The district heating (DH) industry has been characterized by continuous innovation for several decades, but there is limited knowledge on the characteristics of the sector’s innovation activities, arguably the most important information for understanding how the sector can continue to develop and further support the energy transition of society. We perform a systematic literature review (SLR) to identify the types of innovation, the levels of innovation and the relation between different innovations in the DH sector. A total of 899 articles are analyzed and coded into eight groups: fuel, supply, distribution, transfer, DH system, city system, impact and business. Most of the articles (68%) were identified in the groups: “supply”, “DH system,” and “impact”, with a focus on DH from a system or production perspective and its environmental impact. We find that there is limited research on DH firms” challenges, including management perspectives, such as asset management and customer focus. Despite this potential, we find only a limited number of articles related to innovation. Not much scholarly attention has been given to areas of large cost-saving, especially capital cost. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

The district heating (DH) industry is facing an important transformation towards more efficient networks that utilise significantly lower water temperatures to distribute the heat. This change requires taking advantage of new technologies, and Machine Learning (ML) is a popular direction. In the last decade, we have witnessed an extreme growth in the number of published research papers that focus on applying ML techniques to the DH domain. However, based on our experience in the field, and an extensive review of the state-of-the-art, we perceive a mismatch between the most popular research directions, such as forecasting, and the challenges faced by the DH industry. In this work, we present our findings, explain and demonstrate the key gaps between the two communities and suggest a road-map ahead towards increasing the impact of ML research in the DH industry. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Digital product-service system (PSS) innovation requires firms to combine service knowledge with product, sensor, software, data, and customer-facing capabilities. This creates a challenge for resource-constrained service-oriented firms: they may need external partners, yet the choice between complementors and suppliers is neither trivial nor made only once. Given the scarcity of research, this paper explains how a small technology service firm searched for, evaluated, and reconfigured inter-organizational relations while developing a digital PSS for predictive maintenance in district heating networks. Based on a longitudinal single-case study involving interviews, observations, workshops, customer meetings, internal documentation, and secondary material from eleven organizations, the paper traces how partner roles evolved across four phases: early experimentation, development and integration, stabilization, and market expansion. Complementor relations initially enabled access, speed, and cost reduction when the focal firm lacked resources and the PSS architecture was uncertain. As technological interdependencies, quality problems, lock-in, and control concerns accumulated, the focal firm shifted toward supplier relations to gain ownership and reduce uncertainty. Later, downstream complementor search created role ambiguity and competitor risk. The paper contributes to PSS innovation, innovative search, and ecosystem research by showing that partner roles may be fluid, that shifts are shaped by search heuristics, interdependencies, and evolving organizational capability, and that digital PSS innovation unfolds as an iterative process rather than a linear make-or-buy choice. For managers, the findings indicate when complementor relations support low-cost experimentation and when accumulated learning makes supplier relations preferable for ownership, control, and stabilization.

Technologies such as district heating (DH), district cooling (DC) and heat pumps are essential for improving heating and cooling efficiency and supporting decarbonization goals. Although advancements such as nextgeneration DH promises lower temperatures and increased flexibility, these technologies are insufficient to reach such targets in isolation. While there is ongoing convergence between DH, heat pumps, and energy storage, the literature pays scant attention to how actors innovate by combining and integrating these technologies. Thus, there is a significant need for a greater understanding of the innovative efforts of DH firms. This study explains how seven European DH firms innovated to create and deliver value by changing their organizational, technological, and interfirm engagements. By analysing the cases through the lens of platform literature, our analysis reveals a shift away from traditional incumbent value systems and the emergence of new platform-based value systems that incorporate platform envelopment of gas and heat pumps into DH. The changes consist of three distinct innovation pathways. First, incumbent DH firms are improving traditional systems by refining customer interfaces and integrating digital services within their established firm boundaries. Second, smaller collaborative entrants engage with incumbents to form platform-based systems downstream of the incumbents. Third, larger disruptive entrants establish independent platforms with localized, network-connected heat pumps and storage, directly challenging incumbent value systems by offering alternative heating and cooling solutions. The study demonstrates that district heating is no island, but part of an interconnected and evolving ecosystem where innovation emerges through technological integration and inter-firm collaboration © 2025 The Authors.

The literature has played scant attention to how entrepreneurial action transforms ecosystems. This chapter shows how this transformation takes place by drawing on the Austrian theory of capital, which portrays the capital structure as a changing structure of means–ends relationships shaped by entrepreneurial action aiming to satisfy human needs for a profit. New capital resources, such as new tools, create opportunities for new resource combinations, but only some combinations are technically and economically feasible. The extent of this multiple specificity, together with the extent to which entrepreneurs can abstract knowledge by using a tool, will be a powerful factor concerning whether the ecosystem will remain or shift into a hierarchy or market-based value system. © The Editors and Contributors Severally 2025.