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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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    • CommentAuthorAshley
    • CommentTimeNov 19th 2020
     
    Hi,

    As part of larger house renovations we need a new back door and I'd like to make it thermally efficient.

    I'd like to pay around £600 - £700 for this as a maximum, cheaper if possible, and am probably thinking UPVC due to budget.

    However, I have trawled the web for hours and can't find what I would consider to be a good value energy efficient door. Many websites claim that their doors have A ratings, occasionally some specify a u value, but this is usually a general comment and mostly related to glass.

    As for u value that I'd like, it is difficult to say as I haven't seen any proper info, but as close to 1 as possible. If I could get a range of door costs and their u values I can then make a cost / benefit decision, but alas this seems difficult.

    Does anyone have any recommendations / experience they can share?

    Thanks in advance,

    Ashley
    • CommentAuthorEd Davies
    • CommentTimeNov 19th 2020
     
    I'd be very interested in any input on this, too.
    • CommentAuthorRobL
    • CommentTimeNov 19th 2020
     
    From what I can gather, at the cheaper end the best you will do is the largest area of 3G glass you can. That is, the glass is better than the frame.
    •  
      CommentAuthordjh
    • CommentTimeNov 19th 2020 edited
     
    Posted By: RobLFrom what I can gather, at the cheaper end the best you will do is the largest area of 3G glass you can. That is, the glass is better than the frame.

    I suspect that's true at any price. The airtightness of the frame (i.e. number and type of seals) and the hardware (multiple point locks, good quality lock cylinders etc) are the other things you're paying for, plus material choice of course.

    Some people have made their own doors successfully, if you're that way inclined.

    Edit: It might be worth looking at composite doors as well as UPVC.
    • CommentAuthortony
    • CommentTimeNov 19th 2020
     
    I made my own door from a 7x3 door blank, Plus 50mm PIR one side and 10mm the other and clad both sides just over 1oomm thick :)
    • CommentAuthorAshley
    • CommentTimeNov 19th 2020
     
    I would happily make my own door if I knew what I was doing - I'm fine with DIY, but building a door feels a bit more daunting.

    Tony - you don't happen to have a step by step guide? Or any advice?

    Anyone bought a cheap insulated door from the continent?

    Ashley
    • CommentAuthortony
    • CommentTimeNov 19th 2020
     
    • CommentAuthorAshley
    • CommentTimeNov 19th 2020
     
    I couldn't see a link to the gallery from your website, Tony
    • CommentAuthortony
    • CommentTimeNov 19th 2020
     
    • CommentAuthorgoodevans
    • CommentTimeNov 20th 2020
     
    I agree with RobL and DJH - we went for 3G fully glazed front and back doors - they were the best insulated (compared to panels) and cheaper than the panelled doors. Ours were from Munster but you will need to find somone in the trade to order - all supplies from Munster are on the basis of contract law not consumer law.
    •  
      CommentAuthorfostertom
    • CommentTimeNov 20th 2020
     
    Posted By: goodevansyou will need to find somone in the trade to order - all supplies from Munster are on the basis of contract law not consumer law
    Really? Several times I've come close to specifying Munster, as the nearest alternative to Russell, always deterred by lack of tech info and very 'Irish' enthusiastic but confusing communication (I ought to stop saying that, in these enlightened days).

    I suppose contract vs consumer thing wd apply to Russell too.
    And to my other favourite Vrogum via UK agent Indigo @ 1.5x the price, for that genuine English cottage window/Georgian/Victorian/Edwardian (shallow putty-bevel) look.
    • CommentAuthorEd Davies
    • CommentTimeNov 20th 2020
     
    Here's how I work out the maximum I'd be willing to pay for a 0.8 W/m²·K door.

    My front (only) door into the fully insulated part of the house will open into the porch/greenhouse so will be partly protected from the weather and not the first thing people come to. I'm planning to use something which is made as a backdoor for this job.

    A baseline would be this one from Wickes: https://www.wickes.co.uk/Wickes-Humber-Pre-hung-Fully-Glazed-Upvc-Back-Door-2085-x-840mm-Right-Hand-Hung/p/206597# though I think I'll need/want one a bit wider.

    U = 1.8 W/m²·K, £270.

    For roughly 2 m² area and a ΔT of 17 K (average temperature at Wick airport last Dec, Jan, Feb was 5.11 °C but I'd hope/expect the porch/greenhouse to be a tad warmer most of the time) that's a heat loss rate of 34 W. Energy from PV costs about £30/W in winter (about a £1/Wp operating for about 1/30th of the day) so at most decreasing the U value to 0.8 W/m²·K is worth 30 × 34 + 270 = something like £1300. I'd prefer to pay less :wink:

    A similar calculation for 3G vs 2G Velux windows said 3G centre-pivot ones made sense but only just. The thing that swings it is the comfort advantage of 3G if you're sitting next to them. For the top-hung escape windows in the bedrooms the weight and therefore cost penalty for 3G didn't make sense and the comfort factor would be a lot less important so I went for 2G for those.
  1.  
    Posted By: goodevansall supplies from Munster are on the basis of contract law not consumer law.

    I always thought that a contract of sale could not limit your consumer rights, just improve on them. That is if you are selling to the public.
    •  
      CommentAuthordjh
    • CommentTimeNov 20th 2020
     
    Posted By: Peter_in_Hungary
    Posted By: goodevansall supplies from Munster are on the basis of contract law not consumer law.

    I always thought that a contract of sale could not limit your consumer rights, just improve on them. That is if you are selling to the public.

    Yes, that's why firms like Munster won't sell to the public but only to trade customers where contract law is more 'pure'. (i.e. you can sign some rights away - caveat emptor etc) (assuming that Munster do only sell to the trade - I don't know)
    •  
      CommentAuthordjh
    • CommentTimeNov 20th 2020
     
    Posted By: Ed DaviesMy front (only) door into the fully insulated part of the house will open into the porch/greenhouse so will be partly protected from the weather and not the first thing people come to. I'm planning to use something which is made as a backdoor for this job.

    A baseline would be this one from Wickes: though I think I'll need/want one a bit wider.

    U = 1.8 W/m²·K, £270.

    The way I analysed it was the opposite, though in the end I simply bought a commercial PH doorset.

    I decided the function of the external door is weathertightness and probably security - so a conventional doorset is a fairly good fit. Then if there's a porch area the internal door's function is insulation and airtightness so can more easily be home-made and achieve an excellent standard.

    But we did away with the porch, so I went commercial.

    BTW, are you sure about only having one door? We find we use all ours fairly regularly - there are four.
    • CommentAuthorEd Davies
    • CommentTimeNov 20th 2020
     
    Posted By: djhBTW, are you sure about only having one door? We find we use all ours fairly regularly - there are four.
    Thinking of friends' houses where the only door used is the backdoor convinced me that front doors are a bit pointless. For one of them I never even saw the front door until the day I was helping out on the concrete pour for their extension and outside the back door was lava unset concrete. The house I'm in at the moment only has a front door, the kitchen extension was built on to what was the backdoor without providing another one. I can't say I miss it.

    With my house under construction all the other directions out of the house lead to swamp, anyway, beyond a metre or so of hardcore. Really, most of the year you need boots to walk there and need to be careful if they're not at least as high as wellies.
    •  
      CommentAuthordjh
    • CommentTimeNov 20th 2020
     
    Posted By: Ed Daviesthe only door used is the backdoor

    That's quite a walk from where cars are parked in our house, though the back door is the level access to the house for Part M. It's our patio door. The other two are on the east side next to each other, but both have an extra room outside the thermal envelope. The outside door from the 'bin store', which is more used as a pantry, exits to the front (north) and the exit from the sun room/conservatory is on the south-east corner. More dirty things are allowed in via the bin store and conservatory than the front or patio doors and the conservatory stores some gardening clothes.

    Fortunately we don't have a swamp to deal with :bigsmile:
    • CommentAuthorjms452
    • CommentTimeNov 21st 2020 edited
     
    Lots of GRP doors have a foam core.

    If you get a solid one (i.e. no glazing) and no letter box the bulk of the door will be pretty good.

    We got one of these with is 40mm PU core although no certified u-value (other than less than 2!)

    https://compositedoorcompany.com/technical-spec.html

    While there is a thermal break, the threshold is a weak point.
    • CommentAuthorAshley
    • CommentTimeNov 22nd 2020
     
    Hi, thanks for all the comments, very useful.

    I'm intrigued by the idea of maximising the glazing to improve the overall u-value, I found this website which specifies its 3G as having a u value of 0.7 - sound a bit too good?.

    https://www.modernupvcwindows.co.uk/upvc-door-designer.php?t=0-0-0&w=850&h=2000&h0=850&v0=1970&cill=85&o=2&x=000000T&pr=1&p0=AGT40035

    If I opt for a fully glazed door then as a guess the overall u-value should be pretty good...any thoughts?

    Is there much of a difference between companies on the actual door for the price you pay? Is a cheap(er) door a false economy, regardless of the 3G glazing? Any experiences welcome.

    Ashley
    • CommentAuthorjms452
    • CommentTimeNov 22nd 2020
     
    it does look a little too good (it's all down the soft coat spec). See https://spectrum.pilkington.com/ it will give you centre glazing u-values for anything so you can check if it looks too good.

    Cheap is not always worse but the details matter such as:
    Threshold (multiple thermal breaks are now available)
    frame (there are multi cavity ones which are more insulating)
    Air seals
    a door you like that fits your house
    and don't forget security

    Glazing/letterboxes etc. presents lots of interfaces with the rest of the door that are imperfect and where both heat and air can leak through. One big 3G unit is better than multiple little ones from this perspective.
    • CommentAuthortony
    • CommentTimeNov 22nd 2020
     
    At DraughtBusters during the past years we have been encountering quite a few warped and draughty UPVC doors.
    • CommentAuthorjms452
    • CommentTimeNov 22nd 2020
     
    Posted By: tonyAt DraughtBusters during the past years we have been encountering quite a few warped and draughty UPVC doors.


    multi point locking should help a bit here as a well as with security
    • CommentAuthorSteveZ
    • CommentTimeNov 22nd 2020
     
    Our door installer recommended operating the multipoint lock whenever the door was closed, not necessarily locking it, but it helps to prevent warping by pulling the door into the frame each time. The downside might be that the lock gearbox wears out more quickly :sad:
    • CommentAuthorjms452
    • CommentTimeNov 22nd 2020
     
    This co (no interest):

    https://www.justvaluedoors.co.uk/energy-ratings-u-values.html

    say they offer a thermal option for their doors which combined with 3G glazing gets you to U=0.8
    Skimming their doors types the lowest looks more like U=1.1 but it encouraging to find a website selling on price giving thermal options and talking U values.
  2.  
    Posted By: SteveZOur door installer recommended operating the multipoint lock whenever the door was closed, not necessarily locking it, but it helps to prevent warping by pulling the door into the frame each time. The downside might be that the lock gearbox wears out more quicklyhttp:///newforum/extensions/Vanillacons/smilies/standard/sad.gif" alt=":sad:" title=":sad:" >

    I operate the multipoint locks just to catch in the winter as I find that without doing so the doors are not air-tight.
    •  
      CommentAuthordjh
    • CommentTimeNov 22nd 2020
     
    Posted By: Peter_in_HungaryI operate the multipoint locks just to catch in the winter as I find that without doing so the doors are not air-tight.

    Indeed so, they're designed so that activating the multipoint lock pulls the door tight against the seals. That's why lifting the handle takes (a little bit of) effort, whilst the subsequent turning of the key is very easy.

    PS I expect you know this PiH; I'm writing mainly for other readers.
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