CAN: Passive solar greenhouse grows in cold climate with no heating cost

Dong Jianyi, an agronomist, has helped Canadian greenhouse technology move forward, curiously by moving backward. Dong Jianyi claims to use only materials and the laws of thermodynamics to grow cucumbers, peppers, lettuce, tomatoes, and more—even in the frigid Alberta winter—all without using a single watt.

A geologist who abandoned the oil industry due to crashing oil prices, Dong Jianyi’s Fresh Pal Farms is believed to be the largest “passive greenhouse” in Canada. Growing vegetables in China’s cold north necessitates innovation, and passive greenhouses which don’t use electricity are common in that part of the country.

“In northern China, it also gets really cold and pretty dark in winter, but people can grow year-round,” Dong told. “Where I lived in China, there were so many passive solar greenhouses. But in Canada, I didn’t see any on the commercial scale,” he said.

The 300-foot long, 30-foot wide greenhouse is constructed out of a steel frame with two polyolefin plastic roofs. An electric motor allows operators to extend and retract an insulating blanket to trap heat absorbed during the day. This keeps the 10,000-square foot interior space at 82°F compared to outside December temperatures of 20°F. The passive solar greenhouses have a high upfront cost, Dong admits, but they pay back the investment in subsequent years through energy savings, as greenhouses tend to be powered by natural gas.

Read the complete article at www.goodnewsnetwork.org.


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