Green courtyards and roofs in Stora Sjöfallet

The City of Stockholm's requirements for climate-adapted and green courtyards to increase well-being, biodiversity, and properly manage stormwater are clearly evident in the block Stora Sjöfallet.

Developers Wallenstam, SSM, Bonava, and Viktor Hansson were granted land allocations in the Stora Sjöfallet block, between Gasverket and Husarviken, in 2011. The agreement included binding requirements to achieve the Green Space Index and comply with the stormwater strategy. The Green Space Index calculation tool was developed by the City of Stockholm as one of the innovation-driving tools to achieve Stockholm Royal Seaport's sustainability goals. With the help of the Green Space Index and a refined working method, one of the most interesting examples of multifunctional blue and green infrastructure in a dense urban residential area has been created. In 2016, the block was completed with 263 homes and a preschool.

The blue and green infrastructure that has emerged in the block, i.e., in courtyards, facades, and roofs, has involved well-thought-out solutions that support vegetation growth and stormwater retention. Key factors for the success of the initiative have included properly designed planting beds with generous soil depths, an abundance of plants, and serially connected stormwater solutions that provide water to the vegetation. The courtyard consists of narrow pathways with a strict design leading to two larger courtyard spaces with a more relaxed design. The two courtyard spaces, designed in different ways, are connected by a walkway of slate-like slabs laid in gravel. The courtyard can be accessed from Jaktgatan and is connected by stairs in the east and west, and with donkey paths towards Husarviken in the northwest. Terrain walls of light granite form a frame that makes the block stand out against surrounding streets.

Types of nature inspired by the Royal National City Park have been established in the courtyard. The spaces are beautiful focal points for surrounding hones with species-rich environments that offer opportunities for nature experiences. A varied vegetation with tall and low plants and greenery that require light and shade strengthens the area's biodiversity.

The northeastern part of the courtyard consists of a cherry tree grove and an open meadow. The grove forms a canopy over a gravel floor, and the area is furnished with hammocks. The constructed meadow has a clipped grass surface with space for picnics and ball games. The southwestern part of the courtyard has an area with larger oaks and fern plants, horsetails, and sedges that thrive in moisture. Roof water is led to this area via grate-equipped channels and is delayed in a rain garden-inspired wetland. Water is stored in large water barrels that are made available for irrigation and play. Other stormwater is primarily directed towards the planting areas.

For the children there is solid wood seating and climbing sculptures, and sandboxes. A wooden deck extends down the slope towards the waterfront park, offering beautiful views of Husarviken in areas with evening sun. There is also a water artwork.

Sedum roofs are a recurring feature in the block, and trees placed on roof beams have been planted in on one of the buildings. Many of the block's buildings have been fitted with a combination of solar panels and greenery. Vertical greenery has been planted on the surrounding facades.

Landscape architect Mattias Gustafsson from Urbio landskap showcases the Stora Sjöfallet block and discusses the strategic work involving water and greenery in the area. (Swedish only)

Work process

Stora Sjöfallet is one of the first projects in Stockholm Royal Seaport that had requirements to achieve the Green Space Index at an early stage. Initially, the city focused on creating a shared vision and increased knowledge by inviting developers and consultants to competence programmes and forums for sustainable solutions.

It was crucial that developers' landscape architects participated in the entire process, from the early stages to management, to ensure the green and blue functions became a reality. This was done in collaboration with architects, water and wastewater planners, and engineers. To facilitate the collaboration process, a special project coordinator was hired, who was tasked with balancing various requirements, detailed objectives, and measures within the block.

Developers in particular have highlighted the benefits of "the good conversation" with the City of Stockholm and the role of the project co-ordinator, who ensured the project's overall coherence. Throughout the project's different phases, the City has required updated Green Space Index calculations, reviewed supporting documents, and acted as a sounding board in discussions with the landscape architect.

Lessons learned

Creating a well-thought-out green structure in a block is largely about how different functions should interact in a limited space. This can result in areas of the courtyards, as well as roof surfaces, being in the shade. In Stora Sjöfallet, neither trees nor shrubs with edible berries and fruit could be planted because the courtyard is mostly in the shade.

Safety concerns such as fire risk can contribute to a decrease in the Green Space Index. For example, in Stora Sjöfallet, no dead wood could be placed on the roofs.

In summary, the City's follow-up shows that the Green Space Index becomes lower the further the project progresses. This may be due to the fact that not everything is technically feasible, costs become too high, and collaboration between various consultants has not worked as intended.

Another challenge is the handover of maintenance plans from implementation to management to maintain the long-term value of the blocks green structure. Competence development of developers in the Green Space Index will be an important issue going forward.

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Article Published: 17/04/2022 Updated: 27/06/2024