The main purpose of this study is to evaluate the trend of sustainability indices of energy during two first-5-year periods in Iran’ s outlook 2025 (2005-2009 and 20102014). In order to evaluate the sustainability of the energy system, we applied the combined sustainable energy index (SEDI). Our study dimensions included are technical, economic, social, environmental, and institutional ones. After calculating the sustainability of all dimensions, they were normalized based on the HDI index calcu-lation method. Afterwards, SEDI index was computed, i. e., by averaging the 5 dimen-sions. The results indicated that technical, economic, and social dimensions in the first 5-year period had positive sustainability rate, but in the second period, unlike technical and economic dimensions that their sustainability rates increased a little, social dimension rate experienced reduction. Environmental and institutional dimensions and also SEDI index had negative sustainability rate in the first 5-year period. SEDI sustainability rate in the second 5-year period became positive (but insignificant) and experienced a sustainable path. Sustainability rate of the environmental dimension in the second 5-year period with a slight improvement still remained negative, and contrary to this dimension, the institutional dimension became more unstable.