As the climate heats up, the need for cooling is also increasing—which could lead to still more consumption of fossil fuels. By 2035, it’s estimated that half the households in the world will have an air conditioner, which will use twice as much electricity for cooling as today.
But in most climates, it’s possible to eliminate the need for air conditioning by using traditional design techniques for cooling and ventilation, to ensure that the building interior stays comfortable.
The simplest way is to use the wind to push fresh air through the building. This is much more effective when there are openings on opposite sides of the building (cross-ventilation), oriented to the prevailing wind, and when the building is not too deep.
In hot countries, wind towers or wind catchers, like these in Iran, have been used for centuries to channel cooling breezes into buildings. Their design varies a lot depending on microclimate and culture.
Sometimes, when the outside air is too hot, it is first sent through underground tunnels, which can include water deposits to cool the air by evaporation.
This is just one of many methods of evaporative cooling, which also includes fountains, pools, absorbent ceramic pots, and plants—which can also filter the air and provide a privacy screen, as in this example from Vietnam. As always, the right solution depends on understanding the context.
In the humid tropics, natural cooling strategies tend to include using low thermal mass materials which won’t store the heat, lots of shading and screens to exclude the sun, and raising the building on stilts to catch the breeze, as seen in this house in Indonesia.
Of course, wind catchers and cross-ventilation work best when the wind blows, and when the air is cool—at night and during the early morning—so it can take away heat stored in the building’s thermal mass during the day. This is often called night flushing.
Other methods of natural ventilation that don’t depend on the wind include the stack effect, in which hot air rising draws cooler air upward through the building. For best results, this requires an intake of cool air from outside.