The report is a systematic literature review that underpins the IEA DHC DE‑ployment Guide and Toolkit. It surveys peer‑reviewed and grey sources on district heating and cooling (DHC) worldwide, organising the evidence into ten thematic blocks: (1) conceptual foundations and generational frameworks; (2) global market status, typologies and density thresholds; (3) barriers, risks and market failures; (4) policy, strategic heat‑planning and regulatory regimes; (5) ownership models, governance and the remunicipalisation trend; (6) investment, financing and techno‑economic assessment methods; (7) supply technologies, low‑temperature and fourth‑generation concepts, waste‑heat and renewable integration; (8) storage options and district‑scale energy‑flexibility; (9) network design, digitalisation, optimisation and modelling tools; (10) district cooling, integrated heat‑cooling, and emerging tropical solutions. The review also maps spatial‑analysis tools, readiness and maturity frameworks, and social‑acceptance and equity studies. It highlights evidence gaps – notably limited research on cooling, on non‑European emerging markets, and on holistic techno‑economic‑social assessments – and evaluates where the Guide’s prescriptive recommendations are supported or need further validation. The document concludes with a synthesis of methodological quality, a set of evidence‑based recommendations for practitioners, and a research agenda for future DHC studies.
Topics
Generational Frameworks and Thermodynamic Foundations of DHC
Defines first‑through‑fourth‑generation district heating concepts, explains the thermodynamic rationale for low‑temperature and fourth‑generation networks, and outlines density thresholds and their implications for system design.