Hollow-Structured Bilayer System For Windowpane Insulation

A hollow-structured bilayer coating system was developed to reduce heat loss through windowpanes. It was formed by two separate polymer films with stable air gaps in between. The outer surface was enhanced by a low-emissivity layer. Following ASTM C1199, ASTM C518, NFRC-100, and NFRC-102, the heat transfer measurement indicated that a 3-mm-thick bilayer coating could significantly reduce the U-factor from 5.8 to 2.9 W/(m(2) . K). The U-factor could be further lowered if the coating thickness was increased. The overall visual transmittance, haze, and structural integrity were satisfactory. (C) 2021 American Society of Civil Engineers.