The researchers from the Fraunhofer Cluster of Excellence CINES looked at the costs incurred for replacing heating systems and also evaluated the emissions of the various technologies, focusing on existing residential buildings and taking into account the funding that came into force on January 1, 2024 in the Building Energy Act (GEG) and the funding guideline "Federal funding for efficient individual building measures".

"When investing in a new heating system, many people focus primarily on the investment costs. Instead, however, all expected costs, in particular the energy source price including the CO2 price component, should be taken into account over the life cycle. The ratio of electricity, gas and, if applicable, district heating is particularly important when choosing the most cost-effective heating system. This was already the case in the past, but the foreseeable rise in CO2 prices over the next 20 years makes it even more relevant," says author Robert Meyer from Fraunhofer ISE, explaining the motivation behind the study.

Positive cost balance even in older buildings

The study found that heat pumps in single-family homes are not only more environmentally friendly, but also more cost-effective than other energy sources. Overall costs can be further reduced by using photovoltaics to generate your own electricity. In apartment buildings, both the switch to heat pumps and district heating are cheaper than replacing gas heating. This positive cost balance also applies to unrenovated and partially renovated old buildings, although the consumption and investment costs are higher compared to energy-renovated old buildings.

In their analysis, the researchers look at current costs for purchase and installation as well as future operating costs for gas condensing boilers using fossil gas, biogas or hydrogen, for air source heat pumps with and without the use of their own photovoltaic system, for geothermal heat pumps, pellet heating and district heating using the case studies of single-family homes and apartment buildings, taking into account various building efficiency standards. They refer to current regulations (regarding GEG – Building Energy Act) and expected future developments in CO2 prices and energy source prices. In view of the high complexity of the decision to convert a heating system, the experts recommend providing consumers with comprehensible information on expected emissions and energy prices, including CO2 prices, e.g. as part of an energy consultation.