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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorShevek
    • CommentTimeDec 7th 2020 edited
     
    Can anybody suggest a suitable window to replace these windows like-for-like?

    They're horribly inefficent single-glazed sliding windows. It's a block of flats so they need to be like-for-like. (Europe-based would be good also as this is actually in north of Portugal). Sash is 60 mm wide. Fixed light frame is more about 45 mm.

    Given how horribly inefficient sliders are I'm assuming we'll switch to a tilt-n-turn, but open to any suggestions with sliders.
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  1.  
    Has anyone else changed their windows or are you the first?
    • CommentAuthorShevek
    • CommentTimeDec 8th 2020
     
    Some have added secondary glazing, including on the outside. But no one has changed the existing windows.
    •  
      CommentAuthordjh
    • CommentTimeDec 8th 2020
     
    I would ask Portuguese suppliers.
  2.  
    Can't really see the frame profile, which looks powder coated metal(?), but any chance you could replace the single with double glazed units? The bulk of window costs is in the frames, and since you want the same windows but with better glazing...

    Could you photo a close up of the glazing bead area?
    •  
      CommentAuthorfostertom
    • CommentTimeDec 24th 2020
     
    Vitocsa, who I think are Portugese, make well insulated slim profile aluminium windows - at a price in UK, tho maybe more reaonable in home country.
    • CommentAuthorShevek
    • CommentTimeMar 5th 2021 edited
     
    Thanks guys. Here's a close up.

    What I've noticed in Portugal is that PVC is extremely common. Everybody offers it by default, even when we ask for aluminium. I think this is because the aluminium sections they have here don't have thermal breaks. So aluminium has a really bad rep.
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    • CommentAuthorShevek
    • CommentTimeMar 5th 2021 edited
     
    I had to fix one of the external roller blinds the other day and it was, shall we say, a learning experience. It amazes me how they've constructed this building. It looks like the developing world and it's only 20 years old. I'm not so sure I want to be in here if Portugal were to have a big earthquake or tsunami.

    I've drawn some details of the existing windows. No lintels. Half bricks above window head. Nominal 20-30 mm spray foam insulation. Nothing between the internal and external environment except a timber window head board.

    So it seems to me the biggest bang for our buck is going to be to remove the existing roller blinds and replace them with either external venetian blinds which are more compact or ones that go inside the glazing. Then we can fit a lintel of some sort to tape the window head against. Then fill that massive cavity with mineral wool.
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  3.  
    They do the same trick with roller blinds over here, although there is usually a lump of iron as a lintel - and yes they are a thermal disaster, more so with our winter temps. going down to -10 or occasionally more (or should that be less). I took out the roller blinds and stuffed the space with glass fibre insulation - it made a world of difference.
    • CommentAuthorShevek
    • CommentTimeMar 5th 2021
     
    Yeah, I thought about just getting rid of them without replacing with something but it gets pretty hot here in the summer. External shading is pretty handy at that time of year.
    •  
      CommentAuthordjh
    • CommentTimeMar 5th 2021
     
    Could you fit an externally-mounted roller blind box?
    • CommentAuthorShevek
    • CommentTimeMar 6th 2021 edited
     
    No it's a block of flats so it's got to look the same. I also wondered about swapping them for external Venetian blinds (which are more compact and would allow me to fill most of cavity with insulation) but they would look pretty different too. Maybe it could work if I can find Venetian blinds the same colour and same module.

    Blinds internal to the glazing could be a good compromise, but not sure that's going to work either, with multiple panes and sashes in each window.
  4.  
    Your windows are single glazed, and much bigger area than the lintel/shutter box, so will have a much greater heat loss, I'd have thought.

    Could you not strip the internal board at the window head, and make a much better job of insulating around the roller shutter, for a pretty low cost. eg 50mm rigid insulation board of your choice horizontally across the window frame head, then vertically where the spray foam is, then horizontally where the concrete lintel appears to be... a sort of backwards "C" shape. More than 50mm might be possible in the vertical bit, especially if you were to continue the insulation as a sort of IWI across the window head to the adjacent walls.

    Then spend the money you would have used replacing shutters/blinds on getting new glazing beads (or machining the existing), to make rooms for double glazed panes, in lieu of the singles. I hate the thought of ripping out something that's functional, to replace it with something equally functional.

    Have you tried popping out the glazing beads, to see how they fix in place? I'd think it could be a nice hobby, converting the existing to double glazed...maybe that says more about my taste in hobbies :shamed:
    • CommentAuthorShevek
    • CommentTimeMar 12th 2021 edited
     
    Yes I like your thinking GreenPaddy, thanks. We've had some quotes back for windows and one fitter has being giving us particularly good advice (and has a particularly good window, aluminium, with thermal breaks!) so we're going to get them to take a look at the shutter box when they come to measure up and see what they think. I think doing as you describe is a great option.

    The problem with the existing windows isn't just that they're single glazing but that seals are inherently crappy; they leak like a sieve. We have somebody who would like to up cycle them into another building or a greenhouse too.

    The no brainer is that the government here has a scheme where they provide grant money for upgrading energy efficiency of existing housing. In the case of window upgrades they'll pay up to 75% and a maximum of €3500.
    • CommentAuthorShevek
    • CommentTimeMar 18th 2021 edited
     
    When we replace this window, do you think we can simply fill this gap with PU foam or mineral wool? Or should we be placing a DPC between the brick and the PU foam/mineral wool?
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    • CommentAuthorShevek
    • CommentTimeMar 19th 2021 edited
     
    I found a very cool window manufacturer called Cortizo. Well, we found a great installer that uses their windows. It's a Spanish company but they have a distributor in the UK I think. Don't know how well that would work with Brexit now, unless they also manufacturer in the UK.

    Anyway, they have a really great website, in all languages, with every bit of information you'd want, including loads of CAD details, including example interface details.

    So I decided to draw up an exemplar set of details that I'm going to distribute to other residents in the building for them to use if they're thinking about upgrading their windows.

    I went for a new roller shutter in the end, but I'm waiting to see how the price comes back.

    Any comments welcome:
    https://www.dropbox.com/s/hxt18627aigcqbr/Window_Schedule.pdf?dl=1
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