Thermal behaviour and weathering resistance of coil coatings for energy-efficient buildings

In recent years, the aspects of energy-savings in buildings have become increasingly important. Coil coatings are frequently used for roof and façade construction in order to reduce the cost, the building time and the maintenance. In recent years different near infrared (NIR) reflectivity pigments have been developed to increase the capability of paint to reflect the sun’s radiation thus minimizing the amount of energy absorbed by the building. Coil coatings containing both traditional and NIR pigments are considered for the assessment of their thermal behaviour. The same painted system produced by three different producers was considered. Using a small scale house model, a W-IR emitting lamp and thermocouples, the amount of energy absorbed by the painted metallic coupons has been evaluated in order to assess the efficiency of the different pigments under investigation. To evaluate effect of ageing, all the different samples were subjected to five accelerated degradation cycles consisting in 168 h of UV-B irradiation followed by 168 h of salt spray exposure. The thermal properties of samples were collected. The cool pigments resulted effective to decrease the heat absorbance (difference between standard and NIR paints up to 18°C). The thermal properties were found not to be affected by degradation.