Passive solar greenhouse grows in cold climate with no heating cost

Dong Jianyi, an agronomist, has helped Canadian greenhouse technology move forward, oddly enough, by walking backwards. Dong Jianyi claims to use only materials and the laws of thermodynamics to grow cucumbers, peppers, lettuce, tomatoes and more – even in the cold Alberta winter – all without consuming a single watt.

Dong Jianyi’s Fresh Pal Farms is considered to be the largest “passive greenhouse” in Canada. Growing vegetables in the cold north of China requires innovation, and passive greenhouses that do not use electricity are common in this part of the country.

“In northern China, winter is also very cold and quite dark, but people can grow all year round,” said Dong. “When I lived in China there were so many passive solar greenhouses. But I didn’t see any commercial ones in Canada, ”he said.

The 300-foot long and 30-foot wide greenhouse consists of a steel frame with two polyolefin plastic roofs. An electric motor allows the operator to extend and retract an insulating blanket to capture the heat absorbed during the day. This keeps the 10,000-square-foot interior at 82 ° F compared to outside temperatures of 20 ° F in December. The passive solar greenhouses have high up-front costs, Dong admits, but they will pay off the investment in the following years through energy savings, since greenhouses are usually powered by natural gas.

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