A control system for a building zone which is climate conditioned by a climate conditioning system, wherein the climate conditioning system is configured to control at least one climate parameter in the building zone, the climate parameter being at least one of: temperature and humidity, the control system comprising: - a control interface to a building management system, wherein the building management system is configured to receive, via the control interface, a climate parameter target for the climate parameter and to control the climate conditioning system to establish the climate parameter in the building zone in accordance with the climate parameter target; - a sensor interface for receiving a climate parameter measurement ( T i ( i), RH ( i)) of the climate parameter from within the building zone; - a processor subsystem configured to periodically calculate the climate parameter target for respective control periods by, in a current control period ( i): - calculate a current running average value ( T c ( i), RH c ( i)) based on the climate parameter measurement ( T i ( i), RH ( i)) and a previous running average value ( T c ( i - 1), RH c ( i - 1)); - if a difference between the current running average value ( T c ( i), RH c ( i)) and the previous running average value ( T c ( i - 1), RH c ( i - 1)) exceeds a maximum rate of change per control period ( dT lim, dRH lim), limit the current running average value ( T c ( i), RH c ( i)) to remain within the maximum rate of change; - calculate an upper bound ( T max ( i), RH max ( i)) and a lower bound ( T min ( i), RH min ( i)) for the climate parameter based on the current running average value ( T c ( i), RH c ( i)), the upper bound and the lower bound defining a permissible climate parameter range; - determine the climate parameter target ( T sp ( i), RH sp,low ( i), RH sp,high ( i)) based on the permissible climate parameter range so as to cause the climate parameter to reach, or remain within, the permissible climate parameter range; and - via the control interface, output the climate parameter target to the building management system. - a control interface to a building management system, wherein the building management system is configured to receive, via the control interface, a climate parameter target for the climate parameter and to control the climate conditioning system to establish the climate parameter in the building zone in accordance with the climate parameter target; - a sensor interface for receiving a climate parameter measurement ( T i ( i), RH ( i)) of the climate parameter from within the building zone; - a processor subsystem configured to periodically calculate the climate parameter target for respective control periods by, in a current control period ( i): - calculate a current running average value ( T c ( i), RH c ( i)) based on the climate parameter measurement ( T i ( i), RH ( i)) and a previous running average value ( T c ( i - 1), RH c ( i - 1)); - if a difference between the current running average value ( T c ( i), RH c ( i)) and the previous running average value ( T c ( i - 1), RH c ( i - 1)) exceeds a maximum rate of change per control period ( dT lim, dRH lim), limit the current running average value ( T c ( i), RH c ( i)) to remain within the maximum rate of change; - calculate an upper bound ( T max ( i), RH max ( i)) and a lower bound ( T min ( i), RH min ( i)) for the climate parameter based on the current running average value ( T c ( i), RH c ( i)), the upper bound and the lower bound defining a permissible climate parameter range; - determine the climate parameter target ( T sp ( i), RH sp,low ( i), RH sp,high ( i)) based on the permissible climate parameter range so as to cause the climate parameter to reach, or remain within, the permissible climate parameter range; and - via the control interface, output the climate parameter target to the building management system. - calculate a current running average value ( T c ( i), RH c ( i)) based on the climate parameter measurement ( T i ( i), RH ( i)) and a previous running average value ( T c ( i - 1), RH c ( i - 1)); - if a difference between the current running average value ( T c ( i), RH c ( i)) and the previous running average value ( T c ( i - 1), RH c ( i - 1)) exceeds a maximum rate of change per control period ( dT lim, dRH lim), limit the current running average value ( T c ( i), RH c ( i)) to remain within the maximum rate of change; - calculate an upper bound ( T max ( i), RH max ( i)) and a lower bound ( T min ( i), RH min ( i)) for the climate parameter based on the current running average value ( T c ( i), RH c ( i)), the upper bound and the lower bound defining a permissible climate parameter range; - determine the climate parameter target ( T sp ( i), RH sp,low ( i), RH sp,high ( i)) based on the permissible climate parameter range so as to cause the climate parameter to reach, or remain within, the permissible climate parameter range; and - via the control interface, output the climate parameter target to the building management system.