A method of controlling the cooling of servers in a data center including a plurality of server racks each including a plurality of servers, the cooling being provided by aisle cooling units via a cold isle and by server fans, wherein the method includes: obtaining temperature measurements from temperature sensors in the data center, performing an optimization of the total power consumption of the aisle cooling units and of the servers based on the temperature measurements, with constraints on a cold aisle temperature and on an air flow level of the aisle cooling units, and controlling the aisle cooling units based on the optimization.