Method for operating a hydronic heating and/or cooling system, wherein the hydronic heating and/or cooling system comprises multiple temperature zones ; wherein each temperature zone comprises a heat exchanger with a liquid heating/cooling medium and air flowing through the heat exchanger ; wherein each temperature zone comprises a temperature sensor for measuring an actual value of a zone air temperature; wherein each temperature zone comprises a control valve controlling the flow of the liquid heating/cooling medium through the heat exchanger in such a way that the actual value of the zone air temperature is adjusted to a target value of the zone air temperature; characterized in that a difference between the actual value and the target value of the respective zone air temperature is provided to a first controller , wherein the first controller provides as output variable a signal corresponding to a target relative heating/cooling power request of the heat exchanger of the respective temperature zone ; an actual relative heating/cooling power request for the respective heat exchanger is calculated on basis of at least three temperature signals, namely at least on basis of the heat exchanger inlet temperature of the liquid heating/cooling medium, on basis of the heat exchanger outlet temperature of the liquid heating/cooling medium and on basis of the heat exchanger inlet air temperature corresponding to the actual value of the zone air temperature; a difference between the target relative heating/cooling power request and the actual relative heating/cooling power request is provided to a second controller , wherein the second controller provides as output variable at least one control variable for the respective temperature zone . wherein the hydronic heating and/or cooling system comprises multiple temperature zones ; wherein each temperature zone comprises a heat exchanger with a liquid heating/cooling medium and air flowing through the heat exchanger ; wherein each temperature zone comprises a temperature sensor for measuring an actual value of a zone air temperature; wherein each temperature zone comprises a control valve controlling the flow of the liquid heating/cooling medium through the heat exchanger in such a way that the actual value of the zone air temperature is adjusted to a target value of the zone air temperature; characterized in that a difference between the actual value and the target value of the respective zone air temperature is provided to a first controller , wherein the first controller provides as output variable a signal corresponding to a target relative heating/cooling power request of the heat exchanger of the respective temperature zone ; an actual relative heating/cooling power request for the respective heat exchanger is calculated on basis of at least three temperature signals, namely at least on basis of the heat exchanger inlet temperature of the liquid heating/cooling medium, on basis of the heat exchanger outlet temperature of the liquid heating/cooling medium and on basis of the heat exchanger inlet air temperature corresponding to the actual value of the zone air temperature; a difference between the target relative heating/cooling power request and the actual relative heating/cooling power request is provided to a second controller , wherein the second controller provides as output variable at least one control variable for the respective temperature zone . <EOS>