When the city becomes a heat trap: Climate-friendly construction at the BTU

The Professor of Design and Energy-Efficient Construction at the Brandenburg University of Technology Cottbus-Senftenberg (BTU) has for years been guided by a statement she herself puts as follows: “Sustainability is not a trend, but a necessity.” Anyone who speaks to her quickly realises that this is not just a cliché, but an attitude that shapes all her work – as a researcher, as a university lecturer and as someone who comes from a practical background and whose work also has an impact on that field.

Climate walks with local residents

At the heart of her current work is the research project ‘Heat in the City’, which Draeger’s chair carried out in collaboration with Climateflux GmbH and the Berlin Institute for Social Research – led by Staff Member Jil Schroth. What sets this project apart from traditional climate research is a remarkably simple yet effective approach: rather than simply installing sensors and running building simulations, the team sends participants right into the heart of Berlin’s city centre – during a heatwave. They walk, they sweat, they document exactly how the heat feels at that particular street corner or on that sun-drenched square.

The background to this is serious: cities heat up further due to the so-called urban heat island effect, and heatwaves are becoming more frequent and intense. Research into this has so far focused primarily on technical and planning aspects – but hardly at all from the perspective of the people who have to walk through these overheated spaces day in, day out. It is precisely this gap that the ‘Heat in the City’ project aims to bridge by asking: where exactly does it become unbearable, and why?

The answers are now far more than just abstract theory. The Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR) has taken up the findings and translated them into recommendations for action for cities. One of the key findings sounds almost like a simple rule of thumb for Urban Planning: it is not enough to build a few shaded parks. What people really need are cool routes – not just cool places. Climate adaptation, the research essentially says, must not stop at the park entrance. It must take into account the entire route that someone actually travels: to the bus stop, to the supermarket, to school.

A study programme that deliberately blurs disciplinary boundaries

As well as her research, Susan Draeger also heads the Master’s study programme in ‘Climate-adapted Construction and Operation’ at the BTU. The study programme is designed so that precisely this kind of practical problem-solving is practised right from the start. Rather than sorting students into narrow academic disciplines, the study programme deliberately brings together aspiring engineers, architects and planners. Together, they learn how climate-friendly buildings and settlements are created, which building materials and building services are required for this, and, above all, how to work on the same problems in mixed teams – just as they will do later in their professional lives. An important part of the degree programme consists of planning projects in which students practise precisely this: not just at the drawing board, but through collaboration with people who think differently and bring different tools to the table.

Rotterdam as a case study

The course also includes field trips. One such trip recently took Bachelor’s students in Architecture to Rotterdam and Delft University of Technology. The Netherlands is regarded worldwide as a pioneer in dealing with water, heat and climate risks: Rotterdam has built water-sensitive spaces that become retention basins during heavy rainfall, as well as green roofs and multifunctional water storage facilities. For students, a visit like this is often more formative than any chapter in a textbook. They see first-hand how a low-lying, densely built-up city is preparing for the consequences of climate change – and how planning, administration and engineering must work together to ensure that good ideas actually become built reality.

Why this matters to everyone

What Susan Draeger and her team at the BTU bring together – basic research, teaching and the transfer of knowledge to international practice – suddenly makes a cumbersome term like ‘climate adaptation’ very concrete: it is the shade that is missing on the way to school. The walk to the bus stop that feels like an oven. Just how heat-resilient our cities will be in the future is decided not only in government departments and planning offices, but also in lecture theatres like these, where the next generation of planners and architects are learning precisely that: to design buildings and urban spaces in such a way that they can withstand climate change. A necessity, as Susan Draeger would say – not a matter of trend.