Ted H. Short, Warren L. Roller, W. L. Bauerle
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.
Short, Ted H., Roller, Warren L. and Bauerle, W. L. (1981). ENERGY RESEARCH FOR THE PRESENT AND FUTURE U.S.A. GREENHOUSE INDUSTRY. Acta Hortic. 115, 429-436
DOI: 10.17660/ActaHortic.1981.115.48

Acta Horticulturae