Paper Conference

Proceedings of ASim Conference 2016: 3rd Asia conference of IBPSA-China, Japan, Korea


Impact of window spacers on condensation risk and heat transmittance of insulated glazing unit in residential buildings

K. Rhee, J. Yu, G. Jeong

Abstract: Insulating glazing units have been widely used to reduce condensation risks and heat transfer through building envelope. Nonetheless, window spacers are still weak points from the viewpoint of heat loss and condensation, due to relatively high thermal conductivity. For this reason, thermally improved window spacers are considered as alternatives to mitigate heat loss and condensation risk of insulating glazing units. However, it is a little tricky to expect how much condensation risk and heat loss would be reduced by applying thermally improved spacers, because they are usually composed of very thin foil and adhesive, aggravating difficulties in modeling spacers. In this context, simulation study was performed to investigate the impact of window spacers on condensation prevention and heat transmittance of insulating glazing unit in residential buildings. To do this, this study implemented a two-box model by which window spacer is replaced by imaginary rectangles with the equivalent thermal conductivity. For commercially available window spacers, temperature factors and overall heat transmittance were analyzed with THERM and WINDOW program. The results showed that temperature factors could increase from 0.59~0.72 to 0.66~0.80, depending on the window type, when applying thermally improved spacers. In addition, thermally improved spacers could prevent condensation at 4~16°C lower outdoor temperature than conventional window spacers. It was also found that the reduction in overall heat transmittance could be 0.07~0.12 W/m2K, implying that thermally improved spacers could reduce heat loss by 2.8~8.2%. Based on the results, a design chart was suggested to help designers to select a proper window spacer which can mitigate condensation risk and heat loss through the window. KEYWORDS Window spacer, Condensation, Temperature factor, U-value