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The dense city and the urban landscape

SIGNA Group

By Kees Christiaanse

With the sole exception of the immediate post-war period, living space per person has grown steadily throughout the 20th century. But now we are seeing a tendency towards smaller apartments in the centre of European capitals. The reasons for this are threefold – firstly, renewed interest in living in the city, which is leading to a housing shortage. Secondly, increasing demand is pushing up prices, to levels that young generations of urbanites simply cannot afford. Finally, atomisation is bringing about a sharp rise in the number of one- and two-person households. Investors have identified a new market for lots of smaller units rather than a few larger apartments. In Hong Kong, 60-square-metre apartments in modest condition with sub-optimal layouts change hands for EUR 1.85 million – the nightmare scenario for Europe, and one which is already coming to London. Whatever happens, we should make every effort to uphold the achievements of European construction, as they represent the very best standards worldwide.

The fact that well educated people have their sights set on city centres once again is an important factor behind the urban renaissance. It is not so much the propaganda spread by exponents of compact cities, but economic development – the network economy – that is behind the demand for urban spaces. These small households want all of the necessary infrastructure, services and facilities at their fingertips, and unlike in the post-war period, they do not want to commute. They want to live and work in the city. So it is not just offices, but other commercial premises such as urban manufacturers and knowledge-based institutions that are finding their way back into cities, ramping up the pressure on what space is still available. Larger spaces where people can both live and work are very hard to find.

But there is another reason: the most interesting and paradoxical aspect of our digitalised society is that it is fuelling a rise in face-to-face encounters. When computers were introduced, the received wisdom was that paper consumption would dwindle to virtually nothing – but then people ended up printing more than ever before. And the amount of real-world interaction between people who meet on digital platforms is unprecedented. This need for interaction also calls for a built environment with a range of amenities which is easy to reach.

Responding to this trend is less of a question for urban planners and architects; instead it is a policy and governance issue for the cities themselves. Cities are able to determine how land is used, to develop and implement measures designed to optimise density, set housing construction targets and transform entire areas for creative purposes. In many places, office buildings stand empty alongside failed investment projects, and these are increasingly being converted into apartments. These governance policies work much better in continental European than in Anglo-Saxon nations where markets are much less strictly regulated. Once the necessary policy decisions have been made, urban planners and architects can step up and help devise intelligent solutions for road and transport networks, density, typology, leisure and zoning mixes. And they can use their vision to inspire politicians and public authorities.

© Markus Bertschi
Kees Christiaanse

Founder of the KCAP Architects & Planners design firm and former professor of architecture and urban planning at the Technical University of Berlin and ETH Zurich.

Kees Christiaanse received a degree in architecture and urban planning from the Technical University Delft. He joined the Office for Metropolitan Architecture (OMA) in 1980 and was named partner in 1983. Mr Christiaanse later struck out on his own, founding the Rotterdam-based firm KCAP Architects & Planners in 1989.

The focus of Mr Christiaanse’s work has been on mastering the complexity of urban settings and shaping urban flows. He is recognised as an expert in the revitalisation of disused industrial, railway or harbour landscapes and has managed numerous urban development initiatives across the globe, among them Hamburg’s HafenCity.

Mr Christiaanse held a professorship in architecture and urban planning at the Technical University Berlin from 1996 to 2003 and acted as the chair of the Urban Planning Institute at the Swiss Federal Institute of Technology (ETH) in Zurich from 2003 to 2018. He was appointed Chairman of the External Advisory Board for the Architecture and Design department of the Singapore University of Technology and Design (SUTD) in 2013.

As an author, Mr Christiaanse has written numerous books and articles about architecture and urban planning. His many awards and accolades include the 2016 International Fellowship from the Royal Institute of British Architects, a lifetime award recognising his outstanding contribution to architecture, and the 2018 Leadership Award from Germany’s Urban Land Institute to honour the commitment and courage he has shown in delivering sustainable development solutions and greater quality of life to urban centres across the country.

The urban renaissance has pros and cons. One clear advantage is that increased property and land prices bring about a general rise in value for the whole city. This has a positive influence on GDP in the form of capital formation. One drawback is the danger of over-gentrification. But opponents of gentrification turn a blind eye to the fact that this increase in value and squeezing out of lower-wealth groups can in fact lead to regeneration and increased density on city peripheries, in turn adding value to suburban locations. When urban governance is properly balanced, it leads to a win-win situation for all sections of a city’s population. It goes without saying that less-well-off groups such as housing benefit recipients, students, housing cooperatives, NGOs, social and young entrepreneurs and creative associations should always be a substantial part of our city centres. A city should not be a zoo containing elite groups, but a dynamic organism. My friend, professor of urban sociology Arnold Reijndorp, put it this way: “True urbanity arises when some groups dominate, without marginalising others.”

In Rotterdam, KCAP 2008 created a sleek and iconic 40-storey tower with a distinct lower section in the Wijnhavenkwartier district. It has a load-bearing core and a load-bearing facade that becomes transparent the further up it goes, as the load decreases and the views improve. The tower is part of an urban planning concept designed by KCAP for the city at the end of the 90s in the waterfront district to the north of the city centre. As an add-on, we came up with a density formula to transform this part of the city while increasing the proportion of residential space. Each owner was free to build upwards on their plot, but limited to a maximum number of cubic metres per square metre of the plot. This meant that larger plots could put up high-rises while the smaller ones had penthouses. A rule governing thickness prevented the creation of disc-shaped towers. There was no cap on the overall height of the structures, but the rules automatically render overly-tall towers inefficient. However, the towers were expected to fulfil certain requirements related to spacing, sight lines, shade and sun. The eaves of the lower section had to be oriented to the traditional block edge. Although this dynamic set of rules did not dictate the specific appearance of individual buildings, it assured a high degree of coherence in the development. This tug-of-war between control and laissez-faire, which determined minimum requirements while leaving everything else open, is a design balancing act that KCAP has successfully built on. It can also be found in Zurich’s Europa Allee, albeit on a more modest scale.

We took this method and applied it to its extremes in the Jurong Lake District development in Singapore, a high-density, high-rise district that we are currently planning next to the site of the future high-speed railway station. It is a district featuring greened high-rises that are interconnected on multiple levels, even though the individual buildings were planned by different architects and owners. The lower section is set aside for various uses including urban industries. With multiple access points, they are also porous to optimise natural ventilation. The towers themselves are mainly residential and hotel developments, but also have a number of offices for headquarters. A “100% green-replacement-rule” stipulates that the buildings’ footprint must be balanced by green rooftop terraces and sky gardens.

High-rises are becoming increasingly popular in inner city locations – particularly for apartments – both in Europe and elsewhere. Zürich-West, Hamburg’s HafenCity, Wijnhavenkwartier in Rotterdam, as well as parts of London, Paris and Milan are just some of many examples. This type of building is gaining in attractiveness because people want to live in precisely those places where cultural amenities and infrastructure are found. On top of this comes the great views and the relative quiet on the uppermost floors. The key is to build high-rises as part of mixed-use complexes in diversified parts of town. The lower sections can be used for a range of purposes.

Stand-alone high-rises in monofunctional areas are not recommended. Berlin’s Gropiusstadt is a classic example of a large-scale, monofunctional urban estate. It automatically leads to a sense of anonymity and is plagued by systemic errors. The number of apartments accessed by a single core access point is enormous. This erodes residents’ relationships with the building and shared spaces, with neglect and vandalism the inevitable outcome. But we have been aware of this for several decades now – as early as the 1980s, housing projects in Holland were limited to a maximum of 25-30 apartments per central access area. And then people get to know one another. What’s more, the most successful high-rise projects of our day are usually found in established quarters. The high-rises in HafenCity are tied into a highly evolved structure – the Speicherstadt – which creates a sense of identity.
Berlin and Hamburg’s HafenCity both feature buildings that were commissioned by collectives. Alongside residential units, they contain guest apartments, studios, shared spaces and workshops that can be used by all of the residents and families living in the building. And that is an interesting development. Rather than spare rooms, people now have parts of the building that they share with others like car sharing. In this way, generations can adapt their space requirements to suit their particular stage of life and, as time passes, develop a sense of home and put down roots in the location. Working, living, caring for children and collective activities are all part of a natural flow. As there is no longer such a strong focus on the use of individual rooms, buildings have to be more flexible than they used to be.

A well-developed network of outdoor spaces is essential in a city. The relationship between the street, entrance area, lobby, stairwells and gardens is a major catalyst for building a community. I believe that there are clear signs of a shift away from isolated living towards groups who build or rent a building to live there together and share spaces. While the numbers behind the trend are still relatively modest, it provides a glimpse into the future that reveals how urban society is starting to perceive itself as a community again.

There is a foil to the high-density, compact city – and it is not the countryside, but the urbanised landscape. Larger agglomerations such as the Ruhrgebiet in Germany, the Randstad in the Netherlands, the Mittelland in Switzerland and the Po valley in Italy are all special phenomena of urbanisation that cannot be ignored. They are extended network landscapes that exhibit similar properties to nucleic cities – provided that adequate transportation infrastructure is in place. We call them productive landscapes. And here too, is a paradox: as these agglomerations sprung up on fertile land next to water sources, agriculture in agglomerations is much better than it is in inaccessible, less-fertile rural areas. Agricultural output is often highest in the places where the most people live. So there are two city models for the future: the compact city with its cores and the extended urban landscape. The compact city is less of a problem. Thanks to its attractiveness and concentrated spaces, it is highly efficient by nature and relatively sustainable as a result. And the friction between highly divergent interests helps to maintain a balance. The larger challenge is posed by these extended urban landscapes. If mobility, refuse collection and distribution are not organised properly, they become catastrophic spaces, the likes of which can be seen in some emerging economies. Examples include Java in Indonesia, the Ganges region in India, and the river delta that Bangkok sits on. Japan and China have these landscapes under much more effective control thanks to better infrastructure.
The quality of open spaces and mobility are a major challenge for urban planners. In the agglomeration surrounding Zurich, the S-Bahn commuter railway network is so good that people can still live in rural villages and reach the city proper in only half an hour. Or take Amsterdam, Rotterdam or The Hague, where the suburbs are as well connected as only those areas inside Berlin’s S-Bahn ring. These days it takes just 30 minutes to travel from Amsterdam to Rotterdam by express train, so lots of people commute. It is hard to control mobility, as it represents a basic human need and a prerequisite for economic success. And this is precisely what makes it such an important aspect of spatial planning and urban development.