Modern Pastoral

In an essay contributed to the book What Matters, Dickson Despommier, president of the Vertical Farm Project, says that to be truly sustainable, cities must also learn to produce at least a portion of their own food.

The idea of taking today’s indoor farming techniques—including aeroponics, hydroponics, and drip irrigation—and scaling them up as part of massive vertical farms has been around for some time. So far, it’s existed as a series of spectacular renderings. Despommier and others argue that it needs to become a reality for cities—part of a closed loop system that would recycle water and convert solid wastes into usable energy.

This vision of urban agriculture means a radical rethink in the way cities and agricultural lands are developed.

At a presentation at the Federation of Canadian Municipalities’ Sustainable Communities Conference in Victoria (see page 39), Vancouver’s Mayor Gregor Robertson said that part of Vancouver’s vision to be the greenest city in the world by 2020 includes becoming a global leader in urban food systems.

Phil Sande, executive director of Edmonton’s City Centre Redevelopment Project, which aims to create a sustainable, mixed-used community on the city’s former airport lands, says urban agriculture is definitely on the City’s radar. There are five proposed concepts for the redevelopment.   (Look for details on the selection committee’s recommendation at renewcanada.net.) KCAP Architects and Planners’ proposal mentions food and agriculture; Sweco International mentions in its concept video that gardens and urban forms increase the self-reliance of the community, while Busby Perkins+Will goes as far as to interview a landscape architect about urban agriculture.

According to the firm’s pitch video, one of Edmonton’s goals is to be more self-sustaining and feed itself. Whether that goal is realistic remains to be seen.

Kurt Lynn is co-founder of Lufa Farms, which began construction of its 31,000-square-foot rooftop greenhouse in July of 2010. It’s the first of several greenhouses the company plans to build in Montreal and in other cities. Lynn says urban agriculture is a viable path to food independence. “In a sense, it is a complicated way of going back to very local groceries,” says Lynn. “Extending the whole concept, and as these type of facilities become more efficient—and they will—we see food production potentially becoming a part of city planning. We would plan food availability like we plan subway stations.”

Lufa’s greenhouse uses hydroponic and drip-farming techniques to grow 25 different crops, and is expected to yield the harvest of a farm more than 10 times its size. Lisa Figlioli with Lufa says, “There are no other Canadian projects on a similar scale. Neither are there any other projects in the world, so far, on a similar scale.” According to Figlioli, 2,000 families could receive weekly produce deliveries from the greenhouse, although 1,000 families is the goal Lufa wants to reach by the time of the first harvest in mid-April.

In addition to using controlled-environment farming methods, the greenhouse will collect rainwater and filter and re-circulate water used in crop irrigation. The greenhouse itself will act as an insulator. “For the portion of the roof that we cover, there is no heat loss from the building,” says Lynn. That’s particularly useful in a climate like Montreal’s, where winter temperatures can hit the minus 30 degrees mark.

Even with the insulating properties of the greenhouse, those low Quebec temperatures may result in a significant heating bill. During the day, even in the winter if there is any ambient sunlight, demand for supplemental heat is low. In fact, on many sunny days, the greenhouse will actually open rooftop vents to release heat. During the night is the principal heating time, and the greenhouse uses natural gas.

Lynn says, “We minimize energy costs at night by using retractable curtains over the top of the greenhouse and around the sides. This provides extra insulation and reduces heat loss from the greenhouse. In the summers, we use evaporating coolers (for the section of the greenhouse that needs a cooler environment) and, of course, the plants’ natural respiration tends to have a cooling effect on the immediate environment.”

“Some of the energy issues are related to the fact that this [building] is a retrofit,” says Lynn. He says future projects will aim to merge their facilities with new construction, on spaces 100,000 square feet or larger. Several things happen, then, from an energy perspective. Lynn says, “First, you can view the heating and cooling as a single system and optimize heating systems between the two uses. Chances are the building heating and cooling is a subsystem of the greenhouse. Second, with natural gas, we would choose to scrub the carbon dioxide (CO₂) effluent from the boilers and vent the CO₂ into the greenhouse during sunny days where the plants will benefit from it. Third, for larger facilities, we would anticipate using biomass boilers because we could, in fact, provide a large amount of our own biomass.”

It may not be as slickly futuristic as some of the renderings of vertical farms (see here, here, and here). But if this project proves that farming on urban roofs is economically viable, it could transform our cityscapes.

Lynn says there are many opportunities to rethink how cities are organized to include fresh food. “High-density residential structures can be planned with integral fresh food production including, potentially, labour availability. Seniors’ homes, city food banks, prisons, and schools would have greenhouse food production—all integrated as part of their basic form-function.”

Rhonda Teitel-Payne, urban agriculture manager at The Stop Community Food Centre, says, “It’s often argued that we shouldn’t grow food on land because it doesn’t make very much money. That’s where innovation comes in: we can tier things, we can grow on rooftops, and we can grow in small spaces.”

Lynn says urban agriculture could ultimately add a layer of new revenues to a city by virtually expanding its square footage: “We can have different layers with commercial and agricultural zoning—both layers are potentially taxable as independent units.”

Doing this would require a rethink of legal concepts of moveable/immoveable property, and some harmonization of building codes—for example, there are codes for greenhouses on the ground, and there are codes for buildings, but only ambiguity for greenhouses on buildings—but Lynn says the result is taking back arable land lost to development.

Right now, the world devotes an area the size of South America to growing crops and raising livestock. At projected rates of population growth, Despommier says, “We would need an additional area the size of Brazil by 2050, but that much arable land does not exist.”

That means vertical farming may become a common sight for urbanites. Lynn says, 
“I don’t think we have a choice.”