My temperature setpoint schedules follow one setpoint for heating and one for cooling which were provided by the project team that built the houses. I would like to model the deadband around those setpoints. For example, if a heating setpoint were 74F and there was a temperature deadband of 3F, the HVAC would not turn on until indoor temperature reached 77F.
I would like for the indoor temperature of my model to fluctuate some instead of staying exactly at setpoint.
And I am using real weather data that was measured in the backyard of one of the houses.
Thanks,
Evan
From: Jim Dirkes Jim@xxxxxxxxx [EnergyPlus_Support]
Sent: Wednesday, July 1, 2020 1:28 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Indoor Temperature Deadband Implementation E+ v8.8
A few thoughts.....
I'm not sure what sort of deadband you're trying to model, but...
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Do your temperature setpoint schedules reflect the deadband between heating and cooling? (eg, ThermostatSetpoint:DualSetpoint)
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Are you using TMY weather data or actual weather data? (actual weather is preferred for a calibration effort)
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James V Dirkes II, PE, BEMP, BCxP
Team Lead - Building Performance
616 450 8653
Foresight Management
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From: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx> on behalf of Evan Jones evan_jones0212@xxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Wednesday, July 1, 2020 12:47 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Subject: [EnergyPlus_Support] Indoor Temperature Deadband Implementation E+ v8.8
Hello,
I have developed a E+ models of a few houses with differing heatpumps. Two variable capacity, a 1-stage, and a 2-stage. The latter two were installed in 2010, and had a thermostat with a very large temperature deadband.
I am having difficulty reducing my HVAC power error to within 15% at a monthly level during shoulder months like April and October. I have found that it is mostly due to measured indoor temperatures deviating from the temperature setpoint within a wide deadband. In my EnergyPlus models, the indoor temperature stays strictly at the set point with no deviation. For some days, the deadband in the actual homes allows the HVAC to simply stay off and for the temperature to fluctuate inside, while in my EnergyPlus model both heating and cooling turns on throughout the day so that the indoor temperature remains at setpoint.
This problem is exacerbated by the 1- or 2- stage heat pumps. Since they are worse at keeping indoor temperatures steadily at setpoint than variable capacity heat pumps, their errors become much higher and are evident in more months.
I have done some research into the issue and found that it is caused by EnergyPlus’s method of modeling HVACs in a roughly equivalent way using part load curves. I am hoping that there is a way around this.
Thank you very much for your help.
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Posted by: Evan Jones <evan_jones0212@xxxxxxxxxxx>
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