Imatra Electricity Substation

The different parts of the new substation facility extend over an area almost one kilometre long. The powerlines cross two tributaries of the River Vuoksi, one of which breaks into Imatrankoski Rapids, a nationally significant landmark. The new substation building sits next to the historic and still functioning Imatra Hydropower Plant. The imposing but fragile built and natural landscape around the site set high demands for the quality of design and construction. The main design challenge was to form a coherent whole out of widely dispersed and varying parts in a way that does justice to the iconic setting.

Respecting the surrounding landscape, the new substation was designed to be no taller than the nearest old building. Similarly, most of the transmission structures remain lower than the surrounding treetops. The outermost layer of the substation's double-skin facade consists of hand-made long bricks laid in a zigzag profile, a motif the building shares with the triangular steel profiles of the transmission towers. These repetitive forms are based on the rhythmical facades of the old buildings. The design breaks apart aspects of the built context and reassembles them in a new abstracted form, giving a unified identity for the new project.

The realised project balances the needs of crucial infrastructure with the requirements of building in a beautiful and much-loved landscape. As the project has been well received by the general public, it sets an example for successfully realising similar projects in demanding contexts. The owner Fingrid Oyj is currently investing in 50 new substations around the country, and it seems likely that some of the projects would benefit from a similarly careful and thorough approach to design.

The substation is not fenced off from the surroundings and can be approached freely. The greenery around it consists of indigenous plant species that require minimal maintenance and naturally fit with the surrounding forest landscape. The new building has a concrete frame and double-skin facades. The top part of the outer layer consists of a brick lattice that lets light and air pass through. The inner layer consists of in-situ and prefabricated concrete walls cut by a continuous strip window behind the brick lattice. A surplus of brick from cutting the material was used in the site paving, resulting in no waste. Inside the building, the main process equipment room and the lobby receive natural light via the clerestory window strip through which the brick lattice of the double facade can be seen. The interior is defined by the materiality of the exposed, prefabricated concrete parts. The project features three types of transmission structures: a tall tower with vertically arranged cross-arms, two low pylons with a horizontal configuration of cross-arms, and two terminals that connect overhead lines with underground cables. The structures consist of prefabricated sections of triangular steel profiles in repetitive arrangements.