Kalasatama substation is located in a central area of Helsinki, between the former Suvilahti power plant, which has been converted into a cultural centre, and the closed Hanasaari power plant. Designed by architect Selim A. Lindqvist, the Suvilahti power station dates back to 1909 and was Finland's first reinforced concrete building. The old buildings and structures on the site of the present cultural centre are protected. The building programme of the new substation has been laid out so that the whole relates to the scale and coordinate system of the historical context.

The Suvilahti Cultural Centre is a venue for large music festivals and smaller events. Street art is an essential phenomenon in the area, and the City of Helsinki has been offering graffiti artists licensed painting spaces since 2009. The design of the building took into account the wishes of local stakeholders for the continuation and development of activities, which allowed, in an exceptional way, the incorporation of a public function into the substation.

The substation has been structured so that the different parts fit into the scale and coordinate system of the surrounding protected buildings. The height of the new buildings has also been adapted to the context. The substation consists of three cast-in-place concrete boxes clad in metal graffiti fencing and stainless steel woven mesh facades. The materials and structures reference the cultural centre's impressive old concrete and steel structures.

The exterior walls of the transformer buildings are solid in-situ concrete structures bleached with titanium oxide. The walls of the switchgear building have load-bearing internal shell elements, a layer of rigid thermal insulation and an in-situ facade external shell on top.

Due to the client's requirements, the concrete buildings were retracted from the site boundaries. However, we wanted to create something other than a typical infrastructure site with buildings set back from the fence surrounding the site. Instead, we designed a metal double curtain wall that allowed us to bring the facades of the buildings into the site's boundaries in an urban way. The metal cladding extends from the cast-in-place concrete facades with black-painted steel structures. Installing and maintaining underground medium voltage cables was facilitated by avoiding deep foundations under the double façade. In the north-east, graffiti fences were built on concrete foundations as there are no cable routes.

Woven stainless steel mesh was chosen for its depth and the feel of the material. The mesh reacts differently to ambient light, and the appearance of the building changes depending on the position of the sun, viewing distance and weather. The shadows cast by the steel structures create changing patterns on the concrete surfaces. The graffiti fence is about three metres high and consists of hollow aluminium profiles with pontoon joints. The pontoon joint ensures rigidity and also prevents paint fumes from entering the inside of the fence.

The graffiti fence is very popular with street artists. New works are constantly created on top of existing ones and shared on social media. As a result of this constant artistic activity, the appearance of the Kalasatama substation also changes daily.