# Modelica: Using temperature sensor to measure temperature of room

Hi, I am trying to model a system where the temperature of the room is measured and fed into a PID to control the air flow rate of the HVAC system. I am trying to use a temperature sensor [senTem]but it is not measuring the temperature of the room[HVAC_Zone] when the initial mass flow rate is 0. I have provided the nominal mass flow rate to be 0.066kg/s. . I am trying to model it such that the temperature of the room increases due to the heat load and the temperature sensor measures it and depending on the difference between measured temperature and temperature, the setpoint of the Air flow rate is varied and fed into the air flow inlet [boundary]. \What am I doing wrong or missing? Any help is appreciated. Thank you