Imatra Electricity Substation

The project is composed of an electricity substation building and an array of five landscape power pylons and terminals, set in and around the national landscape of the Imatrankoski rapids in Eastern Finland. The building and the terminals are situated close to the Imatra hydropower plant, built during the 1920s and the starting point of the Finnish main power grid. The historical significance of the area was the reason for the client to pursue an exceptional substation facility. The main technical goal of the project was the replacement of old air-insulated switchgear with modern gas-insulated switchgear housed inside a new building. New structures replaced powerline towers to the east and west of the new substation. The removal of the old air-insulated switchgear formed a new open space between the new substation building and the existing buildings. This courtyard-like space has potential for future development. The project crosses two tributaries of the River Vuoksi. The design goal was for the new structures to be in balance with the surrounding built and natural landscape. Except for one tall tower, the new transmission structures are lower in height than the surrounding treetops. The old hydropower plant buildings were primary factors in the positioning and layout of the new substation building. The substation is partially underground to make it as low as the nearest section of the old power plant. The substation building has a concrete frame and double-skin facades. The outermost facade layer consists of hand-made long bricks laid in a zig-zag profile, a motif which the building fronts share with the triangular steel profiles of the new powerline towers and terminals. The material choice is based on the beautiful brick claddings of the old hydropower plant. The top of the masonry wall consists of a porous lattice pattern. The inner layer of the double facade consists of in-situ and prefabricated concrete walls. Inside the building, a double-height entrance lobby provides access to the main process space via a low corridor. Stairs to the machine room and basement can be reached from here too. The main process equipment room and the lobby receive natural light via a clerestory window strip through which the brick lattice of the double facade can be seen. The project features three different types of transmission structures. Architectural and spatial in form, they are built of triangular welded steel profiles in repetitive configurations. The pylons and terminals are similar in form and structural principles, even though different in specific functions. They reference the colour and geometries of the existing, old lattice-type powerline pylons in light grey steel. The design breaks apart aspects of the existing built environment and reassembles them in a new abstracted form. The rhythmical brick-clad classicist facades of the existing power plant buildings served as an inspiration for the new substation facades and powerline structures. The derived design language gives a unified identity to the new project and places it in the context.