At the moment, all energy analysis programs that I am aware of are intended to simulate HVAC and control systems which are operating properly. You can simulate some faults (e.g., a setpoint that is off by a fixed value), but that is not the intention of the modeling software.
I think you will need to tap your creativity in order to simulate and unstable (“hunting”) control loop.
James V Dirkes II, PE, BEMP, LEED AP
Modern building controls are pretty good. And minute wize simulation is uncommon for anual energy consumption simulations. Therefore e+ assumes perfect control as a good approximation.
In TrnSys I have simulated complex systems with PID controlers where my dual heating/cooling thermostats are setup with 4 points, e.g. 20 (heating on), 22 (heating off), 26 (cooling on), 24 (cooling off). But it doesn't stop there...the cooling and heating coils have their own setpoints depending on whether the AHU is in heating or cooling mode. And even more complicated because the coil setpoints have to dynamically adjust within the range from design outlet temp to design outlet temp + tolerance which depend on also the temperature sensor in the return airstream. And similarly the other componants like mixing valve (with economizer function), heat exchanger (with bypass), etc. must all be controlled and work together. This seems to work with very small timesteps 0.025 hr. In TrnSys you must set all this up yourself. I'm glad I'm not a controlls engineer. It is quite difficalt.
E+ does have new thermostat types which turn the heating on and keeps it on untill the upperbound is reached. They are thought for specific applications (see io ref), and should not be generally used. I have not tested them and am wary of overall system and numerical stabillity issues due to my experience in TrnSys.
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