Recycled bridge concrete

At the transition from the old German town to the newer, developed residential area, the Lower Franconian municipality of Niederwerrn, near Schweinfurt, has created a new town centre with a community hall, club room, café, museum and a so-called ‘energy barn’. Several squares are lined up on the site in the middle of the existing structures and the architectural ensemble ‘MittenIm’ has been tastefully integrated into the town by Schlicht Lamprecht Kern Architekten. Most of the materials for the new buildings come from demolished structures, setting an example for sustainable construction and a sufficient circular economy.

The project took its first steps back in 2014, when an integrated urban development concept involving local residents was used to identify specific needs. According to this, there was a great desire for spaces that could be used by people in different ways, such as a market, a theatre for events or for practising ‘Plantanz’, a traditional folk dance event in the region. The long, narrow plot of land available was divided into a series of buildings and squares that now run through the area like a string of pearls. In the central village square, there is also a low water basin that has a positive effect on the local microclimate through evaporative cooling. Special three-layer paving stones provide additional cooling by allowing precipitation to seep away, store it and evaporate again.

New materials through upcycling

The external form of the newly built community centre fits in with the urban scale of the village. Schlicht Lamprecht Kern Architekten distributed the required space in two offset gabled roof buildings. The design was developed as ‘a house made of wood and a house made of stone,’ with the community centre primarily fulfilling the desire for a model project in terms of sustainable construction and sufficient circularity in the building sector. The western wing, i.e. the stone house, as well as the foundations and basement of the eastern wing, consist of around 700 m³ of recycled concrete from a nearby concrete plant. The demolition material, which was upcycled as additional aggregate for the production of the concrete, comes from the Rothof viaduct near Würzburg, around 40 km away, which was built in the 1960s and demolished in 2019. However, the architectural team did not want to leave it at simple concrete. They had the visible surfaces treated, using traditional craft techniques of scarifying and pointing, thereby significantly enhancing them once again. The composition of the recycled aggregate also results in a slight change in colour along the walls, which gives the new buildings a fresh, lively appearance.

Natural interior atmosphere

The ‘house made of wood’ stands on a concrete base, which, due to the difference in height in the terrain, serves as both a basement and an entrance foyer, and is made entirely of wood. The solid spruce walls harmonise visually with the exposed concrete, while the ash floors contribute to a pleasant room atmosphere. Instead of the mineral wool that is usually installed, wood wool has been used here and, with a few exceptions, no foil or adhesives have been applied. For the museum in the historic residential building directly adjacent, the architects followed the idea of a ‘display case’, completely gutting the ground floor and opening up the old half-timbered house to the north. To provide a suitable backdrop for the colourful collection from a century of food retailing in a traditional Niederwerrn shop, the room was plastered with a light clay-straw mixture on top of the soft wood fibre interior insulation.

Sustainable energy concept

The building, now christened the ‘Energiescheune’ (energy barn), can already be seen on the first map of Bavaria from the first half of the 19th century. The theme of sustainability is to be made visible in the renovated building by ensuring that all materials and repairs remain clearly visible. Recycled concrete has been used here as drainage concrete, which is visually reminiscent of rammed earth. The building services for the entire complex are also housed here: visible wooden boxes contain two air/water heat pumps, a pellet heating system and the equipment for the photovoltaic system, whose modules are located on two of the roofs. The energy barn supplies the entire area via a local heating network, with future construction projects – a children's library is to be built – already planned.