Due to the effects of a building's whole life cycle processes on the environment and economy, there is an increasing interest in sustainability assessment of new and existing buildings. In Turkey, there is a large building stock constructed before legislative measures on energy efficiency were implemented. This article defines an environmental and economic sustainability assessment method to evaluate the effectiveness of existing residential building retrofits for reducing their space heating energy consumptions and the resulting emissions. The proposed method is based on the life cycle assessment method, and evaluates the environmental and economic sustainability performance of building envelope retrofits; i.e., adding thermal insulation and replacing windows. The intent of this method is to support the decision making process of building owners, users or architects in selecting the most beneficial retrofit alternatives in Turkey. In its current state, the database based on this methodology covers detached buildings located in Istanbul, with a natural gas-fired central heating system. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.