If you're responsible for anything bigger than your personal computer the chances are pretty good that electrical power is becoming more and more of an issue for you.
The most pressing problems are felt, of course, by wintel operators stocking wall to wall data center racks stuffed with Xeons, but even guys running a couple of decent size Unix machines set in the corners of an eighties data center are coming face to face with executives caught in the grip of some Inflight Magazine's brainless exultation of all things green.
So what can you do if some senior executive mentions your "carbon footprint" and you can't run, change the subject, or point him at someone else?
There's a general right answer: broaden the scope of the analysis beyond data center power usage to look at how structural change in IT can reduce the overall organizational energy bill.
All joking aside, a big data center really can act as someone's water pre-heat facility, but the more common opportunities are in areas like the substitution of video conferencing for physical travel and some of the odder but more interesting ones are in things like considering employee commuting patterns when scheduling meetings.
There are two aspects to this: first focusing outside the data center lets you find opportunities for the data center while getting others to wear most of the visible "carbon footprint"; and, more importantly, this is where most of the IT related opportunities for company wide energy savings actually are.
I'm not going to forget, for example, to mention that a desktop PC "costing" 145 watts to operate and another 150 watts for air conditioning can be replaced with a 4 watt Sun Ray - or that there are additional energy savings available in the server room if you opt to run those Sun Rays from Sun's latest CMT/SMP machines.
The easiest things to implement, however, are those that are both incremental and directly under your control; starting with server positioning. The most common recommendation in data center energy audits is to move the racks around to improve airflow - but the most interesting, if generally unheard, recommendation is to move most of the servers right out of the data center and into user centers. Do that and the marginal cost of heating, cooling, and securing your data center will fall considerably, and you'll spend a bit more on systems administration but both your own staff and users will be happier about the way you run IT.
How the numbers work out for you depends on your situation, but bear in mind that most of the reasons physically centralizing your wintel servers made sense in the nineties no longer apply. Thus the big drivers then were disk storage and the attempt to contain Wintel infrastructure staffing costs - but cost containment failed, most wintel server management no longer needs immediate physical access, and PC SANs no longer make financial sense.
You'd think a rack of Xeons in a user space would use exactly the same power it would in a data center, but that's not true. Beyond the fact that this power use is off your budget, two real things happen: first the gear will usually not trigger significant new cooling costs for the user area, and secondly the stand-alone nature of the thing means that you should generally incur fewer power loses in DC conversion and cooling than you do in a data center.
You'll also have happier user managers because they tend to believe that physical possession of the gear means something, because your sysadmins will have more direct contact with users, and because service delivery will pass through fewer network hoops.
So what's the bottom line? the specifics will vary with your circumstances, but the right answer to executive pressure to reduce energy use in IT is to look for organizational value beyond the data center - because whether you do more or simply distribute better, that's where the customer is, and therefore that's where the value is.