In an insulated window, two pieces of glass are kept together with spacers on each of the four edges. These spacers connect the glass while leaving a pocket of air between them. Seals can fail and cause condensation to develop in between the two windowpanes. Normal wear and tear can cause this with older windows. Depending on the temperature, you may only notice foggy windows only a few times during the year. If you notice foggy glass on your insulated windows, contact us.