Abstract: A method for determining the balance between an amount of supplied cooled air and an amount of discharged heated air in a temperature- and air humidity-conditioned space in which ICT equipment is disposed which gives off heat to passing cooled air so that this air is heated up, wherein the free movement of a reference stream of air in the space is monitored by measuring a signal which is imparted to the air of the reference stream with the aid of a signal source. The invention further relates to an apparatus for determining the balance between an amount of supplied cooled air and an amount of discharged heated air in a temperature- and air humidity-conditioned space in which ICT equipment is disposed which gives off heat to passing cooled air so that this air is heated up, comprising a measuring tube for monitoring the movement of a reference stream of air.