If you've thought about staying in "eco-friendly" hotels, you're not alone.

The most recent report on the subject, conducted in 2009 by travel research firm PhoCusWright, found that more than 40 percent of 1,334 U.S. travelers surveyed said they considered environmental impact important when planning travel.

Still, finding an environmentally friendly hotel isn't easy, although there are shifts in the hotel industry.

Glenn Hasek, editor and publisher of Green Lodging News, points to inspiring initiatives: hotels with a windmill or solar power, an embryonic hotel chain with plans for "revolutionary new environmental practices and sustainability principles," a rising number of LEED-rated hotels and more focus by the industry as the economy improves.

A common problem for consumers, though, is distinguishing window dressing from serious commitment. Some practices touted as "green" -- admonitions to re-use towels, save water, turn off the lights or skip the room makeup, for example -- are also overtly self-serving: They're cheaper for the hotel. Others, such as recycling, providing windows that open or installing some solar panels, are trivial unless they are part of a comprehensive program.

All that green noise not only bestows unearned merit on the underwhelming, but also makes it harder to discern genuine efforts. The PhoCusWright survey found that 56 percent of people are skeptical of companies that tout green practices.

The American Hotel & Lodging Association, which represents U.S. hoteliers, offers green guidelines to its members but no certification, said Patrick Maher, a member who acts as the group's "green guru." His 2020 vision is that more of the country's 5 million guest rooms will be in zero-waste buildings that are off the power grid.

There is no shortage of green certifiers. Given the consumer interest, the U.S. travel market is a-sprout with rating systems: green hearts and coronets, checkmarks, arrows, suitcases, stars and planets, trees, keys and leaves. The problem is that some are for-profit while others rely on self-reporting, with no site visits to verify the claims.

Still, there are a few ways that environmentalists can rest well knowing they're staying at a green hotel.

A good comprehensive source is the website Travelocity. When you search for a hotel on the site, a discreet green leaf, with the words "eco-friendly hotel," appear on some listings. That leaf is awarded based on data from 22 different certification programs, including those of stalwarts Green Globe International, Green Key, Green Leaf and Sustainable Travel International.

Just as important: Travelocity requires periodic independent on-site audits to verify compliance with green practices. It has de-listed about 200 hotels since its program began five years ago.

About 1,100 U.S. hotels have earned the green leaf at Travelo- city. Nine of those are in Minneapolis or St. Paul.

Finding a green hotel

Whether or not you book with Travelocity, you can use it as a resource. To find green hotels in your destination city, scroll through the listings and look for the green leaves. Or refine the search using options on the left side of the screen. Under "Amenities," click on "Eco-friendly."

It's not a nuanced system, concedes Alison Presley, manager of Travelocity's green travel program. Hotels are green or they aren't.

Other hotel booking websites take different approaches, sometimes listing miscellaneous green features of hotels. Orbitz offers such lists.

Hotels.com's online system sorts for properties that are "green/sustainable," but many on the "green" lists are self-certified, as the fine print explains. Kayak and Priceline do not incorporate eco-friendly filters in their booking systems. At Expedia, entering "sustainable" in the search box from the home page produces a list of a hundred cities. You can click on one of the cities for a list of hotels; the criteria for choosing these hotels isn't explained.

A second way to find green lodging is to look for an LEED-rated hotel, of which there are nearly 100 nationwide. A rigorous and expensive program for participants, LEED is run by the nonprofit U.S. Green Building Council. Properties are rated as "certified," silver, gold or platinum (there are only two U.S. platinum hotels). You can find the list by going to www.usgbc.org/hospitality and clicking on "LEED Hospitality Projects," under "Resources."

You could also consider using one of the certification programs that are run by 17 states. They vary in credibility, transparency and toughness. You can easily find them online.

These states require on-site audits for compliance: Alaska, Arizona, California, Connecticut, Florida, Kentucky, Maine, Massachusetts, New York, Rhode Island, Tennessee and Vermont (some compliance audits are described as random or spot checks). By contrast, many state programs allow participants to self-certify. Wisconsin has such a program. Minnesota has no green certification program.

In the past few months I've stayed at four hotels whose eco-friendly credentials are impeccable: the Felix and the Burnham in Chicago; the Westin Times Square and the Ink48 in Manhattan. All were competitively priced, the experience proved luxe rather than hair-shirt and there was no green horn-tooting, just a comfortable stay in a subtly eco-friendly hotel.

Stephen P. Nash teaches journalism at the University of Richmond in Richmond, Va.