Continuing Education: Urban Agriculture
April 1, 2021
It’s been 10,000 years since the agricultural revolution gave rise to cities. Agriculture now covers more than half of the world’s habitable land and is spreading at a rate of about 15 million acres annually. Cities, meanwhile, now comprise more than half the global population (over 80 percent in developed countries), and the numbers are rising. Using current farming methods to feed a global population expected to hit 10 billion by midcentury would require adding new farmland equal in size to the continental United States.
This alarming situation is not even factoring in the impact of the climate crisis, which is expected to alter growing seasons and disrupt the phenological cycles that keep plants and their pollinators in sync. What’s more, new agricultural land mostly comes from felling biodiverse, carbon-sequestering forests to make room for mono-crops that stash very few greenhouse gases and for livestock that actually generate them. That makes the climate crisis worse and farming more difficult.
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In addition to land consumption, agriculture guzzles three-quarters of the fresh water used globally each year, while runoff from fields treated with herbicides, pesticides, and fertilizers contaminates significant amounts of the water that’s left. Then there’s transportation. As farms extend farther and farther from the cities they supply, food is trucked, shipped, and flown vast distances: farm to plate, the ingredients in a typical American meal travel an average of 1,500 miles. From a security perspective, the fact that most of the world’s food production is controlled by just a handful of corporations is unnerving. And from a public health perspective, the emergence of Covid-19 and other new diseases offers yet another indicator of ecological imbalance. It’s time to rethink the way we farm.
Food security, as defined by the United Nations, means that all people, at all times, have physical, social, and economic access to sufficient, safe, and nutritious food that serves their food preferences and dietary needs for an active and healthy life. Key to achieving food security in a way that’s more sustainable than current practices is urban agriculture—not as an outright replacement for rural farming, but as a crucial component in a balanced system.
Urban agriculture can take many forms: rooftop greenhouses, raised beds, and community-farming initiatives such as the City of Atlanta’s “Aglanta” program, which turns underused parcels in utility rights-of-way into farm plots eligible for U.S. Department of Agriculture certificates and associated loans. Ultimately, though, horizontal strategies are not productive enough to make a real dent in the food needs of a city. (If raised beds covered every rooftop in Manhattan, the produce grown would feed only about 2 percent of the borough’s population.) Just as cities grow vertically, so too must urban agriculture, and that means bringing it indoors.
“Controlled environments have been used for many years,” says Chieri Kubota, a professor of controlled environment agriculture (CEA) in the Department of Horticulture and Crop Science at Ohio State University. “Now that multiple issues are making conventional production outdoors more difficult, putting controlled environments in and near cities brings food production closer to potential markets—and also to younger generations of potential farmers who want to live in urban centers.”
Vertical agriculture is a type of CEA that—like high-rise buildings—stacks layers to provide usable area many times the footprint of the site. Instead of growing in soil, which is a heavy way to deliver nutrients, plants in vertical farms are grown hydroponically, aquaponically, or aeroponically. In hydroponics, plants are cultivated in nutrient-enriched water, which is captured and reused so that the system uses as little as a tenth of the water conventional agriculture needs. An aquaponic system pairs hydroponics with fish production, circulating the nutrients in the fish waste to feed the vegetables, and using the plants as a biofiltration system that returns clean water to the fish. Reducing water consumption even further—by as much as 98 percent, compared to field growing—aeroponic systems deliver nutrients in a fine mist to plant roots that are just hanging in the air. And because controlled environments exclude the weeds and pests that trouble field-grown produce, the use of herbicides and pesticides is all but eliminated.
Stacked plants may need to be rotated to make the most of available sunlight, which can be supplemented (or even substituted altogether) with LED grow lights. These can be calibrated to provide blue and red light in optimal doses for each type of plant, and timed to increase plant growth with extended days and growing seasons. (While it’s technically possible to grow any type of crop this way, for now it’s mainly leafy greens and tomatoes that are economically viable.) Cool enough to be strung right in among the plants without burning them, LEDs reduce site electricity consumption (and costs) per square foot of grow area by about a third compared to older technologies, such as high-pressure sodium. “Energy is a game-changer,” says Dickson Despommier, an emeritus professor of microbiology and public health at Columbia University, whose seminal 2010 book, The Vertical Farm: Feeding the World in the 21st Century, is widely credited with kick-starting vertical agriculture in North America. Cost-effective LED lighting opens up the possibility of converting urban and urban-adjacent building types such as parking garages, big-box stores, and shopping malls into productive local farms, he says.
With productivity rates that are orders of magnitude greater than conventional farming, high-rise growing is gaining traction worldwide. The world’s first such system began operations in 2012 in Singapore. The land-strapped city-state, which imports about 90 percent of its food, aims to grow a third of its produce locally by 2030. Indoor vertical farms in the country now produce about 80 tons of greens a year, and the Singapore Food Agency is supporting research into and development of the method as its main bet on the future.
In China, great swaths of arable land have been lost to development (more than 30 million acres between 1997 and 2008) and 20 percent of what’s left is contaminated. At the same time, the country has a strong tradition of urban-adjacent farming. When a 247-acre agricultural site, midway between Shanghai’s main international airport and the megacity’s center, recently came up for redevelopment, global design firm Sasaki proposed that, rather than create yet another tech park, the client take its agricultural mission to the next level. As a result, the Sunqiao Urban Agricultural District is slated to become one of China’s first comprehensive national agricultural zones. Sasaki’s master plan, which has received approval from the Pudong District and is now proceeding for formal approval from the City of Shanghai, expands the district’s role in Shanghai’s food network, integrating vertical agricultural production, research, and education into a dynamic public domain. In addition to research and development facilities and an agriculture production zone, the plan provides for a civic plaza showcasing productive landscapes, a science museum, an interactive greenhouse, an aquaponics display, and a destination market. “It’s urban agriculture on steroids,” says Michael Grove, chair of landscape architecture, civil engineering, and ecology at Sasaki.
The Sunqiao project will include a civic plaza with productive landscapes (top), a science museum, and an interactive greenhouse (above), among other elements. Image courtesy Sasaki, click to enlarge.
Grove identifies three primary drivers for prioritizing urban agriculture globally: the need to curtail agricultural sprawl and thereby protect ecosystems, to reclaim economic agency by diversifying control of food production, and to build community: “Food brings us together,” he says. Behind Asia’s early adoption of urban agriculture, he sees a historic understanding among the region’s societies that the well-being of the population requires systemic support. That may also be a factor in Europe, where the Netherlands is a global leader in controlled-environment technology, and Denmark is home to the world’s latest and largest vertical farm, a partnership between a Taiwanese CEA tech company and a local start-up: with growing shelves stacked 14 deep, the 75,000-square-foot wind-powered facility has the capacity to produce 1,000 metric tons of greens a year.
A hub for teaching, research, and community engagement, located within sight of downtown Columbus and designed by Erdy McHenry Architecture, supports Ohio State’s CEA efforts. Brad Feinknopf
North America has been slower to adopt vertical farming, a lag that Ohio State’s Kubota attributes in large part to the year-round, nationwide availability of produce from California, Arizona, and Florida. But now, she says, climate disruptions and shortages of viable farmland in those states, along with the increasing urbanization of the workforce, strengthen the rationale for controlled environment agriculture. To support Ohio State University’s multidisciplinary research into CEA, a one-acre vertical greenhouse is under construction within sight of downtown Columbus. As part of the facility, the recently completed Kunz-Brundige Franklin County Extension Office serves as a hub for teaching, research, and community engagement around food, health, agricultural production, and sustainability. Both buildings are designed by Philadelphia-based Erdy McHenry Architecture.
Although still tiny, vertical farming is the fastest-growing sector in U.S. agriculture. A projected compound annual growth rate (CAGR) of more than 20 percent from 2020 to 2026 is expected to bring sales to around $10 billion a year. And while significant numbers of start-ups in the capital-intensive sector have failed—as indicated by the track record of several initiatives profiled in this magazine eight years ago —experts say that’s an inevitable aspect of an emerging technology.
Among the growing number of enterprises going strong, however, is Vertical Harvest, the first vertical hydroponic greenhouse in North America. Cofounded by architect Nona Yehia, principal at GYDE Architects, the company began operations in 2016 in Jackson Hole, Wyoming. Jackson is a rural town, but it performs like a city in relevant ways: 97 percent of its developable land is already in use, and, with a four-month growing season, 98 percent of its food is imported. Inspired by Despommier’s work, the need for a local food supply, and the opportunity to provide meaningful work for community members with intellectual and physical challenges, Yehia designed a three-story greenhouse for a 30-by-100-foot municipally owned lot next to a parking garage. “The town councilor who showed us the property thought we’d put up a plastic hoop structure to extend the growing season a couple of months, employ a few people, and call it a day,” recalls Yehia. But she and her business partners wanted to grow as much food as possible, to employ as many people as possible, and to do both year-round. “That’s where the idea to grow up came from,” she says.
Vertical Harvest’s three-story CEA facility in Jackson Hole, Wyoming, produces as much food on a tenth of an acre as on a 10-acre conventional farm. Photos © Vertical Harvest (1), Hannah Hardaway (2 & 3)
With a footprint of a tenth of an acre, the greenhouse produces as much food as would a 10-acre conventional farm. It employs 30 people, more than half of whom have a disability. And it’s profitable. “It would have been easier as a nonprofit,” Yehia says, “but we were committed to creating a replicable model that is not about charity: it’s about empowerment.”
After five years of operation, Vertical Harvest is ready to expand. Construction is scheduled to start this year on a second location that incorporates affordable housing and municipal parking in Westbrooke, Maine. The new 70,000-square-foot greenhouse is expected to provide the equivalent of 50 full-time jobs and to produce 1.3 million pounds of produce a year, supplying hospitals, corporate cafeterias, schools, chefs, restaurants, and caterers, as well as individual customers. “These ecosystems can put out a lot of food,” says Yehia. “Making sure you have customers who can buy at scale is as essential to success as growing plans.”
Vertical Harvest intends to build up to 15 farms in the next five years, with agreements already in place for projects in Philadelphia and Harrisburg, Pennsylvania, and Chicago, and discussion is underway for five other locations. Like the Wyoming and Maine projects, they will integrate social value and community engagement with their agricultural mission. “It’s the perfect intersection to show what architecture can achieve in its social role in our communities,” Yehia says. And while she has run Vertical Harvest as designer, entrepreneur, and urban farmer, it’s entirely possible for architects to advocate for urban agriculture in their more usual role as prime consultants, coordinating the work of other experts.
As CEA picks up speed, the time may not be far off when every municipality will incorporate vertical farming into its civic infrastructure, valued the way public libraries and recreation centers are. “It should be something that we all expect to see when we go to cities,” Yehia says: “infrastructure that grows food and futures, and bolsters the sustainability of the community.”
Continuing Education
To earn one AIA learning unit (LU), including one hour of health, safety, and welfare (HSW) credit, read the article above and watch this video.
Then complete the quiz. Upon passing the test, you will receive a certificate of completion, and your credit will be automatically reported to the AIA. Additional information regarding credit-reporting and continuing-education requirements can be found at continuingeducation.bnpmedia.com
Learning Objectives
Explain how conventional agricultural methods contribute to climate change.
Define terms such as urban agriculture, controlled environment agriculture (CEA), and vertical agriculture.
Describe technologies relevant to CEA, such as hydroponics, aeroponics, and aquaponics.
Discuss how CEA can enhance food security and bring social value to underserved communities.
AIA/CES Course #K2104A
Lead photo: Sunqiao Urban Agricultural District has been designed by Sasaki for a site midway between Shanghai’s city center. Image courtesy Sasaki
KEYWORDS cities / climate change / urban planning