‘A new world opened up for us when we discovered ceramics’

Published by
Christine Jetten / Juan Cruz Rojas
January 1, 2021
10 min

The task was to improve the performance of solarpanels, which are known to underperform when they get too hot. Juan Sebastian Cruz Rojas’ group successfully used ceramics to make façade elements that provide cooling through waterabsorption. This would not have been possible without the indispensable help of Christine Jetten, Juan says. ‘She took me on a tour across ceramics factories and we experimented in her studio. There is so much misunderstanding about ceramics as a buildingmaterial. A world has truly opened up for me.’

The team Master students Building Technology

A so-called Bucky Lab is a workshop where students are not only encouraged to think up new concepts, but also to actually implement them. The group of five students, of which Juan was a member, decided to use ceramics to complete the assignment. ‘It is, of course, remarkable that solar panels absorb energy but already start to underperform above the relatively low temperature of 35 degrees Celsius’, Juan says as he explains the objective of the innovation task. ‘We have focused our research on ceramics.Ceramic bricks are the most widely used building material in the Netherlands, as a notable characteristic of ceramics is that it can absorb water like a sponge. This provides opportunities for cooling façades, but also for improving the output of solar panels placed against the building. During our ‘Photo-ceramics' project, we looked for possibilities to develop a ceramic façade part and also make prototypes that would prove our assumptions.’

We were very excited,but also way too naive’

Sebastian and his colleagues started their project in the autumn of 2020. Professor Koen Mulder pointed them in the direction of Studio Christine Jetten. Jetten is a familiar face at the Faculty of Architecture,where she is a regular guest speaker and lecturer. ‘We had no idea how to work with a liquid material like ceramics. Christine appreciated our enthusiasm for the material, but also thought we were being naive. Fortunately, she invited us to visit her studio in Den Bosch where she introduced us to the material properly.' And while most students could not go on-site due to covid, Juan was granted the opportunity. ‘Christine provided me with a crash course in ceramics, during which I learned everything about thecomposition of the clay, the behaviour of the ceramics and how to shape and fire it. I literally got a feeling for working with the material by making tiles with Christine. It was a very inspiring process.’

Gradually, Juan discovered the most important considerations needed for the manufacturing of the desired façade part. It was about the composition of the clay, which allows you to achieve the right porosity, and about maintaining a sufficient cohesion in the material.

Making the mould proved more difficult than expected. ‘We wanted too much, too complicated’, Juan explains. ‘Working with ceramics is a craft. Christine took me to the Cor Unum ceramics workshop to experience the process of making moulds. It was incredible, one of the best experiences of my academic career so far.' After that, a seemingly endless quest for making a mould for a ceramic façade part that had to be able to absorb as much water as possible followed, as well as the search for the best proportions of the clay’s composition. ‘We had assumed that adding sawdust would improve the porosity of the ceramics. But Christine introduced us to chamotte, the adding of fired and ground up (recycled) ceramics to the clay.' Juan and his team worked on geometric façade sections that could be joined together by a mechanical click system. ‘It was a process which we had to simplify: ‘The simpler the concept and the form, the better. 'Because, as the students soon realized, their invention did not only have to work and contribute to the performance of PV panels, it also had to be feasible and suitable for manufacturing.

 ‘Jetten showed us that you can push boundarieswith ceramics’

Eventually I managed to bring eight ceramic parts, prototypes, back to Delft. ‘A very exciting process, because even during the drying and firing of the prototypes things could still go wrong. Should our models crack in the oven, we would have had nothing to show for our efforts.' But luckily that didn’t happen and, with the eight prototypes, we achieved great results and a second place inthe competition. Juan's team succeeded in producing ceramic façade elements that absorb three times as much water as regular bricks. Due to the lockdown and online education last winter, but also due to the lack of financial resources, the ultimate test could not take place: the actual application of PVpanels in combination with the Photo-ceramic façade parts. It is a great pity, Juan says, but he is now so inspired and convinced that he will continue to work on the concept, even next to and after his studies. He hopes the industry will cooperate with him in further developing the prototype.

‘This project can have a huge impact in countries with a lot of sun and a humid climate, such as India. And all that through merely the discovery of ceramics as a building material. That is how working with Christine Jetten has opened my eyes. I have noticed that architects and students have far too little understanding of the possibilities of the material. The material is seen primarily as aesthetic and decorative and not properly valued as a building material.' And even though that is a missed opportunity, it also offers perspective. ‘Ceramics, or clay, is available in most places, also in developing countries.' Now that he has discovered them, Juan wants to pursue the possibilities: ‘Most innovative projects fade into oblivion at university. But I am convinced I will find a manufacturer who wants to work with me on this project. By cooperating with an inspired specialist such as Christine Jetten, ceramics has a chance to rid itself of a traditional image. Jetten has truly shown us that you can push boundaries with ceramics.’  

The water absorbtion is shown in this video:


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