An important amount of the environmental impacts based on building energy consumption in post-construction period is resulting from facade. Hence investigating these impacts and developing some measures are necessary to create a sustainable built environment. This issue is examined in a research project, which is being conducted to develop a sustainable building assessment method and sustainable renovation techniques for existing residential stock in Istanbul. To determine representative building types, field surveys were conducted, and the projects provided from the associated municipalities were analyzed. This study intends to investigate the effect of facade variations on post-construction period environmental sustainability of some determined building types. According to the results, the increase in the WWR slightly decreases the heating energy consumption, and consecutively the environmental impacts in the thermally not-insulated buildings, while it increases the heating energy consumption, and consecutively the environmental impacts in the thermally insulated buildings. Using thermal insulation, in both types of buildings, in all WWR's and orientations, is considerably effective for reducing both energy consumption and environmental impacts. Global warming potential (GWP) constitutes most of the environmental impacts resulting from building's heating energy consumption. Human toxicity, acidification, eutrophication and photochemical oxidation potentials are in negligible amounts when compared to GWP. (C) 2012 Elsevier B.V. All rights reserved.