A greenhouse cooling system with heat storage for completely closed greenhouses has been designed, based on the use of a fine wire heat exchanger. The performance of the fine wire heat exchangers was tested under laboratory conditions and in a small greenhouse compartment. The effects of the system on the environmental conditions (temperature and humidity distribution) in the greenhouse were simulated to decide on the final lay out of the system. Finally the system was implemented on a large scale in a pot plant greenhouse complex of 2500 m². The system is being tested under practical conditions and compared to a traditional heating and ventilation system in a comparable reference compartment of 2500 m². This paper describes the set up of the greenhouse system, the first simulation results achieved with the system with respect to environmental conditions and energy use.