Just to elaborate, this "low grade heat" makes it physically impossible to recover much energy out of it.
If the ambient air is, say, 0C (273K), and the exhaust air is 30C (303K), then the optimal efficiency for recovering energy from the exhaust is less than 10%.
In other words, if your data center uses 1MW of power, then with perfect recovery equipment, you could generate 100kW off the waste heat, reducing your total power consumption to 0.9MW. Not a particularly big win, especially since your recovery equipment is not going to be 100% efficient.
Without any further treatment, it seems that waste heat is at least enough to heat living and office space (which is probably what they're doing with it).
If you arrived at that 10% by just looking at the K, keep in mind that 0C is ambient temperature and already represents the lowest energy level of that system. I really believe it should be possible to take and use more of that 30° degree difference than a mere 3° off the top, even factoring in heat pumps for consolidating it and moving it around.
The place is "In the middle of a forest at the edge of town", so if you're using the exhaust for heating other buildings, you're going to need long insulated conduits to carry it all, and that's probably not worthwhile AND will lose a lot of the heat to the outside anyway.
If the ambient air is, say, 0C (273K), and the exhaust air is 30C (303K), then the optimal efficiency for recovering energy from the exhaust is less than 10%.
In other words, if your data center uses 1MW of power, then with perfect recovery equipment, you could generate 100kW off the waste heat, reducing your total power consumption to 0.9MW. Not a particularly big win, especially since your recovery equipment is not going to be 100% efficient.