Fix the operative temperature of the zone

asked 2019-06-10 09:24:18 -0500

Mamak gravatar image

updated 2019-06-13 07:24:05 -0500

Hi guys. In am modelling a building with ideal load system. In my model I would like to fix the operative temperate of conditioned zones at 20 for heating and 26 for cooling. I have defined a dual set point thermostat for all the conditioned zones and defined the thermostat on the base of the operative temperature . When I run the simulation, the operative temperatures of the zones in results are not fixed to 20 ( in heating month) and 26 ( in cooling months)...but there is a deviation of approximately 0.5 Celsius .... Any body now how I can fix the temperature? so that in the output variable the operative temperature of the zones be constant. Thanks

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Is the deviation constant or variable? Generally the thermostat is a target - and the HVAC system will try to meet it within the deadband. Your model may have a 0.5 C deadband, which explains the deviation.

mdahlhausen gravatar imagemdahlhausen ( 2019-06-11 15:09:34 -0500 )edit

Thanks for your reply....The deviation is not constant. It is between 0 and 0.5. Where can I manage the dead band in energy plus? Is it possible to fix it at 0 ?

Mamak gravatar imageMamak ( 2019-06-12 05:03:23 -0500 )edit

If you set it to zero, it would result in unstable system operation. You could reduce it, but 0.5C is within the range that most typical HVAC systems can control to. Any finer, and it is representing lab-grade HVAC which is much more expensive. Generally when people say zone temperature is fixed at some value, they imply that it set to that value and varies around a setpoint. Why does your application need it exact?

mdahlhausen gravatar imagemdahlhausen ( 2019-06-12 10:26:53 -0500 )edit

Thank you for your reply...I am comparing the results of energy plus with a new developed software ( that is in the phase of test)....This software calculate the loads by considering that the temperature is constant ... so to make the load comparison reasonable... I am trying to find a way to fix the temperature in energy plus.

Mamak gravatar imageMamak ( 2019-06-12 10:47:00 -0500 )edit

In EnergyPlus, the HVAC equipment (especially ideal loads) attempts to peg the setpoint. Deadbands in EnergyPlus refer to the separation between the heating and cooling setpoints. If you post a link with the full idf here or send it to the helpdesk at energyplus-support@gard.com we can try to diagnose why it's not hitting the setpoint.

MJWitte gravatar imageMJWitte ( 2019-06-13 17:12:52 -0500 )edit