How to Keep Cool Without Air Conditioning During a Heatwave

As temperatures soar as early as May, some households still do not have air conditioning. Fortunately, there is plenty to learn from our ancestors, who knew how to keep cool in extreme conditions without it.

In some areas, installing an air-conditioning system is almost a given, but that is not the case everywhere. In the northern half of France, households are generally more likely to invest in heating for the long winter months. Yet when a heatwave arrives, cooling down can be difficult.

“How did our grandparents manage without air conditioning?” Many people in France will probably have asked themselves this question in recent days, as temperatures broke new records across the country. Although heatwaves are now more common, earlier generations still have valuable advice to offer.

The power of cross-ventilation

Of all the tips handed down from the past, cross-ventilation is undoubtedly one of the easiest and most effective to put into practice. The technique involves arranging ventilation in the home to create a natural airflow running through the rooms. It replaces stagnant hot air with a cooler breeze. Traditional builders designed homes with this in mind, favouring carefully positioned openings on opposite or perpendicular façades to encourage air circulation.

How to use cross-ventilation at home

In practical terms, the approach is based on three key rules:

• Open windows wide in the evening, particularly those facing one another or positioned at opposite ends of the home, so that cooler night air can move through and clear the heat built up during the day.
• Close shutters and windows on the sun-facing side as soon as morning arrives to stop heat from entering the home.
• Keep only a few shaded openings open, maintaining gentle ventilation without drawing in hot air.

In Mediterranean villages, these morning routines can still often be seen: curtains drawn, louvred shutters left slightly ajar and homes kept in partial darkness until evening. This age-old habit is particularly relevant as heatwaves become increasingly frequent.

Why cross-ventilation still works

The effectiveness of cross-ventilation lies in making use of the natural differences in temperature and air pressure between outdoors and indoors. Cooler night-time air lowers the temperature of walls and floors, which retain that coolness and release it during the day, slowing the rise in indoor temperatures. Meanwhile, closing openings on the sunny side helps keep hot air outside.

A useful alternative to air conditioning

As air conditioning is being questioned by public authorities for economic, environmental and health reasons, these methods could prove to be worthwhile alternatives. However, heatwaves can sometimes become so intense that it is difficult to cool homes overnight. In southern France, temperatures did not fall below 30°C even in the middle of the night. Without air conditioning, avoiding heat discomfort is difficult.