More than half of large companies are moving beyond talking and into actual planning stages for making their data centers "greener," according to a study that will be released next month by data center operator Digital Realty Trust.

About 55% of companies have established detailed strategies for making their data centers more energy efficient, according to the survey of senior and C-level executives, including CIOs, at 100 companies with at least $1 billion.

"Being green in the data center means saving money on the bottom line," says Jim Smith, VP of engineering of Digital Realty Trust, which conducted the study to evaluate how serious companies are in green initiatives for their data centers. "Most companies will tell you they're on the quest to be green," says Smith.

"But most are beyond just saying that," he says. More than half of those surveyed are actually putting together green data center action plans, have serious management support of such programs, and are providing budgeting to green strategies, he says.

Sixty percent of those surveyed said their green strategy will become an important factor in vendor selection over the next two years.

Strategies include design changes in new data centers, and also operational changes and other modifications in existing ones, says Smith.

In addition to strategies like server consolidation and virtualization that can reduce energy consumption, other beneficial changes include "tune ups" in the data center, including better managing open space between server racks and bypass air flow, as well as making sure data center temperatures aren't calibrated too cold.

"Most tune ups are simple and can help save a lot," says Smith. For instance, safely raising the temperature in data centers three to four degrees can lower cooling costs 10% or more, he says.

A recent report by the U.S. Environmental Protection Agency found that left unchecked, data center energy consumption by the private and public sectors will soar to $7.4 billion in 2011, from $4.5 billion in 2006.

The Digital Realty Trust report will be released in mid-September.