Design of Greenhouses with High Light Transmittance: An Implementation in Two Different Conditions

Abstract

In periods when greenhouses need heating, heating costs can be reduced if the interior of the greenhouse receives a greater amount of sunlight. For this, the greenhouse surface slope angles need to be increase in such a way that the rays of the sun fall perpendicular to the greenhouse surface in the winter months when they are at a lower angle to the surface of the Earth. In this study, an investigation was made of greenhouse surface geometry which would allow a high level of sunlight penetration in winter conditions in the provinces of Antalya and Muğla, where greenhouse agriculture is widely practiced. The Venlo type glass greenhouse with vertical side surfaces, which is extensively used in the study area, was taken as a reference. Two different models of glass greenhouse were designed with a geometry which would increase the light penetrability of the side wall surfaces, taking account of the global radiation and the hours of sunlight for a six-month period (October to March) in each of the provinces. The geometry of the model greenhouses and the reference greenhouses was compared in terms of mean penetrability to sunlight and the energy values of the sunlight passing through. It was determined that the sunlight penetrability values of the model greenhouses were 7.86% higher than those of the reference greenhouse in Antalya province and 7.36% higher in Muğla province. These results show that the geometry of both model greenhouses was able to benefit at a higher level from the sun’s rays than fixed surface greenhouses. Greenhouses constructed according to the planned geometry will help to reduce the winter heating costs of greenhouse agriculture in mild climates similar to the study area, and help to enable greenhouse production in cooler climates. It is thought that in this way, greenhouse crop production will be possible over a wider area and throughout a longer period of the year.