Not for nothing are law firms in New York and across the country finally stepping up in a big way to the “Law Office Climate Challenge,” issued in March 2007 by the American Bar Association in conjunction with the U.S. Environmental Protection Agency.

Quickly realized cost savings have been “a really good promotional tool” for attracting signatories to the challenge, said Daniel A. Eisenberg, vice chairman of the air quality committee of the ABA Section of Environment, Energy and Resources.

“Our first year was slow, there weren’t a lot of ways we could spread the word,” said Eisenberg, an associate at Beveridge & Diamond in Washington, D.C. “But in the last six months, we’ve noticed a substantial uptick of interest in the challenge.”

Money saved, as the old saw goes, is money earned. For example:

• Erik J. Sekler, executive director of Paul, Weiss, Rifkind, Wharton & Garrison, estimates a combined annual savings of $450,000 as the result of upgrading the firm’s lighting fixtures and laptop computers with more energy-efficient models, switching photocopy machines to double-side default and using recycled paper and ink toner cartridges

• Tania Shah, firmwide director of corporate responsibility at Pillsbury Winthrop Shaw Pittman, estimates $200,000 in yearly savings achieved simply by state-of-the-art lighting and office climate control.

• Christopher M. Zegers, director of information technology at Herrick, Feinstein, attributed savings of about $220,000 to new computer virtualization programs that reduced his firm’s need of 30 servers to about eight — with added and even greater savings in reduced power and cooling needs.

Zegers sees virtualization, which compacts as many as six functions into a single server, as “the biggest cost savings and ecologically sound” advance in green technology. He noted surveys forecasting energy usage by Internet data centers to surpass that of the airline industry by 2015.

Too early to be calculated are individual savings for green-conscience lawyers, such as a special Zipcar opportunity at Pillsbury offices in New York, San Francisco, Washington, D.C., and London — places where renting a car by the hour can make more sense than owning and garaging a personal vehicle, thereby adding to traffic congestion and air pollution.

Under a new partnership with Zipcar, Pillsbury picks up annual membership fees for its personnel — about $100 in San Francisco, slightly higher in New York — and Zipcar reduces its hourly usage rates by 25 percent.

But besides significant corporate and personal economizing, said Zegers, young lawyers especially “want to see that they’re going into a green environment.” Clients, he added, are “more and more looking to their vendors, including their law firms, to see how they’re addressing being green.”

“But money isn’t our motivating factor,” said David A. Crichlow, managing partner of Pillsbury’s New York office.

Noting that his firm, as well as others, contract with car service companies offering hybrid fleet vehicles, Crichlow said, “A lot of this is driven by our wanting to do the right thing. We recognize that we’ve got to do our share to promote a sustainable environment. There are little steps we can all take, but if all firms took them together they’ll have a great effect.”

At Shearman & Sterling, which in common with all firms polled by the Law Journal rolled out its package of environmental initiatives during Earth Day on April 22, green goes from the office to employees’ homes.