It's not easy being green, but health clubs are finding that being good to the planet may also reward their bottom line.

National fitness chains and boutique clubs alike are retro-fitting old centers and building greener new ones.

"Health clubs worldwide are continuing to adopt greener practices," said Kara Shemin, of the International Health, Racquet and Sportsclub Association (IHRSA), the industry's not-for-profit trade association.

Despite the weak economy and rising unemployment, the health club industry is in good shape. An IHRSA survey found that total industry revenues rose two percent in 2009, to $19.5 billion.

And experts think health club attendees, who increased to an all-time high average of 102 days last year, will opt to put their money where the ecological grass is greener.

"As people progressively become more aware of their carbon footprint, and integrate ways to reduce it daily, they will have an expectation that other places they frequent, like their health clubs, will do the same," Shemin said.

"All of Club One and Frog's Fitness' 19 California-based chains have recently been remodeled to be more eco-conscious," said spokesperson Kari Bedgood.

She said renovations include rubber flooring made out of used car tires, roof-top solar thermal water panels and bio-degradable cleaning products.

And Equinox, the nationwide chain of luxury fitness centers, took care to build its new 31,000-foot (9,448 meter) club in Bethesda, Maryland, with the environment in mind.

Due to open in the autumn, the four-story facility is certified LEED (Leadership in Energy and Environmental Design) by the U.S. Green Building Council.

LEED is recognized in the United States and other countries around the world as the standard for measuring building sustainability.

"It's a major focus to make all of our clubs LEED certified," club manager Rachel Sernitsky said." All our new clubs will be LEED certified."

Perhaps no one has gone farther down the green road than Robert Kravitz, who opened Go Green Fitness, a boutique club in Orange, Connecticut, last December.

"I was managing the building (which also includes a shopping center) when the economy turned a few years ago. We had two bankruptcies and tenants left," he explained. "Go green Fitness came about because I wanted to bring the building back to life."

To that end he created a state-of-the-art fitness center that harnesses the energy produced from his spinning classes.

"We are the first ones on this scale," he said. "We have 25 spin bikes. Each has a generator creating watts that are fed through a converter box right into local electric grid. We have an agreement with the power company and should start getting reimbursed in June."

Kravitz, who describes himself as an idealistic entrepreneur, said he didn't want to just wave a green banner.

"I'm navigating a new business in the worst economy. I want to be competitive," said he explained.

From triple-paned thermal windows to wrapped heating and cooling ducts to refracted lighting, Go Fitness is painstakingly green. The spin bikes are wiped with a soybean-based lubricant

"I paid attention to all the details," he said. "There's a lot to the green. It's absolutely a big selling point. People like being part of something new."

He even found new tenants for the shopping center.

"At the end of each spin session we announce the total watts produced. On Saturday we went over our previous high and did 1122 watts," he said. "We announced it and everyone applauded."