Is it too hot at home? This test proves that a simple well -placed fan can really make the difference

In recent days, temperatures have increased significantly and many are looking to preserve a little freshness inside their accommodation. As new heat waves planned for the summer, everyone adopts their own methods – with more or less success – to refresh their interior. Some opt to keep closed shutters and windows, others suspend damp linen, while some rely on more technical solutions such as air conditioning.

By exploring YouTube looking for advice to better support the heat, Guillaume, from the computer service, discovered a video that caught his attention. An engineer presents an ingenious method to create an air current in an apartment without crossing ventilation, based on the principle of Bernoulli – all using a simple fan.

Basic notions in physics

Bernoulli’s theorem, as defined on Wikipedia, states that “within a homogeneous and incompressible fluid, subject only to pressure and gravity, an acceleration is always associated with a drop in pressure”. Concretely, this means that if you expel air through a window (window A), a low pressure area is created, which automatically leads to the suction of an equivalent volume of fresh air by another opening (window B). This phenomenon gives rise to an air flow, even without natural circulation, and thus allows better ventilation in closed rooms.

This process is particularly useful in low -ventilated accommodation. However, during hot weather, its efficiency depends on the external conditions: it only works if the air outside is cooler than that inside. This is frequently the case in the housing facing south, whose walls, exposed to the sun all day, store heat and restore it after sunset. When the external temperatures are very high, the most effective method still remains to maintain windows and closed shutters to limit heat intake.

The opportunity to test this method identified on YouTube was too interesting not to be seized. We have therefore drawn up an verification procedure that is both quick to implement and rigorous in its approach.
The device simply requires two openings overlooking the outside – whether windows located in the same room or separated by a partition, regardless of their size or opening angle – as well as a fan, a tape and an anemometer to measure the air flow.
The installation is very simple: just open the two windows, position the fan facing one (by directing it outward) and installing the anemometer facing the other, so as to capture the incoming air movement.

Optimize the distance

From the first minutes of the experience, the results are felt: placed directly at the foot of the window, the fan has almost no measurable effect. The anemometer remains almost motionless, indicating an air flow too weak to cause the slightest rotation of its blades.