In many buildings, the roof isn't just a protective covering to fend off the elements, but also a luxurious amenity where residents enjoy patio gardens and perhaps even lounge and socialize with neighbors.
However, when celebrated architect Cesar Pelli & Associates designed The Solaire, a new 293-unit residential building in Manhattan's Battery Park City, the vision for the roof's function stretched beyond its basic purpose; the designers and developer saw green. The Solaire is North America's first "green" residential high-rise - constructed using several environmentally friendly features, including two so-called "green roofs."
A green roof is the creation of a contained live garden space on top of a human-made structure, according to the Green Roof for Healthy Cities (GRHC) in Toronto, Canada, a trade association for the green roof industry. Installing a green roof is an innovative and resourceful opportunity for buildings to reap impressive economic and environmental rewards, for both the residents of the building and the general public. Such benefits include energy conservation, improved air quality, water conservation, increase in open space and more.
Green roof plants are not planted or potted, and soil is not used because of its weight and inability to hold water. "A green roof system is an extension of the existing roof, not a bunch of potted plants," says Steven Peck, executive director of GRHC. "The system involves a special waterproof and root-repellant membrane, a drainage system, filter cloth, a lightweight growing medium, and plants."
There are two types of green roofs: intensive and extensive. Intensive green roofs - usually just called roof gardens - are accessible to residents and may include lawns, flowerbeds, shrubs and trees, and even water features like waterfalls or fountains. They are the most expensive to build and require frequent maintenance, including the inspection of the roof membrane (the most crucial element of a green roof), as well as routine inspection and upkeep of the vital drainage systems. By contrast, extensive green roofs are not accessible, require minimal maintenance, and usually include low-key vegetation like mosses, succulents, herbs and grasses.