Overheard at a conference recently: “Oh, well, everybody in the hotel world is green these days, so that doesn’t figure into my decision-making anymore.” Excuse me, but that’s a bit like saying we’re all Americans, so it doesn’t matter if we vote.

When it comes to politics and sustainability, every vote still counts.

Consider that the hotel industry in the United States sits on considerably more than 5 billion sq. ft. of space. It’s the nation’s fifth-largest emitter of CO2, according to the EPA. It’s true we’ve come a long way since The Lenox Hotel in Boston first introduced the guest room card to tell housekeeping not to bother exchanging towels or linens, in 1989. (Although as recently as a few weeks ago, I again witnessed that message being ignored at a luxury hotel in Phoenix. I often wonder if the housekeeper thinks I’ll leave a bigger tip if she leaves clean, fluffy towels every time. I won’t.)

Conserving water and energy, limiting waste, recycling and giving back to local communities has gained increasing momentum in hospitality over the past decade, as it has in our everyday lives. As travelers in general—and meeting attendees in particular—have become more accustomed to sustainability practices, polls show they favor events and businesses that promote them.

One survey found that 95 percent of respondents believe the hotel industry should be undertaking sustainability initiatives, and 40 percent of business travelers are willing to pay a premium for such practices.

In short, a venue’s shade of green should never be ho-hum when planners send off RFPs and choose meeting places. There are 50 shades of green, at least. For your consideration, here are some of the greenest of the major suppliers (in alphabetical order).

AccorHotels, the French hospitality company that owns Fairmont, Sofitel and numerous other brands, has adopted a Planet 21 program that is remarkable for directly touching the guest experience in everything from the banning of plastic straws (in North America) and offering nonchemically bleached bed linen and towels (in Europe) to animal welfare requirements for its restaurants and organic gardens at its properties. It plants a tree a minute from savings on its guest towel reuse program and advocates against sexual exploitation of children.

Caesars Entertainment announced in June it has set targets to reduce carbon emissions by a whopping 95 percent, as part of the Science Based Targets Initiative, a partnership between World Resources Institute, World Wildlife Fund, CDP Worldwide and United Nations Global Compact. Targets are “science-based” if they meet the level of decarbonization needed to keep global temperature rise below 36 degrees Fahrenheit, compared to pre-industrial temperatures. Caesars is also the first gaming company to include vendors in its targets.

Hilton Hotels, in May, said it will cut its environmental footprint in half and send zero soap to landfill by 2030. It’s doubling what it spends to help local and minority-owned suppliers and programs benefiting women and youth around the world. Why? Because its own consumer research confirmed that environmental, social and ethical considerations are central to buying preferences, especially for those younger than 25 years.

MGM Resorts is building a solar farm to power 13 properties on the Las Vegas Strip, in addition to having the nation’s largest contiguous rooftop solar array at Mandalay Bay Convention Center. Last year, the company was recognized by the Department of Energy’s Better Buildings Program for its sustainability efforts across multiple resorts.

Marriott International was recognized as one of the greenest hotel companies even before it added Starwood and The Ritz-Carlton—also leaders in sustainability—to its brands. The company is well on its way to meeting its pledge to reduce its greenhouse gas emissions and other green targets by 20 percent by 2020.

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Green hotel certification programs promise independent verification of sustainability. Here are green certifiers you can trust. They take their roles as watchdogs of sustainability seriously. Look for their logos on websites of hotels and other tourism operators.

EarthCheck: Favored by many leading eco-conscious hotel companies—InterContinental Hotels Group, for one—the EarthCheck six-step process starts with benchmarking to lay the foundation for sustainable practices and ends with several levels of certification. It is based in Australia.

LEED: The U.S. Green Building Council created this program—an acronym for Leadership in Energy and Environmental Design—to certify that buildings meet standards of energy efficiency, conservation and community sensitivity. USGBC’s rating system has four levels: Certified, Silver, Gold and Platinum. Green Building Councils in other countries have similar programs.

Green Globe: Green Globe provides certification, training and education, and marketing services in countries worldwide. The Green Globe Standards are based on Agenda 21 and principles for Sustainable Development endorsed by 182 governments at the United Nations Rio de Janeiro Earth Summit in 1992. Its website lists certified hotels by region and country.

Energy Star: The U.S.-based EPA program rates the energy efficiency of appliances used in businesses. Hundreds of hotels participate in the United States. A score of 75 out of a possible 100 is the minimum to be considered energy-efficient. You can search for certified hotels on its website.