Dell's CIO Robin Johnson and Global Facilities lead Dane Parker joined Fortune editor Brian O'Keefe on stage today at Fortune Brainstorm Green to tell a story you wouldn't expect from a company that sells servers: "the greenest data center is the one you never build." Intrigued?  Well...

A few years ago, said the duo, Dell found itself in a position many of our customers face - we needed more computing power, but we were out of space and maxed out on power to the datacenter. We needed another one - maybe more than one.  But a decent-sized data center can cost around $100 million, not to mention all the materials for construction and the energy to power it. So the team set out to find a better way to accomplish the same goal.

Enter virtualization, which Robin compared to carpooling. "Virtualizing applications and putting several on one server is a lot like putting four people in one car. You get more accomplished using the same amount of energy."

Long story short, by better arranging our data centers, more efficiently dealing with the hot air servers produce (like releasing it outside rather than recooling it and using outside air to cool data centers about 150 days a year - in Texas, no less) and using virtualization to reduce the number of servers, Dell doubled our computing capacity at no extra power and no extra footprint.

With this extra capacity, we don't anticipate needing another data center for another 10 to 15 years. All this at a time when data is exploding at an unprecedented rate. It's a good business story with a positive impact on the environment.  Talk about making "being green" easy and cost-effective. There it is in action!

Just think about what these energy savings this could mean at a macro level. If every mid-sized enterprise, large business and public sector organization optimized their data centers this way, we could compute so much more using so much less energy.

The entire conversation will be available late Wednesday at Fortune's virtual conference site. Check it out.  You can also follow Tweets from the event using hashtag #fortunegreen.