I'm not talking about money.

For many years people thought casino gambling, a industry based on getting people to freely give up their money in the most entertaining way possible, was recession-proof.

Gambling has been enjoyed by humans since ancient times and it proved remarkably resilient to past recessions. Considered a sin or not, people were going too gamble. At least that's what people believed until now, anyway.

The "gaming" industry lately has been losing money like a gambler chasing his or her loses. Revenue is down in in Nevada, Atlantic City and many of the other states with large-scale gambling operations.

But if players are staying away from the tables and slots, many casinos, especially in Nevada, still think it makes good sense to invest in sustainable building practices. It might seem strange at first -- a city and industry built on excess attempting to limits its environmental impact.

But maybe it shouldn't. Part of the reason casinos in Nevada are pushing green building is the generous tax credits the state offers for buildings that are Leadership in Energy and Environmental Design certified -- including casinos.

And perhaps it does make sense for Sin City to save energy -- after all, its air-conditioned, 24-hour-lit-up casino hotels and green golf courses are in the middle of the desert.

Snips has written about this several times, including a cover story in July 2008. The Las Vegas Review Journal had a story recently about what the biggest casinos on the Las Vegas Strip are doing to stay green.

Have any of you worked on green casino projects?