Fighting heat stress at TU/e

July 24, 2019

On the occasion of the upcoming heat wave, we highlight the work of TU/e researchers on heat islands, green roofs, sun blinds, thermal comfort and active cooling.

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TU/e campus. Photo: Bart van Overbeeke

Western Europe is preparing itself for the second heat wave this summer. With temperatures expected to rise to 40 degrees, the Dutch government has activated the National Heat Plan, in an effort to protect elderly and weak citizens from the record heat. Fighting heat stress has also been the focus of much research at TU/e. In this article we highlight the work of some researchers from the Department of the Built Environment on heat islands, green roofs, sun blinds, thermal comfort and active cooling. We also tell you how our students and staff keep their heads cool during these dog days.

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Green roof (left); green façade (right). Photo: Wikimedia commons

Green roofs: solution or just a symbol?

As a result of climate change, heat waves are expected to increase both in frequency and intensity. The demand for cooling energy will also rise, to an expected 72 per cent worldwide by 2100. These problems are aggravated by the so-called ‘urban heat island effect’, which means that temperatures in cities are higher than in their rural surroundings. In a large research project on climate adaptation (Climate Proof Cities), Bert Blocken, Jan Hensen and Harry Timmermans investigated the potential of green roofs and green facades in reducing overheating in buildings. Surprisingly, green roofs were shown to have almost no effect on the internal temperature of well-insulated buildings, and only a very small effect on outdoor air temperature.

 

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Custom-made sun blind. Photo: Cursor

Old-fashioned sun blinds

Due to the heat island effect, the temperature during a summer day in Eindhoven can rise up to 4 to 5 degrees higher than in the surrounding areas. This is not a trivial problem: each summer sees an increase of deaths among the elderly and other vulnerable groups, and with global warming the problem is growing more serious every year. According to Bert Blocken, the most effective protection against heat is just plain old-fashioned exterior sun blinds. Also, according to urban planner Marcel Musch, cities need to become more 'heat-resistant', by having more green and blue areas. More about fighting heat stress and the research of Blocken and Musch in this interesting Cursor piece. Bonus: a how-to-guide for building your own sun blind on the cheap!

 

It’s all about the occupant

In conditions of extremely hot weather, the people living and working inside buildings should be our first concern. Marcel Loomans, who is specialized in building technology and thermal comfort, sees the occupants of buildings as their “most important assets”. Thermal comfort, or the way people experience the temperature inside a building and the way it affects their well-being and productivity, varies from person to person and from building to building. Still, during heat waves the occupant of a building can still do a lot to reduce the effect of indoor heat. In several of his studies, Loomans monitored the occupant activity level to determine the required comfort conditions and building energy use.

 

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House of Tomorrow Today. Photo: TU/e

The House of Tomorrow Today

If you can’t really beat it, embrace it. You might need to travel a little, though, to reach the municipality of Heeze-Leende, where the experimental House of Tomorrow Today (HoTT) was built. Initiated by the research of emeritus professor Jos Lichtenberg, HoTT was completed in 2014. It holds 19 roof windows and large façade openings, which also work as automated sun screen systems. With its 95 m2 of solar panels, HoTT produces approximately 15,000 kWh energy for heating and domestic use, leaving even a comfortable surplus for an electric car. Hot water is provided by six solar collectors, while an air and water heat pump guarantees active cooling. The perfect hideaway during these dog days of summer.

 

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Facade of Atlas building. Photo: Bart van Overbeeke

Keeping our heads cool

And how, you may ask, do the students and staff at the TU/e keep their heads cool? The TU/e Campus uses a sophisticated heat and cold storage system called ATES that helps keep the temperatures in our buildings at a comfortable level. As an added bonus, by storing heat and cold in the soil, TU/e annually saves some three million KWh on electricity and more than 450,000 m³ on gas. In this way, we do our bit to keep future CO2 levels and temperatures at sustainable levels.

 

Henk van Appeven
(Science Information Officer)
Valentina Bonito
(Science Information Officer)