The same property that keeps the smell of wool is the one that helps regulate the temperature. Breathability of the fabric means that much of the moisture absorbed by the material is converted to steam and released into the air.
Wool comes from animals that live in a changing temperature climate, which allows them to regulate the user's temperature well.
Woolen fabrics are easy to clean because the outer surface of the wool fibers is made up of a series of overlapping scales (similar to feathers on a bird), meaning that dirt sits on the surface of the fiber and therefore allows for easy removal. Ventilation several times a year is enough.
