Olivia Wilde celebrates the 20th Anniversary of the Environmental Media Awards held on the backlot at Paramount Studios on Sunday (October 25) in Los Angeles, Calif.

The 25-year-old House actress, who wore a Stella McCartney gown to the event, said Hollywood sets tend to be “very wasteful places,” but things are changing.

“We can try to waste less paper and have scripts distributed more responsibly. We can use corn-based products for craft services and we can go as far as solar-powered trailers,” Olivia told the AP. “It’s not overwhelming if you take it step by step.”

Olivia was recently crowned “Hottest Woman Alive” by Maxim magazine.

20+ pictures inside of Olivia Wilde at the 2009 Environmental Media Awards…

Orlando Bloom hits up the BlackBerry VIP Hospitality Lounge at the U2 and Black Eyed Peas Concert at the Rose Bowl on Sunday (October 25) in Pasadena, Calif.

Also in attendance and pictured here: Grey’s Anatomy actor Justin Chambers, Olivia Wilde, Ginnifer Goodwin, who wore IRO “Patzi” pants, Ryan Phillippe with his BFF Breckin Meyer, Twilight hunk Cam Gigandet and his longtime love, actress Dominique Geisendorff.

Also spotted in the lounge: Alyssa Milano, Ashley Greene, Christian Slater, Jennifer Love Hewitt (with Jamie Kennedy), Kellan Lutz, and Sarah Clarke.

FYI: Orly is holding up a mask of jailed Burmese pro-democracy leader Aung San Suu Kyi, who has been under house arrest for 20 years in Burma. U2 has been handing out these masks at their show and dedicating their song “Walk On” to her each night at their concerts on the 360 tour. Thanks, Mende!!!