Hi, all, I simulate the heating and cooling loads of an office room with a window. I use a packaged terminal air conditioner (PTAC) system in HVACTemplate:Zone:PTAC, which with a DX cooling coil, a heating coil (electric), and an outdoor air mixer. The supply air fan is on/off. There is no any other HVAC system. The thermostat is 20 (heating), 24 (cooling).