Method for controlling a sorption heat exchanger apparatus configured as an open system, in particular a sorption heat exchanger apparatus for direct fresh air conditioning, in which at least two sorption heat exchangers (2a, 2b) with a respective sorption side (3a, 3b) and a respective cooling side (4a, 4b) are alternately operated in an adsorption mode with an adsorption phase and a regeneration mode with an intermediate cooling phase and a desorption phase, in order to carry out quasi-continuous conditioning, - characterized in that, in the adsorption phase, outside air (7a, 7b) is guided through the sorption side (3a, 3b) of the sorption heat exchanger (2a, 2b) and then channelled into a building supply air duct, wherein a sorbent in the sorption heat exchanger (2a, 2b) is laden by taking up moisture from the outside air (7a, 7b), wherein, in order to simultaneously cool the outside air (7a, 7b) and dissipate resulting sorption heat on the cooling side (4a, 4b) of the sorption heat exchanger (2a, 2b), use is made of building exhaust air which, prior to entering the sorption heat exchanger (2a, 2b), is cooled by an adiabatic evaporation cooling system (5a, 5b), and wherein the building exhaust air, which is warm and moist after the process, is removed as outgoing air, - wherein, in the desorption phase in the sorption heat exchanger (2a, 2b) which is currently not being used for fresh air conditioning, the adsorbed water is driven out of the sorbent, for which purpose heated air (7a, 7b) at about 65-85°C is channelled through the sorption duct and removed as outgoing air, and - wherein the sorption.heat exchanger (2a, 2b) heated after the desorption phase is cooled in the intermediate cooling phase between the desorption phase and the adsorption phase, for which purpose outside air (7a, 7b) is channelled through the adiabatic evaporation cooling system (5a, 5b) and supplied to an air shaft for outgoing air, with the result that the sorption heat exchanger (2a, 2b) is cooled from the cooling side (4a, 4b), wherein a maximum of four switching units (6a-6d, 6e-6h) are activated for each sorption heat exchanger (2a, 2b) in order to implement the two operating modes with the three phases of the sorption heat exchangers (2a, 2b). - characterized in that, in the adsorption phase, outside air (7a, 7b) is guided through the sorption side (3a, 3b) of the sorption heat exchanger (2a, 2b) and then channelled into a building supply air duct, wherein a sorbent in the sorption heat exchanger (2a, 2b) is laden by taking up moisture from the outside air (7a, 7b), wherein, in order to simultaneously cool the outside air (7a, 7b) and dissipate resulting sorption heat on the cooling side (4a, 4b) of the sorption heat exchanger (2a, 2b), use is made of building exhaust air which, prior to entering the sorption heat exchanger (2a, 2b), is cooled by an adiabatic evaporation cooling system (5a, 5b), and wherein the building exhaust air, which is warm and moist after the process, is removed as outgoing air, - wherein, in the desorption phase in the sorption heat exchanger (2a, 2b) which is currently not being used for fresh air conditioning, the adsorbed water is driven out of the sorbent, for which purpose heated air (7a, 7b) at about 65-85°C is channelled through the sorption duct and removed as outgoing air, and - wherein the sorption.heat exchanger (2a, 2b) heated after the desorption phase is cooled in the intermediate cooling phase between the desorption phase and the adsorption phase, for which purpose outside air (7a, 7b) is channelled through the adiabatic evaporation cooling system (5a, 5b) and supplied to an air shaft for outgoing air, with the result that the sorption heat exchanger (2a, 2b) is cooled from the cooling side (4a, 4b),