Achieved lowered local temperature

HortaFCUL is a project created and managed by the Faculty of Sciences at the University of Lisbon to raise awareness and promote the practice of permaculture as a solution to the ecological, social, and economic problems the world is facing (1). This initiative began in 2009 on the University campus through a garden, which allowed HortaFCUL to start conducting some activities that could answer some socio-environmental challenges, such as food security and sovereignty, ecosystem degradation and climate change (13), by raising awareness, teaching, and practising many aspects involved in permaculture and urban agriculture (2). Its focus has been on regenerating soil in an urban environment and creating productive landscapes for people and other beings (12). They grow different types of plants (vegetables, shrubs, trees) in different ways (swales, raised beds, greenhouses) to increase plant diversity and foster ecosystems (13).
The project is managed by students and researchers, who hold educational activities, such as courses, workshops, and dissemination activities (events, discussions, fairs, and conferences) (2). The project is organised according to a non-hierarchical sociocratic model, in which all decisions are made as a group, and where all ideas, critiques, and suggestions are seen as added value and an opportunity to improve techniques and knowledge (3). Additionally, it is open to the community, allowing anyone interested to participate and volunteer (1).
HortaFCUL is also one of the pioneering permaculture projects in operation in the Lisbon region and is now recognized as a national reference centre for permaculture (2). Since its inception, HortaFCUL has sought to be a hub that attracts people, organizations, and other initiatives, and it is currently a point of contact between different projects and associations, such as local businesses, educational institutions, and networks (5).

Sri Lanka faces multiple natural hazards, including tropical storms, flash floods, and landslides. As the country's urban population has grown, development projects have encroached on wetlands, compromising their natural flood protection, air and water purification, and carbon storage capabilities. Additionally, hilly regions are at risk of landslides, particularly during the monsoon season, posing significant threats to vulnerable communities (4).
To address these challenges, the World Bank and the Sri Lankan government collaborated on the Metro Colombo Urban Development Project. This initiative focused on nature-based solutions (NBS) as cost-effective and sustainable approaches to risk management (4). By strengthening natural processes and ecosystem services, the project aimed to mitigate hazards such as floods, erosion, and landslides (4). Technical assessments by the World Bank highlighted the importance of wetlands in flood protection, leading to efforts to protect and restore 20 square kilometres of freshwater lakes, wetlands, and swamps (1, 4).
The project supported the Sri Lankan government in reducing flooding in the Colombo Water Basin and enhanced local authorities' capacity to manage infrastructure and services. It prioritised metropolitan investments to mitigate the physical and socioeconomic impacts of flooding and aimed to build long-term capacity for urban management and local service delivery (6).

The schoolyard at Reginhard Primary School in Reinickendorf faced persistent challenges, often becoming unusable due to poor drainage. After rainfall, water would pool, leaving the yard submerged and inaccessible to the 400 primary school pupils. Even in dry weather, the schoolyard was far from ideal: a lack of play equipment made it uninviting, and in summer, the area became excessively hot, offering little comfort or shade. Both children and the school community, including teaching staff and parents, voiced a strong desire for improvement.
Adding to the urgency for redesign, Berliner Wasserbetriebe imposed a discharge restriction, requiring rainwater to be managed on-site. This led to a comprehensive transformation of the school grounds. Large areas were unsealed, allowing water to seep naturally into the ground. Underground seepage systems were installed to enhance drainage, and the redesign introduced green spaces, a school garden, and near-natural play and exercise areas. These changes not only resolved the flooding issue but also created a more inviting and sustainable environment for students.
The focus on ecological and sustainable design improved the microclimate, providing cooler surroundings and enabling outdoor breaks filled with activity and fresh air. The redesign transformed the schoolyard into a vibrant space that meets the needs of both children and the environment.
This project was funded by the Berlin Programme for Sustainable Development (BENE Umwelt) and financed by the European Regional Development Fund (ERDF). (Ref. 3; Ref. 4)

On a small roadside green space in Berlin, a tiny forest was created. The idea of Tiny Forests comes from Japan, there are already some in France and the Netherlands, and since 2020 also in Germany. Tiny forests are constituted of trees planted densely next to each other in small spaces, such as tiny green roadsides.
At Oderstraße, the NGO TinyForestBerlin planted an even smaller forest, a nano forest on a roadside where trees cool down the area, filter the air and create a habitat for insects. Trees in urban areas loosen up the dense and degraded soil, allowing it to store carbon and let rainwater properly seep into the ground to prevent urban flooding. Roadsides are hardly utilised or recognized in their environmental potential, such as hosting a nano forest. Projects like the one implemented by TinyForestBerlin present an approach for collaboration between the district and civil society, as the district's park department lack the capacity to maintain small roadsides. The project at Oderstraße is the first official tiny forest in Berlin, as a previous planting campaign in Friedrichshain was not entirely legal due to missing approval of local authorities. (Ref. 2; Ref. 5)
The TinyForestBerlin association has set itself the goal of creating such small nano-forests all over Berlin. An ambitious project that aims to enrich the city's green spaces and contribute to improving the urban climate. The trees planted on Oderstraße are one of many smaller planting projects that are spread throughout the city on public as well as private land. (Ref. 3)

On the site of a former malthouse in Berlin, a company has developed a sustainable rainwater storage system to prevent flooding in the sealed environment, which had been vacant for several years. Once used for malt production, the site is now home to offices, studios, manufacturing businesses, and hosts sustainable events. The site's transformation includes natural gardens, tenant gardening beds, green roofs, and two outdoor water basins that retain rainwater, creating a blue space for recreation. (Ref. 1)
The two ponds are filled with filtered rainwater, and an underground tank stores additional water, allowing it to seep away gradually. Native plants surround the ponds, creating a habitat for local wildlife. Given that much of the surrounding area is sealed, the ponds help mitigate urban flooding by managing and storing rainwater, reducing the site's reliance on the urban sewage system. Additionally, as Berlin faces extreme heat in summer, the project offers a cooling effect and provides access to filtered water during droughts. (Ref. 1; Ref. 2)
The project is managed and financed by IGG Malzfabrik mbH, which oversees the entire site in Berlin's industrial area and rents out office spaces to various companies. This initiative is part of a broader sustainability strategy that addresses social, economic, and ecological factors, and it is featured in the company’s common good economy report (Gemeinwohl-Ökonomie Bericht). (Ref. 5)

The Torre Sevilla is a commercial building complex with extensive green roofs. The green roofs cover 11000 or 12000 m2 (different sources report different numbers) and aim to contribute to thermal isolation and energy efficiency of the building, improve air quality and provide an urban green space for relaxation and recreation [Ref. 1-3]. The green roofs include a mosaic of different vegetation types and about 60 mostly native plant species. There is a rainwater recovery system that allows the gardens to be irrigated in a sustainable way [Ref. 1-3, 6]. The building finished construction in 2017 and the gardens were initially not available to the public. In 2023, the owner applied for a permit to host events in the gardens, which will allow the public to visit on occasion [Ref. 1, 3-5].

In an architecturally important area of Berlin, situated between the Landwehr Canal, the Kulturforum (the Berliner Philharmonie and the Berlin State Library) and the new construction on Potsdamer Platz, a combination of green and grey infrastructure has been realised to minimise the burden on Berlin’s existing water infrastructure.
Green and non-green roofs harvest annual rain, which flows through the site’s buildings and is used for toilet flushing, irrigation, and fire systems. The roofs retain and then release water to the large on-site buffer pond, which has five underground storage tanks. Next to the roofs, a series of urban ponds and connecting canals have been implemented, with a combined area of approximately 1.2 hectares. They are filled with rainwater, creating an oasis for urban life. Vegetated biotopes are integrated into the overland landscape and serve to filter and circulate the water that runs along streets and walkways. The lake’s water quality is excellent, forming a natural habitat for animals and cooling the surroundings, while fresh water usage in the buildings has been reduced. (Ref. 1; Ref. 2; Ref. 3; Ref. 6)
The project was implemented in the 1990s as part of the development of Potsdamer Platz in the wake of the reunification of Germany. Several architects collaborated on the implementation that was completely privately funded. Beyond its ecological and technical features, the site is a blue natural site in the heavily built city centre of Berlin and allows people to linger and enjoy natural features. The drainage system won several sustainability prices and is considered a successful integration of nature and technology-based mechanisms to foster climate change adaptation. As the rainwater system stores rainwater in underground tanks and ponds, the urban sewage system is relieved during heavy rain, and water can evaporate. Therefore, the small water circle is closed, and the microclimate is cooled. (Ref. 2; Ref. 6)

Biotope City Wienerberg is located in the southern part of Vienna on a 5.4-hectare site that once housed a Coca-Cola factory. It lies at the edge of the Wienerberg recreational area, surrounded by business parks and tower blocks to the west and predominantly detached houses to the east (Ref. 1).
The project embodies the concept of an "urban biotope" (Ref. 2), grounded in the principle that nature's mechanisms of self-regeneration are essential for mitigating the challenges of urban living and climate change. By integrating urban and natural spaces, Biotope City fosters both human-nature connections and social interactions through activities like community gardening. The project’s centerpiece is its extensive green infrastructure, including trees and green roofs, which serve to cool the microclimate, purify the air, enhance water retention, and create carbon sinks while providing habitats for local wildlife. These green spaces aim to improve physical health through cooling effects on hot days and support mental well-being with their calming influence (Ref. 1; Ref. 2).
Biotope City encompasses:
Around 980 flats, including 400 subsidized flats and 200 SMART flats
A school, a kindergarten, and 2,000 square meters of children's and youth playgrounds
600 square meters of community gardens and 3,850 square meters of ground-floor gardens
250 trees, 8,900 square meters of meadows, and 13,600 square meters of green roofs
2,200 square meters of façade greening
The inner courtyards and roof areas are designed for gardening, while façades are greened, and balconies are equipped with integrated plant troughs. Even the spaces between buildings are climate-effective, featuring unsealed catchment and seepage areas to manage water sustainably (Ref. 1).
The project’s implementation took 18 years and involved collaboration among various stakeholders. The concept was initiated by the Biotope City Foundation and funded by eight different investors (Ref. 2).

The Leopold-Rister park, named after a former district officer, is located in the Margareten district in Vienna and was renovated in 2023 based on the community's wishes for recreational opportunities. The park is surrounded by residential buildings and featured a playground for children, some greens and a football pitch. (Ref. 1) On the initiative of the city government, local residents and people using the park were surveyed on their preferences and needs for a potential redesign of the park. (Ref. 8) Within a year, the park was remodelled, featuring the wished for elements by locals, and was opened in 2024.
Spaces for recreation like playgrounds, benches, and gaming tables were increased or installed. To reduce the heat stress of the urban environment, trees were planted that provide shadow and water play for children to cool down were implemented. Already existing lawns and greens were restored, and new shrubs were added to provide habitats for different local insect and bird species. (Ref. 1; Ref. 6)
The project was initiated and financed by the City of Vienna and presents one of many greening activities that the city pursues to adapt to climate change. (Ref. 1; Ref. 2)

The redesign of Reinprechtsdorfer Street in Vienna is a greening initiative aimed at climate adaptation by reducing local temperatures and increasing green space in a densely built urban area. Implemented within one year, the project included planting trees, adding green beds, and widening the pavement to create a more inviting environment. New seating areas, drinking stations, and water play installations were introduced, providing spaces for relaxation, cooling off during high temperatures, and fostering social interaction. Accessibility and traffic safety were enhanced by leveling the pavement with the street and adopting a one-way system for cars.
The project, realized in 2023, was part of Vienna's city-wide "Out of the Tarmac" initiative and was spearheaded by the district and city council. It originated from discussions and a participatory design process with citizens dating back to 2014. Previously, Reinprechtsdorfer Street served as a congested connection between Wienzeile and Gürtel. The plan seeks to transform it into a “climate-friendly shopping street.”
The redesign involves planting 32 new trees accompanied by flower beds, plus three standalone flower beds. Sidewalks were widened, and amenities included parking for 36 bicycles, nine benches, and seating for 46 individuals. Cooling features such as two water installations, three mist columns, and two drinking hydrants will enhance comfort.
Renovation began in spring 2023, focusing first on the 400-meter stretch between Schönbrunner Straße and Arbeitergasse. A structurally separate one-way cycle path will link Schönbrunner Straße to Bräuhausgasse, while the existing cycle lane against the one-way system remained unchanged. (Ref. 1, 2, 6)