how to compensate the temperature difference?

Hi I am simulating a heating system, I have measured the transfer function of the real system, and now I am trying to designe a proper controller to reach to the desired temperature. but I face a small amount of temperature difference, about half a degree. how can I compensate for this? I have changed the controller parameters several times, but I face this problem still, both in simulation and in real system. do I need to use an offset? or is there anyway to do this as simple as possible? the system can not take an overshoot more than half a degree, btw. Thanks,

[Ced]

This questions cannot be answered like that. There are thousands of ways to design a controller, depending on speed, type of system, available hardware, etc. As a rule of thumb, if you have some steady-state error, check if your system has an integrating behaviour. For a slow system like a heating system, a PI(D) controller should do the trick.