J. Damrath, Chr. von Zabeltitz
In 1976 a plant for heating a greehouse by help of sun energy was built in Hannover. The principle is to use the greenhouse itself as sun collector. The greenhouse is heated by sun energy from April to October, except in longer bad weather periods. At daytime the excess radiant energy, which is normally brought out of the house by ventilation, is stored in a water storage by use of heat exchanger supplied with cold water. At night the same heat exchangers serve as heaters, now supplied with warm water from a warm water tank. For cooling and heating tow different water temperatures (6°C for cooling, 45°C for heating) are necessary. These temperature levels are achieved by a heat pump, cooling the cooling water back to 6°C and warming up the heating water to 45°C. The heat pump is automatically stopped, if one of the temperature levels is reached. This design has the advantage that the heat pump works independently of the amount of incoming or needed energy. This means, that it is possible to install a heat pump not for maximum, but only for average energy demand.
Damrath, J. and von Zabeltitz, Chr. (1981). GREENHOUSE HEATING WITH SUN ENERGY. Acta Hortic. 115, 537-542
DOI: 10.17660/ActaHortic.1981.115.60

Acta Horticulturae