Highline balcony glazing: Herford

At the cutting edge: Helping to shape the energy transition

Bi-folding doors for serial renovation in Herford

Renovating existing buildings is the key to decarbonising the building sector and the construction business. A combination of insulation and a transition to solar thermal energy is the most effective means of achieving this, both ecologically and economically. In light of the current renovation status of many of our existing buildings, there is an urgent need for innovative renovation solutions that are designed with affordable living space in mind.

The Energiesprong principle is a serial renovation technique developed in the Netherlands that facilitates fast, environmentally friendly and cost-efficient building modernisation by implementing a digitalised construction process that uses pre-fabricated roof, facade and building technology. The German Energy Agency, dena, has been supervising the implementation of pilot Energiesprong projects in Germany. According to the agency’s estimated, this method could potentially be applied to around 300,000 small to medium-sized apartment buildings built throughout Germany between the 1950s and the 1970s.

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Wohnanlage in Herford mit Photovoltaikanlage

Pilot project in Herford: Renovation reduces carbon emissions by 170 tonnes per year

One of Germany’s pilot projects focuses on the renovation of four 1960s residential buildings in the East Westphalian town of Herford. In 2021, municipal housing association WWS used the Energiesprong principle to transform the severely dilapidated buildings into environmentally friendly, affordable and comfortable living space.

The comprehensive renovation concept included pre-fabricated panels with glazed solar comb insulation, insulated roof elements, a fully electrical heating and hot water supply comprising infrared and flow heating units, and photovoltaic units on the roof and the balustrades of the recessed balconies. Prior to the modernisation, the central and local hot water heating for the 24 apartments were both gas-based. With the renovation work complete, the buildings are now in line with the climate-neural Net Zero standard: barring any unexpected issues, the installed photovoltaic systems should produce more energy over the course of the year than the buildings require for heating, hot water and electricity.

Modernisierte Wohnanlage in Herford mit Balkonverglasungen

Energy-efficient bi-folding doors allow for sustainable expansion of living space

Here at Solarlux, we have always aimed to play a significant role in protecting the environment by tapping into the potential for solar energy collection offered by energy-efficient facade solutions. Our moving glass systems are the perfect accompaniment for any renovation concept. At the Herford site, the balustrades of the recessed balconies have been combined with pre-fabricated bi-folding doors from our Highline system, which provide excellent thermal insulation. The bi-foldings give residents a convenient way to extend their living space and make their balconies versatile areas that can be used in a number of different ways. Shifting the buildings’ thermal insulation level from inside the recessed balcony to the outside ensures that the residents can use the full area of their balconies – something that would not be possible with the all-round thermal insulation used in conventional renovation projects.

Modernisierungsprojekt Herford mit Balkonverglasung Highline

Sophisticated technology from the glazing specialist

Based on an accordion principle, the aluminium elements of the bi-folding door can be folded open along the entire width of the balcony and stowed away as a compact unit at the side. When closed, the elements – which boast a 99 mm sight line in the panel profile joint – let more natural daylight and solar energy into the room.

The multi-functional, fibreglass-reinforced polyamide “bionicTURTLE®” break profile provides stability and durability, and comes with integrated running tracks and guide rails, as well as controlled drainage. With a thermal insulation value of Uw ≥ 0.8 W/m²K, the modular Highline aluminium profile system offers excellent thermal insulation and meets the highest of standards in terms of energy optimisation.

Summary

Thanks to an energy-efficient facade, the use of renewable energy, energy recovery systems and efficient building operation, the site in Herford is now home to four climate-neutral buildings with a total of 24 residential units. The buildings are expected to remain ore or less carbon-neutral for their entire service lives. Current energy and carbon monitoring has shown an 89-percent reduction in primary energy consumption – equivalent to a 170-tonne cut in carbon emissions.

Interview

Municipal housing association WWS Herford works hard to drive forward the necessary energy transition while ensuring it remains socially responsible for tenants and economically viable for the association itself. We met with foreman Ralf Wöhler to discuss the renovation project.

Mr Wöhler, looking back, how would you say the renovation project based on the Energiesprong principle worked out?

The project has been a valuable experience for the WWS, and an important step towards the energy transition. It makes a lot of sense to apply the Energiesprong principle when carrying out modernisation work, as it gives you the chance to save on time and costs compared to traditional renovation techniques. What is important now is that we learn from this experience and use it to gradually optimise our costs and the speed we work at. To a certain extent, I think public housing associations have a responsibility to test new approaches before a corresponding funding framework is set up. Achieving net zero will be a complicated process, but it’s an important one too.

What action would you like to see from politicians and the construction sector?

There’s a lot of interest within the industry in projects like this. In order to make environmentally friendly construction based on the Energiesprong principle possible on a large scale, the powers that be need to provide major support over the next few years so that implementing these projects becomes less of a cost-intensive venture. I’d also like to see dena establish more widespread networking of those involved. The industry has a role to play, too. These developments will open up a pioneering market for companies in this sector – as long as they’re prepared to work with other players. This means doing things like facilitating short delivery routes in order to ensure sustainability.

What impressed you most about this renovation process?

Once the extensive preparations are complete and the building technology is in place, a building can be fully clad in the space of just one day. In just 12 hours, all the big wall panels can be installed and the old building is as good as new – it’s both amazing and fascinating to watch!

How do the bi-folding doors fit into the renovation concept?

Bi-foldings are the perfect solution when it comes to renovating balconies and recessed balconies. The residents can use them like an open-top sports car: when the doors are open it’s a balcony, and when they’re closed it becomes an extension or a wintergarden. It’s also important to mention the extra living space the bi-foldings provide, in planning terms. Only a quarter of a normal balcony counts towards the total area of an apartment, but if it can be fully enclosed, it counts in full.

What was it like, working with Solarlux?

We’ve already learned from working with Solarlux on previous projects that adding enclosures to the existing balconies is in many ways a better solution than removing or renovating them. The organisation was perfect and everything ran smoothly, so we’d certainly be open to working together again in the future.

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