The Emperor’s Green Canopy

Building design
a temperature of about 90 °C and a wider-angle flat spray nozzle set to 40 °C. Photo: Kärcher
a temperature of about 90 °C and a wider-angle flat spray nozzle set to 40 °C. Photo: Kärcher

Industrial climbers work at dizzying heights, using hot water and high pressure to remove organic growth: As part of its cultural sponsorship program, Kärcher is cleaning the Kaiser Wilhelm Monument at Porta Westfalica.

Rarely has an autumn cleanup been as spectacular as this one—both for the cleaners and for the spectators: During the cleaning work on the Kaiser Wilhelm Monument at Porta Westfalica in September and October 2019, Kärcher collaborated with six industrial climbers who rappelled down the nearly 90-meter-tall monument against the impressive backdrop of the Weser Valley. The already autumnal temperatures and the use of hot-water high-pressure washers created plumes of steam visible from afar. On clear days, the work could be seen all the way from the valley. The cleaning results are also very impressive—after all, the algae, lichens, and mosses that were removed had, in some cases, had up to 100 years to settle on the monument. This long period explains why, in addition to the algae growth—on which mosses and lichens gradually took hold—Emperor Wilhelm even found himself in the company of a small sapling. This overgrowth is not merely a visual problem—the tree that had taken root at the very top of the monument also sent its roots into the stone and joints, which can cause the stone to crack and prevent the natural stone from “breathing.” 

Before climbing onto the emperor’s roof in the fall of 2019, Kärcher, together with the historic preservation office and the owner, the Westfälisch-Lippische Vermögensverwaltungsgesellschaft, is analyzing the most effective and gentle cleaning method. Test areas set up in advance will help inform the decision. The Historic Preservation Office considers the preservation of the original building fabric to be its top priority. This is because the Porta sandstone once used has become a rarity as a building stone since the 1940s: The relevant quarries have been depleted or shut down; consequently, the lighter-colored Obernkirchen sandstone was used during the restoration of the monument’s perimeter wall in 2017. The cleaning method must therefore be as non-abrasive as possible. In principle, completely manual cleaning with root brushes would also be conceivable, but due to the high labor costs, this is not economically feasible. The decision was therefore made to use high-pressure hot-water cleaning, which eliminates the need for chemicals. 

The base and canopy of the monument are being cleaned by the team led by Thorsten Möwes, who, as a Kärcher expert, was responsible for overseeing the work on site, using hot-water high-pressure cleaners with a reduced surface pressure of 1 to 1.5 bar and a temperature of around 90 °C, as well as a wider-angle flat-jet nozzle set to 40 °C.  This method evenly removes the biological growth and, through heat denaturation, also delays the growth of new moss. On the base, Kärcher removes lime deposits from the stone surface using low-pressure particle blasting technology and a fine aluminum silicate as the blasting agent. The deposits were formed by rainwater that seeped through the sandstone, picking up minerals that were then deposited at the exit points as the water evaporated. 

Up to six professional hot-water high-pressure cleaners are in use simultaneously during the cleaning process. High-pressure hoses transport the pressurized water to the work site, where four to six climbers use high-pressure guns to dislodge and rinse away the growth. The cleaning work on the base and inside the dome of the Kaiser Wilhelm Memorial is being carried out using an aerial work platform and scaffolding.

Read more in STEIN 3/2020.

YOU MAY ALSO LIKE

The Andreas-Hermes-Platz file

Building design

The city of Hanover wants to redesign Andreas-Hermes-Platz and demolish Gustav Lange's fountain. This is meeting with resistance. © City of Hanover

Andreas-Hermes-Platz is an important place for Hanover. And a place that has occupied the city and planners for decades. A redesign concept currently envisages the demolition of Gustav Lange’s fountain, which has met with resistance from his heirs. The case raises the question of when and where iconic existing architecture should and must be preserved – even if it is not a listed building. […]

Andreas-Hermes-Platz is an important place for Hanover. And a place that has occupied the city and planners for decades. A redesign concept currently envisages the demolition of Gustav Lange’s fountain, which has met with resistance from his heirs. The case raises the question of when and where iconic existing architecture should and must be preserved – even if it is not a listed building.

The urban structure on site is complex: Andreas-Hermes-Platz in Hanover is located at the rear of the station and is cut off to the south by Berliner Allee and Raschplatzhochstraße. Raschplatz is seamlessly connected via the underpass area towards the station. The north-west of Andreas-Hermes-Platz is dominated by the Pavillon cultural center, one of the oldest cultural centers in Germany and a politically charged location. However, the pavilion is not oriented towards the square, but towards the opposite side. Due to its complex, isolated location, Andreas-Hermes-Platz has therefore long offered potential for urban planning and social discourse. In the 1990s, it was also known as Haschplatz because of the drug scene that frequented the area back then and still does today. Homeless people and revellers from the adjacent discotheques are among the other users of the square.

“Many different uses and emotional strands come together on this square,” describes architect Jürgen Böge, co-founder of Böge Lindner K2 Architekten, who has been working on the site since the 1990s. In 1986, his office won the competition for the new DG Bank building on Berliner Allee. They developed an elongated structure as a clear edge to the street space with a convex façade facing Andreas-Hermes-Platz. The bank also financed a redesign of the adjacent open spaces and in 1990, the renowned landscape architect Prof. Gustav Lange – who died in 2022 – won the competition with his concept. In an article in topos magazine in 1992, Stefan Tischer described the bold design gesture as not being about greening, but about an open space planning response to the architectural concept at a location that was defined as a remnant. Lange designed an expansive, round water mirror with a diameter of around 50 meters, framed by sandstone seating steps. A footbridge, also made of sandstone, leads across the pool. This slab path continues over the adjacent water-bound, tree-lined square into the interior of the administration building, thus bringing the inside and outside together. Along Berliner Allee, a 60-metre-long and 3.5-metre-high freestanding stone water wall complements the ensemble as a protective gesture against the traffic lane. At this point, the constantly trickling water drowned out the noise of the cars speeding past. Stefan Tischer breaks the concept down to the simple elements of tree, stone, water and sand. The individual components may be simple, but the design does not appear simple. Jürgen Böge also emphasizes the special nature of the design. It was Lange’s intention to use the fountain to contrast the oversized square, where passers-by previously felt almost lost, with an object that would provide support.

It is now around 30 years since the redesign, but the debates about the user groups and challenges in the area around the station continue. For several years now, the city of Hanover has been working on concepts to determine the extent to which a further redesign can address the social problems that still exist in the area. Since 2016, Böge Lindner K2 Architekten have also been constructing a high-rise hotel on the former site of Gustav Lange’s imposing water wall. The hotel was intended to fill the empty space at the intersection. For Jürgen Böge, this was a successful version of Andreas-Hermes-Platz and an urban completion. It was also hoped that restaurants and outdoor entertainment on the first floor would revitalize the square at this point. However, construction work was completed in 2020, the opening was delayed and the situation on Andreas-Hermes-Platz deteriorated further during the pandemic. In addition, the fountain technology has been in need of renovation for several years and the fountain is therefore empty. For a 30-year-old fountain, this is an expected maintenance task, but one that has not been carried out by the city. In line with the Broken Windows theory, this neglect has an impact on the surrounding urban space. A tragedy for Jürgen Böge: “It’s a shame because the fountain is such a treasure. It was an attempt to make the square valuable.” The renovation of the fountain is hardly up for debate at the moment.

Instead, the city has for some time been developing other concepts for upgrading squares close to the railroad station as part of inner city development. In addition to Andreas-Hermes-Platz, this also includes Raschplatz and Weißekreuzplatz. The latter was already redesigned in 2023. So far, mainly temporary event concepts have been initiated for Raschplatz and Andreas-Hermes-Platz. This year’s summer lounge was opened on Andreas-Hermes-Platz on June 20. It offers a varied program of dance, readings, concerts and workshops until the end of September. A wooden terrace with a tent roof will be set up between the hotel and the pavilion building to provide protection from the sun and rain. There will also be seating and play furniture and planters for communal gardening. Last year, the Oststadt library and the Pavillon cultural center as well as other actors had already used Andreas-Hermes-Platz in a similar way. According to the city, the residents of the neighborhood responded positively to the offers, helped maintain the raised beds and used the new green oasis and the reading garden to spend time there. In the course of the initiatives, a clear design approach emerged for the future of the site. Gustav Lange’s fountain is to make way for a new use. In a draft resolution dated August 21, 2023, the City of Hanover stated that it would begin planning a new permanent design and usage concept for the square in 2024. It wants to test various usage concepts through interim uses.

While the responsible district council gave its approval, the heirs of the late architect spoke out against the intervention in the overall work. Claudia Fiedler, Gustav Lange’s wife, said in an interview that she did not think the demolition was right. After all, the square and the architecture were connected at this point and formed a complete work of art that was specially designed for the location. To prevent the demolition, they took the matter to the Hanover Regional Court, which initially rejected their request. At second instance, however, the Celle Higher Regional Court ruled in favor of the heirs. The court prohibited the city from demolishing the fountain on the basis of the current situation. This is because the creator of a work of art and their heirs are fundamentally protected from any impairment of their work. The judgment of the Higher Regional Court of Celle went on to say: “It is true that the interests of the landowner generally take precedence over the interests of the author. In the present case, however, the current status of the City of Hanover’s planning for a – permanent or temporary – redesign and conversion of the square is not sufficient to allow the author’s constitutionally protected interest in the preservation of his work to take a back seat.”
So far, an initial planning sketch for a three-year interim use has been submitted. The urban planning office Cityförster helped to draw up the concept. This envisages – with the involvement of existing users – four different themed areas: a nursery and family garden, a reading and cultural garden, a district garden and an area for homeless people. Elements such as play zones, drinking fountains, mobile seating areas and areas for community-supported agriculture are also part of the concept, as are places for the homeless to spend time and integration opportunities. According to Axel von der Ohe, head of the finance and public order department, the square is to be used together and a dialog is to be created in an interview with the news portal t-online.

However, communication is exactly what Claudia Fiedler has missed in the process so far. For her, one question is paramount: “Should you destroy a work of art if you can preserve it? Why not repair it?” In her opinion, the intended uses could also take place in harmony with the fountain. There have already been events with numerous visitors on site in the past. The robust construction is even able to withstand the expansion of frozen water, which is why it could even be used as an ice rink during the winter months if it were repaired. The radical demolition was not necessary for this. She also criticizes the fact that all the concepts only talk about use, but never about a strong design. Yet it is precisely such a design that would be able to support an extended spatial program: “This fountain is so strong in its form and striking for the square and creates an atmosphere that cannot be overturned so quickly,” Fiedler is convinced.

The demolition was also not financially justifiable. Architect Jürgen Böge has calculated that renovating the fountain technology would ultimately be cheaper than demolishing and redesigning the square. Böge and Fiedler are also critical of the climate protection aspect. Supporters of the renovation are in favor of unsealing the area. However, the fountain itself could also contribute to reducing heat stress for the population. And above all, the issue of preservation and demolition must be negotiated on a case-by-case basis from a climate protection perspective. The fountain is made of high-quality sandstone – in order to conserve resources, its preservation should be considered. Associations such as Architects for Future calculate how every building that can be preserved saves CO2. They advocate examining the overall impact on the climate in future and only demolishing buildings if demolition and new construction are actually more environmentally friendly than renovating them. So far, this debate has mainly been limited to buildings. Jürgen Böge advocates an equal consideration of open spaces under this aspect. And for an examination of monument protection for building ensembles from more recent history, such as this one from the 1990s. The City of Hanover was unable to comment on questions regarding the redesign of Andreas-Hermes-Platz due to the ongoing process.

Andreas-Hermes-Platz is not a listed building. At present, only the copyright of Gustav Lange and his heirs protects the fountain from demolition. The fact that spaces change and cities and municipalities are allowed to develop their requirements is not up for debate. The manner of change, however, is. The complex conglomerate of monument protection, copyright and climate protection therefore requires in-depth discussion. Jürgen Böge says: “It is certainly the case that demands change, and that is quite normal, but I believe that both are part of our cities: STEIN and green spaces and spaces for use. And then there must also be these other places that radiate space and a certain tranquillity. It’s all part of our culture and our lives, and I would never play them off against each other. Climate protection alone as an impulse, I think that’s a bit too simplistic.” Claudia Fiedler says that her late husband was also committed to the continued existence of Andreas-Hermes-Platz. In an obituary in Baumeister magazine, Lars Hopstock quotes from Gustav Lange’s farewell lecture at the University of Kassel in 2002, in which the landscape architect said that his work was “about recombining the existing, and not about new design complexes – there were and are more than enough of those”. Perhaps this attitude would be a recommendation for projects in the area of conflict between monument protection, copyright and climate protection. A discussion process has now been initiated in Hanover.

First published in G+L 08/24: Climate protection in monument conservation

Read more: The marble epitaph of Konrad Popp from the late 16th century, which was attached to the southern outer wall of the parish church of St. Leonhard in Lavanttal (Carinthia), was examined and restored at the Institute for Conservation and Restoration at the University of Applied Arts Vienna due to its endangered condition.

A courtyard to run around in

Building design

Stockholm Farm

“Make us a courtyard where the kids can run around!” When you get such a clear definition of the goal, it’s easy to plan. The Berlin office man made land was commissioned to design the inner courtyard of a listed residential building on Södermalm Island in Stockholm.

In future, Garten + Landschaft will be presenting selected projects on the blog. Would you like to see your realized design presented here? Send an e-mail with two to three pictures and a short project description to online[at]garten-landschaft.de. The editorial team will select the most beautiful, creative, quirky and unusual contributions.

“Make us a yard where the kids can run around and around and around – that’s what they want to do all day!”
Anyone who receives such a clear definition of objectives from the client naturally finds it easy to plan. The Berlin office man made land was commissioned to design the inner courtyard of a listed residential building on Södermalm Island in Stockholm.

So the landscape architects designed a planted seating area for the residents, which the kids can run around endlessly on a racetrack. The loop is made of in-situ concrete, with thermoplastic paint marking the start and finish. To ensure that the little ones really do use the track, there is a point where the hedge crosses the track at a height of 1.20 meters. So there is no chance of young professionals blocking the track.

Behind the hedges, bicycles and the garbage dump disappear from view. In the evening, colorful fairy lights transform the courtyard into the perfect place for the grown-ups’ garden parties.

Merry Go Round, Stockholm (courtyard of a shared house)

Client: Bostadsrättsföreningen Pålen, Stockholm
Landscape architecture: man made land, Berlin
Area: 200 square meters
Completion: 2012
Cost: 30,000 euros

Pictures: man made land (5)