November 6, 2004
Sod atop a building shields it from cold in winter, from heat in summer, and from sound year round. It makes buildings more hospitable for those who live or work within them. Roof vegetation also makes cities more hospitable for the general population: It cleans air of dust and rainwater of heavy metals, reduces smog, ground-level ozone and other pollutants, and moderates the “heat island effect” that raises city temperatures above that of the surrounding countryside.
For these and other reasons, dozens of cities in Europe and a handful in North America have become green-roof friendly. What started as a fringe environmental movement in Germany in the 1960s has grown to achieve mainstream acceptance. The Gap’s new headquarters in San Bruno, Calif., and Ford’s in Irvine, Calif., both use green roofs to improve acoustics and save resources, and many North American governments fund demonstration projects. The latest convert – Canada’s new Environment Minister, Stephane Dion – may well be right in saying last week, “This will be the future in 10, 20 years from now. You will see that everywhere.”
Green roofs may not bloom everywhere for long, however, under the approach of Mr. Dion and other government backers. Most green roofs are net money losers, even after counting savings for their owners in heating and air conditioning costs, and in lowered maintenance costs. To make up the shortfall, governments provide subsidies and other preferences, some of them sensible. For example, real estate developers must often provide a city with free parkland to win permission to proceed with a project. In lieu of green space at ground level, politicians have begun to accept green space above.
But politicians can be fickle, and preferences granted today can be withdrawn tomorrow, when green roofs are supplanted by another trendy technology. To make the future of green roofs safe as houses, they would need to be financially self-sufficient, by generating revenue. In many large cities, this already happens: Entrepreneurs are turning a profit from their rooftops, often surreptitiously and without need of government programs, through niche agricultural operations that capitalize on niche urban markets.
Many downtown restaurants tend their own rooftop gardens to obtain the freshly picked herbs and vegetables that their specialty dishes require. Toronto’s Royal York Hotel has one of North America’s most extensive open-air rooftop garden, growing enough organic parsley, sage, tarragon, basil, peppermint, spearmint, chives, marjoram and hot peppers to satisfy its restaurants’ 100 chefs from July to September. Speaking for chefs everywhere, John Cordeaux, the hotel’s executive chef, said “Everyone’s dream in any kitchen is to have their own herb garden [because] as soon as something’s cut, it will start to lose its flavour.”
Apprentice chefs pick herbs for immediate use and, between meals, kitchen staff tend the garden, which also grows vegetables such as runner beans and lemon thyme. Being 14 stories up has growing advantages, too. The taller downtown office towers provide shelter from the wind, and some insects and other pests don’t find their way to the roof (“There are no deer here,” the hotel quips), aiding the garden to be organic, a strong selling point in upscale markets.
The Royal York’s rooftop operation is legal – but just. Toronto’s zoning laws, like those in most cities, generally outlaw commercial agricultural activities within city boundaries. Because the Royal York’s agricultural output is peripheral to its restaurant and hotel business, and because it doesn’t sell its produce to other merchants, the city doesn’t enforce its prohibition. But many restaurants don’t have roof space at their disposal, or the staffing flexibility required to economically tend a garden. Urban farmers that opernly tried to set up commercial rooftop farms to service the city’s many tony restaurants, fine grocers, and chi-chi caterers would quickly be put out of business.
Remove these prohibitions and rooftop farms become financially viable without need of government subsidies. They would become a common feature within cities, alleviating the immense demand that now exists for urban gardens. With this new industry would come new jobs, mostly in small operations, many of them providing an important source of income for retirees, home workers, and others who don’t have 9 to 5 jobs. As green roofs became rooted in urban life, food freshness, food quality, and food variety would grow.
Green roofs would provide another quality-of-life amenity, too. Ever since King Nebuchadnezzar decided to please his queen by building the Hanging Gardens of Babylon – one of the Seven Wonders of the Ancient World – atop a large brick building south of present-day Baghdad, roof gardens have been planted in the human imagination. Roman architecture featured hanging gardens and rooftop vegetation, as did the city of Genoa during the Renaissance. In 17th century Russia and 18th century France, many constructed vertical gardens for their beauty. More recently, two of the greatest architects of the 20th century, Frank Lloyd Wright and Le Corbusier, extolled rooftop vegetation. This timeless vision has never been closer.
Lawrence Solomon is executive director of Urban Renaissance Institute and Consumer Policy Institute, divisions of Toronto-based Energy Probe Research Foundation.; www.Urban.probeinternational.org; Next week: Urban agriculture’s immense potential.