Heating drinking water with heat pumps – energy-efficient and hygienically safe

The project addresses the conflicting objectives: whilst heat pumps are central to a climate-neutral heat supply, their efficiency requires low system temperatures – whereas drinking water hygiene (particularly the prevention of Legionella) in centralised systems may necessitate higher temperatures and impose further safety requirements. In multi-family dwellings in particular, this creates a tension between climate protection and health protection, which must be resolved in a practical manner for the roll-out of heat pumps in existing buildings.

The aim of the study is to classify technical options for domestic hot water heating using heat pumps in existing buildings on a scientifically sound basis and to transparently evaluate their energy, hygiene and economic performance. This also encompasses the question of which regulatory, funding and governance adjustments promote hygienically safe and, at the same time, efficient operation. Methodologically, the project combines literature and regulatory analysis, the evaluation of specific technical options, dynamic simulations of typical configurations for heating systems, economic feasibility analyses and projections of energy and system impacts. Based on this, policy options (regulatory frameworks, funding, information) are developed, tested in stakeholder workshops, and the results are tailored to the needs of planners and tradespeople.