High-density building does not necessarily lead to more heat in cities, according to a researcher at the Swiss Federal Institute of Technology Zurich (ETH).
Understanding the Relationship Between Density and Heat
- Densely built-up neighbourhoods can be designed to reduce heat
- The problem is not density itself, but how we organise it
- Thermal comfort is created through the interaction between shade, ventilation, and vegetation
Traditionally, it has been believed that densification leads to higher temperatures due to reduced green space. However, this assumption is not entirely accurate, according to Jan Carmeliet, professor of building physics. He argues that the relationship between density and heat is more complex than this.
Key Factors in Reducing Heat in Cities
- Green spaces and trees provide shade and cool the air
- Free ventilation and the cooling of vegetation contribute to thermal comfort
- An integrated approach is necessary to consider the needs of each neighbourhood, climate, and available resources
In his view, thermal comfort is not just about the density of the city, but about the way spaces are organised. Carmeliet highlights the importance of integrating green spaces, trees, and buildings to create a more comfortable and climate-resilient urban environment.
Breaking Down the Assumptions
“I myself conduct research on heat reduction in cities and I think this assumption is wrong,” says Carmeliet. “The problem is not density itself, but how we organise it.”
According to Carmeliet, urban planners, authorities, and researchers often assume that densification inevitably leads to higher temperatures. However, this assumption is not supported by his research.
Case Studies: Urban Heat Island Mitigation
| Geneva | Example of a densely built-up neighbourhood with green spaces and trees |
| Schönberg, Freiburg | Example of an open but less shady and poorly ventilated settlement |
Geneva is a good example of a city that has successfully mitigated the urban heat island effect through the design of its densely built-up neighbourhoods. The city’s green spaces and trees provide shade and cool the air, making it a more pleasant place to live.
Conclusion
Densification is necessary to save scarce land, but it must not be at the expense of quality of life. By designing cities that offer more living space, but also more shade, air, green space, and nature, we can create a climate-resilient future.
As Carmeliet concludes, densification is not a step backwards, but a sensible key to a climate-resilient future.