Doi: 10.1016/j.jclepro.2015.06.137 The challenge of sustainable building renovation: Assessment of current criteria and future outlook Olatz Pombo a, *, Beatriz Rivela b , Javier Neila a a Department of Construction and Technology in Architecture (DCTA), School of Architecture (ETSAM), Technical University of Madrid (UPM), Avda. Juan de Herrera 4, 28040 Madrid, Spain. b Prometeo researcher. National Institute of Energy Efficiency and Renewable Energy, Ecuador. Avda. 6 de Diciembre N 33-32 e Ignacio Bossano, edificio Torre Bossano, 2do piso, Quito, Ecuador. * Corresponding author: E-mail address: o.pombo@alumnos.upm.es. Phone: +34 91 336 38 89 Abstract The building sector is one of the key consumers of energy worldwide. Thus, the retrofitting of existing buildings provides excellent opportunities for reducing energy consumption and greenhouse gas emissions. This paper presents a critical review of the research undertaken on housing retrofits and discusses the approaches driving the assessment of energy-efficiency measures. It is clear from the existing literature that many retrofitting strategies are quite similar in their approaches, the most common of these being passive strategies such as insulation of the envelope, replacement of windows, and air sealing. However, the assessment methodologies differ broadly and widely, which restricts a comparison of the results across various studies. This current state of the art review highlights the need to apply a life cycle approach in order to find the optimal retrofitting solutions, and to identify the real improvement potential of housing renovation. Life cycle assessment and life cycle cost methodologies have been analyzed by discussing the existing limitations, which can be mitigated by sensitivity analysis. Finally, whilst social impacts were addressed in a few studies, life cycle social assessment was not conducted in any of the papers reviewed. Keywords: housing renovation, retrofitting, sustainability, life cycle assessment, life cycle cost. 1. Introduction Buildings account for 16-50% of total worldwide energy consumption (Saidur et al., 2007), with 40% of Europe´s energy consumption being building-related (European Parliament and Council, 2012). The majority of the current European residential building stock was built during the 1940s-