Worldwide scientific landscape on district heating systems

Abstract This study aims to assess the research trends and progress in the field of district heating, a key technology for improving energy efficiency and environmental sustainability. By analyzing bibliometric indicators such as publication volume, citations, authorship, and keywords, the study provides insights into the growth, regional focus, and thematic evolution of district heating research from 2004 to 2023. The study employs a bibliometric analysis of Scopus-indexed publications on district heating, spanning from 2004 to 2023. Using the Vosviewer software, a cluster analysis was conducted to categorize the research landscape into distinct themes. The results indicate a steady increase in publications on district heating, especially over the last decade, with a significant proportion of research output originating from China and Europe. The cluster analysis identified five primary themes in district heating research: energy sustainability, thermal and geothermal energy, renewable energy integration and district heating networks, buildings, and cogeneration. Furthermore, an analysis of the evolution of research keywords reveals a transition from the focus on renewable energy integration (2014–2016) to a shift towards network optimization techniques (2018) and, more recently (2020), towards digitalization and automation. This evolution is characterised by a focus on digital storage, model predictive control, and demand-side management to enhance system efficiency. The present study provides a comprehensive bibliometric overview and introduces a novel integrative perspective by systematically linking the temporal evolution of scientific production with thematic clustering and policy-relevant implications. It highlights how emerging trends, such as digitalisation, low-temperature networks and sector coupling, are reshaping the future of district heating systems. The findings reveal the growing importance of digital and automated approaches to enhance district heating efficiency and sustainability.