Three-dimensional finite element model of overall, nighttime heat transfer through fenestration systems

Two-dimensional and three-dimensional heat transfer through fenestration systems, subject to design (winter, night time) conditions, was numerically modeled in this dissertation. The numerical modeling was divided into two major parts: (A) numerical modeling of the two-dimensional convective heat transfer on external fenestration boundaries (indoor and outdoor); and (B) numerical modeling of the two-dimensional and three-dimensional heat transfer in fenestration systems consisting of an insulating glazing unit (IGU) and frame.; Two-dimensional laminar natural convection over an indoor fenestration surface was numerically simulated in order to obtain more realistic convective heat transfer coefficient for use as a indoor convective boundary condition in the fenestration system modeling. Two-dimensional laminar perpendicular forced convection over an outdoor fenestration surface was also numerically modeled in order to obtain more realistic convective heat transfer coefficient to be used as an outdoor convective boundary condition from the numerical model of the fenestration system.; 2-D numerical modeling of the combined convective and radiative heat transfer in a glazing cavity, occurring simultaneously with conduction heat transfer in the solid sections of fenestration system (i.e. glazing panes, wood frame, sealant and spacer), were performed for several different sets of external (indoor and outdoor) boundary conditions. One set of boundary conditions was the variable convective heat transfer coefficients obtained from the modeling work done on the indoor and outdoor flows. Two prototype window designs were developed for the purpose of this study. Local heat flux distributions and temperature distribution results are presented for the two prototype windows, for different sets of external boundary conditions. U-values were calculated for the different regions of IGU (edge of glass region and center of glass region) and the frame and compared to available numerical and experimental results.; Three-dimensional heat transfer, including combined convective and radiative heat transfer in the glazing cavity, was simulated for the Prototype No. 2 window. Comparisons were made with the results of two-dimensional numerical modeling and corrections for existing two-dimensional models are recommended.