Numerical and Experimental Analysis of Heat Flow at Window-to-Wall Interface

Abstract

External walls have a great influence on the thermal and humidity conditions in buildings as well as on the possibility of reducing energy consumption. While the structural and material aspects of walls and windows are well known, obtaining a tight connection to reduce thermal bridges between the window and walls still poses a significant problem. Therefore, a new window installation system proposed by the authors, eliminating linear and point thermal bridges at the window-to-wall interface, opens a pathway for lowering energy consumption in buildings and increasing thermal comfort and thermal efficiency. To prove the effectiveness of this system, numerical and experimental analyses of heat flow through an outer wall with a window were carried out. The numerical analyses were performed using the TRISCO software package. It was shown that the proposed solution eliminated the occurrence of linear thermal bridges at the window-to-wall interface (a linear heat transmittance coefficient Ψ ≈ 0.007, which meets the requirements of the passive house, was obtained). Thus, heat losses were reduced by nearly eight times compared to conventional installation systems. Numerical calculations were experimentally verified.

Keywords

• energy conservation
• window-to-wall interface
• heat flow
• heat transmittance coefficient
• thermal bridge
• numerical calculation