A scorching hot city: both highly unpleasant and increasingly common. As the planet continues to heat up and climate zones shift, tropical temperatures, heat waves and drought will put their mark on daily life in the Netherlands on a more regular basis. How can the built environment, where effects of heat are often amplified, be adapted? Fieldlab the Heat Square on TU Delft Campus has the capacity, the design and the sensors to test possible solutions. And your idea or innovation is more than welcome.
The Heat Square at The Green Village used to be a bare, paved square without shelter, like so many in the Netherlands. Anything but climate-proof. But in the summer of 2023, the 630 m² were renovated based on a sophisticated design. Today, the Square is used to study the interplay between spatial, meteorological and hydrological factors, both above and below ground. Because the arrangement of the built environment determines the effect of wind, precipitation and sun.
The layout of the square is now flexible, giving researchers and entrepreneurs room to test innovations. Permanent sensors continuously collect a wealth of data on, for example, soil temperature and moisture content. That is how four researchers from TU Delft were able to study the relationship between the water cycle and the energy balance. The underlying question: how can this relationship be influenced in such a way that urban temperatures remain acceptable and water consumption sustainable?
Investigating urban microclimates
Marjolein van Esch is a researcher at the Faculty of Architecture and the Built Environment and responsible for the climate adaptation component of TU Delft's Climate Action programme. She says that urban climate, heat in particular, is attracting increasing interest as a research topic. "This relatively young field encompasses climatology, meteorology, hydrology, architecture, landscape architecture and urban design." According to Van Esch, there is a dire need for an integrated approach which combines scientific research, spatial design and applications in construction and engineering. "Given the speed of climate change as well as the complexity of the urban microclimate, it just has to be done."
She explains the importance of the Heat Square: “It gives us the opportunity to experiment with such an approach in an almost real-life urban environment. By combining fundamental and applied research, we aim to uncover pressing practical questions. At the same time, we can validate and improve methods and instruments based on all the measurement data collected. The results then benefit our fundamental understanding of the interaction between physical and biological phenomena and the built environment. They contribute to new design approaches and guidelines for heat mitigation that can be tried out in daily practice."
Greenery as natural air conditioning
"Heat development in the city is strongly determined by the thermal behaviour of the building materials and vegetation present," says Eva Stache, designer of the renovated Heat Square. In her design, she combines paving with green spaces and trees. "Stony surfaces heat up strongly, sometimes above 70°C, and release this heat to the surrounding air." Plants, provided they can soak up enough water from the soil, evaporate water on hot days to cool themselves. By transpiring, they extract thermal energy, or heat, from the air, which is transferred with the water vapour to higher layers of air. Thus, greenery can act as natural air conditioning and cool the environment. Stache: "However, data on the thermal behaviour of vegetation in urban space are still scarce and largely unstructured." That is why she started her PhD research at the Heat Square on the effects of urban vegetation on the urban climate.
Martine Rutten is also curious about how greenery behaves under different conditions and how it can be used effectively in relation to the local climate. She is a former associate professor of water management and climate adaptation at the Faculty of Civil Engineering and Geosciences. "The Heat Square can shed more light on the effects of greenery on cooling through evaporation, wind and shade. Furthermore, we also want to find out how large water buffers should be in order to provide urban greenery with sufficient water. And what the effects of soil composition are on water consumption and heat."
Colleague Miriam Coenders, also active as a researcher in the renovated fieldlab, knows all about evaporation processes as a hydrologist. "Especially in times of drought and during heat waves, plants apply specific survival tactics that affect water consumption and air temperature." Using new sensor technology, she will closely monitor the behaviour of vegetation on the Heat Square. Measuring and modelling the heat and water balance in different ways will make it clear how effective applied spatial measures and innovative methods and techniques are. Rutten: "Municipalities and architects can use this information for climate-adaptive urban design."
Fieldlab for climate action
In its Climate Action Programme, TU Delft integrates various disciplines to get a grip on the consequences of climate change and to visualise possible solutions to a variety of problems. This involves both fundamental and applied research. One of the places where insights are gathered and tested is the university fieldlab The Green Village. This is where, since 2020, the Heat Square has been located, a test site of the VPdelta programme in which entrepreneurs and researchers study the effect of applied climate adaptation. Think of paving that absorbs and evaporates rainwater, or systems for collecting and purifying rainwater. Such systems are desperately needed during dry periods, for example to keep public green spaces healthy.
More information
Pictures of the Heat Square made by Robèrt Kroonen.
Want to know more about the possibilities of the Heat Square, or do you already have an idea or innovation to test? Feel free to drop by The Green Village (Van Den Broekweg 4) or contact them using one of the options below.
About The Green Village: The Green Village, fieldlab voor duurzame innovatie
About the Climate Action Programme: Climate Action (tudelft.nl)
Dave Boomkens, press officer Climate & Energy TU Delft: D.J.Boomkens@tudelft.nl
Fleur Dassen, communications advisor The Green Village: F.Q.Dassen@tudelft.nl
Martine Rutten
Eva Stache
Marjolein van Esch
