... system used for central heating for nearby houses or office buildings. 40-60 degrees celsius through radiators makes sense. ...
Forced hot water heat temp is 82-98C. 40-60 for radiant heat (not really common).
Would have to be fairly special houses -- central heating (for apartments) usually means *steam* heat (convenient, because no return pipes with steam).
That's part of the problem. It's difficult to retro-install the systems, you basically have to build the neighborhood at the same time as you build the data center. I can't find where I got this from but i think they might have used underfloor heating.