The National Energy Efficiency Programme (E03) is the structural instrument for the energy transition in São Tomé and Príncipe, designed to reduce inefficient consumption, technical losses and emissions in all sectors — residential, public, productive and transport. Led by MIRN and implemented by DGRNE, the programme promotes institutional reforms, technical and financial support, network modernisation and the expansion of sustainable technologies, integrating directly into PANEE 2021–2050 and PADRES 2024–2035. The initiative operates at the national level and combines efficient public lighting, energy labelling, clean cooking, electric mobility, and governance and capacity-building mechanisms, positioning the country to achieve a modern, affordable, and low-carbon energy system between 2025 and 2035. With a total estimated investment of USD 45 million, distributed among grid modernisation (33%), domestic efficiency (16%), clean cooking (18%), electric mobility (22%) and management/capacity building (11%), E03 creates a dynamic domestic market for clean technologies — from LED lighting to efficient appliances, improved stoves, electric vehicles and charging infrastructure. The expected impacts are profound: more than 12.9% energy savings by 2050 (≈9 GWh/year), an annual reduction of ≈6 million USD in fuel bills and new opportunities for local SMEs in installation, maintenance, services and recycling. This is a strategic investment that combines modernisation, sustainability and economic competitiveness, accelerating the energy transition in São Tomé and Príncipe.