To create a comfortable, inviting and expressive green environment at the base of a 92 meter high office building. A garden both for the office workers and urban dwellers. Special care was taken to create a temperate wind climate, ecological connections with the adjacent historical forest and urban green zone, and providing additional recreational options to ease the pressure on the vulnerable, small and old, oak forest. The underground car park means an extra challenge for the vegetation in an area of 1,1 ha in the center of the City Garden.
respect for nature and biodiversity
This urban project includes both indigenous vegetation and a range of exotic perennials and bulbs. Both are contributing to the biodiversity of the garden. Exotic perennials and bulbs are better adapted to the conditions of a roof garden. They also provide an abundance of food for insects and birds. Towards the border the vegetation develops into a woodland edge, with a natural vegetation of grasses, herbs, shrubs and trees. This area gives more food and shelter. The character of the planting encourages animals from the neighbouring urban forest and green zone to forage and nest here. Special care is taken to support the local bat population (6 different species) in the adjacent historic park. Treks for bats have been strengthened, and especially for these ‘target animals’ additional shelter is provided in the main building. The green mantle operates as an offshoot of the ‘Sterrebos’ and creates a spatial and ecological connection with the woodland park. These existing elements are used by bats for orientation, and form the structure that anchors the place in the urban and landscape fabric.
optimisation of ecological processes and methods in garden management
The garden is part of a 20 year contract that includes design, construction and maintenance of garden and buildings. This made it possible to invest in the ‘prairie planting’ system. Every individual plant has the opportunity (sufficient space and suppression of weeds through the lava gravel cover) to develop and mature fully. The vegetation sustains itself with a minimum of work, without fertilisers, herbicides, etc.
innovative ideas on recycling and up cycling
The series of ponds is not only a pleasing visual element, it is part of the water management of the roof garden (purification, buffering). It provides variety in habitat, enlarging the biodiversity. During construction the trees at the edge of the site were protected, so they could play a role in the new lay out and ecological infrastructure. Additional planting and maintenance add to the development of a rich woodland edge: a natural succession of flower meadow, shrubs and woodland edge.
raising public awareness for ecological gardening
The City Garden shows the wealth of plant life (colour, texture, smell, seasonal change) and the fauna it attracts (butterflies, birds, bats). It sets an example of the possibilities of daily experiencing nature in our everyday environment. Next to wide paths crossing the site, there are small tracks providing a more individual encounter with flora and fauna. The way visitors respond, tells us that they are genuinely inspired.
Diversity is a key feature of nature. Over 250 different species were planted and over 50 were sawn, creating a wide range of ecological conditions. The garden changes continuously thought the seasons.
a green roof avoiding Urban Heath Island Effect
The paved surface is substantially reduced by bringing the car park underground. The garden with an abundance of planting and the series of ponds on the roof of the car park have a distinct cooling affect on the environment.
breaking the wind
Environmental factors have had much influence on the design. The over 90-meter high building called for a design that focuses on creating shelter from (fall) winds.
Three meter high screens, lightly curved and covered with ivy, form a radial pattern. They keep the wind off the ground. The positioning is wind effective and visually sufficiently open to vistas enabling a fine spatial perception and comfortable social security.
ideal conditions for cyclists
The office workers are encouraged to travel by train and bicycle to reduce the consumption of fossil fuels. The location is in walking distance from a train station and well connected to bike routes. The underground garage includes 1500 places for bicycles and a workshop where bikes can be repaired while you work. The building houses showers and change rooms for cyclists.
reusing, infiltrating and purifying rain water
The roof construction has a strong impact on the water balance, which is designed to treat rainwater in a responsible way: infiltrate, retain and reuse. The series of ponds is part of the water management of the roof garden (purification, buffering). The rainwater from the roofs is fed back into a buffering layer, feeding the prairie vegetation in dry periods.
The project as a whole (office complex, pavilion, parking garage and City Garden) has achieved BREEAM excellent **** (in use certificate)
a public garden
Instead of a private office car park and garden, the client (National Department for Public Buildings) agreed to make an underground car park and a public garden for both office workers and the public. The garden even houses a pavilion with a restaurant which is a popular during the week and in weekends. In the garden people are walking and jogging, at the pavilion visitors drink and dine, locals stay and relax and at the same time is a peaceful spot to enjoy the richness of nature.
an innovative contract
The project is realised under a Design Build Finance Maintain Operate (DBFMO) contract. A 25 year maintenance contract for the garden was included in the construction contract. The design of the garden and the maintenance plan were designed together. This contract guarantees a high maintenance standard for the garden for the next 20 years. This is extra special because the land is private and the contract is public.
Entrant office name: LODEWIJK BALJON landscape architects
Role of the entrant in the project: landscape architect
Other design firms involved: UNStudio
Project location: Groningen, the Netherlands
Design year: 2007-2012
Year Built: 2008-2013