Renewable energies lead the energy transition towards a more sustainable and environmentally friendly energy system. Decarbonization and environmental policies, such as Europe’s 2030 Climate Target Plan, favor and encourage this change. Geothermal energy as a renewable energy can play a critical role in the decarbonization within the heating sector. It is an efficient, safe, and clean energy that is not being implemented with the same trend as its counterparts. This study addresses two issues in the implementation of geothermal energy: the calculation of thermal needs and the economic difference in implementation compared to conventional supplies. Therefore, this study presents a simple methodology for sizing calculations for housing developments and economic comparison of the same installation powered by natural gas or low-enthalpy geothermal energy. The comparative terms considered are the initial installation and the annual expense. This comparison seeks to calculate the payback period of the initial geothermal installation, which has been carried out considering various economic scenarios.