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Housing - New Build: Condensation on the outside of my windows

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  1.  
    • CommentAuthortony
    • CommentTimeOct 10th 2009
     
    Can you tell me why?
      IMG_1299.JPG
    • CommentAuthorjamesingram
    • CommentTimeOct 10th 2009 edited
     
    Is it because of the temperature difference

    A window fitter I know doesn't like argon fill etc as the customers complain of this external condensation,
    I presumed it just meant the windows are working well as a insulator ?

    nice windows , will you be putting some costs and supplier on your site in the future ? could be helpful for people.
  3.  
    Posted By: tonyCan you tell me why?
    Same reason car windows get condensation on them on the outside. With damp air and a clear sky, radiative cooling of the surface brings it below the dew point. Because your windows are good insulators, there isn't enough heat flowing through them to keep the outer surface above the dew point.Looking at the photo I can see that the sky was clear.

    The only solution I can think of if it bothers you is to treat the window surface with something like the products one sometimes sees that are supposed to prevent car windows steaming up on the inside. I think some glass now is available with a self-cleaning coating which may do the same thing.

    Paul in Montreal
  4.  
    We skint motorcyclists used to rub a potato on the inside of visors to prevent steaming up.....
    • CommentAuthorJulian
    • CommentTimeOct 10th 2009
     
    Tony
    I have had the same experience with my new windows - the first really good 2G windows I have ever had. I came to the same explanation that Paul suggests above (although not as eloquently put). Its never been a problem with crappy old inefficient 2G or 1G windows so it takes a little getting used to. After a while I decided it was a good sign - rather like having unmelted snow on your roof while others are clear.
    • CommentAuthorJeff B
    • CommentTimeOct 10th 2009
     
    Shocks and horror!! The clear patches around the perimeter of the glass must be due to thermal bridging. Presumably all down to the aluminium seals around the DG unit. Probably quite negligible heat loss though, so "sleep well and don't have nightmares" as they say.
    • CommentAuthorJulian
    • CommentTimeOct 10th 2009
     
    I think that'll be relative that thermal bridging Jeff...Tony will have specified warm edge spacers!
    • CommentAuthorTerry
    • CommentTimeOct 11th 2009
     
    So, for those in the market to buy an energy efficient house, the ideal time to look would be after a good snowfall on a nice clear morning.
    The house with a good covering of snow on the roof and external condensation on the windows is the one to go for - simples.
    • CommentAuthortony
    • CommentTimeOct 11th 2009
     
    Then go back and see how long the show takes to melt:smile:
    • CommentAuthorTerry
    • CommentTimeOct 12th 2009 edited
     
    So condensation on the outside of your windows has to to be the green building equivalent of a secret handshake surely?
    As regards the rest of the ceremony, instead of dancing around outside until the snow on the roof melts, could we not just stick to hopping around on one leg and tying knots in our trousers?
    • CommentAuthorfuncrusher
    • CommentTimeOct 12th 2009
     
    It's the dewpoint obviously - but why is the question. Quite often we get external condensation on our 200 years old single glazed windows - and they are extremely thin crown glass. So its not just a case of high insulation properties - far from it. I think the answer may lie in the geography and climate. Sudden arrival of warm fronts can cause dramatic rises in temperature and 100% relative humidity, causing instant condensation on everything - roof, walls, windows, cars etc. This kind of phenomenon is only likely near the western seaboard, as the warm front effect is blunted as it travels inland. Warm fronts often arrive in calm conditions with the imperceptible breezes: wind follows later. The effect is rather like an incoming tide: the warm air creeps in around obstacles and creates pools of warm damp air, sometimes with fog. I've encountered several cases where a field enclosed by trees has filled with warm balmy air, which is gradually seeping via a gateway into the next field which is at least 10deg colder. Its quite startling when encountered. Tho the warm front like the tide engulfs in less than 10 minutes, the condensation can last hours until the underlying material has warmed up sufficiently - but even then the humidity is so high the condensation may not evaporate easily.
    • CommentAuthorJulian
    • CommentTimeOct 12th 2009
     
    Interesting FC. That certainly sounds plausible. We have poor quality existing 2G windows next door to the new ones. New have condensation but old ones don't. We're in the SW. But I don't think Tony's that near the sea are you Tony?
    • CommentAuthortony
    • CommentTimeOct 12th 2009
     
    No about as far away as you can get in the UK
  14.  
    Is it not more fundamenal? It's colder on the inside than the outside? To quote Only Fools and Horses, the renowned Green Building Solutions series, "Del, it's so cold in our bathroom, there's condensation on the outside"

    I live in a solid-walled Victorian terrace with the heating off at the moment (Well, broken actually!) and the outside temperature warms up quicker than the inside in the mornings. I've routinely woken up to condensation on the outside of my double-glazed windows.
  15.  
    All we can tell for sure is that the temperature of the outside surface of the window is below the dew point. Without additional information its not possible to say why this is.

    However, as Tony has triple glazed windows & large amounts of insulation its unlikely to be due to the inside air temperature lagging behind the outside air temperature. Its more likely that the windows have been radiating into the night sky &/or moist air has just arrived.

    David

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