Heatwave: How to Keep Cool Without Air Conditioning

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

In some areas, installing an air-conditioning system is almost automatic, but this is far from the case everywhere. In the northern half of France, households are generally more inclined to invest in heating for the long winter months. Yet when a heatwave arrives, cooling down can prove difficult.

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

Keeping cool without air conditioning

The power of cross-ventilation

Of all the tips passed down through the generations, cross-ventilation is undoubtedly among the simplest and most effective to put into practice. It involves arranging the ventilation of a home to create a natural draught running through the rooms. This replaces stagnant warm air with a cooler breeze. Traditional builders designed homes with this principle in mind, placing openings strategically on opposite or perpendicular façades to encourage air circulation.

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

• Open windows wide in the evening, especially those facing one another or positioned opposite each other, so that cooler night air can circulate and clear out the heat built up during the day.
• Close shutters and windows on the sunny side as soon as morning arrives to stop heat from entering the home.
• Keep open only a few shaded openings, maintaining gentle ventilation without drawing in hot air.

In Mediterranean villages, these morning habits can still often be seen: curtains drawn, louvred shutters left slightly open, and homes kept in half-light until evening. This long-standing practice is especially relevant as heatwaves become increasingly frequent.

Why does cross-ventilation still work?

The effectiveness of cross-ventilation lies in using the natural differences in temperature and air pressure between indoors and outdoors. Cool night 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.

At a time when air conditioning is being questioned by public authorities for economic, environmental or health reasons, these methods could offer worthwhile alternatives. However, heatwaves can sometimes become so intense that cooling homes overnight is no longer easy. In southern France, temperatures did not fall below 30°C in the middle of the night. Without air conditioning, it is difficult not to suffer from the heat.