> To prevent the server stacks overheating, tech companies spend vast sums on cooling technology - more than a third of a data centre's hefty energy bill may go on air conditioning.

Data center cooling isn't necessary. I saw a presentation by Christian Belady, the general manager of Data Center Services for Microsoft's Global Foundation Services (GFS) group, where he spoke about how they don't cool their data centers anymore. He tested the theory by putting a bunch of racks outside in a tent to see that they wouldn't overheat.