Green rooftops improve the city’s air and water quality, save energy and reduce heat during hot summer months.

A “green roof” is an engineered rooftop that uses a lightweight, grid-like roofing system which can be made of anything from turf grass to trees and shrubs–not too different from the sod roofs that were used in rural areas for centuries. Why is a green roof a good thing? Created to help reduce the level of heat absorbed by the building below, green roofs also keep sewer systems from getting overtaxed, since they absorb more rainwater. Though the cost of installing green roofs is higher, they last longer than regular rooftops–temperature changes make black tar roofs expand and contract, leading to a shorter lifespan–increasing a building’s value as a result. Another financial plus: Current New York State legislation allows for tax abatements for green roofs to offset their cost.

Since the early 2000s green rooftops have been growing in NYC. The Post Office added a green roof—which at nearly 2.5 acres is one of the nation’s largest—at its Morgan Processing and Distribution Center in Midtown Manhattan. The West Village restaurant Bell Book & Candle has a green rooftop on which some of its menu items are grown for a short trip to the dining table. A handful of newer NYC apartment buildings like Riverhouse at 1 River Terrace and the Chocolate Factory condos at 689 Myrtle Avenue in Brooklyn have given themselves the green roof treatment. Created in 2010 as part of the mayor’s NYC Green Infrastructure campaign, the 14,000 square foot area on the seventh floor of Zeckendorf Towers at 1 Irving Place is the largest residential green roof in NYC. The rooftop above Union Square aids city infrastructure by capturing rainwater, cutting down on flooding in the nearby subway station.

Check our list to find out more about Manhattan’s greenest apartment buildings.