A method of controlling operation of an HVAC system having actuator driven valves for adjusting the flow of fluid in the HVAC system and one or more sensors (F, F1, F2, F3, Fi) for sensing operational parameters of the HVAC system, the method comprising: transmitting sensed operational parameter values from the one or more sensors (F, F1, F2, F3, Fi) via a telecommunications network to a cloud-based HVAC control center; transmitting current valve position values from the actuators (A1, A2, A3, Ai) via the telecommunications network to the cloud-based HVAC control center calculating in the cloud-based HVAC control center control values for the actuators (A1, A2, A3, Ai), using the current valve position values from the actuators (A1, A2, A3, Ai), the sensed operational parameter values from the one or more sensors (F, F1, F2, F3, Fi) and calibration values stored in the cloud-based HVAC control center, the calibration values indicating operational parameters of the HVAC system at defined valve positions and defined conditions in the HVAC system; and transmitting the control values for the actuators (A1, A2, A3, Ai) from the cloud-based HVAC control center to the actuators (A1, A2, A3, Ai), wherein the method comprises controlling a flow of air into a plurality of zones (Z1, Z2, Z3, Zi) of a variable air volume HVAC system having actuator driven dampers (D1, D2, D3, Di), which operate in a range from a minimum damper position to a maximum damper position for adjusting the flow of air into a zone (Z1, Z2, Z3, Zi) of the HVAC system, and one or more flow sensors (F, F1, F2, F3, Fi), wherein the method further comprises transmitting flow measurement values from the one or more flow sensors (F, F1, F2, F3, Fi) via the telecommunications network to the cloud-based HVAC control center; transmitting current damper position values from the actuators (A1, A2, A3, Ai) via the telecommunications network to the cloud-based HVAC control center; calculating in the cloud-based HVAC control center the minimum damper position for the actuators (A1, A2, A3, Ai) such that the pressure in the HVAC system does not exceed a defined maximum pressure threshold, using the flow measurement values from the one or more flow sensors (F, F1, F2, F3, Fi) and calibration values stored in the cloud-based HVAC control center, the calibration values indicating operational parameters of the HVAC system at a defined calibration pressure in the HVAC system and at different damper positions; and transmitting the minimum damper position from the cloud-based HVAC control center to the actuators (A1, A2, A3, Ai). transmitting sensed operational parameter values from the one or more sensors (F, F1, F2, F3, Fi) via a telecommunications network to a cloud-based HVAC control center; transmitting current valve position values from the actuators (A1, A2, A3, Ai) via the telecommunications network to the cloud-based HVAC control center calculating in the cloud-based HVAC control center control values for the actuators (A1, A2, A3, Ai), using the current valve position values from the actuators (A1, A2, A3, Ai), the sensed operational parameter values from the one or more sensors (F, F1, F2, F3, Fi) and calibration values stored in the cloud-based HVAC control center, the calibration values indicating operational parameters of the HVAC system at defined valve positions and defined conditions in the HVAC system; and transmitting the control values for the actuators (A1, A2, A3, Ai) from the cloud-based HVAC control center to the actuators (A1, A2, A3, Ai), wherein the method comprises controlling a flow of air into a plurality of zones (Z1, Z2, Z3, Zi) of a variable air volume HVAC system having actuator driven dampers (D1, D2, D3, Di), which operate in a range from a minimum damper position to a maximum damper position for adjusting the flow of air into a zone (Z1, Z2, Z3, Zi) of the HVAC system, and one or more flow sensors (F, F1, F2, F3, Fi), wherein the method further comprises transmitting flow measurement values from the one or more flow sensors (F, F1, F2, F3, Fi) via the telecommunications network to the cloud-based HVAC control center; transmitting current damper position values from the actuators (A1, A2, A3, Ai) via the telecommunications network to the cloud-based HVAC control center; calculating in the cloud-based HVAC control center the minimum damper position for the actuators (A1, A2, A3, Ai) such that the pressure in the HVAC system does not exceed a defined maximum pressure threshold, using the flow measurement values from the one or more flow sensors (F, F1, F2, F3, Fi) and calibration values stored in the cloud-based HVAC control center, the calibration values indicating operational parameters of the HVAC system at a defined calibration pressure in the HVAC system and at different damper positions; and transmitting the minimum damper position from the cloud-based HVAC control center to the actuators (A1, A2, A3, Ai).