Another urban agriculture conference was held in Canada mid-August, this
time in Toronto – an event largely focused on rooftop farming inside
and outside of greenhouses.
Another urban agriculture conference was held in Canada mid-August, this time in Toronto – an event largely focused on rooftop farming inside and outside of greenhouses.
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| Lufa vice-president Kurt D. Lynn and founder and president Mohamed Hage, with Yahya Badran, the building contractor and engineer. Advertisement
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Hosted by community groups “Green Roofs for Healthy Cities” and “FoodShare,” the Urban Agriculture Summit brought together a diversity of players who are making urban agriculture happen – private companies, social housing advocates, and others – to share what’s already working and discover what’s possible.
The company leading the rooftop greenhouse charge in Canada is Lufa Farms. The company announced earlier this year that it has “broken even” on its prototype energy-efficient rooftop greenhouse in Montreal.
TWO MORE FARMS TO OPEN SOON IN MONTREAL
■ A second Montreal-area greenhouse of approximately 44,000 square feet is about to begin construction, and a third of 120,000 square feet is planned for construction in late fall. The company has plans for U.S. expansion as well.
Energy Edge now presents details on their greenhouse design, as well as the company’s development of a turnkey urban greenhouse system that can be located in any North American city. The following answers were provided by Kurt Lynn, Lufa Farm’s vice-president and co-founder.
Describe the size of the Montreal greenhouse and what is grown there. On what building or type of building is it located?
Lynn: The greenhouse has 31,000 square feet of growing space. It grows five varieties of tomatoes, two of cucumbers, three different pepper varieties, eggplants, various herbs, various lettuces, bok choy, kohlrabi and chards. The host building is a two-storey, mixed-use commercial space.
What allowed the greenhouse to reach its “break even” point – when you sold the first harvest? The price of natural gas? How much does the building or the size of the greenhouse have to do with being able to break even with expenses of running the greenhouse? Other factors?
Lynn: The key issue in the economics of the greenhouse is selling direct to the consumer. As you might expect, a rooftop greenhouse is more expensive to build than a greenhouse on the ground.
To compensate for this, we operate on a CSA basis, which allows us to keep a larger percentage of the retail dollar.
EFFICIENCIES OF SCALE WITH LARGER FACILITIES
■ A larger greenhouse would provide better economics because there are many efficiencies of scale that would be possible.
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| PHOTO COURTESY LUFA FARMS
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Please describe the energy curtains you use, high-efficiency boilers – size, type, other energy efficiency features.
Lynn: For the curtains, we use XLS REVOLUX made by Svensson and the three boilers (one and two backups) are EVO boilers made by Hamilton Engineering. Other environment/energy features include rainwater capture, composting (later biomass production we hope), and of course, the fundamental energy synergy between the building and ourselves.
The greenhouse “provides hot areas for some vegetables, cool areas for others, and several ‘micro-climates’ within each.” How is the temperature of these areas controlled? What crops are found within each area or microclimate?
Lynn: In the hot section, we use conventional hot-water heating controlled by zones. These harbour tomatoes, cukes, peppers, eggplants and certain herbs. The cool section is controlled with water-evaporative coolers and energy curtains (to block direct sun). These are for greens, bok choy and selected herbs.
Please tell us about the turnkey system for urban rooftops that you are developing. What is involved with this – how will features be tweaked if the greenhouse is located in a place like Edmonton?
Lynn: As a proprietary group of technologies, we won’t go into details on this.
However, there are four components: the engineering of the greenhouse itself to manage live loads onto the building, the polyculture crop management system that schedules our plantings and just-in-time-harvesting techniques, our biocontrol monitoring and management, and our order-to-harvest system.
Generally speaking, these things won’t change dramatically moving from a Montreal location to Edmonton. The temperature ranges are very similar, actually plus or minus 2 to 3 C.
Investment growing in rooftop farming
■ Editor’s Note: In addition to Lufa Farms, there are at least three other North American players with a focus on rooftop greenhouses.
Verticrop (www.verticrop.com ), owned by Vancouver-based Alterrus Systems Inc., is building a new commercial greenhouse atop a parking garage in Vancouver, scheduled to open soon. The company also has several U.S.-based projects in various states of progress, says CEO Christopher Ng.
The 6,000-square-foot greenhouse is located on the downtown EasyPark parkade on Richards Street. The area has good light access despite being surrounded by tall buildings. The greenhouse is encased in double-walled fluoropolymer sheets (ETFE) and has one common growing area.
Two IBC SI 80-399 boilers will be employed for winter heating, powered by electricity. Vancouver’s electrical grid is fed from the province’s many hydro-electric power plants. Ng also says a system to reuse rainwater will be set up at a later date.
Alterrus has formed a wholly-owned subsidiary called Local Garden to market and distribute the produce, and this may involve the use of bicycles for delivery. “We also hope to have our city’s top chefs using our produce,” says Ng.
Toronto-based Urban Produce (www.urbanproduce.ca) is actively looking for building owners and developers in Toronto and Vancouver who have an interest incorporating their greenhouse facilities onto their structures.
Urban Produce both builds and operates commercial-scale (up to 45,000 square feet) rooftop greenhouses.
“Our greenhouse farms utilize energy curtains, rainwater capture technology and recirculating irrigation systems, LED lights, evaporative cooling systems, power for irrigation pumps and ventilation systems from solar panels, and waste heat capture from the building below,” says executive director of marketing and communications Neil DeGasperis.
“Depending on the variety of crop selection we determine with our food retailers, we can have up to three or four separate temperature zones within one greenhouse farm.”
New York-based BrightFarms (www.brightfarms.com) has over 10 rooftop greenhouse projects in the U.S., and recently announced a year-round deal with the A&P grocery chain to provide it with New York City-grown vegetables from the company’s (and the country’s) largest hydroponic rooftop greenhouse.
Treena Hein is editor of Energy Edge.
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