THE USE OF FRESNEL LENSES TO REDUCE THE VENTILATION NEEDS OF GREENHOUSES

In this paper we present some aspects and results concerning irradiation control in greenhouses as an alternative ventilation method, by using glass type Fresnel lenses instead of the typical glass type covering material.
These lenses can be mounted on the greenhouse roof and our study is focused on their application in low and medium latitude countries with high solar radiation and temperatures, as in Greece and other Mediterranean countries.
Fresnel lenses separate the direct from the diffuse solar radiation, so they are suitable for irradiation control in the greenhouse interior space, provided the light has a certain minimum intensity and is without sharp contrasts.
Linear Fresnel lenses can be combined with thermal, PV or hybrid photovoltaic/thermal (PV/T) type absorbers to convert surplus solar radiation inside the greenhouse into electricity and heat in order to reduce the interior temperature of the greenhouse.
The suggested systems are studied regarding their performance in covering the thermal and electrical needs of a typical greenhouse unit, focussing on the ventilation process and giving the estimated benefits.

International Symposium on Greenhouse Cooling

M. Souliotis, Y. Tripanagnostopoulos, A. Kavga

Greenhouse, Solar Energy, Illumination, Ventilation, Energy Saving

https://doi.org/10.17660/ActaHortic.2006.719.9