Belgium

Candidate – Belgium

Submission by: City of Antwerp

Project name: Garden streets

 

Short description

To cope with climate challenges, the city of Antwerp began experimenting with a new integrated co-creative urban planning process in 2017, known as “garden streets”. Garden streets are designed with the goal of maximising (1) greenery, (2) blue-green infrastructure, and (3) social cohesion.

In 2023, following an intensive urban planning process, the first five streets were transformed into garden streets. An outcome of the experimental garden streets is its pioneering and innovative role showcasing that all cities and communities can realise garden streets, even within the most dense areas. Therefore, the next step is to upscale the concept of garden streets further by applying the lessons learned from the urban planning and design process, thereby enhancing the liveability. Within the city of Antwerp, more garden streets are being designed based on the lessons learned of the first experiment. However, an unexpected result is that the concept of garden streets is starting to become well-known within Belgium, leading to the emergence of new garden street designs that will be implemented in the near future in other cities and communities.

Social cohesion

Social cohesion ranks among the primary goals of garden streets, acting as remarkable catalysts for encouraging unity within urban communities. By involving street users from the project’s initial phase, these streets evolve into interactive shared spaces, fostering experimentation, co-creation, and inclusivity. Street users, acknowledged as authorities on their street’s liveability, initiate green spaces through planting and maintenance efforts. As the name suggests, Antwerp’s garden streets foster shared ownership and responsibility, achieved through collaborative activities like gardening, maintenance, and events. The designs also encourage communal interactions, offer recreational opportunities, provide gathering spots, and feature play areas that promote spontaneous encounters. For instance, in Bloemstraat, residents maintain 80% of the greenery, and co-creative workshops initiated communal activities such as summer brunches and street festivities. Moreover, these inclusive garden streets accommodate people of all ages, background and abilities, ensuring everyone’s participation, fostering a neighbourhood identity, and strengthening unity and social cohesion.

Biodiversity

Biodiversity is inherently linked to garden streets and the city of Antwerp is committed to a strict policy of using native, insect-friendly plantings. By maximizing the presence of high-quality greenery, we enhance biodiversity. Garden streets cultivate pockets of greenery, fostering habitats for diverse plant and animal species. Whenever possible, trees are planted in a manner that allow them to grow up to 100 years boosting the green volume and its positive impact.

These trees significantly improve the quality and quantity of natural habits. Garden streets form micro-ecosystems contributing to biodiversity and acting as a corridor between the urban core and its surroundings promoting a healthier and more resilient urban ecosystem.

Recently, greenery maintenance shifted to focus on biodiversity. For example, we adopt less frequent, higher grass mowing (extensively maintenance) nurturing the growth of diverse herbs attracting insects and organisms that coexist with trees and shrubs contributing to pest control.

Economic factors in urban environments

Garden streets illustrate how innovative urban design, coupled with blue-green infrastructure, have positive economic outcomes. No specific data, such as property value or long-term maintenance costs, are available yet. Nonetheless, the initial investment cost only slightly surpasses that of a regular street. Maintenance expenses are comparable, despite the significant increase in green space. Co-maintenance by street users and a reduction in grey infrastructure suggest no substantial rise in maintenance costs.

The process has also led to new agreements on investment costs between Antwerp and our sewage partner, jointly investing in blue-green infrastructure as the new designs reflect a reduced strain on the sewage system.  

Other indirect economic benefits occur, such as (1) greener surroundings correlating with improved health, (2) urban revitalization attracting new residents and events, (3) stimulating local businesses, and (4) tourist guides traversing garden streets. Garden streets represent a long-term community investment, promising enduring economic advantages.  

Climate

Garden streets have substantial climate adaptive potential, primarily due to their incorporation of blue-green infrastructure and water-sensitive design. Notably, their drainage system is designed to capture and re-use and locally infiltrate rainwater. For instance, a case in Lange Riddersstraat, where two years of  rainwater monitoring reveal zero runoff into the conventional sewage system, i.e. not a single drop of rainwater. Instead, rainwater is either reused through manual pumps (utilizing four water basins covering 4,000 m²) or naturally infiltrated via the greenery and water-permeable infrastructure. This dual approach effectively mitigates flood risks, fosters groundwater refill, and establishes a balanced water cycle, even during dry periods.

The presence of greenery and trees also significantly regulates temperature, increasing evaporation and providing shade, which fosters cooler microclimates. This, in turn, enhances thermal comfort and mitigates the urban heat island effect. For instance, In Jan Olieslagersstraat, climbing trees with a wide shape are planted to create maximal shade and leaf volume.

 

Wellbeing of users/visitors

After the presence of five garden streets, an increase in citizen demand for garden streets in their own neighbourhoods is observed. Garden streets enhance the well-being through multiple factors.

The presence and visual and sensory aspects of trees and flowering plants in densely populated zones significantly stimulates physical activities like walking and recreational activities. Furthermore in Aziëlaan, the design incorporates multifunctional street objects that encourage children’s play, offer gathering spaces for spontaneous interactions, and facilitate social encounters.

Additionally, the act of gardening and maintaining the greenery right outside one’s home reduces stress, enhances social connections with neighbours, and increases psychosocial well-being. It creates a sense of ownership and social involvement, as seen in collective planting events like those in the garden quarter of Berchem. An affecting example involves a wheelchair-bound man who, unable to access his patio, found solace in a safe sunny spot among “his little garden” on the street.

 

Selection, origin and quality of used products and materials 

Construction materials: Antwerp prioritizes circular economy principles in construction. Locally sourced materials, low-impact design, and material repurposing are central. Sustainable choices like permeable pavements and recycled materials reduce environmental impact, e.g. the water-permeable materials are easy to maintain or restore as the stones are not attached with mortar and can easily be re-used or renewed.

Antwerp also actively promotes recycling, such as reusing asphalt in new layers and repurposing concrete stones. Also cobblestones and other natural stone products are stored in our depots and reused in upcoming projects, emphasising sustainability and resource efficiency.

Greenery: Antwerp has an own tree nursery to cultivate a variety of tree species which are planted in public spaces creating a safety buffer by unforeseen tree replacements and diseases. Other trees, shrubs, perennials and flower seeds are bought with long-term contracts with accredited nurseries such as indigenous organic growers. The quality of the seeds and plant is always checked by the nursery staff to ensure high quality selection.

Moreover, the principle “the right tree at the right place” is used ensuring a balanced distribution of all species at street and city level to safeguard tree and greenery loss due to diseases, pests and climate change (drought). 

 

Overall design  

Garden streets embody multifunctional spaces, integrating walking, cycling, car traffic and gardening. Guided by a holistic urban design, they unite aesthetics, functionality, sustainability, climate resilience and social cohesion. The outcome is visually appealing, socially vibrant, and fully accessible streets.

Innovative integral design solutions are conceived and implemented. For instance, in Aziëlaan urban elements function as bench and plant protection and in Bloemstraat, a basketball field is also a water buffer for rainwater overflow. This integration of superstructure and underground is realised through a collaboration between Antwerp and their sewage partner.

Materials are selected through research-by-design respecting Antwerp’s historical context. Close cooperation among designers, engineers, and material producers is pivotal. For instance, in Lange Riddersstraat,  a red water-permeable clay brick was crafted to blend harmoniously into the specific historical context of the city centre.

The design process is co-creative with street users from the outset. A “dreaming workshop” to captures their experiences and ideas. For instance, a contemporary rainwater-reusing hand pump and water run-off to greenery in Lange Riddersstraat sprang from participants’ dreams of their medieval well and a river flowing through the street.  This collective approach, paired with innovative design solutions, creates garden streets that characterize urban synergy and sustainability.

Impact on the environment  

Garden streets have a transformative impact on the environment that stretches well beyond their immediate vicinity. The used materials and circular principles (see above) strongly reduces the environmental impact. Also, they cultivate a symbiotic relationship between urban development and nature, exhibiting a remarkable impact on various dimensions, as illustrated throughout this text. Their impact on the environment is multi-dimensional. For instance, carbon sequestration through plant growth, improved energy efficiency via reduced air conditioning usage, and enhanced air quality are observed. Garden streets function as natural air purifiers, noise reduction areas and mitigate the urban heat island effect while improving stormwater management.

These streets also create diverse urban ecosystems, while simultaneously creating urban green corridors that interlink larger green spaces into a cohesive network. Furthermore, garden streets serve as educational examples of climate adaptation measures within urban contexts, raising awareness and knowledge regarding sustainable practices. They serve as living laboratories, providing platforms for residents, schools, and visitors to grasp urban planning complexities. Their holistic and circular approach shows the harmonious interplay between urban living and nature. By creatively addressing environmental challenges through innovative design, these streets stand as prototypes of sustainable urban development.

 

Innovation value of the project

Garden streets exemplify a paradigm shift in urban planning and design. Noteworthy value of innovations include:

  • Incorporating new construction materials like water-permeable elements and buffering sub foundations, enabling rainwater infiltration.
  • Establishing blue-green infrastructure, featuring hand pumps for roof water reuse and redirecting street runoff to greenery.
  • Prioritizing visible above-ground blue-green infrastructure, reducing pressure on sewage systems, supported by economical agreements with a sewage partner regarding cost allocations.
  • Adopting an new design paradigm, starting with unpaved streets and selectively paving to ensure universal accessibility.
  • Fostering community engagement, empowering street users as liveability experts, green space initiators, and maintenance contributors.
  • Instituting a monitoring and evaluation process, capturing vital lessons to facilitate potential upscaling.
  • Shaping a collaborative framework that foster collaboration among local authorities, urban planners, street users, producers, and technical experts across domains like greenery, mobility, water, and heat.

Antwerp’s pioneering role is highlighted as it realized the first garden streets in Belgium and also assessed their design, processes, and environmental impact. The gained knowledge and lessons, both successes and failures, are shared through field trips, talks and technical exchanges. This promotes the scaling up of garden street, facilitating climate adaptation and encouraging city resilience.