In the northern part of Europe energy for greenhouse heating is required both in summer and winter. In many Mediterranean countries greenhouses are not heated even in cold nights. This can have a considerable effect on quality, yield and cultivation period of horticultural products. For that reason also in southern regions more and more greenhouses are heated.
Up to these days greenhouses in horticulture have been mainly heated by the fossile energies oil, gas and coal. The prices for the fossile energies are low at present. Therefore little notice is taken now of the aspects of energy conservation and alternative energy sources in practice and in also science promotion.
This way leads into the wrong direction. The low price situation will not remain like this. Although the availability of the fossile fuels is still secured for the coming time, their prices will rise in the future. The day may come when the crude oil is only available for chemical industry and for driving engines but not for the combustion for plant production. At that moment alternatives must have been developed.
If plant production in greenhouses shall be further guaranteed, alternative energy sources in addition to other energy conservation methods have to be used for greenhouse heating as far as technically and economically possible. Using alternative energy sources is combined with considerable investments. Thus all possibilities for energy conservation have to be taken into consideration before using alternative energies.