The climate in towns and cities can be considerably hotter than in the surrounding areas. However, putting more thought into planting green areas, the materials used and the positioning of streets and buildings can make all the difference. According to PhD candidate Marjolein Pijpers-van Esch, this is something that urban architects and designers should be taught during their degree programme.
The so-called ‘urban heat island’ effect can account for a 9-degree Celsius difference between a city and its direct surroundings. The amount of stone and brickwork is an important factor. A city built from concrete and stone is much hotter than an urban environment with shady parks and tree-lined streets. A lot is already known about the positive impact of trees and plants on heat island problems. Using pale materials which reflect the sun for façades and paving also has an effect on the microclimate, and a brick building retains heat for longer than a building with a steel or glass façade. The role of wind in an urban climate can also be controlled: if a high-rise building is properly designed, people will not be blown off their bikes. And a closed building block helps to reduce noise in the city. “In short, urban designers have a whole set of knobs and buttons at their disposal, which they could use to improve the microclimate. This applies to every place and every urban design project,” says Marjolein Pijpers. “The question we should be asking ourselves is why they don’t make better use of this knowledge?”
For her doctoral research ‘Designing the urban microclimate – A framework for the dissemination of knowledge on the urban microclimate to the urban design process’, she analysed everything we already know about the urban microclimate and the possible implications for the health and welfare of residents. In addition, she approached a large number of urban architects to ask them how they accrue their information about the urban microclimate. Do they prefer text and statistics or pictures and diagrams? Their answers left no room for doubt: urban designers are not keen readers; they prefer pictures. Her research showed that although there is a lot of interest in the subject and there are a lot of questions, in practice, new research is mainly limited to sunlight studies. If studies of the microclimate are conducted at all, they usually take place at the end of the design process.
What can we do? In the first place, the subject should become an integral part of degree programmes in urban design, states Pijpers. “If you don’t know what works and why, you won’t be able to apply it.” She would also like to see more mandatory legislation. Cities that are unnecessarily warm, too noisy and have high levels of air pollution are a health hazard to the population. A well-designed city should always include a properly designed microclimate.