Energy efficiency of the lettuce greenhouse production

In this paper the influence of greenhouse construction on energy efficiency in winter lettuce production was estimated fir different double plastic covered greenhouses in Serbia region. In order to see whether the greenhouse structure influences energy consumption, energy inputs were estimated for lettuce production in four different greenhouse structures (a tunnel and gutter connected structure and three multi-span greenhouses). On the basis of lettuce production output and the energy input specific energy input, energy output-input ratio and energy productivity were estimated. Results show that the lowest energy consumption was obtained for gutter connected greenhouse with two bays, 3.11 MJ/m(2). The highest energy consumption was multi-span greenhouse with thirteen bays, 3.30 MJ/m(2). The highest value for output-input ratio was calculated for the multi-span greenhouse with thirteen bap, 0.85 and the lowest for the tunnel structure, 0.47. Regression equations show the nature of the greenhouse structure influence on these parameters