It should not be difficult to design an air-conditioning system so that the "waste" heat is pumped to somewhere useful. For example, into the building's central heating/ hot water system, so that in winter the boiler has to burn less fuel, and in summer the hot water is "free". (You might still have to dump some unwanted heat on the outside). Better still, in summer, run a ground-source renewable heating system backwards - heat up a chunk of earth or rock with the "waste" heat, and then pump that stored heat back inside when winter arrives.
Of course this is easier still if you design the server centre together with an appropriate quantity of nearby residential accomodation as your "heatsink", rather than as a standalone unit in the middle of a commercial centre.
It's called joined-up thinking, and there's far too little of it going on.