Energy saving potential of greenhouse climate control

As energy costs are one of the main production costs many efforts were made to reduce the energy consumption of greenhouses. One possibility is the development of new control strategies (e.g. wind-dependent control [B.J. Bailey, Wind development control of greenhouse heating, Acta Hort. 174 (1985) 381-386]). But in most cases the energy saving potential of control seems to be overestimated. In this paper the main influences of control strategies on energy saving are discussed. For example calculations of energy consumption were made for several control strategies. The results elucidate that there are only minor differences in heat consumption for the investigated control strategies and therefore energy saving potential of control is also small. For online optimisation of control it is more important to increase the yield in order to maximise the net income of the grower. As the heating costs are about 10% of the total production costs a reduction in yield of 1% must be compensated by more than 10% energy saving. (C) 1998 IMACS/Elsevier Science B.V.