The study compared 93 U.S. hotels certified by the U.S. Green Building Council's Leadership in Energy and Environmental Design ratings system - which takes into consideration such factors as water efficiency, energy use and indoor environmental quality - against 514 comparable hotels without the certification. Hotels in the study largely were upscale or luxury properties in urban and suburban locations. Prior to certification, the LEED-certified hotels had an average daily rate that was $10 higher than the noncertified hotels. In the two years following the certification, that average premium jumped to $20, according to the study. "Considering those challenges, it is remarkable that LEED-certified hotels match competitors' occupancy levels within a year of certification," the study reported. "The LEED hotels quickly made up the occupancy deficit recorded in the year prior to certification, and they outperformed competitors for two years following certification." Download the report at Cornell University (free registration)