Air ducts of cage racks are connected to the main duct, through which heat and metabolic products from animals are discharged directly outside.
As the exhaust from the racks is not discharged into the room, the ventilation rate can be reduced without compromising the room environment.
The inside of the racks are fully ventilated at the rate of 50 to 100 times per hour, while the frequency of ventilation of the rearing room is cut to 5 to 10 times per hour. In effect, the total ventilation rate is reduced, therewith fan energy consumption and heat source energy consumption are reduced, too, and this leads to energy cost saving.