EnergyPlus simulation calculates 367 instead of 365 days

asked 2023-03-09 07:33:47 -0500

sz1980's avatar

updated 2023-03-09 14:33:19 -0500

Hi everyone,

I am right now sitting at an issue that I cannot explain and decided to turn to this community:

I am running an EnergyPlus Simulation for 365 days and somehow get at the nd always 367 days of data. I cannot explain this.

RUNPERIOD 1,             !- Name
1,                       !- Begin Month
1,                       !- Begin Day of Month
2007,                        !- Begin Year
12,                      !- End Month
31,                      !- End Day of Month
2007,                        !- End Year
Monday,                  !- Day of Week for Start Day
Yes,                     !- Use Weather File Holidays and Special Days
Yes,                     !- Use Weather File Daylight Saving Period
No,                      !- Apply Weekend Holiday Rule
Yes,                     !- Use Weather File Rain Indicators
Yes,                     !- Use Weather File Snow Indicators
;                        !- Treat Weather as Actual

This is my RunPeriod.

Maybe someone has an idea from where the additional days might come here. My weather file has only 365 days.

Best, Simon

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@sz1980 If you review the CSV or ESO output file from EnergyPlus, and you're including heating/cooling design days, the first rows of data will be for the design days before the run period results (usually an annual simulation). It sounds like you have two design days, perhaps one heating in winter and one cooling in summer. Is that the case?

Aaron Boranian's avatar Aaron Boranian  ( 2023-03-09 09:53:47 -0500 )edit

@Aaron Boranian, thanks a lot for this hint and the explanation. A CSV is not returned from the simulation, but the ESO contains the 365 days. This needs now an explanation and I should have added this to the question when I stated it: I am running Eplus programmatically via Python and collect the outputs for each timestep. I am trying to narrow the problem down to the EnergyPlus configuration or the output collection in the Python program. However, it appears that I do have two design days.

sz1980's avatar sz1980  ( 2023-03-16 04:50:39 -0500 )edit

@Aaron Boranian Where can I see in the IDF if they get used? Also, if a year does not start on a Sunday, but I configure Sunday as a starting day, does Eplus then simply adjust the weekly schedules (this is what I am reading from the Reference Manual) or does it add days for until the weekday of the starting date arrives?

sz1980's avatar sz1980  ( 2023-03-16 04:51:53 -0500 )edit

@sz1980 the SimulationControl object has a "Yes/No" input field for Run Simulation for Sizing Periods. If that is set to "Yes", ESO/CSV files will contain design day results.

Getting start day to align between IDF and EPW is important if you're using actual weather data (AMY, or actual meteorological year). If you're using typical weather data (TMY), it's not important.

Aaron Boranian's avatar Aaron Boranian  ( 2023-03-17 10:45:51 -0500 )edit

The Day of Week for Start Day input field of the RunPeriod object sets the day of the week for Jan 1. The weekday/weekend definitions of schedules in the IDF will then progress from that day of the week. So, if you set that input field to Sunday, the first day of the simulation will use a weekend profile and the next day (Monday) will use a weekday profile.

Aaron Boranian's avatar Aaron Boranian  ( 2023-03-17 10:48:42 -0500 )edit