The objective of this study is to offer a view on the different environmental factors that affect health (sound, light, colour, temperature) in the design, planning and organization of school premises. To achieve this, the authors first outline the problems leading to unhealthy situations. They subsequently analyse all the building and planning factors behind those problems based on a study carried out in the Autonomous Community of Galicia, in the north west of Spain. The study took as its subject all secondary-level education centres built in Galicia since the Spanish Basic Act on the Educational System (LOGSE) was passed by the Spanish Parliament in 1990. To conclude, the article offers a number of guidelines to be taken into account when designing a school environment.