Until the whole world is on carbon free renewable power, data center equipment is made of biodegradable plastics and easily recyclable and you stop buying servers, you're going to have to conduct an annual audit of how green you are and look for areas of improvement.  Are you ready to start?

There's no single one-size-fits-all template I can offer for this task.  Before you begin, you have to have a baseline, preferably one that has a multi-year perspective.  How much energy are you using? How much energy is carbon-free? How much water? How much computing are you doing per watt? Are you more efficient per watt now or less so?  I know there are a number of different metrics to choose from, but measurements should be relevant to your management -- operational expenses (OpEx) is always going to be relevant. Anyway you can lower OpEx by saving energy is always going to be a good thing.

As an organization, the executive and IT leadership of your firm has to sit down and set down some priorities.  Do you want to simply use less energy or do you also want to reduce carbon by some percentage? How green do you want to be -- less energy, more recycling, LEEDs compliant? How old are your facilities?  How rapidly is your business growing?

Meeting your goals maybe a multi-year plan, especially if you don't have a big budget.  But if you are already buying equipment for a growing business, you can -- and should -- set requirements for energy efficiency and work in as much eco-friend electronics as is practical. 

Justifying replacement costs for equipment should factor both energy and maintenance costs, since maintenance tends to go up as a factor of age.  Older equipment also falls into the category of more headaches due to support (Obsolete software, hardware, more/different inventory items to deal with) resulting in a drag on productivity.  I'm not advocating a monoculture hardware shop, since that makes you dependent upon a single vendor's failings -- security, business, or otherwise.  On the other hand, having to deal with 17 different vendors '  products is a bit much, even if there is a single-point-of-contact (i.e., "One throat to choke") handing all the support issues.

Also check to make sure you've done the obvious to save energy.  Get rid of all your CRTs? Using LED rather than plasma for your big screens in the network operations center (NOC)? Hot and cold aisles?  Timers or motion sensors on your data center machine room lights? Move up the temperature settings from 68 degrees F to a more balmy 72, 74 or even 78 F?  There are a lot of little incremental tweaks you can roll into the data center to save energy without affecting productivity.

My "big budget" capital expense favorites for improving green usage are in cooling and site generated green power.  If you've got an older HVAC-style system running at sweater-wearing temperatures, it's time to replace at and keep your data center a bit warmer in the process. Adding solar panels, wind, or a Bloom Energy server reduces your carbon footprint in most cases -- unless you've got your own geothermal or hydro power secured -- and keeps you less dependent upon the existing power grid in case of a larger outage.