The research aims to analyze the thermal performance of what is becoming a very common practice of glazing up balconies in fully exposed heavy weight buildings in Lebanon. Two apartments in one residential building, are monitored simultaneously for four full and consecutive days in late June 2011 one with a glazed balcony the other with a shaded one. Once the building's thermal simulation are calibrated using the EDSL TAS [1] software, parametric runs start by testing different orientations, followed by further shading and spatial manipulation and finishing with construction and thermostatic manipulations, giving an in-depth overview of the thermal performance of those balconies vis-a-vis the internal spaces. The research concludes with practical design recommendation and solutions for keeping with the glazing yet reducing considerably the annual cooling load. (C) 2015 Elsevier B.V. All rights reserved.