PA21E is a programme for schools, which fits into the city’s Agenda 21. It was designed in 2000 in the Environmental Education and Participation Division, of the city’s Environment Department. Through this programme, the educational communities are involved in diagnosing, providing solutions and undertaking commitments to make a more sustainable city, beginning with their immediate environment, the school itself. A slogan that summarizes of PA21E philosophy is “Many small people, in small places, doing small things, can change the world” (Eduardo Galeano).

Schools are seen as extremely important in the advance towards more sustainable cities because of their function of educating future adults and their multiplying effect in the community via families. All non-university level schools participate in the PA21E: nursery (0-3 years), infants (4-6) primary and junior (7-12), secondary (13-18) and all levels of special education schools. In 2009-10, there were 326 schools participating. In 2008/09, over 260 projects were carried out on: energy and water saving, noise reduction, paper saving, waste prevention, composting, sustainable mobility, organic gardens, biodiversity promotion, responsible consumption, improving communication, building participation and co-existence etc. This programme encourages inter-generational interaction around climate protection. It has been replicated by other Spanish, Italian, Portuguese and Latin American cities.