This joint research project aims at analysing and demonstrating low exergy concepts for the refurbishment of multifamily houses. Low exergy system concepts should be matched with an extended typology for multifamily houses. Furthermore, the refurbishment processes should be analysed systematically and assessed in respect of economic aspects, the achievable user comfort and emission reductions. Afterwards the heat pumps and components being developed in the joint research project will be demonstrated in connection with different heat sources, storages and heat transfer systems. The monitoring results will be scientifically evaluated and compared with the results of the simulations in order to enable a profound assessment of different system concepts.