Cooling hot cities by giving LIFE to buildings

With heatwaves becoming more intense due to climate change, city residents and workers need help to stay cool. Green spaces can provide shade and respitefrom the heat, but not all cities have room for new parks or trees amidst the buildings and busy streets. One answer could be to turn the concrete jungle itself into a green space - and that's exactly what the BIG4LIFE project aims to do.

BIG4LIFE promotes green roofs and building facades to demonstrate how so-called 'building-integrated greenery' (BIG) can improve city life in Lleida, Barcelona and El Prat de Llobregat in the Catalonia region of Spain in collaboration with local communities. Urban greening solutions like this are a key part of the New European Bauhaus initiative and are being highlighted by the EU Covenant of Mayors' Cities Refresh campaign, which focuses on ways municipalities can cool their built-up spaces.

The BIG4LIFE project team is collaborating with those responsible for maintaining 8 different buildings that have existing greenery built into their structure, studying how they are boosting biodiversity, the impact they are having on people nearby and how they can be maintained with minimal costs. Among the buildings included in the project is an office in the Tibidabo amusement park in Barcelona which has plants growing on its outside walls. Another is a historic residential buildings in the old town of Barcelona, where a green roof serves as a community space for the residents of the building.

Part of the challenge is ensuring the vegetation can survive in the harsh Mediterranean climate and demanding urban environment, where concrete, glass and metal absorb heat and raise temperatures. BIG4LIFE combines a method of water conservation known as xeriscaping with planting drought-resistant species, while reducing evaporation and run-off with stones or mulch to cover the soil. The project is also working with residents and owners of the buildings to ensure they can be part of the ongoing maintenance of the greenery incorporated into them.

'BIG4LIFE will demonstrate that by applying xeriscaping and networking approaches, supported by suitable smart solutions, not only is the long-term viability of BIG systems feasible, but the ecosystem services they provide can be enhanced,' says project manager Laura Herrera Díez, of the University of Lleida.

The team have already refurbished a failed green roof on the L'Artesà Auditorium in El Prat de Llobregat, removing weeds and replanting with drought-resistant, sun-loving sedum. Camera traps enable the team to study the birds and animals visiting different buildings - the green roof of a research facility in the Agrobiotech Park in Lleida, for example, attracts birds including magpies and house sparrows.

Another project contributing to the aims of the Cities Refresh campaign is Life + A_GreeNet , which combines soil restoration, urban forests, green walls and green roofs to boost climate resilience in several cities on the Adriatic coast of Italy. In the summer of 2023, for example - when temperatures topped 30°C for weeks at a time and hundreds died from extreme heat - the project's Climate and Health Observatory called for solutions including urban greenery, fountains and urban lakes, whilst reducing the area covered by asphalt. Many of these are now being integrated into urban plans which aim to reduce surface temperatures by 4-10°C by 2030.

'The challenge that climate change presents us is not only technical, but also cultural and political,' says Laura Antosa, project manager of Life+ A_GreeNet. 'We need to rethink urban spaces: quality of life and people's health must be at the heart of design.'

BIG4LIFE and Life+A_GreeNet are highlighted as part of the Cities Refresh campaign. They also contribute to the EU Strategy on Adaptation to Climate Change and the New European Bauhaus.