An analytical framework for assessing the integration of the waste heat into a district heating system: Case of the city of Riga

Reaching carbon neutrality in cities is the ambition that determines decarbonisation strategy of district heating (DH) systems. Waste heat diffused in the urban environment gives floor for considering this heat for integration into the DH systems. This article presents an analytical framework for assessing the integration of waste heat (WH) into a DH system. The framework is used to estimate whether a selected case study area (city of Riga) can achieve carbon neutrality by implementing three different pathway scenarios of an efficient DH system. The system dynamics modelling approach is used to operationalize the framework and identify the drivers of waste heat integration. Energy, economy, environmental and social indicators are selected and assessed. In case of waste heat integration, the primary energy factor is reduced 2.6 times and 86% of CO₂ emissions are avoided. That moves the selected DH system closer to the carbon neutrality target yet does not allow to achieve it completely. The results show that a positive contribution is made to consumer welfare as the result of avoided heat expenditure. Thus, providing DH system's services that utilise waste heat is justified not only from an environmental, but also from an economic and a social perspective.