Testing of the condensation characteristics and light transmissions of different plastic film covering materials

In this study, eight model pitched roof greenhouses for the investigation of optical transmission of agricultural plastic films were designed and constructed in Samsun, Turkey. Light transmissions associated with time and condensation characteristics were determined in the experimental greenhouses covered with UV stabilised polyethylene (UV + PE), IR absorber polyethylene (IR + PE), polyethylene with no additives (PE) and double layer polyethylene films (D-Poly). Comparison of light transmission of the films over a period of 3 months showed that all films in a dry state had higher transmission than that in a wet state. Light transmission of D-Poly was found to be the lowest while that of PE was the highest. The average loss in transmission due to dirt was approximately 9-15%. Drop size and water condensation were highest in IR + PE followed by UV + PE and PE. Comparative analysis implied that results of our research, conducted with vegetation, corroborated the findings of previous studies conducted without vegetation. (c) 2005 Elsevier Ltd. All rights reserved.