Supply air is typically distributed under floor from
self-contained packaged units using the space provided under a raised floor,
with perforated panels, diffusers or registers built into the floor panels.
This permits easy access and relocation of the cooling as well as the
computer equipment. In some cases, ceiling plenums supply the cool air. This
overhead supply should be limited to applications where air supply isn't so
critical and there is limited need for flexibility is not great.