Rooftop Farm Couples Science with Sustainability
August 24, 2011 | Kelly Hatton
Finding fresh, high-quality produce in Montreal is a challenge. The long and winding road that produce typically travels from farm to market in this city means that it must be harvested far before it’s ripe in order to survive long shipping distances. The downfalls of the current supply chain – heavy fuel use, food safety risks, and the lack of personal connection between farmer and consumer – inspired Mohamed Hage, president and founder of Lufa Farms, to develop a model urban farm that would provide local, sustainable food to city dwellers.
Hage envisioned a farm that would bring food production back to the city, grow high-quality produce using space and resources efficiently, and create direct and meaningful relationships with consumers. To realize his vision, he teamed up with experts in business, engineering and agronomy who shared his vision of innovative urban food production.
After four years of research and development and $2,000,000 dollars in private investment, Lufa Farms has arrived. Situated atop a Montreal office building, Lufa Farms is a 31,000 square foot greenhouse that couples science with sustainability. This is the first year of production for the rooftop farm, which currently grows enough food to provide for the needs of 1400 people.
Hage and team hope this newly minted greenhouse will be only the first of many commercial rooftop greenhouses that his company builds in Montreal and other urban centers across North America.
Inside Lufa Farms
Lufa Farms’ greenhouse and growing methods were designed to optimize production in a limited space. In this controlled environment, crops can be grown year round.
“Greenhouse growing systems maximize production and yield because we’re able to tailor our climate settings and irrigation formulations to the environmental and nutritional requirements of the crops, so they essentially grow in the optimum environment with sufficient nutrients at all times,” said Lauren Rathmell, a biochemist who works on the growing and research teams at Lufa Farms.
The farm uses hydroponic production systems to grow its produce. Lufa Farms uses Nutrient Film Technique (NFT), a hydroponic technique in which a film of water containing nutrients necessary for plant growth is recirculated around the bare roots of plants, to grow specialty greens, herbs and lettuces.
Larger crops including tomatoes, cucumbers and eggplants are grown in coconut husk fiber and fed nutrient solution via drip irrigation. According to Rathmell, the coconut husk fiber growing medium helps reduce the risk of introducing soil borne disease or weeds in the greenhouse.
In an effort to conserve water, rainwater is captured and used to irrigate crops. The closed system prevents water loss due to runoff; any excess nutrient solution is filtered, balanced and reused.
“Our ability to recirculate our irrigation water reduces our water and nutrient use by at least 40 percent,” said Rathmell.
Though not Certified Organic, Lufa Farms is committed to practicing what it terms ‘responsible agriculture.’ Biological controls, such as the integration of beneficial insects, bacteria and fungi, are used to control pests and prevent disease. Pollination happens naturally, thanks to a bee colony kept in the greenhouse. No GMO crop varieties are used.
The greenhouse is divided into two sections according to season. In one section cool weather crops are grown, while warm weather crops are grown in the other. Crops are planted to create microclimates within each section. The ventilation system, plant spacing and amount of light can all be manipulated to optimize plant growth.
Sunlight is used whenever possible as a light and heat source. Automated energy curtains are also used to conserve heat within the space. When temperatures drop, sheeting extends along the walls and over the top of plants. “When they’re all deployed, they basically create an insulation box inside of the greenhouse, trapping warm air and preventing heat loss,” explained Rathmell.
Another energy-saving aspect of the operation is minimal transport. While the average head of lettuce travels up to 1500 miles from farm to plate, all of Lufa’s produce is distributed within the radius of the city.
A Subscription Model
Produce is sold via a subscription model, similar to a Community Supported Agriculture (CSA) program. Each week, subscribers pick up a basket of fresh produce at one of several drop-off locations throughout Montreal. The farm also offers corporate subscriptions for Montreal businesses. Employees of participating companies may purchase baskets at discounted rates to have delivered to their workplace.
Lufa Farms harvests the produce on the same day as delivery. During the regular growing season, customers can choose to have their weekly basket supplemented with produce Lufa can’t provide, like berries and root crops, from various organic farms in the Montreal region. Baskets are available in a variety of sizes and range in price from $22 to $42 per week.
“We’ve projected to grow enough produce for 1000 baskets a week at this greenhouse, which is enough to feed about 2000 people,” said Rathmell.
A Prototype for Future Rooftop Farms
Plans for another greenhouse, three to four times the size of the current farm, are underway.
“We’re hoping to expand first to another location in Montreal, and we’ve also started research on expanding to other cities like Toronto and Boston,” said Rathmell. “Hopefully, we’ll be able to begin construction on the second Montreal greenhouse within the next year.”
Installing large greenhouses atop building rooftops in city centers is a relatively new concept that comes with inherent challenges. Hurdles include high startup costs, finding locations that can withstand the structural load of a greenhouse, and navigating city zoning and code requirements that were not written with the concept of commercial rooftop greenhouses in mind.
Learnings from the initial project have informed the company’s current greenhouse development strategy.
“We’re mostly coordinating with construction companies for subsequent projects so that the greenhouse can be integrated into the design of the building from the start,” said Rathmell. “This also gives us the opportunity to become a part of new industrial constructions that would normally be built without regard for urban agriculture or ecological design.”
Rathmell also noted that support from the local government and community has been paramount to Lufa Farm’s initial success.
“So far, it’s been really well received,” she said. “We’ve gotten a good response from consumers, and we’re proving that it can be done.”
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