Nature-Based Solutions in schools: a green way to adapt buildings to climate change in Solana de los Barros, Extremadura (Spain)

Several NbS were designed, implemented, and tested in a primary school in Solana de los Barros (Badajoz, Extremadura, Spain), as part of the myBUILDINGisGREEN LIFE project.

The implemented measures can be classified into four main categories: green roofs, green facades, ventilation, and development of outdoor areas.

Firstly, green roofs have been implemented in the school building. Green roofs are a promising option to reduce the temperature in buildings while increasing local biodiversity, making the living environment more pleasant and providing the option of a direct learning experience on adaptation to climate change for the students.

The pilot building tested three types of green roofs with a variety of more than 25 native plant species. The first solution was an extensive green roof (mBiGCUVE 1), while the second solution was a roof with an inner air chamber located between the roof and the vegetation substrate (mBiGCUVE 2). It was tested to retain higher temperature, while also improving humidity levels and thus reducing auxiliary irrigation demands. The third solution included a more sustainable substrate (mBiG-SUS) that allows for better rainwater filtration. The main sustainability of this substrate lies in the fact that it is composed of recycled aggregates for the realisation of the roof drainage. Two of these green roofs reuse excess water by gravity to make it available for irrigation.

The second category of NbS is green facades. The implemented green facades system includes a system of planters set on metal structures parallel and perpendicular to building facades. It includes climbing plants that protect the facade from sunlight. There is also a vertical awning system with mineral substrate for vertical vegetation growth. It includes plants for hydroponic irrigation that incorporates nutrients into the system and allows their growth on the mineral substrate. In an internal corridor of the building, an indoor vertical garden with a wide variety of plant species has been installed to maintain adequate humidity levels and contain the high temperatures experienced in this room. This system requires continued maintenance and pruning to avoid the fall of the wall due to overweight.

Next, a ventilation system was included in the building, allowing fresh air to circulate in the school during the night and morning hours (9:30-10:00 / 12:30-13:00). The induced natural ventilation system was created by programming the automatic closing and opening of five windows. This measure cools the environment, reduces the indoor CO₂ concentrations and favours re-oxygenation inside the classrooms.

Further interventions were carried out in the school playground. In addition to planting trees for natural shading, several measures have been implemented such as:

• Vegetated Pergola: it includes a planter system set on metal structures similar to the one described for the green facade but without anchoring to building facades. It includes deciduous climbing plants.
• Porous paving: permeable surfaces that improve rainwater infiltration, reducing runoff into the sewage system. This type of pavement also allows the growth of natural vegetation.
• Wooden structures for shading of recreational areas: these structures are located in playgrounds with a high occupancy rate by pupils. They were designed in collaboration with the educational community of the pilot building.

In order to measure the impact of the solutions implemented in the pilot building, a monitoring plan has been developed and the measurements were carried out. As NbS require a long time before all the effects become measurable, the monitoring scheme will continue after the end of the project, until spring 2028. This long-term monitoring scheme has been included in the After-LIFE Plan of the myBUILDINGisGREEN LIFE project, which is available in the results sectionof the project website. A framework of 22 indicators was established to measure: a) temperature change (indoor temperature inside and in the building envelope, outdoor temperature and humidity, and estimated energy and heating savings); b) water management (estimated savings related to water consumption and savings in rainwater management); c) green area management (increased plant and animal biodiversity and number of recovered native plant species suitable for integration in green areas); d) indoor air quality and noise reduction (CO₂ concentration levels inside the classrooms, noise reduction levels from outside and pollution levels through installation of bio-indicator species and training in their observation); e) urban regeneration (energy efficiency and increase in green area (surface area and percentage));, f) governance and participation (citizens' perception of urban nature, number of education policies and strategic plans for climate change adaptation that include NbS and open participatory processes); g) social cohesion (number of agreements with stakeholders for possible replication activities); h) public health and well-being (reduction in the number of pupil absences and teacher sick leaves) and i) economic opportunities and employment (number of jobs created, creation of new skills in self-employed and NbS-related businesses in the area and reduction of school staff absenteeism). More information on the monitoring plan can be found in a dedicated video from the online training created in the framework of the myBUILDINGisGREEN LIFE project.