Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
I would recommend doing a test simulation of just January 1 (set in RunPeriod object) to see what initial values are for the following output variables:
Output:Variable,*,Site Ground Temperature,Timestep;
Output:Variable,*,Zone Air Temperature,Timestep;
Output:Variable,*,Surface Inside Face Temperature,Timestep;
Output:Variable,*,Surface Outside Face Temperature,Timestep;
In your IDF, it looks like you are already reporting Zone Air Temperature but have commented out the other three. For this test, I would also recommend using 15-minute timesteps instead of 1-minute timesteps that the IDF is currently set up for (for testing, timesteps that short are overkill and not necessary).
EnergyPlus performs a warmup process to determine appropriate initial values for temperatures at the beginning of the run period simulation. Surface and air temperatures are set to 23C at the beginning of this warmup process, but EnergyPlus might be converging on different values. You can see this in the output variables from the very first timestep of your run period simulation, which appears in the output CSV file. If temperature values are different between surfaces and the zone air, then heat transfer will occur between them and cause them to change temperatures as a result.
You could also include various output variables for weather data to see their values in the output CSV and confirm that you created your custom EPW file correctly. In your IDF, it looks like you are already reporting Outdoor Air Drybulb and Outdoor Air Relative Humidity. I would recommend adding other variables that could impact surface or zone air temperatures (Wind Speed, Solar Radiation, etc.).
