Bathroom Exhaust Vent
Most the time when you see something like this on
the exterior of a house it will be a bathroom exhaust fan. Do not get
these confused with the dryer vents. Dryer vents look the same and are
usually less than 1 foot off the ground.
Most builders don't put it bathroom exhaust vents anywhere near the entryway to a home anymore. They were actually having problems with people walking up to the front door wearing hats and having their hats blown off of their head.
Every once in a while in a newly built home you will find a problem like this. For the most part though you are not going to be seeing bathroom exhaust fans or any other sort of exhaust fan leading into the entryway of a home.