Promoting sustainability in educational systems is crucial for preserving resources and diminishing negative impacts on the environment. A key aspect of this is enhancing energy efficiency within educational institutions. By implementing energy-efficient building systems, advancing the use of renewable energy sources, and incorporating sustainable practices into the curriculum, educational institutions can decrease their environmental impact and conserve resources for future generations. Active participation from all stakeholders, including managers, teaching staff, and students, is essential for the success of these efforts. Providing students with a comprehensive education on sustainability equips them to apply this knowledge in their future professions, thus contributing to a more sustainable society. This research paper aims to explore ways to increase sustainability in Latvia's vocational education system, with a specific focus on reducing energy consumption in buildings and increasing the use of renewable energy sources. A study of 23 professional schools has been conducted to understand the current state of sustainability in the educational system, including data collection on energy consumption and surveying the schools on their current energy efficiency practices, renewable energy sources, and environmental policies. The energy efficiency and renewable energy production measures have been optimized for each school. A composite indicator has been developed to rank and compare schools based on their sustainability, promoting the use of energy-efficient and renewable energy sources within a limited budget. Results of the study show that by implementing mandatory and optional measures, the schools can significantly decrease primary energy consumption by 32% and greenhouse gas emissions by 33%.