It’s a tricky one, but becoming increasingly common. When you moved to blades, did you consolidate and reduce the number of machines?
This next one probably isn’t what you want to hear, but many people who implement blades or pizza boxes tend to fit out the racks at lower density than possible, to allow air to circulate better. Is there a reason why you couldn’t spread 7 racks worth of kit over double the square footage (going back to your original 400) and half the density?
What is the average CPU utilization of your servers?
If they are under-utilized, you are consuming space, power and heat for components that aren’t really justifying their cost. If you didn’t consolidate already (or, if you did but utilization is still low) you could try that to reduce the number of physical machines further. VMware ESX would be well-suited to this. You could also try using workload management software to provide resource management capability to enable you to consolidate even further and host more apps on each physical or virtual machine. This could lead to a dramatic reduction in density, and if the boxes were under-used anyway, a corresponding reduction in heat/power etc. Something like Smartpeak software could work quite well.
Let me know how it goes, this is a fairly topical problem for the industry right now so I’m interested.