Intro
The redeveloped Kerckebosch neighbourhood is a particularly fine example of nature-inclusive development. The original neighbourhood consisted of eleven large flats in a forest. Ten of the eleven flats were demolished to make way for the new neighbourhood.
Kerckebosch is located in the eastern part of Zeist and borders a nature reserve belonging to Utrechts Landschap. The redevelopment opted for nature-rich neighbourhoods that connect to the landscape. The main premise in the vision for Kerckebosch was to maintain large parts of the existing forest and to ensure that all houses would have a direct relationship with the forest.
Motive and context
The existing apartment buildings were in need of renovation and replacement. The 706 rental flats in ten apartment blocks from the 1950s were replaced by 1,100 homes in a mix of 50% social sector and 50% private sector, from starter homes (rental/purchase) to vacant plots. In addition, 100 care homes, a community school, and a multifunctional centre have been added. One apartment building with 74 flats remained and was sustainably renovated.
Process and cooperation
For developing the area, the municipality of Zeist and housing corporation Woongoed Zeist set up the Wijkontwikkelingsmaatschappij (WOM) Kerckebosch. From the beginning, wUrck was involved as a landscape architect in the design and ‘organic’ development, as there was no complete urban development plan at that time. Based on BDP.Khandekar’s 2008 master plan and the public space manual compiled by wUrck, the project was gradually developed for each area. The reason for this organic development was the financial crisis.
For the spatial starting point, the green buffer model, from the master plan prepared by the office BDP.Khandekar in 2008, was used.
Based on the handbook for public space prepared by wUrck, the sub-development plans for the various development sites in the six buffer zones were drawn up, the urban layout and the main infrastructure were designed, and the green natural and residential areas were defined. The latter areas include the nature areas between the partitions, the school campus, the outdoor area of the shopping centre and the energy square.
Resident involvement
The plan was largely developed integrally together with local residents. The strongly involved original residents, who love nature and their neighbourhood, are also among the new residents of Kerckebosch. The basis for the development plan was laid during a number of residents’ evenings.
In the project, the developer placed vegetable garden boxes that are tended by the residents. These are well maintained, and more are being continually added. Calisthenics equipment was also installed at the residents’ request, with the residents also committing to use it for at least five years and to organise activities.
Description of the design/ Design and approach
The original landscape, forest, and heath are the main carriers of the plan. The district has six neighbourhoods situated amongst woodlands, moors, and a park-like landscape. There is a main thoroughfare; secondary roads provide access to the neighbourhoods.
The mix includes vacant plots and flats, as well as terraced, patio, back-to-back, quadplex, and care homes for the new and old residents of this diverse and lively new neighbourhood. Complementing the programme are multifunctional services and amenities (doctors, pharmacy, music school, gymnasium and neighbourhood café́), schools, childcare facilities, and the refurbished shopping centre.
In the design of the public space, but especially also in the transition between public and private, the aim was to make the ‘living in nature’ theme actually tangible at every spot. This applies not only to the arrangement of the houses. The specific qualities of this special location are also preserved along the main access, in the residential streets, and in the differently designed nature areas.
To preserve the wooded character of the neighbourhood, the premise was to spare as many existing trees as possible. Thus, the main access road, Kerckeboschlaan, meanders through the forest, so to speak. The existing elevation differences were incorporated and reinforced in the design. The wooded areas between the hedges were connected to the Utrechts Landschap nature and recreation area. In some places, these forest areas were enriched with open heathlands.
Water
Kerckebosch is part of the former drift sand area on the Utrechtse Heuvelrug between Doorn and Zeist. Limited elevation differences occur in the area. The soil type to which this shifting sand soil belongs is loamy to slightly loamy fine sand. The groundwater is at a considerable depth, making the vegetation dependent on precipitation.
The sandy soil allows direct infiltration. Water that falls on Kerckeboschlaan, the main access road, is drained to the surrounding area via the convex road, where it can seep into the ground.
A four-step scheme for handling rainwater, ranging from most-desirable to if-necessary, has been worked out for the residential streets. The parking spaces are made of permeable paving. The ground-level houses drain on their own property and the flats by means of wadis. Crates or an infiltration transport sewer may be used where necessary.
Wadi
The maximum water level in the wadi is 30cm. This is a nationally established standard implemented in connection with minimising the risk of drowning.
The municipality of Zeist states that an infiltration facility may not have an overflow into the wastewater system. No silt head or drainage system is used in the wadi.
In Zeist, it was chosen to mow the wadi manually to prevent damage to the wadi and because of the lack of space due to the trees next to the wadis. Damage to the wadi could reduce its infiltration capacity.
A minimum of 30cm of draining sand is provided around the infiltration pit for optimal functioning and infiltration.
There should be no oak trees near the wadi. Oak leaves decompose more slowly than other leaves and may limit the infiltration capacity of the wadi.
The wadi is located in a forest environment with deep shade. This increases the chances of moss growing. Moss can limit the infiltration capacity of the wadi.
The municipality of Zeist requires the supply pipe to be at least 3 metres from the centres of the trees to prevent root growth in the pipe. (Water level)
Greenery and biodiversity
The ecological principles of the design are in line with the natural processes of a forest. The processes in a natural forest ensure great variety (old and young forest, clearings, and forest edges simultaneously present in different places). This variety of forest structures is the best guarantee for a wide variety of plant and animal species using the forest. The workshop with residents also showed that ‘variety’, ‘native species’ and ‘real forest’ were found to be important values.
Appropriate to the landscape, different zones such as oak-beech forest, clearing, oak-birch forest, and heath have been designed into the plan.
There are two nature types around which the houses are grouped, living in the forest and living on the heath:
Living in the forest
Living in the forest means that the surroundings are relatively shady, with trees often standing right up to the façades/yard boundaries and roads winding between the trees. The undergrowth is adapted to the shady environment, and where undergrowth is naturally lacking, it is planted in the immediate residential area.
Where many trees have been removed to enable construction, new trees are planted. At maturity, the oak-beech forest is a fairly dark forest type with an open shrub layer but occasional groups of rhododendrons and solitary shrubs such as holly and goat willow. The undergrowth can be species-rich.
- Basic range of oak-beech forest:
- Trees: Oak, Beech, Birch, Pine
- Ornamental shrubs: Rhododendron, Holly, Goat willow, Euonymus, Buckthorn
- Ground covers: Periwinkle, Pachysandra, Ivy, Bracken fern
- Herbs: Kerckebosch Herb Mix
Basic assortment of oak-birch forest:
- Trees: Oak, Birch, Pine
- Ornamental shrubs: Holly, Hazel, Euonymus, Rowan, Buckthorn,
- Witch hazel, Wild apple
- Ground covers: Ivy, Hellebore
- Herbs: Kerckebosch Herb Mix
Living on the heath
Living on the edge of the heath means living in sunlight with openness and views. It should be noted, however, that this is not a vast, bare heathland area and that many solitary trees and clumps of trees have remained. Heath will never be 100% covered and, moreover, it only blooms for a limited period of the year. The image will therefore mainly consist of heather and grass with stands of trees.
Basic selection:
- Trees: Oak, Birch, Pine
- Ornamental shrubs: Common broom, Juniper, Petty whin, Common gorse, Wild apple, Creeping broom
- Understory planting: Blueberry
- Herbs: Kerckebosch Herb mixture, seed-rich heather hay
Specialisation
Some locations require special planting. In these places, more cultivated species are combined with the natural species found throughout Kerckebosch. For example, on the campus, close to the buildings, this type is applied.
Basic range:
- Trees: Groups of oak, beech, birch, pine and solitary specimens
- Ornamental shrubs: including Rhododendron
- Ground covers: Periwinkle, Pachysandra, Blazing Star, Moor grass
- Herbs: Kerckebosch Herb Mix
Fences and gardens
All fences are co-designed. In keeping with the whole, there are ground rules for fences; most fences are green, hedges, planted trellises, or wooden fencing.
The gardens are quite small. Bins are placed underground as much as possible, so there is no need for plastic bins in the garden. Residents’ pruning waste is reused for dead hedges in which animals can live. A chipper is therefore not needed and nothing has to be disposed of.
Green play facilities
Natural play with elements from nature is obvious in Kerckebosch. The basis is already there: with winding paths, hills and bushes, an exciting space is created. Supplemented with natural elements such as poles, boulders, sand and water, the child’s imagination will be stimulated again and again.
Here and there, play equipment is a nice addition: a swing, a slide or an adventurous playset.
Provisions for wildlife
Most single-family houses have large overhangs where birds can make their own nests. For bats, separate nesting blocks have been installed in the façades. In social housing developments, the developer himself has attached boxes to the façade. Nesting boxes also hang in the trees. The reason for this was mitigation; at the time the old social housing building was demolished, replacement housing had to be provided for the animals. Due to this intervention, the bat colony doubled in size.
Result
The design and approach resulted in a very attractive, climate-proof, and nature-inclusive neighbourhood. All rainwater is infiltrated locally, and local biodiversity has been enhanced. Residents are active in the neighbourhood, taking over management tasks, playing sports together, and organising activities.
Maintenance and management
Utrechts Landschap took over the nature reserve in the district at a cost of one euro. This amounts to about half of the area. The development company WOM now maintains the heath together with Utrechts Landschap and the residents. Once a month, 15 to 20 volunteers help on Saturdays, together with children. Education and information are also provided. For instance, it is explained that you cannot just walk your dog on the heathland. After all, it is poor land, and it must remain poor.
Everyone who moved into the neighbourhood was and is made a member of Utrechts Landschap by the development company. The cost, 15 or 20 euros per person times a thousand homes, is for the development company in return for more involvement and awareness of the residents. The forester organises regular excursions.
Learning points
Building among the trees
Builders are horrified by the idea of working in the middle of the trees, because where will you set your scaffolding, how are you going to excavate a basement? It seems impossible at first. Nevertheless, there are now trees one metre from the façade. The neighbourhood development company chose to leave as many trees as possible. The trees that were cut down were all reused in the area, including for playgrounds.
Cost
The developers found that nature-inclusive development is not more expensive, but it does take more planting time.
Management
Buyers should be well informed in advance about other management.
It is important to make good agreements with the municipality about management. Not everything goes well from the start. Most managers still work according to traditional specifications, so training is needed. Moreover, sometimes nature-inclusive management is even cheaper.
Residents can be made co-responsible for certain aspects of management.
Resident participation
Encourage good ideas from residents, but also ask for commitment.
Use nature education to promote social cohesion.
Sources:
- Kerckebosch Zeist, wUrck, 2023, https://www.wurck.nl/wp-content/uploads/Kerckebosch-Zeist-11.pdf
- Ecological Vision Kerckebosch, Goderie ecological consultancy, 2011
- nl, KAN Lunch Café: Lessons from Kerckebosch Zeist, with Paul Kersten (wUrck) and Evert-Jan Roelofsen (WOM Kerckebosch), January 2021,