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Amsterdam reaps success with cooled artificial grass in the battle against heat

Cooling artificial grass with subsurface water storage

As one of the implementors of the CitySports project, KWR is helping address urban problems associated with climate change. Cities are vulnerable to extreme heat, drought and rainfall. A contribution can be made to urban cooling through the storage of rainwater below artificial grass pitches. Research is being carried out in Amsterdam on the temperature and the evaporation of a conventional artificial grass pitch, a naturally-cooled artificial grass pitch and a natural grass pitch. The initial comparative results are promising: the cooled artificial grass pitch, on 25 June at a temperature of 35.9 degrees, remained more than 26 degrees cooler than the conventional artificial grass pitch.

CitySports project

On hot days artificial grass sports pitches can heat up to 60 degrees or more. This adds to the city’s heat levels. It also means that the advantage of artificial grass – namely its robustness, which makes it playable throughout the year – comes with a significant downside. Natural grass contributes to cooling, because it absorbs and then evaporates rainwater. The grass and the surroundings thus stay cool, and less rainwater is discharged into the sewers. The CitySports project is studying how the positive properties of the two kinds of sports pitches can be combined, how this works technically and how the players experience it.

Only 1 degree hotter than natural grass

Starting last spring, research began within the CitySports project into the cooling of artificial grass pitches by storing rainwater below the pitch. The initial measurement results are promising: the cooled artificial grass pitch, on 25 June at a temperature of 35.9 degrees, remained more than 26 degrees cooler than the conventional artificial grass pitch. This means that the cooled artificial grass was only 1 degree hotter than natural grass. It is true that the cooled artificial grass evaporated about half as much water as did the natural grass (3.8 mm versus 7.2 mm), but it far exceeded the water evaporation levels of conventional artificial grass (0.5 mm). Earlier in the spring the cooled artificial grass stored rainwater, which it then used for evaporation and cooling, just like a natural grass pitch.

Surface temperatures measured on the test surfaces for the different systems between 23 June and 27 June, 2020.

In this Water & Maritime Top Sector project (in the Water Technology programme of the Top Sector Alliances for Knowledge and Innovation), KWR is working with the municipality of Amsterdam, Waternet, DutchBlue, Veolia, Drain Products Europe and Marineterrein Amsterdam.