What..?

Around the world, at all levels of government, green roofs are recognised as an important response to climate change. A green roof system is an extension of a building’s existing roof which involves a high quality water proofing and root repellant system, a drainage system, filter cloth, a lightweight growing medium and plants.

• Below: DPI Marine and Freshwater Resource Institute research facility at Queenscliff, Victoria, an award-winning design by Lyons Architects.

But it can also be a rooftop food production system that meshes the technologies of aquaponics, vermiculture, rooftop water harvesting, and solar-powered air moisture harvesting.

Green roofs can provide a wide range of public and private benefits, including significantly reduced fossil energy use, reduced peak runoff of roofwater, aesthetically pleasing cityscapes, longer roof life, and reduce ‘heat island effects’ of cities.

Green roofs can provide building owners with a new revenue stream, plus reduction of organic matter going to landfill, and reduced air pollution through less use of diesel fuel in cities.

Non-food green roof systems may be modular, with drainage layers, filter cloth, growing media and plants already prepared in movable, interlocking grids, or, each component of the system may be installed separately.

Green roof development involves the creation of “contained” green space on top of a structure. This green space could be below, at or above ground level, but in all cases the plants are not planted in the “ground” but in a special compost.

In North America, the benefits of green roof technologies are being increasing understood as the green roof industry moves from novelty to common practice.

In Europe green roof technologies have become very well established since the 1980s. This has been the direct result of government legislative and financial support, at both the state and municipal level. Such support recognizes the many tangible and intangible public benefits of green roofs.

Green roof technologies represent opportunities for significant social, economic and environmental benefits, particularly in cities, as well as documented opportunities for a ‘green-collar’ economy. Many cities offer grants and subsidies for green roofs, and there is a mounting body of evidence that they can work as profit-generators for building owners and developers.

• Above: Westin Awaji Resort, Japan, photo courtesy of Graeme Hopkins and Churchill Memorial Fellowship.