Annex
Windows are usually maintained above -air dew point to prevent condensation and mold growth by heated supply air flowing over them. Heavy window frames on the interior side interfere with the proper flow of this heated air by the Coanda effect (a corollary of Bernoulli’s principle). There are many ways to mechanically address window condensation issues. Air supply can be dumped on glazing from both above and below. Fin tube heaters have also been effectively employed along sills in many instances.
* Also see: ASHRAE Handbook of Fundamentals81