Two-dimensional, laminar natural convection over an isothermal indoor fenestration surface (glazing/frame assembly) was analysed using the penalty function approach finite element method. The room air, far from the fenestration surface, was assumed to be still and at a constant temperature of 70 deg F (21 deg C). Several different fenestration configurations were analysed including one where the overall surface was assumed to be a flat plate. The results are reported for three typical configurations, namely, no frame (flat plate), a single-step frame, and a double-step frame. For the last two configurations, the geometries of the glazing and frame were varied, and comparisons between the resulting surface convective heat transfer coefficient values are reported. Recommendations on the local indoor surface convective heat transfer coefficient to be used in two- and three-dimensional heat transfer analysis of fenestration systems are presented.

KEYWORDS: convection, isothermal, indoor, surfaces, windows, heat flow, comparing, heat transfer coefficient, window frames, glazing.