ISHS Acta Horticulturae 115: Symposium on More Profitable Use of Energy in Protected Cultivation
ENERGY RESEARCH FOR THE PRESENT AND FUTURE U.S.A. GREENHOUSE INDUSTRY |
| Authors: | Ted H. Short, Warren L. Roller, W. L. Bauerle |
| Abstract:
Older glass greenhouses can be modified for energy conservation by 1) lap-sealing to save 20%, 2) air-inflated-double-plastic-over-glass to save 40% to 60%, or 3) retrofitting with rigid-double-wall-acrylic to save 40% to 60%. The important environmental factors in making a successful transition have been the effects of CO2 depletion, changes in the relative humidity and light quality at the plant canopy. Humidities increased by 15% with double covers, but less condensation and dripping occurred because the ceiling surface was always warmer. Average light transmission at plant level was 65% with single glass and acrylic and 45% with double-plastic-over-glass. A new energy efficient greenhouse concept being developed is to pump polystyrene pellets between double plastic greenhouse covers at night. The polystyrene reduces night heat loss by 90% and allows the greenhouse to collect and store solar heat during the daylight hours. The pellet system combined with alternate energy sources such as a solar pond or power plant waste heat may result in a major growth of greenhouses near metropolitan areas in the future. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
