In the Ölstånkan quarter of the Swedish town of Örebro stands a timber building dating from 1909 that is of historical and cultural interest. Tyréns has been commissioned to optimise the acoustic performance of the building, which has been unoccupied since the 1980s and is now to be converted into new homes.
“Acoustic prediction is easier in concrete buildings. All the details are not as critical as they are inside a wooden building. Moreover, during the renovation process we need to comply with new construction standards for a building that was built according to standards from the turn of the century,” says Alexander Henriksson, Acoustics Engineer at Tyréns.
Today's requirements and standards for acoustic performance are defined in the building regulations of the Swedish National Board of Housing, Building and Planning. Although the building regulations have changed to some degree, their current form is relatively similar to what it has been for the past twenty years. The regulations are designed to prevent noise-related disturbances and to ensure a comfortable and healthy living environment from an acoustics point of view.
“The new construction standards apply when carrying out renovation work that requires a building permit or making changes to a business. Unfortunately, many local authorities have limited knowledge of this. Measurements of sound levels have been conducted relatively consistently in the major city regions since the 1990s. It is only in recent years that the areas outside the major city regions have started to become aware of the building regulations for acoustics. Inspections and verifications are becoming more common. However, knowledge in this area varies considerably from one municipal region to the next,” says Daniel Wärnelid, Acoustics Lead at Tyréns.
The timber building will be converted into eleven apartments on six floors with its portico, staircase, entrance hall and communal spaces on the ground floor. The floor structure between floors five and six is concrete. Elsewhere the floors are separated by a lightweight wooden structure with timber beams, which generates high impact sound levels*.
The project is governed by important details that require constant presence of Tyréns’ acoustics experts. As well as having a solid understanding of the acoustic regulations, the work also involves tracing events back in time through multiple different drawings and documents. The building in the Ölstånkan quarter has been used for various purposes over the years, from single-person households to an assortment of businesses. It has also been damaged by fire on several occasions and has been renovated. These events have obviously affected the character and identity of the building.
“Most companies are reluctant to take on old buildings, especially timber structures, because of the complexities involved. From a building acoustics perspective, we know it is possible to manage most sound-related problems. Lack of knowledge is usually the problem for many. And when that’s the case, it’s easier to demolish the structure and start from scratch. We’re looking forward to breathing new life into Ölstånkan and preserving its cultural heritage for future generations,” says Daniel Wärnelid.
*Impact sound level – a measure of a building's ability to insulate a space against structurally-borne sounds from another space. For example, footsteps in an adjoining apartment or on a staircase.