Even if temperatures plunge to -40 C, the SAIT greenhouse can maintain a balmy 25 C or higher, using minimal electricity and unconventional power sources. It can also keep temperatures from spiking when heat waves strike in the summer.
The greenhouse is currently producing micro beet greens, sunflowers, mustard greens, radishes and other leafy vegetables. Urban farmers behind the project will soon begin planting seeds to grow tomatoes, peppers and basil.
When temperatures drop inside the greenhouse, a compressor blows soap bubbles into a hollow cavity in the walls and ceiling to act as insulation, trapping heat inside. A boiler run from biodiesel also turns on automatically to maintain the warmth.
Deep fat fryer oil
Officials running the greenhouse convert oil from deep fat fryers on campus into biodiesel. A boiler burns the fuel to heat hot water to warm up the building. All the deep fat fryers in restaurants, cafeterias and the culinary school produce an estimated 2,000 to 3,000 litres of waste oil a month.When the greenhouse’s boiler is running at full tilt to counter -40 C temperatures outside, it sucks up about 50 litres of biodiesel a day. In milder weather, such as Wednesday’s above-zero conditions, the boiler will use much less, about three to five litres daily.
“There isn’t a greenhouse like this anywhere that has all of this technology like this, that I know of,” said David Silburn, a research associate with applied research at SAIT.
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