In summer, the temperatures in the apartment can rise quite a bit. With this trick, the room will be pleasantly cool again in no time.
Neither a fan nor an air conditioner is needed for this simple trick. You already have everything you need for this at home: a 1.5-liter plastic bottle and water. The full bottle is placed in the fridge overnight and placed on the top of your room the next day (e.g. a closet). It is best to place the bottle on a plate, as condensation can form.
This simple trick cools a room of about 20 square meters by a few degrees for about three hours. Two bottles can also be used for larger rooms.
Tip: Do not fill the bottle completely, as it will expand when it freezes and could otherwise burst.