I have a question regarding a big change in results from running the same .idf in EnergyPlus version 8.5 vs version 8.9.
I noticed the difference when I had to update some studies that I have done previously since I couldn’t recreate the same results. I located the difference to be that I was now running version 8.9 instead of 8.5 previously. Here is an example file, run in version 8.5 and version 8.9, with the same idf: Files
Does anybody know what changed in the EnergyPlus versions that is causing this difference (I guess it has to do with the calculation methods for the objects in the idf file)?
I’m inclined to stick with EnergyPlus version 8.5 because when running a comparison with a different simulation tool (IDA ICE) there is very high correspondence of results, which there is not when comparing IDA ICE to version 8.9
* UPDATE *
Thank you very much for your input @mdahlhausen - here are some more details:
Note - Good catch that HVAC equipment sizing has changed, but since I'm modelleling and ideal system that keeps the temperature between 22 and 24 degC, in my mind the yearly energy consumption should be the same, do you agree?
+++++ Version 8.5 +++++
Cooling peak load (before sizing factor): 975.40212 W
Heating peak load (before sizing factor): 174.39179 W
Zone Ideal Loads Supply Air Total Cooling Energy (Yearly): 1086.916048 kWh
Zone Ideal Loads Supply Air Total Heating Energy (Yearly): 121.428125 kWh
Min Air Temperature: 22 degC
Max Air Temperature: 24 degC
+++++ Version 8.9 +++++
Cooling peak load (before sizing factor): 870.05914 W
Heating peak load (before sizing factor): 132.20619 W
Zone Ideal Loads Supply Air Total Cooling Energy (Yearly): 1016.466383 kWh
Zone Ideal Loads Supply Air Total Heating Energy (Yearly): 75.030207 kWh
Min Air Temperature: 22 degC
Max Air Temperature: 24 degC
+++++ Idf object +++++
HVACTemplate:Zone:IdealLoadsAirSystem,
Fraunhofer, !- Zone Name
Fraunhofer_HVAC, !- Template Thermostat Name
, !- Availability Schedule Name
40, !- Heating Supply Air Temp {C}
, !- Cooling Supply Air Temp {C}
0.008, !- Max Heating Supply Air Humidity Ratio {kg-H2O/kg-air}
0.0085, !- Min Cooling Supply Air Humidity Ratio {kg-H2O/kg-air}
, !- Heating Limit
, !- Maximum Heating Air Flow Rate {m3/s}
, !- Maximum Sensible Heat Capacity
LimitFlowRate, !- Cooling Limit
autosize, !- Maximum Cooling Air Flow Rate {m3/s}
, !- Maximum Total Cooling Capacity
, !- Heating Availability Schedule
, !- Cooling Availability Schedule
None, !- Dehumidification Control Type
, !- Cooling Sensible Heat Ratio
, !- Dehumidification Setpoint
None, !- Humidification Control Type
, !- Humidification Setpoint
None, !- Outdoor Air Method
, !- Outdoor Air Flow Rate Per Person
, !- Outdoor Air Flow Rate Per Floor Zone Area
, !- Outdoor Air Flow Rate Per Zone
FraunhoferOutdoorAirCntrl, !- Design Specification Outdoor Air Object Name
, !- Demand Controlled Ventilation Type
DifferentialDryBulb, !- Outdoor Air Economizer Type
, !- Heat Recovery Type
, !- Sensible Heat Recovery Effectiveness
; !- Latent Heat Recovery Effectiveness
