The City Council voted to pass several bills that Mayor Michael Bloomberg said will help achieve his goal of reducing the city's carbon count by 30% by 2030 by making buildings more energy-efficient.

New York City's hundreds of thousands of buildings — skyscrapers, hotels, stores, office buildings and apartment towers — generate the majority of the city's emissions, according to a report released by the Bloomberg administration in 2007.

Building operations, which consume electricity, natural gas, fuel oil and steam, account for 79% of the city's greenhouse gas emissions.

Among the legislation passed Wednesday is a law that requires owners of buildings larger than 50,000 square feet to conduct energy audits once every 10 years and to make environmental "tune-ups" to operations and maintenance systems, like replacing weather stripping and insulating hot and cold steam pipes.

The legislation initially required building owners to make more costly environmental improvements to their buildings, like major overhauls to heating and ventilation systems or replacing windows, but the Bloomberg administration dropped that because of opposition from building developers and real estate interests.

The mayor said this week that, in this tougher economic climate, requiring such improvements would unfairly burden building owners.

Also, the bill as originally written would have allowed landlords to pass along the cost of mandated building improvements to their tenants, even though the landlords would be saving money by reduced energy bills.

Despite the change, environmental groups praised the legislation and said it puts New York City far ahead of other U.S. cities on addressing buildings emissions.

"It's one of the most comprehensive, aggressive efforts anywhere in the country," said Donna De Costanzo, a senior attorney specializing in energy policy at the Natural Resources Defense Council.

The council also passed a measure creating a New York City energy code that existing buildings will have to meet whenever they make renovations.

A third bill requires buildings larger than 50,000 square feet to upgrade their lighting systems to comply with the new energy code by 2025.

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