Articles
NATURAL VENTILATION OF GREENHOUSES IN DESERT CLIMATE
These conditions are favorable for greenhouse horticulture to produce winter cropping.
Development of greenhouses during recent years in these regions in Israel is very rapid.
Development started with utilizing low and high tunnels, the latter showing significant horticultural advantages.
The Institute of Agricultural Engineering was involved in developing greenhouses to assist in the specific needs of the desert areas in achieving the following:
- Low cost of construction and maintenance.
- Simple construction and covering procedures.
- Large continuous growing space.
The result is a no-gutter, roof ventilated (‘French system), 5000m2 square structure.
Ventilation of this structure is achieved by opening the four sides and ‘wedges’ in the roof (total 15% of horizontal area).
Theoretical considerations taking into account natural ventilation and dry weather, forecasted acceptable climate inside the greenhouse during winter and spring days.
Comparison of temperature and humidity in the low structure with a conventional (30 m length; 4 m gutter height with openings on two sides and gables) showed small differences in temperature while relative humidity in the low greenhouse was higher – closer to required humidity.
Climate and horticultural experiences of the first year will be presented with description of essential structures and ventilation details.