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Help against space constraints: creative compression
Help against space constraints: creative compression
Video: Help against space constraints: creative compression
Video: The power of creative constraints - Brandon Rodriguez 2023, February

Life and living in German city centers is becoming increasingly popular. The space in the center of the cities is limited. But there are options. Manuel Herz, Professor of Architectural, Territorial and Urban Design at the University of Basel, shows us successful examples of creative compaction.

There are still numerous inner-city vacancies, building opportunities in the courtyards have not been exhausted and many roofs could be added. Numerous municipalities sponsor buildings that take advantage of such opportunities for densification because this can prevent natural spaces from being sealed.

In addition, the urban development structures are better used. The architect Manuel Herz was able to gain experience with the densification of a vacant lot in Cologne a few years ago and, as a professor in Basel, also deals with the design of urban spaces.

Why is the further concentration of our cities so topical?

Manuel Herz: So far, dense buildings have always had a negative aftertaste. That is changing. You can see that there are cities that are very compact and still have a high quality of life. For example Manhattan, which could hardly be more exciting and exciting. Many small parks there contribute to a good attitude towards life. Attractive Paris is also much denser than our German cities.

Why is dense living often negative for us?

This was particularly the case in the 1960s and 1970s, when many people dreamed of living in the green with their own garden. This ideal has become less attractive to many. I personally welcome the trend towards more density, partly because it will significantly reduce our energy consumption. For example, densely populated Hong Kong uses much less energy than the relatively sparsely populated Houston in Texas. In extensive settlements, you also drive a lot more by car. In dense cities you can do almost everything on foot or by bike. In addition, many people today value the cultural diversity and heterogeneity of a big city.

How do building laws and a sensible densification harmonize in Germany?

The building legislation regulates the maximum development of a property. This is what the number of storeys, or GFZ for short, is the ratio of the usable area built to the size of the property. This number has a significant impact on the density of a settlement. In inner-city zones, this value is set to a factor of 1.2. For example, I can build half of the property on two and a half floors. That is a relatively low density.

Is that always the upper limit?

No, this is not a tough limit, but the yardstick from which you start. In long discussions with the planning offices, the GFZ can often be expanded upwards. Many building authorities in larger cities are now of the opinion that this limit is generally somewhat too low.


Unconventional & gaudy: The red house in the south of Cologne not only uses a vacant lot, but also the leeway that municipalities have when it comes to interpreting the building laws. Despite the narrowness of the property, bright and airy rooms have been created in the cheekily designed upper part of the building that make you want to live here.

Photo: Boris Becker

You designed a house in Cologne in a very narrow space. What was your experience like?

That was not an ideal starting point: a vacant lot. The property is very narrow and good lighting of all rooms was difficult. I called the house "Legal / Illegal" because part of the building literally adheres to all the rules, while another part tries to question and break as many rules as possible. If we had always interpreted the set of rules literally, we would not have had the best solution for the quality of living, architecture and urban development.

You designed a very unusual house

That was also due to the situation: outside there was a historic gate to the street. I really wanted to keep it and thus keep the street escape. But above all, good living space with enough light should be created on a building plot five meters wide.

What is the concept of this building?

There are two systems: the lower two floors form a straight, very transparent building. It has the “legal volume”, so to speak the legal density that is possible here. Above it is a second body that offers more square meters than is actually allowed by law. The outer skin of this "illegal" building is bright red …

… and has a pretty cheeky shape

This created spacious rooms for living, which are very well exposed, because we were able to design the windows according to the optimal light. I have to say: Of course the upper part of the house has also been approved.


Rear view

Photo: Boris Becker

You are currently building a second vacant lot in Cologne

It is not far from the first house, in a kind of urban tooth gap with a former supermarket that is being torn down. There is a new building with two very different types of living: On the street side, we complete the property and the block construction with a thin building, only eight meters deep. One apartment per floor is created here. This results in a spacious, loft-like floor plan for the rooms with light from both sides. The rear buildings, on the other hand, go vertically over three levels. These town houses are more oriented towards family use. Many rooms have a terrace or other exit, and there are numerous small gardens. This is very urban and dense living with a high quality of life.

Why do we need densification in our cities at all?

We simply cannot afford to seal the ground by building on the green field. Many people no longer want to be stuck in traffic for an hour or more a day to get to work or take the children to school. And argued the other way around: the densely populated inner cities are livelier and more diverse than any other place. The distances are shorter in densely populated areas. All of this means more quality of life. This is why the inner cities are becoming more attractive, and more apartments are needed there and of course a higher density.

Where is there still potential for compression?

There are areas in many cities that can be reused or reused: old industrial areas, for example. These areas are often close to the city center, the train station or the river. Cologne or Basel are examples of this.

How do you find a vacant lot?

You should keep a watchful eye and, if in doubt, walk the appropriate streets. I myself have built twice for investors in Cologne who found their plots in the same way.


Densification of our cities means new building opportunities in the centers: attractive loft apartments and town houses are being built on the site of an old supermarket in Cologne.

Photo: ETI GmbH and Manuel Herz Architects


Photo: ETI GmbH and Manuel Herz Architects

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