If you designed the system like this from the start or when replacing it anyways, N+1 redundancy might not me much more expensive than one big cooling unit. The systems can mostly share their ductwork and just have redundancy in the active components, so mostly the chillers.
Of course these systems only get replaced every couple decades, if ever, so they are pretty much stuck with the setup they have.
> If you designed […]
University department IT is not designed, it grows over decades.
At some point some benefactor may pay for a new building and the department will move, so that could be a chance to actually design. But modern architecture and architects don't really go well with hosting lots of servers in what is ostensibly office space.
I've been involved in the build-out of buildings/office space on three occasions in my career, and trying to get a decent IT space pencilled has always been like pulling teeth.
> Of course these systems only get replaced every couple decades, if ever
This is despite the massive energy savings they could get if they replaced those older systems. Universities often are full of old buildings with terrible insulation heated/cooled by very old/inefficient systems. In 20 years they would be money ahead by tearing down most buildings on campus and rebuilding to modern standards - assuming energy costs don't go up which seems unlikely) But they consider all those old buildings historic and so won't.
> In 20 years they would be money ahead by tearing down most buildings on campus and rebuilding to modern standards - assuming energy costs don't go up which seems unlikely) But they consider all those old buildings historic and so won't.
It has nothing to do with considering those building historic.
The problem is unless someone wants to donate a $50-100M, new buildings don't happen. And big donors want to donate to massive causes "Build a new building to cure cancer!" not "This building is kind of crappy, let's replace it with a better one".
It doesn't matter that over 50 years something could be cheaper if there's no money to fix it now.