1. A controller arrangement for a building system, the arrangement comprising: a sensor module comprising a wireless communication device and a microelectromechanical sensor device operable to generate a process value; an actuator module comprising an actuation element and a wireless communication device; a controller operable to obtain the process value from the sensor device and provide a control output to the actuation element, the controller further operable to communicate with at least one of the sensor module and the actuator module using wireless communications, the controller further operably connected to receive a set point value, wherein the controller is operable to generate the control output based on the process value and the set point value.