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Before sunrise it's cool inside the greenhouse. It's been a quiet night. Dawn arrives with the sun fingering the walls and roof of the structure. As the morning sun intensifies, the temperature inside rises. At a certain point it touches off a computerized temperature gauge. From three generators white soap foam begins to flow. The foam flows through the thin plastic walls and draws a shade over the plants and people inside. For several hours the amazing foam absorbs the sun's heat and keeps the greenhouse cool. After a few hours, the foam fades away and flows back into a thermal mass reservoir where the heat is stored for warmth during the night. In spite of intense August heat outside, inside the greenhouse the temperature remains comfortable for plants, easy on human workers.
Agrispace, a Montreal-based company building transparent solar structures, has developed this extraordinary soap-foam technology that uses the cell-like structure of bubbles to insulate and shade. Comparison testing with conventional solar technologies shows cost savings of up to 90 percent. Agrispace built its first greenhouse in Calgary, Alberta, and has also built the 4,000-square-foot greenhouse at Maharishi School in Fairfield. Based on natural mechanisms, Agrispace's bubble technology can be used to insulate and shade many kinds of buildings where natural lighting is a premium and costs must be kept to a minimum.
What is a Greenhouse?
A greenhouse can be as simple as the sunny back room in your grandmother's house, to cold frames built close to the ground, to huge glass structures made for commercial vegetable and fruit production. Because plants can't thrive in extreme temperatures, greenhouses are often built to extend the growing season beyond the seasonal norms in hostile climates--like Iowa's.
But current greenhouse technologies are not always ideal. They incur huge expenses for air conditioning, heating, and ventilation. Open doors and windows can create ventilating cross breezes, but they also invite insects in. Also, plants thrive in an atmosphere with high levels of carbon dioxide and humidity. Air conditioning and cross breezes dry the air and reduce carbon dioxide levels.
While greenhouses do extend the growing season, temperatures can still be too extreme for profitable production. In the south, greenhouses close during summer months because they are simply too hot inside for people or plants. In cold climates, greenhouses close from October to February because it's too expensive to heat them.
New Solar Designs
Agrispace's low-tech designs benefit the greenhouse industry by cutting operating costs and providing ideal environments for plant life. These new designs resist heavy weather, reduce maintenance costs, and lend themselves to organic or hydroponic production methods.
"Because we can offer an 80 to 90 percent energy cost savings to the owner of the greenhouse," says Agrispace president Ron Bessette, "it is profitable to operate our greenhouses year-round and in almost any climate. The benefit of having local greenhouses is the quality of the product. Consumers will always buy organic produce that is vine-ripened rather than the still-green tomatoes trucked in from somewhere else."
Reducing Heating & Cooling Costs
Eighty to 90 percent cost savings? With the development of the soap foam method of regulating the greenhouse environment, Agrispace has effectively cut out the expenses of ventilation, heating, and cooling during extreme temperature swings. With this new technology, the greenhouse is much more of a closed system, which allows moisture to be retained and recycled, and for carbon dioxide levels to remain high and nourishing to the plants. The net result is that greenhouse owners, even those living in Iowa, get plants producing year-round yields.
Not only is this technology cost-effective, but it creates an ideal environment. Out in nature, constant direct sunlight can stress plants. A bright cloudy day is best for plants. "Our automated system of a blower and soap foam mimics nature's cloud cover, and that's probably what I like best about it," says Bessette. This technology replaces conventional--and expensive--motorized curtains many greenhouses use to provide shade.
Agrispace has begun with greenhouses, but clearly sees a future in building gymnasiums, solariums, or any building where the owners want natural lighting and low operating costs.
The Soap Foam Technology
Invented by Richard Nelson, a Canadian agronomist, these state-of-the-art greenhouses have environmental control systems that mimic nature's processes. In the 1980s, Nelson received research grants and commercial partnerships to research solar energy technologies. It was during this time that he explored the insulating value of soap foam, and then perfected its flow dynamics and viscosity. "We developed a simple soap like that used in shampoo or toothpaste, and add a stabilizer so that it lasts a long time," he says.
Agrispace built its first greenhouse using this revolutionary technology in the winter of 1995 for an entrepreneur in Calgary, Alberta. The greenhouse was 12,000 square feet. The owner is now offering vine-ripened tomatoes year round. His current crop is already pre-sold, and he is expanding his greenhouse to an area of three acres.
Modular Construction
The greenhouse at Maharishi School is based on the Calgary design, but it is even better, says Bessette. "We modularized the construction to simplify it and make it less expensive," he says. "We changed from a steel to an aluminum frame because it has a longer lifespan and can be shaped more easily." He also says that with these changes the modularized parts of the greenhouse could be mass produced and assembled by two people.
The walls and roof of the structure are tubes, made of DuPont's Teflar, a fluorocarbon-based plastic. It is non-toxic and has twice the lifespan of other plastics. Teflar has an advantage over glass because of the ease of repair--it can be patched quickly with a high-frequency welding process. The frame is wrapped horizontally in this plastic. But unlike a simple sheet of plastic, these sheets are the hollow tubes, or ducts, through which the soap foam flows, making the walls translucent, rather than transparent, on hot days.
Agrispace for the World
With its many advantages, Agrispace technology could easily extend sustainable agriculture opportunities around the world, in extreme hot and cold climates, and in arid countries as well. "Agrispace-designed greenhouses don't require open ventilation because they don't get overheated, so there is much less evaporation," says Bessette. "Irrigation water is recycled, so there is only minimal water replenishment needed. We can even recycle inside condensation for irrigation."
Agrispace greenhouse designs cooperate with nature to provide the best environments for crops, the best business edge for growers, and the best products for consumers. It's plain to see that such technology has the edge for a naturally bright future.
