Origin

The character 軒 combines a vehicle-related element on the left with a sound hint on the right. The 干 component tells you roughly how to pronounce it (similar to "kan" or "ken" sounds), but doesn't contribute to the meaning. The 車 element on the left originally referred to wheeled carts and vehicles, but in this case it appears to function as a classifier for things that extend outward or overhang—much like the protruding eaves of a roof or the extended structure of a building. Over time, 軒 came to mean the eaves of a house and eventually became a counter word for counting houses or flat units, treating each building as a distinct countable object.