On Thu, 25 Jan 2007, Bill Woodcock wrote:
Obviously convection is the best way, and I've gotten away with it a few times myself, but the usual answer to your "why not" question is "Fire codes." Convection drives the intensity and spread of fires. Which is what furnace chimneys are for. Thus all the controls on plenum spaces. But when you can get away with it, it's great.
Lots of codes, energy conservation codes, fire codes, building codes, etc. Although people may gripe about power and cooling, one fire can really ruin your day. Energy can turn into heat in either controlled or uncontrolled ways. Anyone who is interested should look at the conference proceedings and papers published by ASHRAE. There was a presentation a few years ago which explained why Equinix, although I don't think it used the name, has those 30foot high ceilings painted black :-) Some of the energy conservation codes cost energy when applied to areas beyond their design assumptions. I noticed AT&T changed its standards. NEBS still applies in COs, but AT&T has published new standards for what they call Internet data spaces. Nothing earthshaking, but it was interesting to see some of AT&T's risks assessments change. As I suggested years ago, equipment design, cooling design, power design, geography design are all inter-related. Which is the premium for you?