Children and young adults spend more time in schools and educational buildings than in any other place, except at home. Classrooms are the place for pupils and students to learn and get educated. It is known for some time that unsatisfactory environmental conditions can have both short-term and long-term health effects, and can affect productivity or learning ability of pupils and students. In the last decades, many studies all over the world have been performed to document the indoor environment in classrooms and to examine relations with diseases and disorders. At the same time, energy efficiency strategies and climate actions seeking for zero greenhouse gas emission, are introduced. It is questioned whether the design and/or retrofit of highly sustainable educational buildings might introduce even more problems with health and comfort of its main occupants. The main aim of this Special Issue is to study both IEQ and energy of new, retrofitted and existing educational buildings to shed light on the interrelations between health of pupils and students and energy efficiency strategies in different parts of the world.