Tropical and subtropical greenhouses - A challenge for new plastic films

In subtropical and tropical regions it is necessary to get a cooling effect if high irradiation heats up the greenhouse. It is possible to use covering materials, which contain absorbing, reflecting, interference, photo- or thermochromic pigments. Reflecting and coloured films containing absorbing pigments intercept PAR and give a shading effect throughout the year. More intelligent materials with interference pigments are able to reflect parts of the NIR more selectively. Photo- and thermochromic materials are in principle able to keep out NIR only during periods with high irradiation. For the subtropics there is a need for thermic films, which prevent the transmission of FIR during cold nights and so create an insulating effect.