In this study, changes on light transmittance of greenhouse covering materials produced by CO-EX technology with multi-layered CO-EX UV+ IR+EVA and UV+IR+EVA+AD additives was investigated during their service life of 24 months. As physical properties, global solar radiation (GSR) and photosynthetically active radiation (PAR) transmittance of greenhouse covering materials were determined. Initial GSR transmittances were determined as 92.7% and 83.6% for UV+ IR+ EVA and UV+ IR+ EVA+AD added PE, respectively. The plastic films of UV+ IR+EVA and UV+ IR+EVA+AD had losses of GSR transmittances of 7.3% and 13.2% at the end of their service life, respectively. These losses were due to accumulation of dust and dirt on the exterior surface of films. Initial PAR transmittance of UV+ IR+ EVA and UV+ IR +EVA+AD films were determined as 80.1% and 83.0%, respectively. Both of the plastic films of UV+ IR+ EVA and UV+ IR+ EVA+AD had PAR transmittance losses of 6.2% and 4.9% at the end of their service life, respectively. (C) 2016 Published by Elsevier Ltd.