PURPOSE: To achieve an energy saving when air conditioning is controlled so as not to cause a difference in temperature among a main room and other rooms with different indoor loads by a method wherein the main room is air-conditioned as usual, whilst the other rooms are air-conditioned with a mixture of fresh air which is tatally heat exchanged with the exhaust and cold air produced by the air conditioner.

CONSTITUTION: In case of controlling the temperature of a breeding room 10 which is a main room, a front room 20 and a corridor 30, the main room 10 is supplied, through a blow-off port 12 provided with a filter, with cold air C and hot air H from an air conditioner 40 which are mixed properly by a terminal unit 50. Whilst, the front chamber 20 and the corridor 30 are supplied, through blow-off holes 22 and 32, respectively, with mixtures of fresh air H' which is totally heat exchanged by a total heat exchanger 80 with the air conditioner exhaust system and cold air C from the air conditioner 40 which are heated by reheaters 61 and 71 of terminal units 60 and 70, respectively. In this case, mixing of the heat exchanged air H' and cold air C is controlled on the basis of a dew point temperature set so as to minimize the reheat guantity under the condition of a temperature set for the main room 10 and a predetermined relative humidity.