Retrofit strategies to improve energy efficiency in buildings: An integrative review

•An integrative literature review was carried out, with 269 papers reviewed.•Italy publishes the most on the subject, followed by China, Spain, and the USA.•Improving the envelope’s thermal insulation is the most used strategy worldwide.•Other aspects of retrofits were discussed, including benefits and disadvantages.•Future retrofit assessments were suggested based on the conclusions. Given the high energy consumption and greenhouse gas emissions associated with buildings worldwide, sustainable strategies that provide conscious use of natural resources and suitable conditions of indoor environments for users are essential. In this sense, the objective of this paper was to present an overview of retrofit strategies aimed at improving energy efficiency and sustainability in buildings. The work is based on an integrative literature review of studies carried out in several countries over the last seven years. The main benefits of the retrofit strategies are reducing energy consumption, decreasing pollutant emissions, and improving the indoor environmental quality for the occupants. Active retrofit strategies are related to building systems and renewable energy sources, while passive strategies use natural resources more efficiently and generally at a lower cost. Methods and software can support the selection of the best retrofit strategies for each building. This paper compared and discussed the relevant results of the case studies, which comprised 72.9% of the papers selected for the integrative review. In all types of buildings and climates, the most discussed retrofit strategies were building envelope insulation, improving the climatisation and lighting systems, and using renewable energy sources – representing approximately 70% of the strategies. There was also a significant frequency of optimisation of natural lighting, natural ventilation, and ventilated façades in non-residential buildings or other types, mainly in semi-arid, temperate, and Mediterranean climates. Finally, recommendations for future studies were presented.