Techno-ökonomische und ökologische Analyse von Sanierungspaketen aus Gebäudehülle und LowEx-Systemen: Bericht zu AP 5

The aim of work package 5 of the project "LowEx concepts for the heat supply of existing multi-family buildings" is a techno-economic evaluation of the renovation packages – renovation measures on the building envelope and replacement of the heating system – for existing multi-family houses in Germany. For this purpose, investments in LowEx systems with heat pumps (HP) in an existing medium-sized apartment building with an older gas boiler, in which refurbishment measures are to be carried out, are evaluated with regard to their economic and ecological effects and compared to a modern gas-fired condensing boiler. A distinction is made between different levels of renovation and refurbishment scenarios. In addition, the perspectives of both landlord and tenant as well as the sensitivities of the profitability of the investment with regard to the input data are examined. The results show that a reduction in CO2 emissions of up to 800 kg/m² compared to the original system can be achieved through energy-related envelope refurbishment with a change in the heating system to a mono-energetic HP (corresponds to a reduction of 85 % over the period under consideration). In the target year 2045, the CO2 emissions can even be reduced by approx. 95 % by the mono-energetic HP. In the main scenario, the renovation package A60b (bivalent outdoor air heat pump system with gasfired condensing boiler, HP designed for 60 % of performance based on a bivalence point of -5 °C) in combination with insulation measures on the exterior wall and windows is the most economical from the point of view of the energy-related additional investments. Due to the long observation period of 25 years, the economic efficiency of the LowEx systems compared to a new condensing gas boiler is strongly influenced by the future development of gas and electricity prices. However, the net present value of the LowEx systems remains positive in almost all scenario combinations considered in the sensitivity analysis.