the botijo fridge by hester van dijk from netherlands

Water evaporates at any temperature between 0 degrees Celsius and 100 degrees Celsius. When evaporating, water withdraws heat from its surroundings. You can feel this when you wet a small part of your skin and blow against it, the wet part will become colder than the rest. This simple principle has been used during hundreds of years, for example in the Spanish botijo, a self-cooling water bottle made of unglazed earthenware.

In the future, the need to find environmentally friendly alternatives for everyday products will become increasingly urgent. This botijo fridge, a refrigerator that cools its content by water evaporation has been designed out of this necessity. Basically it is a metal container covered with water absorbing textile that is constantly being kept wet. The container sticks through the façade of the kitchen. This is because outside buildings the air humidity is usually lower, which results in a cooler fridge. On the other hand, it is still possible to access the fridge from the kitchen so it’s just as easy to use as a normal fridge. In order to increase the size of the cooling surface compared to the content, the fridges are smaller than a normal fridge, one would need several botijo fridges to be able to store the same amount of food.

The temperature inside the fridge ranges from around the freezing point in winter, till about 15 degrees Celsius on a warm summer’s day, depending on the air temperature and humidity. Most of the time the fridge is 10-12 degrees Celsius, which is a good temperature to store wine, fruit and vegetables.