The air conditioning is not free. Downtime isn't free. Depending on design, if the DC isn't very monolithic, then you can run with components failing and not

The air conditioning is not free. Downtime isn't free. Depending on design, if the DC isn't very monolithic, then you can run with components failing and not causing much trouble, replacing when available, if your apps are designed to run on a zillion small CPUs, as I believe Google and Amazon are, instead of a giant monolithic computer, 1970s style. Could have heavier AC for critical components, the main routers and disk farms, for instance. Details of the calculations unknown to me.