Vocabulary for the fourth generation of district heating and cooling

The fourth generation of district heating is an established expression for new features and configurations.This generation’s overarching goal is to develop heating concepts for smart energy systems contributingto the net-zero carbon emission society by substituting older district heating generations, originallydeveloped for fossil fuels. The evolving technology generation has to consider the future challenges oflower heat demands, increased cooling demands, and integration of renewable and recycled thermalsources. Driven by these challenges, the district heating and cooling community is fast growing and verydynamic in its innovation. This trend can be observed in the development of cold networks for bothheating and cooling. Several new systems in Europe, North America, and Asia have applied newlydeveloped heating and cooling network configurations. It is essential to consolidate these novel technicalsolutions into the entire family of fourth generation at this stage of development to efficiently andeffectively deploy and expand district heating and cooling solutions. This paper exemplary discussesambiguous terms to demonstrate the shortfall of not having a broad and internationally accepted vo-cabulary. The conclusion gives suggestions for harmonising expressions, terms, and definitions intro-duced and used during the last years. An interactive vocabulary will facilitate innovation and a commonlanguage.