The perfect sound insulation concept with balcony glazing

Making perfect use of a busy brownfield site

“Verbindungsbahn” refers to the railway junction line in Hamburg, Germany. For many years, one brownfield area right next to the Verbindungsbahn remained unused due to the high noise levels. This is a conflict that could be resolved in 2017 with a new building and the right noise protection concept. The “An der Verbindungsbahn” residential complex – the brainchild of building owner GS-Bau GmbH from Neu Wulmstorf – includes both a commercial unit and an underground car park for the residents. The new build includes a number of different living options, from townhouses with separate entrances to small maisonettes and multi-storey apartments, and even panoramic suites. The fittings of the individual flats vary, as they are tailored to the needs of each individual buyer. Located in the Rotherbaum district of Hamburg, the flats offer excellent connections to the city’s infrastructure. The local neighbourhood has everything the residents need for their day-to-day lives, with plenty of opportunities for shopping and going out.

An attractive living space despite the noisy surroundings

For many years, the land was deemed unsuitable for residential property due to its high noise levels. After countless preliminary designs and building permits, the increasing need for new flats in the city and the rising demand for living spaces in the centre finally gave this project the boost it needed to get off the ground. Hamburg-based architects’ bureau LRW Architekten und Stadtplaner were the eventual winners of the contract. “The new building fills in the edge of a pie-shaped plot that was previously home to a low-rise commercial building. The residential block, which still exhibits many of the facets of the architectural style from when the city was founded, had no protection from the noise emissions coming from the railway tracks and the main road,” says architect Thomas Winkler. “With its double-skin facade, the new build is an attractive living space in spite of the noise, and it offers an unobstructed view of the neighbouring ‘Planten un Blomen’ park – and even of the Elbphilharmonie symphony hall in some places.”

Ingenious systems

How well the concept has turned out is reflected by the WohnbauPreis Hamburg award the bureau received for the project in 2017. “This project demonstrates how sound insulation can be used for high-quality, liveable solutions on flat construction – which is especially important in light of the scarcity of land in inner-city areas,” says architect Thomas Winkler.

Where the noise from the main road, An der Verbindungsbahn, and the neighbouring railway lines once flooded unabated into the interior of the block, closing off the edge of the block to create a new, quiet courtyard has also benefited the new building’s neighbours. “Essentially, the noise was one of the key considerations of the building design, alongside ensuring that it met city planning standards with regard to the neighbouring buildings. By making the building deeper and thus shifting its main mass, we were able to offset the large section facing the road and move as much of the residential space as possible into the ‘quiet’ area of the structure,” the architect explains.

Proven balcony quality

In order to complete the sound insulation, a double-skin facade comprising almost completely frameless glass elements combined with delicate, pre-fabricated facade sections made of reinforced steel was developed for the side of the building that faces the main road, An der Verbindungsbahn. The desired functionality was achieved using SL 25 slide-and-turn elements. The fully transparent, frameless elements are seated on the transparent balustrades of the facade and offer airborne sound insulation up to 22 dB. The elements also offer the advantage of making it easy to open up the outside of the double-skin facade. Thanks to the slender protrusions beyond the facades, this enables residents to create an open balcony – or, if the indoor facade is open, a recessed balcony – that transitions seamlessly into their indoor living space. When closed, the elements not only provide efficient sound insulation but also act as a temperature barrier – a feature that contributes noticeably to the low energy consumption of the residential areas beyond.