| Two-dimensional heat transfer through fenestration systems is the main theme of this thesis.; The first objective of this dissertation is to verify the influence of air leakage on the energy rating (RE) and the specific energy rating (RES) of residential windows and to suggest changes to the corresponding Canadian standard (CSA). More specifically, three major assumptions in the current RE standard are verified: (i) the interaction between air leakage and conduction heat transfer in the frame, (ii) the variation of air leakage with changing meteorological conditions and (iii) the effect of temperature dependent air leakage caused by thermal contraction/expansion of the frame. For the window geometries and air leakage rate investigated, results show a significant gap, from 1,4 to 4,0 W/m 2, between the energy rating calculated according to the proposed modifications and the energy rating calculated using the current CSA procedure.; The second objective of this research is to evaluate the effect of internal natural convection on the heat transfer coefficient (U) of a complete fenestration system. Three cases are examined, one case with parallel plates and two cases with glass plate deflection corresponding to center-point pane spacing reductions of 17,8% and 28,9%, respectively. Comparisons between these three cases reveal significant differences in the flow field and in the value of the heat transfer coefficients (U) in the frame, the center and in the edge of glass. The differences in the U-factor for each of these three zones are between 0,6% and 7,6% for the parallel plates case and the deflected plates.; Part of this study is concerned with simulations of heat transfer in insulated glazing unit (without the window frame). The complexity of the flow is put in evidence by the presence of unsteady secondary cells in the cavity.; An experimental study aimed at determining, apparently for the first time, the surface temperature inside an insulated glazing unit is also presented. The comparison of vertical temperature profiles between an IGU with and without glass plate curvature show a temperature difference of about 1°C in the central region. (Abstract shortened by UMI.)... |
