Vrijburcht: a privately funded climate–proof collective garden in Amsterdam

Over the past 130 years, global temperatures have risen by an average of 1.0 °C. The Netherlands has experienced an even higher rise: according to the Royal Netherlands Meteorological Institute KNMI climate dashboard , the average temperature in this country has risen by about 2 °C between 1901 and 2020. Due to the ability of warmer air to hold more moisture, more intense rainfall events are projected. In Amsterdam intense rain showers often lead to flooding due to the limited permeability of the city’s surface areas. Getting rid of the water seems a first and obvious reaction. However, under a future climate, dry periods may occur more often during the summer months, requiring irrigation of urban vegetation in public and private spaces. Water should therefore be preserved within the urban environment. Also, temperatures, including extreme values will rise in all scenarios developed by the Royal Netherlands Meteorological Institute ( KNMI ). This will be accompanied by more hot summer days and more frequent heat waves during which the built environment may become unpleasantly warm.

The primary objective of the Vrijburcht building block project was to offer an attractive and sustainable building for people to live, work and meet by creating a mix of affordable housing, ateliers/offices and public space. The complex was primarily financed by the residents-to-be. All houses are reached via the courtyard that functions as a central and informal area for residents to meet. At the same time it should reduce the risk of pluvial flooding, store rainwater for irrigation and decrease heat stress by providing a good micro-climate to the users of the building.

Vrijburcht is a mixed-use cohousing complex located on Steigereiland, an artificial island in Amsterdam in the IJmeer lake. The complex comprises 52 apartments, two guest rooms, a care home for six youths with slight mental impairments, a shared hobby space, a cycle shed and a parking garage, a day-care centre, a café with a water-side terrace, a theatre, a floating platform for swimming, and a landing pier for a sailing club. The courtyard garden provides solutions to prevent or reduce flooding from extreme rainfall, minimize water scarcity during dry periods and heat stress during hot summer days: Rain water from the roof tops is collected in two tanks that are buried in the garden and can in total contain 6000 l of water. This water is used for irrigation of the garden and the plants on the surrounding terraces/balconies and covers the total irrigation needs in most of the years. The car parking garage is constructed under the building and the garden is paved minimally to create maximum permeability for rain water in the garden. Relief is created so that water flows from higher parts to a marsh-like environment. This prevents flooding of the garden and enhances vegetation diversity by creating dryer and wetter environments across the courtyard garden. Drainpipes are detached from the facades at ground-floor level and together form a pergola construction for creeping plants. This minimizes the impact of eventual leakages on the facade. Creeping plants are also used at the exterior of the building were they cover wind screens to form green facades. Green roofs were also create The many trees in the garden provide shade and thus contribute to an agreeable microclimate on hot summer days. Solar panels (without sedum vegetation) in different parts of the roof have been installed. In 2022 solar panels with herbaceous vegetation roof on a few extra parts of the project have been installed as well. To realise the building complex and courtyard garden, a collective private commissioning (CPC) initiative was started allowing residents to organise themselves and realise their wishes (see also ‘Stakeholder participation’). Although the climate change adaptation outcomes of the project are not actually monitored, residents are currently enjoying the space that is creating well-being of the residents and a good micro-climate (see Costs and Benefits).

The costs to set up the garden itself were € 55.000, excluding the costs of the rainwater storage facility (€ 17.500) and a greenhouse (€ 30.000). The total costs of the building complex were € 16 million. The costs of the garden were carried by all residents/users as part of the total costs through the Vrijburcht Foundation (see also ‘Stakeholder participation’). The garden was a collective wish of the stakeholders. It was financed by them by making compromises in the overall design of the complex: the overall budget was fixed but the garden could be financed by optimising other aspects of the building design. On annual basis the costs for maintenance of the garden amount to € 3.000, including the contribution of a gardener next to the voluntary work of the residents. Also costs of the maintenance are carried by the inhabitants and ‘De Key’ as part of the regular service fees of the building, managed through the homeowner association. A garden commission takes care of the overall aspects of the maintenance of the collective garden. Benefits are difficult to express in monetary terms. The garden contributes to the well-being of the residents through a good micro-climate. Inhabitants for example do not feel the need for air conditioning in their houses. Water for irrigation of the many plants on terraces besides the courtyard garden comes from the rainwater storage facility which meets the water needs in most years. Flooding of the garden during intense showers is prevented. The garden is also a recreational place where residents meet, thus underlining the collective aspect of the complex. It also provides fruit/vegetables and serves as a green playground for children.

Main success factors of the initiative are: The building construction/development process was a collective process with the common wish for a building that was sustainable in both social and climate context. The concept of the green and sustainable courtyard was broadly supported by all stakeholders. Early involvement of landscape architects in the collective process was a key element to integrate the green space with the building and to reserve enough money from the total project budget to realize it. The Vrijburcht Foundation consisted of people that invested a lot of time and effort in the process, which is a prerequisite in a collective and private commissioning. The landscape architects brought in their professional experience into the process management as members of the Vrijburcht Foundation. The (social) housing foundation ‘De Key’ provided financial warranty by financing the houses that were not yet sold and other social and commercial services (e.g. day-care centre and housing for slightly disabled people, the day nursery, the cafè). ‘De Key’ also provided experience in overseeing the construction phase. This enabled the start of the building at the stage in which there were not yet enough private participants. ‘De Key’ took part in the Vrijburcht Foundation but gave the private participants space to develop their own concept. Low-tech measures were taken which made the garden affordable and sustainable (e.g. use of common creeping plants instead of technical solutions for green facades). Although many positive factors created the conditions for a successful intervention, the real challenges were financing to cover the high cost of the project. The involvement of the ‘De Key’ housing foundation was one of the winning strategies to address this issue. Another big task was to ensure enough residents’ participation. Participation was a core element of the project but, despite a general willingness to collaborate in the decision making by residents, the real engagement of residents was not simple to achieve.