Swiss study: five easy ways to stay cool in hot weather

What's the best way of coping with the hot weather in your home? KEYSTONE/DPA/Thomas Warnack

Even without air conditioning, it is possible to significantly reduce the perceived temperature inside your home. A study by the Lucerne University of Applied Sciences and Arts has explored this question in a care home for elderly residents.

Design researcher and interior architect Ute Ziegler co-led the study between 2022 and 2026 (see box below). Drawing on the findings, she proposes five practical yet often overlooked tips to help reduce heat stress in everyday life without relying on electric cooling systems. These recommendations complement official advice from the Federal Office of Public Health (FOPH), such as avoiding physical exertion and staying well hydrated (see infobox).

1) The power of scents: menthol, mint, lemon or rosemary

Scents can play a surprisingly important role in thermal comfort. In the Swiss study, fragrances such as menthol, mint, lemon and rosemary were diffused in rooms using professional equipment.

The results indicate that these scents can influence what the researchers call “thermal comfort.” Menthol, for instance, is believed to activate cold receptors in the skin, creating a sensation of coolness even though the actual temperature remains unchanged.

Ziegler personally favours rosemary and is interested in testing a blend of lemon and menthol to enhance the cooling effect.

2) Cotton satin bed linen for cooler nights

The choice of bed linen can make a noticeable difference. Smooth cotton satin sheets, ideally in blue-green shades, proved particularly effective in the study. This smooth fabric is said to wick away heat more effectively than a thicker material such as flannel.

According to Ziegler, the combination of smooth bed linen and fragrances was one of the study’s most successful strategies, significantly improving participants’ well-being.

3) Refreshing sounds

Soundscapes are also thought to influence how we experience heat. While the effect is not physical, it operates through psychological and neural mechanisms.

The brain continuously combines information from multiple senses. Certain sounds, such as running water or natural environments, can trigger expectations and emotions that alter our perception of temperature. The sound of running water or nature sounds can, for example, increase heat tolerance.

The ‘Cooling Library’ at the Lucerne University of Applied Sciences and Arts

The “Cool Down” research project at the Lucerne University of Applied Sciences and Arts tested various cooling concepts to make the summer heat more bearable for residents of a care home in canton Lucerne.

Its findings have been compiled into a ‘cooling library’External link (‘Cooldown Toolbox’), which presents ten different approaches to coping with high temperatures. Although primarily designed for older people and care institutions, many of the recommendations can also be applied at home.

Because individuals experience heat differently, the researchers stress the importance of tailoring measures to each person. They also highlight the methodological challenges associated with their study, which necessitate further investigation of the findings through new applied research.

4) Choose blue and turquoise

Numerous studies highlight the influence of colour on human psychology and well-being. By applying this knowledge to interior design, it would therefore be possible to create an atmosphere that is perceived as cooler.

The perception of heat could be influenced by the colour of the walls or by the lighting. Under bluish or cool white light, participants in the Lucerne University of Applied Sciences and Arts study perceived the room temperature to be significantly lower than under warm white light.

5) Smart ventilation: cooling at night and creating draughts

While influencing perception is helpful, it is equally important to prevent hot air from entering buildings and to cool indoor spaces when temperatures drop, especially at night.

In this regard, adopting an effective ventilation strategy is essential, says Ziegler. The researcher recommends taking advantage of the cool air at night. Opening windows on opposite sides of the home creates cross-ventilation, allowing for rapid air exchange.

Early in the morning, ideally around 7am, it is advisable to close all windows and lower the blinds or close the shutters to keep the heat out for the rest of the day.

Advice from the Swiss Federal Office of Public Health

Very hot days can have adverse effects on health. The most vulnerable groups are older people, those with chronic illnesses, young children, infants and pregnant women.

The Federal Office of Public Health sets out three golden rules for periods of hot weather:

– Avoid physical exertion

– Protect yourself from the heat and keep your body cool

– Drink plenty of fluids, eat light meals and adjust your medication

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Translated from German, sub-edited by Simon Bradley/amva