SAN JOSE, Calif. — So you’re an electronics lover who cares about treading lightly on the planet. How do you know if that shiny new gadget was made with hazardous materials, or whether the manufacturing process created tons of carbon emissions?

Several organizations offer tips and detailed guides on how to buy green electronics.

And there are a few surprises: The environmental group Greenpeace, which staged a noisy protest outside Hewlett-Packard’s Palo Alto, Calif., headquarters just two years ago, bestowed its highest rating on the giant PC and printer manufacturer for 2011.

HP also ranked highest among consumer tech companies in a recent report by Newsweek, which relied on two private consulting firms to assess the environmental practices of the 500 largest public companies in America.

Both reports praised HP’s efforts to document and control greenhouse gas emissions from its own manufacturing processes as well as its extensive network of suppliers. Greenpeace’s annual guide to consumer electronics goes further — reporting in detail, for example, on the components used in HP’s computers and other products.

Most big companies today boast of their efforts to reduce pollution, consume less energy and encourage recycling. Both the Greenpeace and Newsweek reports attempt to sort through the corporate hype by evaluating specific practices and standards.

Among consumer tech companies, Dell and Apple also won relatively high ratings on both reports.

Research In Motion, which makes BlackBerry smartphones, was ranked last by Greenpeace after the environmental group concluded the company lagged far behind its competitors in disclosing detailed information or goals in such areas as energy efficiency, carbon emissions and use of toxic materials.

In response, RIM said in a statement: “We are continuing to improve our sustainability practices and have a number of initiatives under way.”

Greenpeace in particular says it hopes consumers will use its findings as a shopping guide. But the group doesn’t provide much information about individual products. More specific ratings can be found at websites maintained by the federal Energy Star program and the EPEAT organization, which is supported by a coalition of industry, government and environmental advocacy groups.

Every product with an Energy Star designation is certified to meet minimum federal standards for energy efficiency. The Energy Star website includes detailed tables of information, but it can be difficult to wade through the technical information and draw a comparison.

To help consumers compare products, the federal Energy Star program recently announced that it will start identifying models that are among the “most efficient” 5 percent of their product categories. For now, the new designation is only offered for appliances and televisions, but it may be extended to other categories next year.

EPEAT provides more helpful comparisons by rating individual models of electronic products, based on criteria such as energy efficiency, use of hazardous materials and whether the manufacturer helps recycle old products.

On its website, EPEAT gives bronze, silver or gold stars to individual products, depending on whether they meet the organization’s minimum criteria or whether they achieve additional goals.

How much do consumers care about these factors? Surveys by the Consumer Electronics Association have found a majority of shoppers say they want to buy products with “green” attributes. But Tracy Stokes, a marketing analyst with Forrester Research, said she’s not convinced those qualities are the deciding factor when shoppers consider a new personal computer or smartphone.

“Performance and price would be key factors, first,” she said. “It has to do what it’s supposed to do.”

Greenpeace spokesman Casey Harrell acknowledged he couldn’t quantify the impact of environmental ratings. But he said the guide, though produced on an irregular schedule in the past, draws more visits to the group’s website than any other feature.

“It’s by far one of the most popular things we do,” he said, adding that Greenpeace gathers extensive data from each company and also consults independent sources and audits for confirmation.

Guides to green gadgets

• Greenpeace ranks and reports on electronics manufacturers at: www.greenpeace.org/international/en/campaigns/toxics/electronics/Guide-to-Greener-Electronics/

• Newsweek used research by two private consulting firms to compile its own ranking of companies, both in tech and in other sectors: http://greenrankings.newsweek.com

• EPEAT, a consortium of industry, government and advocacy groups, rates individual products on such criteria as energy efficiency and use of hazardous materials at www.epeat.net

• The U.S. government provides detailed listings of products that have earned Energy Star designations for using power efficiently; go to www.energystar.gov and click on “Find Energy Star Products”

• The Consumer Electronics Association, an industry trade group, offers tips on buying and recycling electronic products at www.greenergadgets.org

Source: Mercury News reporting

Greenpeace rankings

• Top five consumer electronics companies, in order: Hewlett-Packard, Dell, Nokia, Apple, Philips

• Middle five: Sony Ericsson, Samsung, Lenovo, Panasonic, Sony

• Bottom five: Sharp, Acer, LGE, Toshiba, RIM

Source: Greenpeace