Lufa Farms of Montreal said it has "broken even" on its prototype 3,000sq m glasshouse on a two-storey office building in its home city. The energy-efficient glasshouse produces tomatoes, cucumbers, peppers, herbs and green leafy vegetables.
Eschewing artificial pesticides, fungicides or herbicides, it incorporates thermal screens and rainwater capture as well as "energy synergy" with the host building.
According to company co-founder Kurt Lynn: "As you might expect, a rooftop greenhouse is more expensive to build than one on the ground. To compensate for this, we operate on a CSA (community-shared agriculture) basis, which allows us to keep a larger percentage of the retail dollar."
The firm is now installing glasshouses at two further sites in Montreal, with expansion in several US cities planned for next year. Lynn's co-founder Mohamed Hage explained: "We placed our first greenhouse in Montreal to prove the economics of our business model. If it worked in Montreal, it will work any place south."
But he added: "Retrofitting an existing building is often much more difficult than intercepting new development because of the various structural requirements of rooftop greenhouses."