An experimental study has been conducted to examine free convection in a window with an enclosed aluminum Venetian blind. The unique feature of this experiment was that the blind slats were heated electrically to simulate absorbed solar radiation. Centre-glass convective heat transfer measurements and temperature field visualization were obtained using a laser Mach-Zehnder interferometer. Measurements were made for three plate (glazing) spacings, three blind slat angles, three blind heat fluxes, and two plate temperature differences. It was found that a recently proposed simplified model, called the Reduced Slat Length (RSL) model, closely predicted the experimental results when the flow appeared to be laminar and steady. Under these conditions, the temperature field and lateral heat transfer was dominated by conduction. Under some conditions, evidence of highly unsteady/turbulent flow was observed. As expected, the RSL model performed poorly under these conditions.