|Authors: ||M. Teitel, H. Liang, S. Ozer, J. Tanny, H. Alon|
|Keywords: ||solar radiation, net radiation, tomato, insect-proof, roof shape|
In warm and mild winter climates insect-proof screenhouses are often used to grow plants.
These screenhouses are usually much cheaper than fully climate-controlled greenhouses and enable growers achieving reasonable yield, at good quality.
The insect-proof screenhouse structures are often built with different roof shapes for various reasons.
An experiment was done to determine the light distribution above the canopy in screenhouses with two different roof shapes: flat and zigzag.
The roofs of the screenhouses were made of a "50 mesh" screen.
The light intensity was measured simultaneously in the two screenhouses, at their mid-length, across nearly two spans (14 m). The data was collected in the morning, midday and afternoon.
Results show that light distribution in the transverse direction is more homogenous in the flat screenhouse than in the zigzag one.
However, average light intensity across nearly two spans was very similar in the two houses.
Light intensity in the screenhouses was about 55, 60 and 52% of ambient values in the morning, midday and afternoon respectively.
Although the screen in the screenhouse with the flat roof was installed two years earlier than in the screenhouse with the zigzag roof only slight effect of degradation in light transmittance of the screen material was observed in that house.
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