"Everything that has made our city great today, all of them, were built by people looking forward," Doctoroff said. And despite opposition, despite getting laughed at, the creators of each project went forward with what are now considered some of the most iconic parts of the city. "Those New Yorkers made our New York possible. We believe today it is our turn."

He outlined for attendees Mayor Michael Bloomberg's recently announced plan for a cleaner better New York City by 2030, which includes significantly cutting the city's emissions, building more than 265,000 housing units, cleaning the waterways and improving the mass transit system. The look ahead, Doctoroff said, was fueled by the fact that unchecked growth will mean the estimated one million new residents will be unable to find affordable housing and 23 of the 26 subway lines will be over congested. (11 lines are already at maximum capacity.)

Creating a greener New York will require significant capital. Doctoroff said that the subway system improvements alone are facing a $30 billion gap, with the first phase of the Second Avenue line already $1 billion in the hole, and three more phases waiting in the wings.

During a following session, Carl Weisbrod, president of Trinity Real Estate, said he recognizes making buildings more environmentally friendly will mean a significant capital commitment from building owners. (New York City offices are said to produce 70% of the city's emissions, while the city as a whole produces 1% of the entire country's emissions and 0.25% of the world's.) "Unless the current office space is retrofitted, the mayor's plan to decrease emissions is not going to be possible," Weisbrod said.

Developers are often weary to build green as constructing with environmentally friendly products automatically means a more expensive project. But every time green was mentioned, developers and owners alike echoed the tenants' desire to locate in these types of buildings. Steven Roth, chairman and CEO of Vornado Realty Trust, said he can only think of two developers in the city actively pursuing green development. "The others have to be pushed along, [often by the tenants]." He went on to say any developer looking to build now would be unwise not to build a green facility.