The debate about whether a raised floor is designed and installed for a data center has gone on for years, with the fate of raised floor seemingly coming to an end. However, when diving into the matter, the decisions are often about the best way to manage cables, supply cooling water and airflow, and supporting high-density equipment. When building or renovating the decision isn’t to be taken lightly.
Many don’t see the need to have raised floors any longer. Decades ago, the raised floor was used to transport air for a lower power density as well as hide cables for mainframes and servers. In a way, the argument was to keep the arrangement that we always new worked for the data center. But beyond this, the need to design for raised floors today has been to support not only the cabling infrastructure, but to keep chilled water piping, drains, and other things that might cause issues for IT equipment from being overhead or otherwise in the way.
Flexibility has been another reason to have raised floors in the data center. Beyond being a plenum for supply air flow and a pathway for network cabling, power can also be run underfloor. This allows owners to get away from proprietary, expensive, and inflexible overhead power solutions. But that raised floor flexibility can be a bane to operations later. As time goes on and deployments come and go, a nest of dense cabling will remain below.
With cabling and power overhead, access in and around is needed, as well as close coordination with fire protection sprinkler piping, ductwork, and other obstructions overhead. The overhead solution also typically requires at least a step ladder for access, which be viewed as taking more time to deploy new cabling and more of a risk from accidents.
Having a raised floor for supply air flow is not always the most efficient as impediments like cables, piping, and more end up restricting areas and cause uneven underfloor distribution. Additional unique equipment has been developed to mitigate these issues, but many have the opinion it shouldn’t be necessary. And if the raised floor height isn’t high enough there are few ways to reconcile low flow, pressure, or hot spot issues.
Sometimes its about the looks, though, and a neat data center can be key to perception. A raised floor can have better aesthetics and depict a cleaner room for tours and clients while hiding power and cabling underfloor.
The cost of a raised floor is also a factor in the debate, with the higher the floor the more investment is required. Other factors of having a raised floor might be seismic leveling, additional insurance costs, ramps, building height, and fire codes. Some jurisdictions may look at any plenum space taller than 3’ as a potential storage area, triggering the need for additional fire protection piping to cover below the raised floor. It should be noted that for slab-only designs the cost of the overhead cable and power management should be considered.