A model of beauty and sustainability
Beautiful and high-quality construction stands the test of time, lasting from generation to generation. It creates buildings that people grow attached to.
Lahti City Hall, designed by Eliel Saarinen in 1912, is a landmark building in the history of Finnish architecture.
It’s comprehensive renovation between 2020 and 2023 serves as an example of how a valuable property can be refurbished in accordance with circular economy principles. The remodelling process of City Hall was awarded an honorary mention in the Best Municipal Circular Economy Actions competition in 2022.
Lahti was granted city rights in 1905, and although it was then a small town with fewer than 3,000 inhabitants, it demonstrated bold confidence in the future by constructing a city hall that cost more than twice the city’s annual budget.
City Hall was a true multi-purpose building of its time, housing municipal offices, the fire department, a police station, and a jail. Over the years, it has provided workspace for many others, including the city administration, a library, the magistrate’s office, the district court, the pastor’s office, and the Finnish Broadcasting Company Yleisradio.
During the Winter War, an incendiary bomb hit City Hall, damaging the tower and attic. The attic was again destroyed in a fire in the early 1980s. The building was restored after these events, with the most recent major renovation between 2020 and 2023.
– Throughout its history, City Hall has adapted to the needs of different eras while preserving its identity, says City Architect Johanna Palomäki.
In a circular economy, demolished buildings are material banks, as materials can be reused and recycled. During the renovation of City Hall, 99 percent of demolition waste was repurposed.
Built to last – the key to preservation
Lahti City Hall exemplifies how a building is best preserved when it remains in its original use and is restored with respect for its heritage, says Palomäki.
– The decision-makers took a bold step. The renovation was a significant financial investment for the people of Lahti, but it demonstrates what it truly means to foster a sustainable environment. More than a hundred years ago, the city made a major investment in Eliel Saarinen’s building—and now, it has been renewed once again.
– Preserving our existing built heritage remains essential. Lahti has a huge number of buildings from the post-war modern era. We must recognize their value—otherwise, they will not be preserved for future generations, Palomäki notes.
Heritage from recent decades is not always widely appreciated.
– We should be cautious about making hasty decisions regarding more recent buildings. The evaluation of aesthetics should be left to future generations—they will determine what is worth preserving.
As an example, Palomäki uses Keskustalo, a 1960s concrete building near Lanu Square, whose protection is currently being discussed.
– Preserving and refurbishing is always more sustainable than building new structures. And when we do build new, we must ensure the quality is so high that people grow to love the buildings and do not want to see them demolished.
99 percent of demolition waste was reused
A major renovation like that of Lahti City Hall involves large material flows, offering significant opportunities to conserve natural resources. The building has a floor area of approximately 5,000 square meters. The renovation involved stripping nearly all surface structures across four floors, opening intermediate floors, and dismantling the roof.
A total of 609 tons of waste—99 percent of all material removed—was reused. Of this, about 70 percent was concrete and brick waste, which was processed into CE-certified Demorock recycled aggregate, replacing virgin natural materials. Energy and wood waste were sorted for use as recycled fuel.
Crucially, some dismantled materials were restored and reintegrated into the building. For instance, most of the wooden doors and all the windows were repaired and reused.
The old courtyard cellar was demolished to make way for a new one, and about 95 percent of the excavated soil was repurposed by an earthworks contractor. One thousand two hundred bricks from a dismantled courtyard chimney were also salvaged for facade repairs, particularly for restoring the tower.
In Lahti, high recycling rates for demolition materials are standard practice and integral to all city construction projects. The City of Lahti is part of the European Union Green Deal agreement for sustainable demolition.
Lahti City Hall, designed by Eliel Saarinen, was completed in 1912 and represents late Art Nouveau architecture. It is one of Saarinen's most significant buildings in Finland and a key milestone in Finnish architectural history. With Alvar Aalto's Church of the Cross, the City Hall forms a ceremonial axis along Mariankatu, marking the heart of Lahti's grid-plan city centre.