the model quality will depend heavily on the simulation setup, I want to make sure the IDF is physically reasonable and not producing misleading results due to configuration errors. I have provided my current file as well as the weather .epw and the latest .err output in my google drive here .

Please let me know if you need any further information to judge my current setup! Thanks a lot for any guidance.

Bela

answered 2026-04-01 17:58:55 -0500

rraustad

14264 ●91 ●13 http://www.ucf.edu/

updated 2026-04-01 18:22:27 -0500

You can change the last For to "For: AllOtherDays," for all your schedules to get rid of the errors. This will include the other day types which is important for annual energy use. The VRF warnings for Curve output at rated conditions = 1.136 are not an issue.

Schedule:Compact,
  OCCUPY-1,
  Fraction,
  Through: 12/31,
  For: WeekDays SummerDesignDay,
  Until:  8:00,0.0,
  Until: 12:00,1.0,
  Until: 13:00,0.5,
  Until: 17:00,1.0,
  Until: 18:00,0.3,
  Until: 24:00,0.0,
  For: Weekends WinterDesignDay Holiday,
  Until: 24:00,0.0;

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Comments

Thank you for your help. Something I noticed when running the file for a shorter period (from the 12th of January to the 16th of January) using a constant heating setpoint of 22 degrees in form of:

Schedule:Compact, Htg-SetP-Sch, Temperature, Through: 12/31, For: AllDays, Until: 24:00,22.0;

that the zone only rarely reaches that setpoint. Could this be a sign of undersizing? If so how can i fix that issue? I added a plot of the output to the drive folder.

u_bela ( 2026-04-07 06:06:03 -0500 )edit

The pull up time in your plot looks like it's only a few hours. This is actually normal for properly sized equipment. You can increase the capacity to reduce the recovery time but you do not want a system so large that the recovery time = 0, 1 to 2 hours is more realistic. Commercial building types will start HVAC 1 - 2 hours prior to occupancy for this very reason (and also reduces the "hours setpoint not met while occupied" occurrences).