Racks tend not to do well in cool spaces they are very space efficient and very poor heat efficiency. It is tossed as an option but often the people whom suggest it have 'snake' rooms where the ambient air temps are 80ºF.

I run a rack in a cool room but have had to use dual heating for both warm and cool and needed to insulate the rack as well to keep heat loss at a minimum. It is a big job and lots of time effort and cash to get right. I spent 10 days of adjusting the empty rack to get the temps correct and stable.

My rack is PVCx and sucks at holding heat before the modifications I made. I am currently in the process of designing a new one that will hopefully hold heating better than the one I have. In a cool room I'd not use PVC or PVCx or melamine but in stead look at stress skin panel construction as it is more efficient insulation from heat loss. you can build your own with out too many problems look up 'stress skin panels' use 1/8 door skin on the exterior and interior skins rather than chip board.

If you have a cool room perhaps you might give thought to stackable enclosures. Instead they cost more to build but well designed they cost less to run. Just a thought.