<;P>;PROBLEM TO BE SOLVED: To obtain an air conditioning system avoiding a damage of plants by making temperature and humidity in a space uniform in heating air conditioning in the large indoor space for plant growing. <;P>;SOLUTION: A closed air conditioning target space for growing plants is equipped with: a plurality of heat pump type air conditioners; a combustion type heater; circulation fans provided in the heat pump type air conditioners, respectively to stir air within the target space; a control device for controlling these devices; and a communication means for sending and receiving signals among the heat pump type air conditioners, the combustion type heater, the circulation fans, and the control device. During heating operation by the heat pump type air conditioners, the control device gives operation permission with respect to the corresponding circulation fans, and the circulation fans repeat operation and stop for each predetermined time. <;P>;COPYRIGHT: (C)2011,JPO&INPIT