Sorry for the delay in this comment but I want to set the record straight about the 'Condensation advice' on the Miriad website.
The guideline was produced using some previous documents issued by Polyplastic in the early 80's and whilst still current, does have one point that causes ambiguity. The 'metal framed' windows referred to are the much older variant of metal framed windows that tended to be glazed with glass panels....hence the next comment "Fit Polyplastic double-glazed acrylic"..pointing out the benefits of double glazed windows per se. These older varieties of metal frames were a very simple metal profile with no cold-bridge insulation properties whatsoever employed. This line in no way refers to the Polyvision windows now fitted throughout Europe.
The line referring to metal framed windows has now been removed to avoid any confusion.
As regard to the information detailed within this thread about condensation, then I would have to concur with the thoughts of JOHN L on 21st Feb entirely. Condensation is a natural phenomenon that results from humidity, especially so during an overnight period if the caravan is not well ventilated. The temperature outside the caravan being drastically different to that inside the caravan, literally can cause a badly ventilated caravan to 'sweat'. JO-ANNE'S initial comment on 16 Feb and indeed IAN-SWIFT's comment of 27 Feb underline this, with excess humidity in both instances resulting in severe condensation build-ups on internal walls and within lockers. If humidity has risen to this extent, then it is no surprise that condensation is evident too on window frames. Ventilation really is the key!
The Polyvision windows supplied by Polyplastic are manufactured using a complex aluminium profile that includes a Polyeurathane cold-bridge to help with insulation. For the last 7 years approx 100,000+ Polyvison windows have been supplied each year throughout Europe to such customers as Dethleffs, LMC, Knaus, Hobby, Giotti and Le Voyageur, as well as Swift, Bailey and Vanmaster within the UK. Speaking from our experience within the UK, we do receive some queries each year about condensation on windows (in general, not just Polyvision) and in all instances ventilation, resulting in temperature stabilisation is the answer..just like at home, if a window shows condensation upon it, you would open it (ventilation) to clear it????
After writing this I have spoken to JO-ANNE in an effort to explain the above. Hopefully this helped clarify the situation.
Richard Toon
Miriad Products Limited