New York City lawmakers have proposed a multifaceted program to reduce the carbon emissions of the city’s 1 million existing buildings. The “Greener, Greater Buildings Plan” introduced on April 22, Earth Day, by Mayor Michael Bloomberg and Council Speaker Christine Quinn would require all renovations—commercial and residential, public and private—to be green renovations. While signature high-rises such as Foster + Partners’ Hearst Tower and Cook + Fox’s Bank of America Tower have magnified the image of sustainable architecture, the environmental impact of new construction is limited by the preponderance of older buildings. “It’s in existing buildings that the real progress lies,” says Rohit Aggarwala, director of long-term planning and sustainability for the Mayor’s Office of Operations.

Comprising four energy-related bills and two programs for financing and job training, the plan closes a loophole that has until now allowed renovations to skirt the International Energy Conservation Code if they encompass less than half of the building. Owners of buildings larger than 50,000 square feet, which constitute nearly half of the city’s total built square footage, would also be required to conduct an energy audit every 10 years and make efficiency improvements that would pay for themselves within five years. These market-based criteria address a general concern that regulation, in the words of Kohn Pedersen Fox principal Paul Katz, “can sometimes create a disincentive to do what’s best.” The city will also apply for $16 million in stimulus funds to help pay for energy-efficient retrofits.

The “Greener, Greater Buildings Plan” is the latest piece of Mayor Bloomberg’s PlaNYC 2030, a comprehensive, 25-year effort, launched in 2007, to reduce New York’s carbon emissions by 30 percent. In a press release, the mayor’s office said this new program could reduce the city’s total carbon footprint by 5 percent—roughly equivalent to eliminating all carbon emissions from Oakland, Calif. A hearing on the plan is scheduled for June 11.