AMSTERDAM — A national heatwave plan has been activated in the Netherlands. Health experts in Amsterdam have urged households to hang curtains outside their windows to moderate heat.

Eline Coolen, the heat coordinator at the city's public health institute in Amsterdam, urged city-dwellers to rig up temporary curtain rails or drape curtains or sheets outside to stop the sun's rays from reaching large windows. She also urged people online to make DIY adjustments to stop the sun from touching windows to reduce heat transfer into houses. Coolen said, "In Dutch houses, but also in many houses in northern Europe, you have very big windows."

"We have always built for the winter, when you want as much sun and warmth in your house as possible," Coolen said. "But every year in Amsterdam alone, 110 people die because of the heat – and that could rise to as many as 600 in the future without serious measures."

Werner Hagens, the coordinator of the Dutch heatwave plan, said, "You can make changes in the area, more green spaces, you can make changes in the building, like screens and maybe other cooling mechanisms, but you can also give perspectives on how people inside them can minimise heat." He added, "These temperatures can form a risk for people in vulnerable health … and it reduces the risks."

The Netherlands' national public health institute, RIVM, identifies three levels of action for heat management: behaviour, housing, and urban design. Researchers in Utrecht are trialling fake trees and shadow art to cool pavements and pedestrians and are working next to a pergola covered with greenery.

Sandra Phlippen, an economist and head of climate strategy at ABN Amro, discussed the financial implications of heat. "One night of sleep loss [costs] close to €200 [£173]," Phlippen said. "Imagine a street where there are 100 people living, everybody sleeps terribly for three nights because of a heatwave and the next day they're unproductive. That's your investment in trees for the whole year."