Energy consumption in residential buildings contributes significantly to negative environmental impacts such as climate change and ozone depletion, and the implication for carbon dioxide emissions reductions in buildings during the construction phase as the embodied carbon and the operation phase in the form of operational carbon are widely acknowledged. Investment on creating a sustainable built environment especially through energy retrofit strategies for buildings has been progressively increasing over the last decade. To identify optimum energy retrofit strategies for reducing both energy consumption and CO2 emissions, this paper presents a simplified life cycle model and implements this to a case study focused on different climate regions of Turkey. The objective of this study is to develop effective strategies on the improvement of building energy performance for different climate regions, which is important for optimum use in the sense of country resources and decision makers. Also the energy and environmental performances of the residential buildings regarding these strategies are assessed on the basis of a comparative method in the framework of life cycle. In this study based on life cycle energy and environmental performance, the alternatives related to energy retrofit strategies were evaluated in order to improve the energy performance of the existing residential buildings. In this context, the effect of each measure on life cycle energy consumption and CO2 emissions was determined by using the 'Life Cycle Energy (LCE)' and 'Life Cycle CO2 (LCCO2)' analyses developed based on the life cycle assessment (LCA) method.