With a view to ensure adequate control of risks associated with environmental impacts from energy consumption, the scope of the Integrated Management System in Greece was expanded, in 2016, with the development and certification of the Energy Management System according to the ISO 50001 standard. ISO 50001 Energy Management System, in combination with the existing ISO 14001 EMS, is a major tool for the implementation of energy conservation measures and the improvement of energy efficiency. The scope of the System is gradually expanded and in 2021, was implemented in 22 building complexes (including technology and office buildings, data centers, call centers, shops and the head office of the OTE Group) and 59 mobile telephony base stations. Results are encouraging since energy savings exceed 6% in buildings / shops, 10% in data centers and 15% in mobile base stations. The strategic aim of OTE Group, is to further enrich its portfolio with facilities certified according to ISO 50001 (Greece).