The green residential block explores the functionality of green areas on apartment building rooftops. The project combines an experimental green roof and green façade design with research. The aim was to use the experimental construction of green infrastructure to examine the feasibility of landscaping on the roofs of blocks of flats. The objective of the project is to investigate how different species are managing in the challenging conditions at the seashore in the Jätkäsaari district and how growing locations and substrates affect the growth. The development team of the project included biologists, horticulturists and sociologists. The study is led by the Fifth Dimension research programme from the University of Helsinki. The architect of the building is Talli Architecture & Design.
The vegetation consists primarily of traditional garden plants and those found in Finnish nature. The study also examines the effects green areas have on urban runoff, energy efficiency and dweller happiness. The information collected in The Greenest of the Green project will help in designing ecologically and socially sustainable nature-based solutions.
Each of the green roofs has its own profile, research set-up and character. The southern topmost terraces are open meadows: biodiversity roofs. They are designed strongly for research purposes and offer habitats for insects. The seventh-floor roofs have fruit gardens and serve as recreational areas adjacent to the sauna facilities. The community room opens onto the kitchen garden where inhabitants can grow their own food and plants. The kitchen garden has multiple cultivation boxes and a large shared greenhouse.
The green continues from the roofs to the facades of the building. The street-side facades are covered with wooden and steel lattices for climbers to grow on and are dotted with large steel planting boxes. The house yard green roof has a play area, butterfly bar and research areas. The special concrete paving is meant to absorb nitrogen dioxide.
The City of Helsinki awarded the project the Rakentamisen Ruusu 2017, an annual award to highlight exemplary building projects. The Scandinavian Green Infrastructure Association gave The Greenest of the Green block the Scandinavian Green Roof Award 2018.
All the roof areas are open to residents and designed to enable many types of recreational use. On the kitchen roof, the residents have established a co-operative to manage the shared cultivation areas. The roof can also be used for parties and barbecues.
During daytime, the sauna terraces are open for everyone to enjoy fruits, berries and the views provided by the roof. During evenings they serve as a more private area for sauna users. The topmost roof, the biodiversity roof, provides a more tranquil place for observing the surrounding areas and nature on the roof. The social profile of the roofs becomes more private the higher up the roof is located.
The climate conditions for the green roofs in The Greenest of the Green are challenging. Near the shoreline and high above ground level, the winds are often fierce and the sun can be scorching. Nevertheless, there is something green growing on almost every surface.
The vertical green façade is manually watered from the roof and each growing box on the façade also has two irrigation tanks to ensure sufficient water. Irrigation tanks are also used at street level, where the substrate is very shallow. All but the biodiversity roofs have a water retention and drainage element. The biodiversity roof is designed to manage without irrigation or fertilisers. Eventually, the multiple layers of green will be visible from far away.
The vegetation throughout the site is chosen to be hardy but diverse. Most plants, including the trees, produce flowers and many produce fruits or berries as well. The layered, diverse species support each other against the rough elements but also attract pollinators and sometimes even birds. The gravel on top of the substrates has been especially chosen so that invertebrates can nest and over-winter in it. Additional structures, such as stone piles, low stone walls and tree trunks are situated along the roofs to support nesting.
The biodiversity roof is a dry meadow with a thin substrate and no water retention. In total, the roofs and walls account for six different substrate mixes, all with different pH levels, nutrition values and composition. Harvestable plants include rowan, apple trees, strawberry, arctic bramble, herbs and currants.
Architect: Talli Architecture and Design
Research Group: The Fift Dimension – Urban Ecology Research Group, the University of Helsinki
Project location: Länsisatamankatu 36 / Hyväntoivonkatu 4, Helsinki, Finland
Photographs: Pyry Kantonen Photography