Demonstration of Energy-Conserving Techniques for Retrofitting Commercial Greenhouses

摘要

Curiously, although all commercial greenhouses receive abundant solar radiation daily, they are not solar reliant. No attempt is made to capture, store, or conserve the potential solar heat. Instead, most excess heat is simply vented to the outside and is lost. Then, when the greenhouse later needs heat, it is artificially supplied by burning fossil fuel. With the average commercial greenhouse using ten (10) times the energy per square foot required to heat a well insulated home, any attempt to utilize solar heating techniques promises to not only save fossil fuel but save an important state industry from decline. Many commercial operators, facing ever increasing energy costs, feel they may not be able to remain in business. Using simple passive solar heating techniques, a commercial greenhouse was retrofitted to make it more solar reliant. To conserve energy, the east, west, and north walls were insulated with two inch painted plastic foam insulation. One hundred and twenty black painted water-filled steel drums were used inside the structure to capture and store solar radiation. Two other commercial greenhouses of identical size, orientation, and temperature level were used to give side by side comparison to the solar retrofitted structure. The three greenhouses were monitored daily for temperature and effect on plant growth or rate of flowering. No adverse effects were found due to diminished lighting from the north wall insulation during the test period. Energy savings were impressive, the solar reliant structure using 46% less fuel oil during the 12 week test period. As a result, the owner of the commercial operation where the test was conducted is converting all his quonset style greenhouses to solar reliant design. (ERA citation 09:000391)