The hydro-power plants along the watercourses of the Oulu River, together with the communities connected to them, form a totality that was realised by means of modern architecture and building techniques, yet modelled on early industrial communities. It was built in the middle of the wilderness of northern Ostrobothnia and Kainuu. The harnessing of the watercourses of the Oulu River was the largest integrated construction project in post-war Finland intended to ensure energy production.

The work commissioned by Oulujoki Oy was a long-term and comprehensive assignment among the works of Aarne Ervi and his architect’s office from the 1940s to the 1960s. A total of seven power plants were built on the Oulu River, six of which were designed by Ervi: Montta, Pyhäkoski, Pälli, Utanen, Nuojua and Jylhämä. Additionally, three power plants were built at the headwaters, along the Emäjoki River, which begins at Suomussalmi: Seitenoikea, Aittokoski and Ämmä, as well as the Oulu Pikkarala substation and transformer substation. The first and largest power plant was Pyhäkoski and Leppiniemi housing area linked to it, the construction of which began during the Interim Peace in 1941. The complex was finally complete in 1963 when the new community hall in Leppiniemi was taken into use.

Aarne Ervi, who had set up his own office in 1938, worked on Finland’s reconstruction projects, in particular tasks concerning standardization, but also on Oulu’s planning projects at the turn of the 1940s and 1950s. The construction along the watercourses of the Oulu River was a realisation of Ervi’s thinking regarding regional planning.

The construction of hydro-power plants along the Oulu River provided Ervi with a concrete opportunity to test and apply architectural ideas at all levels, ranging from regional planning to the smallest building details. The layout of the power plant communities followed, on the one hand, the modernist urban planning ideologies of low density, adapting to the surrounding nature and terrain while also, on the other hand, the early industrial communities based on the hierarchical structuring of the area. The architecture of the buildings supports the town planning ideas. The power plants together with their surrounding service buildings are simple and monumental, whereas the residential areas form a lush park-like environment. The architecture of the residential areas is small-scale, carefully detailed and of high quality both technically and architecturally. The housing construction forms a typological system, which was applied in all the power plant areas. In all his design tasks, Ervi emphasised the development of building technology, standardization and industrial prefabrication.

The power plants built for Oulujoki Oy are nowadays owned by Fortum Oy and still produce electricity. The housing areas have been sold to private owners. The protection of the areas has been secured by means of the town plan regulations, as well as the guidelines for building and repair methods linked with them. The totality is still well preserved and the communities are vibrant.

Oulujoki Power Plants and Communities are listed on the DOCOMOMO Finland registered selection of important architectural and environmental modernist sites.

Text: Helena Hirviniemi / DOCOMOMO Finland