Blinds - why do they open north and not south?

The setting of the shutters is to keep the temperature of the air inside and the air outside the same. Because the shutters have many gaps, the air can circulate, but the internal temperature cannot be raised due to the intrusion of sunlight due to the shutters, so it should be avoided. sun exposure.When the window faces south, even though the window has a slanted downward slope, sunlight will still enter from a high place, so it faces north.