The temperature in our family room has always been a little
different than the rest of the house. We attributed to the wall
of windows that made it unique. Recently, I heard a howl outside
and felt a breeze blow through the room! So we started looking and
found at the bottom center of every horizontal sliding window frame,
there is an oval shaped hole that goes straight to the outside. You
can really only see it inside if you look down the axis of travel of the
window. What is this hole, why is it there, and what should I use to fill
it? Anything else I should be aware of? My first thought was to just use
the GE Silicon.

Thanks