A few days ago I was watching some bees in the CBD of the city where I work. They were foraging around some discarded food; there were no plants anywhere nearby, no pollen -- just buildings and pavement. The bees got me thinking about dysfunctional and dying colonies in the US (and now in South Africa) and the impact on agricultural yields. And that started me on a train of thought about growing food in urban areas. I've talked about urban agriculture before, but this is a new angle -- I promise.
I'll get back to the bees and food in a moment, but I need to talk about city buildings first.
Land parcels are regularly cleared in central cities to make way for new buildings. While some of the demolished buildings have bits and pieces collected for recycling or reuse elsewhere (windows, timber, bricks, sanitary fittings, and even crushed concrete), and may even be replaced with more resource-efficient buildings, I have to wonder whether this is the most sustainable approach to replacing the existing inefficient stock. With all the energy that goes into creating a building in the first place, and the huge volumes of demolition waste, there is increasing emphasis being placed on a cradle-to-grave analysis for making environmentally sound decisions. But it's not so easy to calculate the full impact in each particular case, so it's very difficult to build a case for preservation if the developer is pushing for a clean slate.
We tend to assume that greenfield development is inherently worse than redevelopment, and it probably is; but many building rating systems do not even consider whether a new building has replaced farmland, a derelict industrial site or another building. Usually it is easier for a property developer to start afresh rather than modify an old building, but surely there are cases where repurposing would be environmentally better than building a new one, even if the new one happens to be awarded LEED platinum status (or the Green Star equivalent). It would take some analysis to answer this question, but the point is that the question should be asked. It's the same concept we apply to many other products: it's better to find a new use for a discarded glass bottle than to recycle it.
Fortunately there are rating tools for building refurbishments, and there is also Arup's Existing Buildings Survival Strategies to guide building owners on potential strategies to extract new life and business value out of old buildings -- reducing operating costs and environmental impact at the same time.
Many of the EBSS strategies relate to ways of reducing energy consumption or improving indoor air quality, thus reducing business costs and creating a healthier environment for those who use the building. Some strategies are fairly obvious, while others have benefits that are based on enhancing the image of the building (and the owner) by demonstrating commitment to preserving the environment. One of these strategies is the use of productive landscapes. This is motivated as a form of urban agriculture, but I would suggest that productivity should be more broadly defined to include pollination by bees, food sources for birds, biodiversity, and perhaps other purposes that incluce aesthetics and social wellbeing. (I mention biodiversity for its contribution to a healthy ecosystem -- we need the ecological resilience that this provides in order to support various other forms of productivity.)
Direct human food production might not be appropriate in situations where there isn't anyone available to manage and harvest the produce (although to some extent this might be overcome with yardsharing), so where there is land (or roof space) that would otherwise be barren, it would be helpful to identify other uses.
Direct human food production might not be appropriate in some urban situations, like where there isn't anyone available to manage and harvest the produce (although to some extent this might be overcome with yardsharing). So where there is land (or roof space) that would be barren otherwise, it would be helpful to identify other uses and types of plants.
There is another side to the question of productive land. It might be argued that buildings themselves are productive if they support a manufacturing or agricultural process, and I can't help wondering what would be considered environmentally responsible choices if we factored that into the equation too. Commercial farms can't operate without a factory producing equipment somewhere; and what about an office that houses an agricultural cooperative? Or even a bank that provides finance to the farmer? Bees provide a service industry, after all, so don't other services count?
The question opens up an ugly can of worms, but it does highlight the difficulty in trying to make complex decisions more manageable. And that is one of the many challenges we face at this stage of learning how to incorporate environmental impact in our planning and design processes.
Which brings me to a final point about the relationship between planning and urban agriculture. There is a thought-provoking piece on BLDGBLOG from 19 June that raises the idea that the potential for food production could be an input to urban design. Engineers and spatial planners lay out city roads and development areas to meet requirements ranging from the flow of effluent in sewers to the optimal locations of commercial districts and community services. Would it be feasible to add "food production" to the list of requirements?
During the energy crisis of the 1970s, some municipalities and researchers produced guidelines for the optimal layout of suburbs in order that houses could make best use of the sun as a source of energy. The crisis subsided and these guidelines were quickly forgotten, but I don't see why they shouldn't be dusted off and reformulated to allow for the latest thinking on passive building design and to add urban agriculture. Nicola Twilley writes on BLDGBLOG:
Hungry City [a book by Carolyn Steel] traces how food has shaped both the city and its productive hinterland throughout history, from the Sumerian city of Ur to today's London via the markets and gates of ancient Rome. Steel provides a wide-ranging historical look of food production, importation, regulation, and culture, before putting forward her own intriguing and potentially revolutionary proposition: what would happen if we consciously used food as a design tool to create a "sitopic" city? Steel's coinage here, sitopia—from "sitos" (food) and "topos" (place)—is derived from her realization that "food shares with utopia the quality of being cross-disciplinary... capable of transforming not just landscapes, but political structures, public spaces, social relationships, [and] cities." And because "food is necessary," a sitopian city (unlike its utopian cousin) would remain tied to reality and of universal relevance.
There are more thoughts in the BLDGBLOG piece about things needing to be done to make productive gardens successful, ending with this:
In her book, Steel quotes Cassiodorus, a Roman statesman who wrote: "You who control the transportation of food supplies are in charge, so to speak, of the city's lifeline, of its very throat." At the moment, Steel tells us, roughly 30 agrifood conglomerates—unelected, and with no responsibility other than to their shareholders—have almost unfettered control over London's food supply. Until that changes, urban agriculture can't help but remain "at the artwork stage"—an inspiring, attractive, and completely optional extra.
Update on 12 Oct 2009:
Urban agriculture really does need structures and services to support it, such as Detroit's Garden Resource Program Collaborative (GRP)—a network of more than 850 thriving Detroit gardens.
What makes the Detroit model so special? In addition to their large annual yields, the farms show strong community involvement and rate of return—over 80 percent of the gardeners in the GRP return to the program each spring. “More importantly,” says Atkinson [director of urban agriculture at Greening of Detroit], “it means these gardeners continue to provide all of the benefits that urban gardens bring to Detroit neighborhoods year after year, such as food access, neighborhood stability, property-value increases, crime reduction, social capital, and youth enrichment.”