At the presentation of the ZJA35 book at the Hortus Botanicus in Amsterdam on 4 June 2026, Dirk van Weelden was asked to speak about the making of the book. He chose to share his observations and thoughts on the identity of ZJA and translate them into tips for the future.
'In 1991 I got to know Rein Jansma, as a fellow computer-pioneer of Willem Velthoven, with whom I was making the magazine Mediamatic at the time. Through a play I wrote for the theatre company of Rein’s wife, Maartje Nevejan, we became friends. My beloved, Annemie, went to work for ZJA in 2007. In the years that followed I found myself in the role of an in-house writer who sometimes contributes to tenders, writes project texts and writes the texts for the office books. Like this anniversary book. What I do in those cases is to be of service: to ask questions and to formulate, as vividly and clearly as possible, the Why and the How behind the designs. Now, I was educated as a philosopher and then, almost forty years ago, became a writer of novels, stories and essays. This 35th anniversary seemed to me the perfect occasion to step outside my role for once. To think outloud and follow my own thoughts.
I will begin here. If you are looking for the briefest formulation that describes what is distinctive about ZJA’s design practice, it is roughly this: the conviction that you have to play in order to fulfil your duty as an architect well. That means several things at once; let me unpack it. First there is the idea that architecture begins with a searching, experimental exploration of material, geometry and construction possibilities. Rooted in an open-minded, perhaps even childlike pleasure in interacting with the unknown.
But for ZJA architecture is also a play with the commission: the best design emerges when you question, challenge, expand, ignore and sometimes even reverse the perceptions, the unspoken assumptions embedded in the brief. Both kinds of play that contribute to the quality of the design do so by adventurously deviating from what efficiency, convention, prevailing opinion and tradition prescribe.
All that researching, questioning and playing is not an end in itself. There is such a thing as the duty of the architect. Ultimately, the intention is that it should lead to good architecture, and at ZJA that is based on the conviction that it is a serving art form: the results are not autonomous Art. They do not exist for the greater honour and glory of the architects’ egos, and certainly not in order to call into being the myth of a Brand or a Style. ZJA produces spatial and technical designs that serve society. More precisely: they make daily life more sustainable, more comfortable and safer for the mass of ordinary people who travel by car or public transport to their work or family, who go to a concert or a football match, who go out to do sports or make an outing and need somewhere to leave their car.
It fits this characterisation very well that ZJA works from an enthusiastic techno-optimism, that is, the conviction that technology and industry bring humanity progress.After 35 years, some critical qualifications can be made here. It has never been a deaf and blind, unqualified techno-optimism. It bears little resemblance to the current pseudo-religious, wishful-thinking and unscrupulous Californian variant. At ZJA people are aware of how recalcitrant and elusive matter can be. How many unforeseen harmful side effects and complications a technical intervention can have. Technology and science form an always uncertain and incomplete process of knowledge. But daily reality too, and the impact on the natural environment, mercilessly expose the blind spots and limitations of technology.
At an early stage, the scientific insights into climate change and the biodiversity crisis gave ZJA cause to research sustainable, circular and ecologically qualitative solutions. In other words: technology and industry are also part of the problems we have as humanity and do not automatically provide the solution. That requires a critical and innovative attitude towards the application of new technology. ZJA practises a self-critical techno-optimism. What makes ZJA special is that, consciously, between 10 and 15 percent of the available time and labour of its staff is spent on what you might call research, play and experiment. What cynics will dismiss as playing around or unnecessary luxury, Rein, Rob and Reinald, when I asked them about it, called the humus, the fertile soil from which the distinctive quality of ZJA’s designs can germinate and blossom.
Anyone who looks back sees splendid examples of this. The exhibition at Arcam was bursting with attempts, tests, intuitive models. Sometimes they led to little. Sometimes genuine discoveries came out of them, even patents, and sometimes the results complemented the design process in a brilliant way.
In making this anniversary book I have thought about the composition of the humus from which the special biotope that is called ZJA has arisen. What does that germinating ground consist of, the one Rein, Rob and Reinald spoke about? First of all, of course, of the professional knowledge, the architectural ingenuity present among the staff. Then of geometrical speculation, material experiments, and the processing of observations of natural processes or studies of ancient building systems. And thirdly of the physical tests, usually at scale. In this way more practical matters already come into view. Such as Rein’s virtuosity at the lathe and with the laser cutter. How he looked at the patterns in drifting dunes. Or the combination of mathematical insight and skill with the sewing machine of Jack Bakker. Or Rob’s stubborn curiosity about ways to test and improve the bearing capacity of compacted sand.
As far as the renewal and enrichment of the constructive part of your humus is concerned, things are going well. Research and experiment in that area receive ample attention. You belong among the most progressive architectural offices when it comes to parametric design, the use of generative algorithms and modeling systems. Knowledge of materials and technical design is also increasing rapidly. But while working on the anniversary book I was struck by the great significance of all the non-technical elements in the ZJA humus. My contribution today is to ask for attention for those.
I said: finding good architecture by researching, by playing. That other play, the ability to play with the commission, to keep asking questions, to leave the beaten paths — that playful contrariness — does not come out of thin air. Such headstrong, sometimes difficult energy is more than a character trait or habit. It is a mentality, one that also has historical and social roots. Moshé was the child of an idealistic Amsterdam carpenter in the crisis years. He was born in Haifa, but the family returned to Amsterdam in 1939, disappointed in Zionism. The deportation to Bergen-Belsen, the traumatic reception on returning to Amsterdam, the coercive atmosphere of post-war reconstruction. All these were experiences that made him combative, idiosyncratic, contrary, inventive.
In the ZJA humus there are also traces to be found of the fact that Rein was the son of a mathematician from the Dutch East Indies with green fingers, and of a much older father who was a political activist and carpenter/artist. A circle of friends of designers and inventors. A milieu in which it was not illogical to become an unyielding autodidact. Rob fertilises the ZJA humus with his background in a building family from Ankeveen, his love for the landscape there and his training as a sculptor. Reinald brings in the pioneering spirit of the farmers in the Wieringermeer.
No one can calculate or prove how, but these things too form micro-organisms in the ZJA humus: that Ralph draws inspiration from landscapes and the anatomy of birds, that Kay is building a boat, that Erik’s sense of wonder does not stop at architecture, but also extends to the dimly understood possibilities of the human body in sport.
They are all those elements that seem to arrive of their own accord, a gift through the people. It is about personal, cultural and social experience and skills. Think, therefore, also of experience with making things, with tools. Experience with technical and industrial production processes and the people you find in those factories and workshops. And there is more that contributes to the humus of ZJA in improbable, unforeseen ways: active knowledge of visual art, music, dance, of nature in all kinds of places on earth, the most diverse histories, cultures and languages. There are some fifteen nationalities walking around the office.
I walk around at ZJA and sometimes think: they only half realise how special and rich they are. ZJA arose from an improbable collaboration, and still consists of a mix of extremes and worlds foreign to one another. In that spirit it has become a place that offers room to people who want to design serving architecture on the basis of a playful and investigative engagement with the unknown, the improbable. There is an enormous amount of knowledge and experience among the people who work at ZJA that is still only partly known and has remained untested.
It may seem to be about personal peculiarities, but they are much more than that. It is about forms of knowledge and experience of which it has not yet been tested how they can stimulate the germination of designs. Actively looking for the possibilities of what you do not yet know: that is the core of real research. You do that because you expect to have something to gain from new insights and critical questions. From what can be found beyond that which counts as useful, efficient, profitable and technically possible. Those thoughts and critical observations do not come out of thin air; they arise in people. And really not in everyone, nor in just anyone at random.
What does that look like in practice, this active valuing of those non-technical life forms in the humus? To begin with: inviting all current and new staff to formulate out loud what they think they can add to the research and experiment taking place in the ZJA humus in terms of their very specific experience, skills and cultural backgrounds. If, in the future, designs have to be made for environments that areresilient in emergencies and war, then a computational designer who grew up, for example, in Ukraine, a banlieue, a township or squats may be of more use to you than one who grew up in a semi-detached house in Rijswijk. If you design buildings with multiple public functions, you may well have something extra to gain from people who come, for instance, from Africa or India. Because of their experience with temporary structures, the interaction between different groups in shared environments. They know something you do not know, they know examples, traditions and architects you do not know. At least, if you address them on that, invite them into it and actively look for it. Such a new view of the humus calls for you to take the initiative to maintain and activate it. All that non-technical, non-professional experience may prove to be valuable expertise. You simply do not know immediately how. Your own past teaches you how valuable that is. Moreover, discovering it is a game that makes people a closer group, a better team. Perhaps that game sometimes leads to involving ecologists or anthropologists on a project basis, or to inviting artists, philosophers or historians when gathering feedback on commissions and first sketches. When questioning commissions. Perhaps you involve designers and artists who investigate strange materials and think like inventors.
What does the future ask of ZJA? That this self-critical form of techno-optimism stays on course. That all the modeling, designing and building truly benefit people, their living environment and the regenerative capacity of nature, and do not have the opposite effect. That is an enormous task. The future therefore calls for a very fertile ZJA humus. It does not sustain itself automatically. It asks for care and nourishment, renewal. For the right people. What kind of people are you looking for? People who are ingenious and contribute to brilliant designs for bridges, stations, swimming pools and stadiums. People who succeed in converting the experience and the pain of their ancestors, the infinite wonder at plants and animals, the practical intelligence of eyes and hands, the playful and wondering gaze of an inventor, a musician or artist, and the desire to serve society, into good architecture. People who make architecture for people.'
© Dirk van Weelden 2026
