To reach international climate goals, the research about energy consumption have to focus more on existing buildings. In the building sector, the increase of energy efficiency of buildings will not be sufficient to reduce the consumption of fossil resources significantly. Therefore the application of renewable energies have to increase as well. Seasonal heat storage systems can support this process because the storage enables heat supply and heat demand to be decoupled time-wise. Nevertheless, innovative systems, which are using renewable energy for heating, are always in a competition with conventional heating systems, which are using gas or oil. They must be equally efficient in technical and economic aspects. For that reason, this study is focused on the comparison of a heat supply with seasonal heat storage systems in connection with a solar thermal system and a heating system with gas. For this comparison a technical system and an operating model was established. This system was analyzed by his economic parameters with complete finance plans. As a result, it is shown, that sustainable heat supply is not much more expensive than conventional heat supply. In addition, the social acceptance of different stakeholder is affected by these parameters. Therefor expert interviews with investors were done.