The green residential block in the new city district of Jätkäsaari was conceived by Talli Architecture and Design in co-operation with LOCI Landscape Architects and the Helsinki University Urban Ecology Research Group. Soon after completion the City of Helsinki awarded the project with the Rakentamisen Ruusu 2017, an annual award to highlight exemplary building projects.

One of the project’s objectives is to explore the functionality of green areas on apartment building rooftops and to gain valuable insight into the impacts green roofs may have on housing and the sense of community. The study covers an exceptionally extensive green development project in urban environment residential building. The study also examines the effects green areas have on urban runoff, energy efficiency and, for example, dweller happiness. The project is part of the City of Helsinki’s Developing Apartment Building programme.

The cross-disciplinary development team included biologists, horticulturists and sociologists, who had to establish what should be done. Architects and landscape architects then had to figure out how to do it.

The building also experiments with growing plants on the facades. The street-side facades are covered with wooden and steel lattices for the plants to grow on and spotted by large steel planting boxes. The facade behind the lattices is made of sandwich-structured elements with a coloured concrete surface. The yard side facades of the U-shaped block are characterised by access balconies. The circulation solution is cost-efficient and enables apartments with windows on opposite walls. All apartments come with the same, prefabricated bathroom module.

The design of seedbeds and risk-free structures was an essential part of the project. The southern topmost terraces are open meadows (biodiversity roofs) whereas the seventh-floor roofs more forest-like. They serve as recreational areas adjacent to the sauna facilities. The sixth-floor roof terrace is sheltered by glass walls to give protection to the residents’ allotment gardens. The common club rooms open onto the terrace, which also contains a large greenhouse.

The building’s final appearance will only be achieved over the years when the vegetation takes over, perhaps in unpredictable ways.