Why did the Navajo build hogans in the desert?

Most of the Navajo Nation is at the elevation of between 5000 and 8000 feet. Some mountains are 10,000ft. It is cold with snow in the winter and it gets cold at night. Hogans are warm in the winter and cool in the summer because of the thermal mass of the earth on top of the log structure. In places where it got too hot during the summer in the daytime, people built brush shade shelters or ramadas called chaha'oh.