The building sector is responsible for 50% of worldwide energy consumption and 40% of CO₂ emissions. Consequently, a lot of research on Building Energy Efficiency has been carried out over recent years, covering the most varied topics. While many of these themes are no longer of interest to the scientific community, others flourish. Thus, reading trends within a field of knowledge is wise since it allows resources to be directed towards the most promising topics. However, there is a paucity of research on trend analysis in this field. Therefore, this article aims to analyse the evolution of the Building Energy Efficiency field of knowledge, identifying the recurrent themes and pointing out their trends, supported by statistical methods. Such an analysis relied on more than 9000 authors’ keywords collected from 2000 articles from the Scopus database and classified into 30 topics/themes. A frequency distribution of these themes enabled us to distinguish those most published as well as those whose academic interest has cooled down. This field of knowledge has evolved over three distinct phases, throughout which, eight themes presented an upward trend. These findings can assist researchers in optimising time and resources, investigating the topics with growing interest, and possibilities for new contributions.

This article presents a bibliometric analysis on the Lean System over the period ranging from 2006 to 2017, showing the evolution of the publications over the years, the number of publications per country, the main journals, the most prolific authors, the most used keywords, and eventually barriers for the implementation of the Lean System. The greatest growth of publication rate occurred from 2014 to 2015. The countries with the most contribution have been the United Kingdom, the United States, and Sweden. The publications have been concentrated primarily in twelve journals. The bibliometric map of keywords presented them grouped into six clusters. Several underlying factors like technical and managerial aspects, planning, and leadership can explain the main barriers for the implementation of the Lean System. According to the literature, the understanding of such barriers is the best way to reduce the implementation-time and reach profitability and competitiveness. Therefore, the main contribution of this work is to make the evolution and importance of publications in this area are better known, helping organizations in the knowledge of the Lean System implementation barriers present in the literature, and in reformulating the curricula of undergraduate and postgraduate in disciplines related to Lean System. Finally, a future scientometric analysis on the subject is suggested, covering the analysis of evolution of publications, scientific journal, and authors distributions, by means of bibliometric laws, like those by Price, Bradford and Lotka, respectively.