We’ve been reading one or two homeowner reviews where they’ve complained of exterior condensation on ‘A’ rated energy glazed windows. It’s the outside face of the exterior pane that condensates – not the interior of the pane (between the sealed airspace).
They’re worried the condensation, and sometimes frost (where the condensation has formed before freezing) indicate there’s a problem with their double glazing.
On the contrary, it means they’re working perfectly well as specified.
The issue arises because the glazing and window construction is so efficient, interior temperatures never reach the outer pane sufficiently to ward off the condensation forming.
In some cases you’ll notice the edge of the pane where it meets the window frame itself shows less condensation – this is due to the small amount of heat transference through the frame, and again is perfectly normal.
The condensation usually occurs in the mornings and soon clears.
Still, it can be a bit of a shock to wake up, throw back the curtains to be greeted with an opaque window due to condensation.
With October, reportedly, being the worst month for condensation affecting ‘a’ rated double glazing, the glazing industry advice is don’t panic. Your energy efficient windows are being just that.