Recently, I went to Denmark for the United Nations Convention on Climate Change. As part of that historic gathering, the mayor of Copenhagen invited leaders of the world’s top cities to discuss our own green agendas, share our most innovative ideas, and send a unified message to national governments about the crucial role cities play in combating climate change.

When I met with my fellow mayors, I was thrilled to report that New York City is leading the green charge here in the United States. Earlier this month, the City Council passed our “Greener, Greater Buildings Plan”, a landmark package of legislation that will shrink energy costs by $700 million a year for all New Yorkers, create an estimated 17,800 jobs, and reduce New York City’s carbon footprint by nearly 5 percent. That’s the equivalent of making a city the size of Oakland, California completely carbon neutral. This legislation represents the largest step we’ve ever taken towards meeting the ambitious greenhouse gas reduction targets laid out in our PlaNYC sustainability agenda.

Most people think of green buildings as new buildings, but one of our most important buildings more efficient, especially the large buildings which account for 45 percent of the city’s entire energy consumption. The four bills passed last week require large commercial buildings to take several steps that will conserve energy, reduce carbon emissions, and ultimately create green jobs.

For example, these buildings will be required to upgrade their lighting and install sub-meters, which will give tenants who currently pay energy costs at a flat rate the ability to see how much they’re actually consuming. And if they consume less, they’ll save money.

Buildings will also have to report their own energy usage on the Internet. That will allow potential tenants and buyers to factor energy-efficiency into their decision to lease or buy a commercial space. Finally, new laws will require building owners to conduct energy audits once a decade and implement energy-efficient maintenance practices, which will result in major savings. And because we think government should lead by example, all large city government buildings will now conduct audits, and we’ll complete all retrofits that will cut energy costs and pay for themselves within seven years.

All told, these new laws will clean our air, lower our energy costs and spur economic growth. I was glad to share this latest success with the leaders gathered in Copenhagen, and I have no doubt that it will inspire other cities around the globe to take their own leaps into a greener, greater future.