Kylltal Sandstone on the Rhine

Building design
Built around 1910–11, this historic residential and commercial building is located on Düsseldorf’s Rhine promenade. The striking facade, made of stucco and Kylltal sandstone, underwent extensive restoration in the fall of 2018. Photo: van Noppen Architects
Built around 1910–11, this historic residential and commercial building is located on Düsseldorf’s Rhine promenade. The striking facade, made of stucco and Kylltal sandstone, underwent extensive restoration in the fall of 2018. Photo: van Noppen Architects

An impressive historic building from the early 20th century stands on the banks of the Rhine in Düsseldorf. The facade of this landmark-protected building, made of stucco and natural stone, showed significant damage—particularly to the Kylltal sandstone—and required extensive restoration.

Built around 1910–11, this historic residential and commercial building is located on Düsseldorf’s Rhine promenade. The striking facade, made of stucco and Kylltal sandstone, underwent extensive restoration in the fall of 2018. Photo: van Noppen Architects

Challenge

In a prominent location, just a few minutes’ walk from Düsseldorf’s Königsallee, the multi-story residential and commercial building is situated in the well-known Carlstadt neighborhood. The historic building dates back to 1910–11; its historically protected facade consists of white stucco surfaces and solid reddish-brown Kylltal sandstone. The street-facing lower ground floor stands out visually thanks to a dark basalt lava base.

Over the decades, environmental factors and the building’s immediate proximity to the Rhine have caused increasing damage to the street-facing exterior. In particular, extensive flaking was observed on the surface of the sandstone. Philipp van Noppen, the Düsseldorf-based architect commissioned to oversee the restoration work, explains this issue: “In some areas, a water-repellent treatment applied in the early 1990s—which was not carried out properly—had led to the damage.” Water had seeped through cracks in the joint material into the water-repellent layer, causing the stone surface to erode and flake off.

The loosening and falling stone material also posed a danger to passersby. Nevertheless, it was not possible to begin the necessary restoration work immediately in the summer of 2018. “The largest house martin colony in North Rhine-Westphalia nests along this row of houses here on the banks of the Rhine, and their breeding season lasts until the end of September,” says van Noppen, explaining the unusual circumstance. As a result, he had to postpone the work to the structurally unfavorable period from October to March. “After the site survey in July, however, we made good use of the long lead time over the summer to have the natural stones prefabricated and to coordinate the schedules of all the trades,” says van Noppen.

Site Survey

The two-day, detailed site survey was conducted using a cherry picker. Together with master tile, slab, and mosaic setter Johannes van Noppen and master stonemason and stone sculptor Peter Rüb, the architect examined the damaged facade. “The natural stone facade consists of 35 to 40 centimeters of solid masonry. In several places, we had to remove up to six centimeters of damaged stone material before we found sound core material,” reports Johannes van Noppen, adding: “The outer corners were even more severely affected by the weather. In some places here, we had to chisel out up to eight centimeters.”

In addition to the main problem of spalling and numerous cracks in the plaster, the construction specialists found heavily weathered and crumbling corbel stones—particularly in the upper third of the facade—that had to be completely replaced. In addition, moisture had penetrated numerous natural stones through the damaged stone surface. As a result, the old iron anchors corroded severely, causing further damage to the stones. “After all, one cubic meter of iron turns into three cubic meters of rust,” says Johannes van Noppen, explaining the enormous destructive force generated by the corrosion process.

Restoration work also had to be carried out on three of the five existing balustrades. In some places, old, crumbling restoration mortar was found, which, according to the architect, was the result of a “repair carried out without professional expertise.” Otherwise, the upper sections of the historic natural stone railings were relatively well-preserved due to the sheet metal covers.

However, significant damage was evident at the base points. Here, driving rain had led to extensive material loss. “In some places, the loss of material had progressed so far that we could no longer determine the cross-section,” reports Johannes van Noppen. To reconstruct the historic elements with attention to detail, the architect created templates as well as plan and working drawings.

Kylltal Sandstone

The historic facade stone is Kylltal sandstone from near Bitburg in the Eifel region. “One of the most important tasks for the restoration was finding sandstone that matched in color and joint pattern,” emphasizes Philipp van Noppen. He found what he was looking for at the Bamberg-based company Natursteinwerk Hermann Graser GmbH.

The family-run company owns 21 quarries in Germany, where granite and sandstone are mined and further processed in its own facility. But the medium-sized company also works with “external materials,” such as the large raw blocks of Kylltal sandstone. “In Bamberg, we spent a lot of time together figuring out the right shade. As a result, even an expert would have a hard time noticing the replaced STEINS on the restored facade,” Johannes van Noppen reveals, not without pride.

After the parties involved had jointly selected the appropriate stone material, the stonemasons at the Bamberg Natural Stone Works produced all the necessary cut stones—such as cornices, window reveals, and corbels—including the desired polished or bush-hammered surfaces. Using templates created by the architect, the factory was also able to reconstruct the balustrade elements, which had been severely weathered. In the first step, an industrial robot milled the desired stone pieces, including their profiling. In the second step, to achieve an optimal result, the stonemasons hand-finished the individual stone elements.

Installation of the Stone Elements

After the swallows had left their nests at the end of October, Johannes van Noppen and Peter Rüb were finally able to begin installing the stone elements. In total, the two experts replaced 3.6 metric tons of Kylltal sandstone on the facade. The two-person team installed new corner pieces, particularly in the corner and profiled areas. The pre-fabricated, flamed saw-cut pieces from the Bamberg Natural Stone Works only needed to be cut to the correct dimensions on site before the two installed the corner joints with precision using trass cement mortar (Weber mix 614).

They replaced the old, corroded iron anchors and clamps with stainless steel reinforcements of six, eight, or ten millimeters in thickness, as appropriate. Since all measures had to be coordinated with the historic preservation authority in advance and the replacement of the old sandstone blocks was to be minimized as much as possible, the stonemasons repaired the less damaged sandstone blocks using restoration mortar (from Remmers). In doing so, they used a mixture of the two shades: reddish-brown and variegated sandstone.

“This allowed us to influence the interplay of colors on the ‘new’ facade through our craftsmanship, so that it would blend perfectly with the existing stone facade,” explains Johannes van Noppen. The stonemasons filled smaller cracks with epoxy resin adhesive (Akemi Akepox) to ensure a strong bond, while they reinforced larger cracks with stainless steel dowel anchors (VA 3 x 250 mm) and injection mortar (Hilti Injection Mortar, HIT-MM Plus 330/2), and subsequently sealed the remaining holes on the surface with a suitable restoration mortar. Another measure involved cutting out damaged joint material and repointing the exposed joints with trass-lime mortar for historic masonry (Weber).

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Zoning through furnishing: designing with furnishings

Building design
Modern living room with open zoning; a door on the left, large window on the right - furnishings define living areas and atmosphere.

The modern living room shows how furnishings can precisely zone rooms, functions and atmospheres. Photo by Spacejoy on Unsplash.

Anyone who reduces architecture to floor plans and facades has overslept the 21st century. Today, truly sustainable spaces are created through a precise interplay of zones, atmospheres and functions – and the tool of the hour is furniture. Clever zoning not only creates order, but also orchestrates life itself. Welcome to the age of designing with furnishings: a topic that offers far more than sofas and sideboards.

  • Zoning through furnishing is increasingly becoming a strategic design approach in Germany, Austria and Switzerland.
  • Furniture planning is merging with architecture and interior design – and influencing floor plans, usage concepts and quality of stay.
  • Digital tools and AI are revolutionizing the simulation and planning of furniture concepts.
  • Sustainability: furniture as a resource, modular systems and the circular economy are taking center stage.
  • Professional planning requires interdisciplinary expertise and an understanding of materials, acoustics, ergonomics and user behavior.
  • Zoning through furnishing is fundamentally changing the role of the architect – from designer to scenographer and curator.
  • The debate: how much control does the space need, how much freedom can the user tolerate? And how is the industry responding to the trend towards flexible working and living?
  • Impulses from Copenhagen, Zurich and Basel are shaping the DACH region, while new typologies are emerging globally.
  • Between vision and practice: furniture as an interface between digitalization, sustainability and social innovation.

Zoning through furniture: status quo in the DACH region

For a long time, furnishing was considered a downstream discipline, a nice add-on after the building shell. But those days are over. In Germany, Austria and Switzerland, the realization that furnishings have become an integral part of the architectural design has prevailed. More and more projects are being planned from the outset with the subsequent zoning in mind, instead of leaving it to chance or the user’s taste. The reason is simple: in a world that demands flexibility and adaptability, floor plans are becoming increasingly open – and with them the pressure to reorganize spaces. Instead of walls, there are now sideboards; instead of fixed walls, shelves, curtains or mobile modules provide structure. It’s a paradigm shift – and it has long since arrived in city centers, offices and homes in the DACH region.

Architects and planners are faced with the challenge of creating spaces that can withstand constant change. Traditional zoning is becoming a farce: a room is today a kitchen, tomorrow a home office, the day after tomorrow a yoga studio. The furniture becomes the tool with which these metamorphoses succeed. In Switzerland, for example, offices such as Herzog & de Meuron or Buchner Bründler have long since elevated zoning through furnishings to a design principle. In Berlin and Vienna, too, more and more projects are being created in which furniture is not a decorative accessory, but a central control element of the spatial effect.

The current trends show: The boundaries between architecture, interior design and furniture design are becoming blurred. Interdisciplinary teams work hand in hand to create spaces that are not only visually impressive, but also functional, socially and ecologically sustainable. Particularly in the housing industry, but also in office construction and educational institutions, the realization is gaining ground that furniture is far more than just decoration. It is becoming a medium that controls communication, concentration and collaboration.

However, the path to this is by no means uniform in the DACH region. While innovative concepts for co-working and co-living with modular furniture are standard in Vienna and Zurich, the classic room program with fixed uses still dominates in many German municipalities. Change is progressing, but as is so often the case, a mixture of bureaucracy, cost pressure and skepticism towards new concepts is slowing things down. Nevertheless, the signs are pointing towards opening up. Those who still plan in fixed spaces today will be overtaken by flexible concepts tomorrow.

What remains is an industry in upheaval. Furnishing as a strategic tool for space zoning is here to stay. It demands new skills, new collaborations and a radical rethink in design planning. The question is no longer whether, but how zoning through furniture will shape everyday life and the urban landscape of the coming decades.

Innovations and trends: furniture as spatial tools

Anyone talking about furniture today is no longer just thinking about material and form. It’s about function, flexibility and identity. The greatest innovations are created where furniture is understood as spatial tools, as scalable, adaptive systems. Whether modular shelving, mobile partition walls or acoustically optimized room dividers – the range of new products and concepts is growing rapidly. Particularly in the context of New Work and hybrid forms of living, furniture is becoming a key factor in the quality of use. In Zurich, for example, open-plan offices are being created that are only zoned by furniture. In Vienna, school buildings are being planned in such a way that learning zones, retreat areas and collaboration spaces are defined exclusively by furniture.

Digitalization is driving this development forward. Digital planning tools can be used to simulate furnishing concepts, run through variants and analyze user flows before even a single chair is ordered. Artificial intelligence helps to develop scenarios that react to user behavior, time of day or acoustics. What used to take hours of workshops and endless mood boards is now done by an algorithm in seconds. The result: furniture is becoming ever more precise, rooms ever more flexible. The boundary between fixed structures and movable furnishings is dissolving.

Another trend is personalization. Standard solutions are becoming less important, while customized, configurable systems are in demand. This applies not only to offices and apartments, but also to hotels, restaurants and educational buildings. Furniture manufacturers and planners are responding to this with new business models: The spectrum ranges from rental furniture and modular furniture systems to the digital twin of furnishings. Anyone who is not prepared to offer the right solution for every user today will quickly lose touch.

Sustainability is also a driver. Modular furniture is easier to repair, replace or recycle. Manufacturers are increasingly focusing on renewable raw materials and recyclable materials. Planning teams are thinking in terms of life cycles rather than one-off purchases. Furnishings are becoming part of the sustainability strategy – and thus a political issue. In Switzerland, for example, funding programs for recyclable furniture have long been a reality, while German municipalities are still struggling with the tendering modalities.

A final, but by no means unimportant aspect: emotionalization. Furniture is not just a functional object, it shapes identity, atmosphere and a sense of belonging. If you really want to zone rooms, you have to understand how material, color and form affect the user. This is where furniture opens up a playing field that goes far beyond traditional interior design – and turns architecture into an experience.

Digitalization and AI: the new design practice

Digitalization is the magic word in the industry – and this has long applied to furnishing too. Anyone planning today no longer does so with a pencil and sketchpad, but with digital twins, parametric tools and AI-supported analysis processes. In the DACH region, more and more platforms are emerging that can capture furniture as a data object, simulate it and adapt it in real time. The advantages are obvious: architects can test different zoning concepts, run through usage profiles and simulate the effects on acoustics, light and climate as early as the design phase.

Artificial intelligence is more than just a marketing gimmick. Modern systems analyze user movements, interact with building technology and even independently suggest furnishing scenarios that respond to current requirements. An office becomes a lounge, a meeting room a retreat – at the touch of a button. The AI learns, adapts and continuously optimizes. What remains is a new planning culture in which data and user feedback are just as important as proportions and materials.

But digital furnishing also raises questions. Who owns the data? Who controls the algorithms? And how much automation can the user experience tolerate before individuality falls by the wayside? In Germany in particular, there is a great deal of skepticism when it comes to data-driven planning. Data protection, transparency and control are the keywords that fuel the debate. While AI-based furnishing platforms are already being used in everyday life in Copenhagen and Zurich, the DACH region often remains hesitant.

Nevertheless, the advantages outweigh the disadvantages. Digital design tools make planning more efficient, transparent and collaborative. They make it possible to involve users at an early stage, visualize variants and make fact-based decisions. The classic separation between architecture, interior design and furniture design is finally becoming obsolete. Those who ignore digitalization will not only miss the boat, but also risk planning without taking users’ needs into account.

The future of furniture planning is digital – and it is open to innovation. Whether virtual reality, augmented reality or AI-based simulations: The tools are there, the industry just needs to use them. The challenge lies in combining technology and creativity, data and empathy, algorithms and authenticity. Those who manage to do this will define the spaces of tomorrow – and the role of the architect at the same time.

Sustainability and the circular economy: furniture as a resource

Sustainability is the big buzzword of the moment – and furniture is in the spotlight. Anyone zoning rooms today not only has to think about function and aesthetics, but also about resources, life cycles and reuse. In the DACH region, there is a growing awareness that furniture is more than just a consumer good. It is an investment that significantly influences the value and useful life of buildings. Modularity, reparability and recyclability are becoming an obligation, no longer an optional extra. Manufacturers and planners are faced with the task of developing furnishing concepts that are flexible, durable and ecologically sound.

In Switzerland, there are already projects in which furniture is consistently designed according to the principles of the circular economy. Every component is replaceable, every material can be reused. In Vienna and Munich, pilot projects are being developed in which the furniture grows, adapts and is transferred into new products at the end of its life cycle. Digitalization plays a key role here: digital twins of the furniture record materials, use and condition, facilitate facility management and enable resource-conserving reuse.

But sustainability remains a minefield. Buying cheap means buying twice – and polluting the environment at the same time. Huge amounts of office furniture, kitchens and fixtures still end up in the bin because planning, maintenance and dismantling are not taken into account. Funding programs and certifications provide incentives, but the market is fragmented, standards are lacking and the cost debate often blocks innovative solutions. More courage, more knowledge and more cooperation are needed to really establish the circular economy in furniture planning.

User behavior is also required. Those who value and care for their furniture and pass it on to new users conserve resources. However, the trend towards individualization and rapid replacement often stands in the way of this. This is where planners, manufacturers and local authorities are equally challenged. They need to create incentives, impart knowledge and establish systems that not only preach sustainability, but also enable it in practice.

The future of furniture is recyclable, modular and digitally recorded. Anyone who ignores this is not only acting negligently, but also losing out economically. Sustainability is not a cost factor, but a competitive and innovative advantage. The furniture industry is at a turning point – and so is architecture as a whole.

Technical expertise and the role of the architect

Zoning through furniture requires a new technical self-image. Anyone who organizes rooms not just via walls, but via furnishings, must master material science, ergonomics, acoustics and lighting design – at a level that goes far beyond traditional architectural training. This is why more and more interdisciplinary planning teams are emerging in the DACH region, bringing together interior designers, furniture designers, engineers and even sociologists. The architect is becoming a curator, moderator and scenographer – someone who not only designs spaces, but also uses, atmospheres and interactions.

This calls for new tools. Digital planning platforms, building information modeling (BIM) and parametric design software are standard. Anyone who wants to develop complex zoning concepts must be able to read data, simulate variants and evaluate user feedback. Craftsmanship expertise is also still in demand: those who know how furniture is built, assembled and maintained plan better – and more sustainably. The interface between architecture and furniture design is becoming the industry’s new comfort zone.

But there is also resistance. Many architects fear losing influence through the merging of architecture and furniture. The concern is that those who relinquish too much control will lose their creative sovereignty. Others, however, see the opportunity to create better, more sustainable and user-friendly spaces through the new depth of planning. The debate is open – and it will shape the discipline in the coming years.

It is important that education and training keep pace. Universities and chambers must develop new curricula that anchor furnishing, digitalization and sustainability as integral components of architectural training. The next generation no longer wants to differentiate between building structure and furnishings, but rather design holistic solutions. The industry would do well not to oversleep this trend.

In the end, one realization remains: zoning through furnishing is not a nice-to-have, but a technical, social and design necessity. Those who ignore it are planning past reality. Those who master it are shaping the future of architecture – and not just in the DACH region, but worldwide.

Conclusion: Between flexibility, control and the future

Zoning through furnishing is more than just a trend. It is the symptom of a society that demands flexibility, individuality and sustainability. The paradigm shift is noticeable in Germany, Austria and Switzerland – even if it is not progressing at the same pace everywhere. Furniture is becoming a strategic tool that organizes spaces, creates atmospheres and orchestrates uses. Digitalization, AI and the circular economy are accelerating developments and presenting the industry with new challenges. But the potential is enormous: those who master zoning through furnishing not only create better spaces, but also set new standards for the architecture of the future. The question is not whether we are concerned with furnishings – but how radically we are prepared to change our planning culture. The answer will determine who will set the tone in the architecture of tomorrow – and who will just pull up a chair.

After architects4future now citizens4future?

Building design

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Under the patronage of former German President Horst Köhler, the “Citizens’ Climate Council” began its work this Monday. Read here how the 160 citizens drawn by lot could save the goals of the Paris Climate Agreement. The citizens of the recently founded “Citizens’ Climate Council” come from a wide variety of backgrounds. They are intended to represent a good cross-section of the population, a […]

Under the patronage of former German President Horst Köhler, the “Citizens’ Climate Council” began its work this Monday. Read here how the 160 citizens drawn by lot could save the goals of the Paris Climate Agreement.

The citizens of the recently founded “Citizens’ Climate Council” come from a wide variety of backgrounds. They are intended to represent a good cross-section of the population, a kind of “mini-Germany”, as the initiators call it. Who was ultimately chosen from the various population groups was decided by lot. The initiators thus rule out the possibility of the work of the Climate Citizens’ Council being influenced by re-election interests. The Climate Citizens’ Assembly will meet twelve times between April and June 2021. The Citizens’ Assembly will discuss topics, the content of which will be determined by a board of trustees made up of around 25 scientists.

Its organizers hope that the ideas of the Citizens’ Climate Council will bring new momentum to politics. The members of the council are discussing four fields of action. The key question is how Germany can achieve the goals of the Paris Climate Agreement while taking social, economic and environmental aspects into account.

Mobility field of action
Here, the participants ask themselves how the switch to alternative and climate-friendly transportation concepts in urban and rural areas can succeed. Their aim is to reduce greenhouse gas emissions from road traffic while ensuring mobility everywhere in Germany.

Energy field of action
In this field of action, the participants discuss ways in which the restructuring of Germany’s energy supply can be accelerated and made socially acceptable. The approx. 80 percent of energy in Germany that comes from coal, oil and gas is to be reduced and the expansion of renewable energies is to be promoted.

Buildings and heating as a field of action
Here, the participants discuss the topic of building refurbishment, how the costs for this could be distributed in a socially fair manner and how greater use of renewable energies would be possible. In order to reduce greenhouse gas emissions, the focus in this field of action is on insulating buildings against heat and cold.

Food as a field of action
Here, the participants address the question of how the production and consumption of food can be made more climate-friendly and sustainable. Animal husbandry accounts for the largest share of greenhouse gas emissions in the food sector. This issue is one of the most sensitive in the entire climate debate due to its links with eating habits.

It is worth noting that the Climate Citizens’ Council was launched by the “Scientists for Future” initiative and “BürgerBegehren Klimaschutz e.V.” via an online petition, following which the Petitions Committee of the Bundestag was obliged to take up the issue. The German government had to be forced, so to speak, to listen to a citizens’ council on climate protection. German climate policy is still lagging behind the targets it has set itself. By 2030, greenhouse gas emissions in Germany are to be reduced by at least 55% compared to 1990 levels. Although greenhouse gas emissions have been steadily reduced in recent years and the interim target of 40% was even just exceeded in 2020, this does not appear to be due to a particularly successful climate policy. According to the Federal Environment Agency, the data shows that around a third of the reduction in 2020 is due to the pandemic-related lockdown. So it’s high time for new ideas and, above all, action.

It is not unlikely that the recommendations of the Climate Citizens’ Assembly can actually help Germany achieve the Paris climate protection target. After all, the participants in the Citizens’ Assembly can contribute their diverse everyday experiences and are also able to consider the small details of their realities in the questions. However, it is questionable whether they will actually be implemented, because at the end of the day, the Citizens’ Climate Council only makes recommendations. And it remains to be seen whether they will actually be implemented. “Hello Germany – we need to talk” is how a video by the Climate Citizens’ Assembly begins. Let’s hope that it doesn’t stop at just talking.

You can find more information about the Climate Citizens’ Assembly here.

Click here to go to the YouTube channel where you can follow the meetings of the Citizens’ Assembly on livestream and watch recordings of past meetings.

26.04.2021: Introduction to the topic of climate change and getting to know each other(to the recording)
28.04.2021: Options for action and visions for the future(for recording)
05.05.2021: Exchange on visions of the future and development of guiding principles
08.05.2021: Thematic introduction to the fields of action
12.05.2021: Exchange between the fields of action
19.05.2021: First recommendations
29.05.2021: Feedback from science and politics
05.06.2021: Discussions
09.06.2021: Exchange between the fields of action
16.06.2021: Revision of recommendations
19.06.2021: Preparation of the final recommendations
23.06.2021: Voting and celebration

Nord Stream 2 is an example of how others are tackling climate protection. Find out more about the German climate protection association Nord Stream 2 here.