Wetenschap - 26 november 2015

Making water really cool

Roelof Kleis

That water cools on a hot summer day is only partially true. Yet it is still possible, thinks landscape architect Sanda Lenzholzer. She receives 400,000 euros in funding from the STW to find out more.

On a hot day, water absorbs a lot of energy. It therefore functions like a kind of heat battery which gets charged during the day, somewhat mitigating the urban heat island effect. But after sunset this battery slowly discharges, adding to the heat island effect in the night. Something can be done about that, thinks landscape architect Sanda Lenzholzer. If water features are designed smartly, water can be a truly cooling element in a hot city. In the next two years she gets to show exactly how that works in the project Realcool.

Realcool focuses on a couple of options which might work. One approach is to create more shade so the water heats up less. By for example hanging screens above the water, or by planting vegetation on islands – floating or otherwise. Another option is to increase evaporation. Water that evaporates absorbs energy from the surroundings, creating a cooling effect. The larger the water surface, the greater the evaporation. Lenzholzer: ‘That is how fountains, for example, cool down the air temperature.’ Extra vegetation beside or in the water is another way of increasing the evaporation. Trees evaporate a lot of water through their stomata.

Tekening: Zhonglin Gao en Sanda Lenzholzer
Tekening: Zhonglin Gao en Sanda Lenzholzer

The research method is another new aspect of the project. Lenzholzer is applying ‘research by design’, an approach in which the best spatial solution using scientific knowledge in an ongoing process. Designers, urban spatial managers and the public are all closely involved in that process. City residents get to give their views on the proposed designs through questionnaires. So visualizing the designs is an important part of the project.

Model calculations should then reveal whether the solutions really do work. Actually building something is not within the scope of a two-year project, says Lenzholzer. That is up to the designers who can get to work with the readymade prototypes afterwards.

The Realcool project is run by Wageningen UR and Amsterdam University of Applied Sciences HvA. It receives 400,000 euros in funding, two thirds of which goes to Wageningen. Realcool is one of nine projects funded by SWT and NWO within the new programme Research through Design in the top sector Creative Industry.

Lenzholzer is pleased with this new programme. ‘It is the first time that design is recognized as a serious component of academic research. Research through design is one of the specialisms in our chair group.’