The objective of this project is divided into two tasks. First the effect of the thermal performance of the window and the size of the window's niche on the downdraught from the window will be investigated. In the second task, the interaction between the thermal performance of the window, heating and ventilation systems on the indoor climate will be analysed. Both experimental and numerical methods will be used for the analysis. The measurements will be carried out in an well-insulated room in the laboratory hall at the Department of Built Environment, Royal Institute of Technology, Gävle, Sweden. The simulation of the temperature and velocity distribution in the room is performed by solving the governing equations for the conservation of mass, momentum, energy and the radiative heat exchange between the surfaces by the finite element method. The measurements will be used for validation of the model for the numerical calculations.
Based on numerical calculations within the enclosure in a window construction a new correlation for the Nusselt number in a rectangular enclosure has been obtained. The numerical calculations have been performed for a physical model with two vertical panes with constant surface temperatures. The correlation for the Nusselt number is a function of the aspect ratio and the Rayleigh number. The correlation covers aspect ratios and Rayleigh numbers that are of interest for window constructions. The numerical results have been validated based on numerical studies and measurements from other investigators. The results from this work are presented in the following paper, "Numerical convection within a Rectangular Enclosure in a Window Construction", which where presented at the CIB World Building Congress 1998.
The effect of thermal performance of the window is investigated on the downdraught for different supply air velocity and different sizes of the niche of the window. Temperatures and air velocities are measured in the area below the window and in the occupied zone close to the floor. The results of this project are presented in the following paper, “ Experimental Investigation of Downdraught from Well-Insulated Windows", which is submitted for publication in Building and Environment, The International Journal of Building Sciences and its Application. Also a conference paper from this part of the project with the title, “Effect of Window Bay on the Downdraught from a Well-Insulated Window" and is published in the Proceedings of the RoomVent 2000, 9-12 July 2000, Reading, UK. At the end of 1999 are The Licentiate Thesis “Thermal Analysis of Well-Insulated Windows". was presented in 1999.