Newsweek today is releasing its second annual ranking of the nation's greenest companies, and there are very few changes from last year's. Dell and Hewlett Packard swapped first and second place, with Dell this year scoring a perfect 100.00 and HP scoring 99.32. (In last year's ranking, HP scored 100 points, and Dell earned 98.87.

Rounding out the top five in this year's rankings are IBM with 99.20 points, Johnson & Johnson with 99.02 points, and Intel with 97.57 points. J&J is the only non-technology firm in the top 10 this year, with investment firm State Street dropping from sixth place last year to 35th place this year.

GreenBiz.com executive editor Joel Makower explains the Newsweek methodology in a blog post today:

[T]he basic methodology remains unchanged. Newsweek’s rankings assess the 500 largest publicly held companies, determined by a combination of market cap, revenue, and number of employees. Each company gets a Green Score derived from three separate metrics:



• an "Environmental Impact Score," compiled by Trucost, based on more than 700 metrics of company performance, including greenhouse-gas emissions, water use, and solid-waste disposal;



• a "Green Policies Score," from MSCI's RiskMetrics Group, reflecting an analytical assessment of a company’s environmental policies and initiatives; and



• a "Reputation Survey Score," resulting from a survey of CEOs, corporate environmental officers, and academics conducted by CorporateRegister.com. The first two -- Environmental Impact and Green Policies -- each account for 45 percent of the total score, with Reputation making up the final 10 percent.

Technology companies once again take the lion's share of the top spots in the list, and Newsweek's Kathy Deveny explains in an article posted this morning:

Tech companies dominated this year’s Green Rankings -- in part because they make low-impact products, like software, that inevitably have a smaller environmental footprint than, say, a utility (though PG&E did hit No. 20 on the list, thanks to a commitment to renewable energy.) But bottom-line considerations are a big part of what’s driving tech companies in the green direction. In their quest to create products that are cheaper to manufacture and operate, tech firms are devising solutions that have the added benefit of saving energy or reducing waste. Hewlett-Packard, No. 2, says its current IT systems use 66 percent less energy than those designed in 2005. “A lot of the innovation in this space is coming out of business pressure,” says Michael Mendenhall, HP’s chief marketing officer.

For many tech companies, cooling their own data centers requires enormous amounts of energy. Yahoo, No. 9, has been a leader in designing environmentally sustainable data centers, including a new facility in New York that consumes 40 percent less electricity and 94 percent less water -- enough to provide drinking water for 200,000 people for a year -- than conventional data centers.

Newsweek’s goal in these rankings is to quantify companies’ actual environmental footprint, policies, and reputation. To accomplish this, we joined forces with top environmental researchers: MSCI Research, which tracks environmental, social, and governance data; Trucost, which specializes in quantitative measurements of environmental performance; and CorporateRegister.com, the world’s largest directory of sustainability and environmental reports. Our editorial partner, ASAP Media, founded by Peter Bernstein and Annalyn Swan, coordinated the project.

The complete list of the top 20 companies in Newsweek's 2010 green rankings, as well as their scores, is below.

Overall Rank Company Green Score 1 Dell 100.00 2 Hewlett-Packard 99.32 3 IBM 99.20 4 Johnson & Johnson 99.02 5 Intel 97.57 6 Sprint Nextel 94.98 7 Adobe Systems 94.15 8 Applied Materials 92.67 9 Yahoo! 92.67 10 Nike 92.66 11 Accenture 92.04 12 Advanced Micro Devices 91.17 13 Cisco Systems 91.07 14 Johnson Controls 90.94 15 Baxter International 90.59 16 Eaton 90.54 17 Bristol-Myers Squibb 90.45 18 Office Depot 90.14 19 Allergan 90.02 20 PG&E 88.64

Also included in this year's rankings are industry-specific leaders:

Industry: Name: Banks & Insurance Travelers Basic Materials Ecolab Consumer Products NIKE, Inc. Financial Services CB Richard Ellis Group Food & Beverage Coca-Cola Enterprises, Inc. General Industrials Eaton Health Care Baxter International Inc. Industrial Goods Accenture Media, Travel & Leisure Starbucks Corporation Oil & Gas Baker Hughes Pharmaceuticals Johnson & Johnson Retail Office Depot Technology Dell Transport, Aerospace United Technologies Utilities PG&E Corporation

Newsweek also named the top 10 greenest companies in the world with this year's list:

1) IBM

2) Hewlett-Packard Company

3) Johnson & Johnson

4) Sony

5) GlaxoSmithKline

6) Novartis

7) Deutsche Telekom

8) Panasonic

9) HSBC Holdings

10) Toshiba

For more details, visit Newsweek.com/green.