From the Bottom to the Top: Sustainable Heat Pumps in Residential Buildings

Society urgently needs solutions to heat the building stock below 100 °C sustainably. Compared to combustion-based solutions, heat pumps provide low-temperature heat. Therefore, heat pumps avoid high exergy losses due to very high temperatures that occur due to combustion.

This presentation provides an overview of suitable heat pumps for residential buildings depending on the refrigerant choice (from the bottom), the thermodynamic process design, and the system controller functions (to the top). Since design and control are mutually dependent, their interdependencies must be studied to exploit the full sustainability potential of heat pumps in residential buildings.

We highlight recent challenges in the refrigerant choice, the heat pump design, and the controller development (superheat control, defrost strategies, and model predictive control). These topics reveal the high potential for sustainable heating solutions and the need for future research to maximize their sustainability. In this context, sustainability has three dimensions:
(1) economy,
(2) ecology,
       and
(3) social aspects.

Sustainable heat pumps must therefore be
(1) cost-effective in investment, operation, and maintenance to achieve an economic optimum,
(2) relieve the climate to achieve an ecological optimum,
       and
(3) meet further user requirements to achieve a social optimum.

The simultaneous optimization of all three dimensions is a very complex task and requires innovative approaches to be developed in the future.