This article is part of our Rising Star Portfolio series.

One of the reasons I purchased Google (Nasdaq: GOOG) for my Rising Star portfoliowas its longstanding desire to design a greener business. It recently made an essential step, disclosing hard facts about its carbon footprint.

Google says it makes the world greener with its products and services, and the company itself has been carbon neutral since 2007. Google has revealed that its servers use less energy per user than a light bulb left on for three hours, and it offsets that usage. Furthermore, Google's digital world of information reduces consumer energy use -- required for driving around to seek out physical information and media, for example. And goodness knows, it would be difficult to drive around and find pandas sneezing or dancing babies like you can find on YouTube. Life was hard in the olden days.

Google has deliberately focused on reducing electricity use and boasts having built some of the most energy-efficient servers and data centers in the world. For example, its newest Finnish facility uses a seawater cooling system that just sips electricity instead of guzzling it.

In addition, Google uses a great deal of renewable energy, including solar panel installations at its headquarters, wind-powered data centers, and carbon offset purchases to cancel out the greenhouse gas emissions it can't avoid. It's also made massive investments in renewable energy. 

As eager as Google has been to talk up its green street cred, it has taken a while for it to disclose actual hard data about its electricity consumption. (As it turns out, it approximates the amount required to power 200,000 homes). Environmental experts like one quoted by The New York Times may offer Google grudging kudos, but they still point out that Google's figures don't factor in energy used by the myriad devices consumers use to access the company's data and services, not to mention ever-increasing corporate usage.

Tech companies have traditionally been energy hogs, making their choices significant. Yahoo! (Nasdaq: YHOO) designed "chicken coop" data centers to reduce its power drains (and costs) and is eyeing hydropower. Apple (Nasdaq: AAPL), on the other hand, uses much-maligned, dirty coal to power its new North Carolina data center.

Increasingly, companies' disclosure of their environmental performance records matters to shareholders. Google, Apple, eBay (Nasdaq: EBAY), and Akamai (Nasdaq: AKAM) are the only four major tech companies that disclose global emissions information for their data centers driving cloud computing and Internet services, as a matter of fact.

It's good to see that Google's become more transparent about its consumption, solidifying its leadership and bulking up the greenery surrounding its brand. As sustainability grows in importance, companies that fail to address their wastefulness will prove riskier, and maybe even costly for investors. Google's leadership in this area shores up its importance in my Rising Star portfolio.