The Single Energy Sustainability Index combines three key sustainability indicators: environmental, social and economic. The use of indicators makes it possible to create an overall index that shows not only how green the region is, but also includes the well-being and economic situation of its population. The study uses a universal formula that is adapted to the case study of Latvia. The energy sustainability index formula combines 12 weighted indicators. The multi-criteria analysis method AHP was used to determine criteria weights for this purpose. Latvia’s overall sustainability index was calculated at 0.48 and only the Riga region (0.65) exceeds the index value for Latvia as a whole. Using this sustainability development index, it is also possible to analyse possible future development scenarios for energy sustainability in Latvia and its regions. To assess the potential for future development and sustainability of regions in Latvia and other countries, it is necessary to continue the study.