In recent year, for the purpose of reducing carbon dioxide emissions through energy saving, new architectural materials are developed for ceilkling, wall, floor, window and door to improve insulation performance of houses. However it is difficult to estimate their influence on overall insulation of houses. In this paper, a polycarbonate window coated with nano hollow particles was picked up, and then a multiscale numerical simulation was conducted for a model room. The homogenized material properties of coated layer were evaluated through asymptotic homogenization simulation, and quivalent properties of laminated window were obtained by the mixturing rule. The overall insulation performance of the model room was discussed from finite element simulation of nonsteady thermal conduction problem.