The evaluation of a country’s energy system performance is centred on three key imperatives of the energy triangle: –Security: ensuring a stable and resilient energy supply through diversification (across the energy mix, trade partners and electricity generation sources), grid and power supply reliability, and robust infrastructure to enhance adaptability to external shocks –Equity: ensuring access to energy for all (consumers and industries), energy affordability and price stability while supporting economic growth and development –Sustainability: advancing the environmental performance of energy systems to support a low-emissions, resource-efficient, clean-energy future by reducing carbon dioxide (CO2) and methane (CH4) intensity, improving energy efficiency, lowering per-capita energy and emissions footprints and increasing the share of clean energy in final demand through balanced demand- and supply-side measures A country’s energy transition progress also depends on its transition readiness – the ability to establish a strong enabling environment for the transition. Transition readiness is driven by the following core enablers: –Regulations and political commitment: creating robust policies and regulations that are essential for cultivating a competitive energy transition –Infrastructure: ensuring the physical and digital infrastructure is robust enough to support the transition to a low-carbon economy –Education and human capital: developing a skilled workforce capable of meeting the demands of the emerging clean energy sector –Innovation: developing cutting-edge technologies in energy systems, essential for sustainability and security –Finance and investment: ensuring a sustainable financial ecosystem that can attract investments at scale to support energy transformation As part of the ETI, countries were assessed using 43 indicators that captured key aspects of the energy transition across the three key imperatives of equity, security and sustainability, as well as the transition readiness dimensions. The data was sourced from many different organizations, with emphasis on ensuring data quality through relevance, coverage, comparability, recency and quality of sources. ETI scores use a 0-100 scale, with 100 representing the highest global performance for each indicator and index component. Results reflect the latest available data at the time of collection. Combined with index improvements, these changes reduced the comparability of the 2025 ETI with previously published editions. Moreover, while no index can fully mirror all the factors and complex realities impacting energy systems and transitions, the ETI scores aim to reflect both performance and contextual circumstances. Also, external factors – such as commodity market fluctuations, geopolitics, international climate action and financial market conditions – influenced certain dimensions of a country’s score. As such, scores should be interpreted as a reflection of both performance outcomes and enabling conditions, and viewed in the context of each country’s structural realities rather than as an absolute ranking of transition progress (Box 1). Further details on the methodology are available in the appendix. Key terms of the ETI methodology BOX 1 Score reference All scores in this report (from individual indicators to the overall index) are based on a 0 to 100 scale, with 100 being the highest possible value. Scores reflect the most recent data and updates available at the time of production.System performance score This score reflects how a country’s energy system was performing in terms of security, equity and sustainability, using 23 indicators to give an overall picture.Transition readiness score This score reflects countries’ preparedness to support future energy needs, using 20 indicators assessing enabling factors such as regulation, infrastructure, capital and investment environment, human capital and innovation capacity.Global and regional averages References to global, regional or overall scores for the index or its components refer to the simple average of all country scores – not adjusted for size, gross domestic product (GDP) or population unless noted. Fostering Effective Energy Transition 2025 9