ISHS Acta Horticulturae 691: International Conference on Sustainable Greenhouse Systems - Greensys2004
THERMAL SCREEN EVALUATION IN SOILLESS TOMATO CROP UNDER GLASSHOUSE |
| Authors: | S. Le Quillec, E. Brajeul, D. Lesourd, D. Loda |
| Keywords: | climate management, energy costs, energy savings, climatic parameters, fruit quality, yield |
| Abstract:
The first objective of this study was to determine the value of the SLS 10 (Ludvig Svensson) thermal screen in cutting energy costs in a soilless tomato crop under heated glasshouse. The second one was to improve climate control under a thermal screen. The thermal screen was mostly used during the night in the 2001 trial with a decrease of the night temperature setpoint (- 0.5°C). It was used intensively in the 2002 trial with an increase of the night temperature setpoint (+ 0.5°C from January to March) and day ventilation temperature setpoint (+ 1.0°C). It was also used intensively in the 2003 trial with an increase of the night temperature setpoint (+ 0.7°C during January and February) and day ventilation temperature setpoint (+ 1.5°C). In the 2001 trial, the average inside night temperature decrease of 0.2°C and the use of a thermal screen for 52% of the time during the spring period led to 22% energy savings, less precocity and greater fruit weight with a thermal screen at the beginning of harvest. In the 2002 trial, the average inside night temperature increase of 0.3°C and the use of a thermal screen for 58% of the time during the spring period led to 30% energy savings with little effect on quality and yield. In the 2003 trial, the average inside night temperature increase of 0.1°C, the average inside day temperature increase of 0.3°C and the use of a thermal screen for 58% of the time during the spring period led to 27% energy savings and no effect on quality nor yield. These results obtained for the Nantes area showed that it is possible to optimize an intensive use of a thermal screen by an adjustment of inside night temperature setpoint and day ventilation temperature setpoint. 30% energy savings were obtained with no effect on quality nor yield. These trials also enable us to calculate a profit earning capacity of 2 to 4 years for a thermal screen in a soilless tomato crop. However, it will be difficult to apply this intensive use of a thermal screen in the West of France because of high night relative humidity under thermal screens. | |
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