Aquifer Thermal Energy Storage (ATES) Systems is a technology to sustainably and economically provide space heating and cooling. However, it cannot be applied everywhere because successful application depends on the presence of a suitable aquifer and favorable climatic conditions. Despite some operational ATES systems, the Spanish ATES market is immature, and there are no regulations or guidelines developed. To foster ATES adoption in Spain, this paper introduces a potential study considering the resource potential, technical, economic, and environmental aspects. The GIS-based approach is focused on the geographical identification and assessment of the aquifer potential for ATES and climatic conditions. This allows to distinguish those areas considered more suitable for ATES systems for the residential and for the tertiary sector. The results show where in Spain potential for energy and GHG savings with ATES can be found. 38% of the aquifers in Spain show potential for ATES and 63% of large urban areas in Spain are located in such areas. Also, 50% of the population lives in areas where the residential sector seems to be suitable for ATES based on the climatic conditions. Energy and GHG savings can reach up to 91% and 68% respectively, derived from the use of ATES.