[serene911]

If the insulated units have failed, it's very obvious because you will have moisture and
condensation on the inside of the units. If the windows are clear they should be fine.
Not sure what you mean by caulking.If the windows are in a vinyl frame there is a snap
bead that holds the glass on one side.On the other side is a glazing tape that goes between
the glass and the frame. The only caulking you might have would be between the frame
and the wood casing or siding. Wood frames are similar although some companies instead
of using glazing tape will caulk between the glass and the frame which essentially glues
them together making it much more difficult to replace the units. Even with insulated units
the insulating value is low. Windows are rated with a U value. If you convert the U value to
an R value it usually is between approx. 1.8 to 2.8 depending on the unit and if it was Low E
glass on the exterior lite.