Predicting overheating

The temperature in a house affects the health of those who live there. To learn more about interior temperature, scientists installed a thousand temporary sensors in Rotterdam.

To document the temperature in our country, the Royal Netherlands Meteorological Institute (KNMI), has set measuring stations in many places. The one for Rotterdam is located just outside the city, close to the airport, where it is invariably slightly cooler than it is in the built environment. We therefore do not know much about the heat of either the port city itself or the buildings within it.

Such knowledge is relevant. For example, when temperatures are higher, the death rate amongst people 75 years of age and older increases, and the birth weight of newborns is lower. For this reason, Alexander Wandl and Frank van der Hoeven from the department of Urbanism (Architecture and the Built Environment) are conducting a more precise investigation of how temperature affects the health of Rotterdam residents. They would also like to explain why it is warmer in one part of the city than it is in the other.

They sent students into the city to install 800 sensors in households and 200 in public spaces. After each sensor had recorded the interior temperature every five minutes (both night and day) for two months, the scientists were able to compare the data. Wandl: ‘What I found most surprising is the overwhelming amount of data. I received no fewer than 18 million data points. At first, my software was unable to process them.’

Results from the analysis of the big data showed among other things that at night, the western part of Rotterdam remains 5–6 degrees warmer than it is in the rest of the city. ‘In the Spangen and Bospolder communities, it does not cool off at night’, notes Van der Hoeven. ‘This is because of the high building density and paved surfaces in these communities, which absorb a great deal of warmth during the day and release it again at night. This means it remains warm in the houses as well’. What can be done about it? ‘In the Netherlands, when we make buildings energy-efficient, we pay attention only to the situation in de winter, while we should also make sure that no energy is needed for cooling in the summer. The municipality could help in this regard by having more water and trees in the city’.

To be able to better monitor the relationship between the energy-efficiency of buildings, the heat in the city and the health of younger and older people, the researchers would like to conduct permanent measurements of interior temperatures. ‘But that is a dream for the future. At this point, we are appealing for large-scale collaboration through crowd-sensing’, explains Wandl.

At night, the western part of Rotterdam remains5–6 degrees warmer than in the rest of the city.

(Photo: Sam Rentmeester)

(Photo: Sam Rentmeester)

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