Rooftop Montreal greenhouse uses careful energy managment and claims to have proven concept is financially feasible in Canada
By Treena Hein
Lufa Farms stated publically yesterday that it ‘broke even’ earlier this year on its prototype energy-efficient rooftop greenhouse in Montreal, and that it’s ready to move forward with its “ultimate goal” – to develop a turnkey urban greenhouse system that can be located in any North American city.
Construction of Lufa’s first greenhouse in Antonio-Barbeau in Montreal began in July of 2010 (according to the company’s website), first by preparing the roof and creating the necessary structure and then by completing the framing and glass installation. The internal systems, heating, electrical, insulation shades, and other components were completed at the beginning of 2011.
Lufa states, “Our heating systems are designed to absorb as much natural heat from the sun and the building before supplementing with high efficiency boilers. Our automated systems automatically deploy energy curtains during the night time to further cut down on our energy needs.”
“The heating demands of a greenhouse occur almost exclusively during the night. Night time temperatures in cities tend to be much higher than in the country due to the thermal mass of city buildings and roads and the heating of city homes and offices.”
“We use a lot less natural gas than equivalent facilities operating in the winter. And we offset the gas we do use by not requiring our produce to be refrigerated and transported around the world to reach our consumer.”
“The combined respiration of the plants in the greenhouse – collectively an enormous evaporative surface – cools the air and helps to reduce the “heat island effect” created by the typical black tar roof. This contributes to lowering the cooling requirement for the building underneath the greenhouse.”
“Future Lufa Farms greenhouses will be much bigger than our first greenhouse on Antonio-Barbeau. We expect that they will use biomass heating (using recycled plant or wood fibre).”
The Lufa farm design both captures rain water and recirculates all water. “This, and by using drip irrigation, allows us to use a fraction of the water and nutrients needed in conventional field agriculture,” the company states. “It also means we don’t load the municipal drainage system and our plant nutrients don’t end up in lakes and rivers…Our first farm in Montreal has also created a large water ‘buffer system’ around the greenhouse. This slows the rate at which uncollected rainwater flows into city sewers.”
“Our rooftop greenhouse is not like other greenhouses…To be suitable for an urban rooftop, our greenhouse had to be stronger, able to withstand greater snow loads and to meet exacting urban building codes. Our basic greenhouse design has also been created with the goal of easily integrating into both new construction and existing buildings.
Again, unlike typical greenhouses, the Lufa Farms’ greenhouse provides multiple growing climates for the vegetables cultivated within it. It provides hot areas for some vegetables, cool areas for others, and several “micro-climates” within each. In this way, the greenhouse optimizes the growing conditions for its plants.”
“Many of the crops end up planted in pouches of coconut husk fiber which is used because it is clean and contains no weeds. These pouches are then hooked up to drip-irrigations sytems in long rows. The greenhouse keeps bee hives inside the structure to support pollination of the plants.”
Regarding whether their produce is organic, Lufa states:
“At our farm, we have carefully selected the ways we grow and cultivate plants and the substances we use to do so. For example, early on we made the decision that we would not use any synthetic or unnatural pesticides, herbicides or fungicides in our agriculture. Also, we decided that we would only use ‘bio-controls.’
We have also chosen to use various hydroponic methods of agriculture. But using these methods is not considered ‘organic.’ Yet we chose hydroponic methods versus classic soil agriculture because it allows us to grow high quality, highly nutritious plants with minimum water and nutrients and to do so in a safe and conscionable way…
We recognize that organic certification is a means of offering consumers the confidence that their food is safe and free of harmful substances. We believe that certifying organizations will at some point establish appropriate standards of measure for agriculture in controlled environments. Until then, we will continue to offer our consumers the same degree of food confidence, a transparent relationship with our consumer, and a high quality of tasty, nutritious food.”