The conference, sponsored by the U.S. Green Building Council, runs Tuesday through Friday at Toronto's main convention center. More than 25,000 are expected to attend.

What’s being called the world’s largest environmental construction conference and trade show opens tomorrow in Toronto.

Greenbuild, sponsored by the U.S. Green Building Council, runs Tuesday through Friday at the city’s main convention center. More than 25,000 are expected to attend.

USGBC officials said Canada’s largest city has been a leader in green construction, with 44  structures certified under the Leadership in Energy and Environmental Design program, and hundreds more seeking approval.

"Toronto and the Canada Green Building Council have been a tremendous force in the recent growth of the green building movement in Canada," said Rick Fedrizzi, president, CEO and founding chairman of the USGBC. "Toronto's building market has continued to boom and prosper and it's the perfect backdrop for the 10th anniversary of Greenbuild."

In addition to the trade show and hundreds of educational seminars, organizers have booked speakers such as New York Times columnist Thomas Friedman, former Canadian prime minister Kim Campbell, ABC News political commentator Cokie Roberts, and New York City Mayor Michael Bloomberg.