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Green Building Bible, Fourth Edition
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Products: 4g

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  1.  
    • CommentAuthorNovice1
    • CommentTimeMay 19th 2012
     
    Would be grateful for your feedback and help.

    About to look at these 4g quattro windows. Mostly for sound as we live next to a busy road. AFAIK frame is rehau but have struggled to get any further info on airtightness, seals and frame insulation etc

    http://www.envirowindowsanddoors.co.uk/quattro-quadruple-glazing-window.html

    Upside (sound, cheaper than mirror heat glass, will compensate for other challenging features of project (ie. large, north elevation glazing, south elevation road noise)
    Downside (??seems only available up to 1.2m2, UPVC, seller seems like middleman with little grasp on all specs needed to make window properly 'eco', )

    Beyond the vague detail, cringe worthy pressure selling and dubious pseudo-science on the site has anyone else come across these and discounted/used them?
    Cheers
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 19th 2012
     
    http://www.youtube.com/watch?v=Qph0io5oBMk
    At the end he talks about 3 layers and comfort.
    • CommentAuthorJoiner
    • CommentTimeMay 19th 2012
     
    Steamy! :cry:

    Similar technology was touched on in the 'heated glass' thread. Some more here...

    http://windows.lbl.gov/adv_sys/hi_R_insert/HiRSummaryPaper.pdf

    ... so not strictly 4g, more 3g- or even 2g-plus.

    And also found this from Fakro... http://www.prnewswire.com/news-releases/fakro-quadruple-glazed-roof-window-offers-lowest-u-value-141589813.html

    ...which I can't remember any of you lot who went to Ecobuild mentioning.

    The "4g" systems seem to consist of 2g or 3g with an extra "non-structural element".
    • CommentAuthorNovice1
    • CommentTimeMay 19th 2012
     
    Thanks guys

    I actually think it is a true 4g ie 4 glass panes

    see http://forum.expertexpert.com/viewtopic.php?f=9&t=74

    Opinion was summarised on the above thread. Just wondered if GBF brains had any thoughts or experience?
    •  
      CommentAuthorJSHarris
    • CommentTimeMay 19th 2012
     
    I'm planning on using the 4G Fakro roof windows, and also 4G Internorm windows. The latter only really use the outer pane as a weather and noise shield, as it's not permanently sealed to the other panes and can be opened for cleaning (and it allows internal blinds to be fitted).
    • CommentAuthorTimSmall
    • CommentTimeMay 19th 2012
     
    Faced with the same problem, I'd consider putting a thick triple glazed unit into the Rehau Geneo PHZ, as I think it allows for some fairly thick sealed units. Unfortunately I don't know which specific options are available, but I think it will go over 60mm.

    Have a play with something like Pilkington Spectrum Online - which will give you noise reduction figures I believe.

    In general to get better sound reduction, you need thicker glass (but this adds weight, and reduces the amount of light which will come through), or thicker cavities. Added weight will reduce your max window size without reinforcement...

    Try 4mm float - 22mm argon - 4mm soft-coat - 22mm argon - 4mm soft-coat

    U value = 0.53, g value = 0.53

    You could also swap out one or more of the 4mm panes for thicker ones.


    Other profiles and window materials are available of course!
    • CommentAuthorJoiner
    • CommentTimeMay 19th 2012
     
    Novice - yeah, sorry, my references were to the links I posted. It's clear from the Enviro site that theirs is a true 4-pane system, giving a make-up of 4-8-4-8-4-8-4, I was looking elsewhere to see if anyone else did anything similar, achieving similar performance with less weight.

    Weight is significant at 40Kg/m2, although heeled and toed the unit would become a structural part of the window, despite which it is probably what limits the size to the 1.2m2 you quote in the OP, although heavy duty friction hinges are available I'm wondering if the opening geometry on such a wide sectioned window would push them to their limit even if within the given weight weight capacity of the hinge, even on top-hungs.
    • CommentAuthorWMS
    • CommentTimeMay 20th 2012
     
    To the best of knowledge, Rehau will not guarantee this window, enviro are not manufacturers, they buy the window in from Ireland ( not munster ) I also believe that the 2 inner panes are greenhouse glass, to thin, be very careful of what you buy, Rehau have not tested this window, Enviro are very economical with the truth, they say they use krypton on their 3G windows, but the glass supplier does'nt use krypton, I have nothing to gain here, just passing on some knowledge.
    • CommentAuthorTimber
    • CommentTimeMay 20th 2012
     
    If you want good acoustic specs, you need differing glass thinknesses and big cavties.

    Best spec for double is normally 10-20-6.4lam

    For triple, I would imagine 4-8-4-8-4 are not great acoustically, but it has been a while since I spec'd a window for acoustic reasons, so don't know what the numbers are like.
    • CommentAuthorJoiner
    • CommentTimeMay 20th 2012
     
    Acoustically, it's always been my understanding that panes should be of different thicknesses to stop sympathetic resonance. Only ever done it with 2g because that's all I've ever been required to fit.

    Obviously, the more layers of glass you've got then the greater the reduction in noise, but even greater if an "intervening" pane is of different thickness.

    I'd imagine the introduction of a "non-structural element" would reduce the transmittence even more (???) acting like a shock absorber???
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 20th 2012
     
    Simple Harmonic Motion is described like this:

    y=A.sin.(k.m^-1.t)^0.5

    Where:
    A=Amplitude
    t=Time in seconds
    m=Displacement in metres
    k=System Properties

    :cool:
    • CommentAuthorTimber
    • CommentTimeMay 20th 2012
     
    Joiner - you are correct. Ressonance of small air spaces coupled with glass of the same thickness causes poor performance at certain frequencies. Big air voids, and glass of different thicknesses is the key.
    • CommentAuthorRobinB
    • CommentTimeMay 21st 2012
     
    I have recently been wondering about setting two 2dg windows one in front of the other. Seems potentially less costly and I could add some kind of insulation between the two frames. I haven't really investigated this much though.
    RobinB
    • CommentAuthorJoiner
    • CommentTimeMay 21st 2012 edited
     
    What about the dampening effect, if any, of systems that include a "non-structural element"? Anyone any thoughts, any links? I can't find any (acoustic) references.

    Was just wondering. :smoking:
    • CommentAuthorTimber
    • CommentTimeMay 21st 2012
     
    Robin - that works well acoustically - I spec'd that on a job many years ago being built next to the A12 in London that had particularly onerous internal target noise level.
    •  
      CommentAuthorJSHarris
    • CommentTimeMay 21st 2012
     
    It's a bit complex trying to analyse the noise suppression of multiply glazed windows. I looked at it a while ago and you've got several spring/mass systems interacting, hence the advice to keep the glass thickness's different and the gaps different to avoid resonances. Each pane of glass has a mass and a stiffness (the spring bit), with stiffness being determined by the size of the pane, its thickness and the Young Modulus of the particular type of glass used. This latter point is quite important if one of the layers isn't glass but a material with low mass and Young's Modulus, such as a film, as then the film layer might as well not be there in terms of reducing sound transmission. The air in the gaps also has a mass, again dependent on the size of the pane and the width of the gap, together with a "springiness" that comes from its compressibility, and generally each gap will act independently of the others, with only a small level of coupling between them (unless the separating layer is very flexible).

    The sound attenuation comes from the mass of the glass together with the damping effect of the air between the panes. It should be possible to model this easily enough as a series of edge-constrained plates and sealed spaces, but the modelling would need to be done for the exact size of window needed, as there is a strong effect from pane size (big panes will be less stiff than small panes).

    As the frame is likely to conduct sound (and probably heat) better than the glazing units, there has to be a trade off somewhere between the higher transmission through more frame parts and the reduced transmission through smaller, stiffer, panes.

    It's probably not worth worrying about too much for domestic size windows, as I suspect the general rules of thumb regarding different gap sizes and glass thickness are probably good enough.
  17.  
    The Munster guy I spoke to mentioned he exported some quadruple glazed windows to Sweden.
    • CommentAuthorJoiner
    • CommentTimeMay 21st 2012
     
    VH - Coals to Newcastle?

    Jeremy - the job I did with the acoustic units was stormproofed to allow gaskets to seal the air gaps around the internal and external gaps and to cushion the casement frame from the window frame. (Only the incredibly noisy situation convinced the CO to allow the stormproofing.) The house was on a busy, narrow road with pavements just 3ft wide, along which hammered a succession of quarry lorries, full the one way, empty the other. The customer said the new windows had "transformed" her life.

    They'd viewed the property over a weekend!
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 22nd 2012
     
    Posted By: JSHarrisThe air in the gaps also has a mass, again dependent on the size of the pane and the width of the gap, together with a "springiness" that comes from its compressibility

    That will be the Bulk Modulus then:

    K=-V(dP/dV)
    Where dP/dVis the derivative of the pressure with respect to the volume and is probably the key to damping the panes, so maybe just differing air gaps is all that is needed.
    May be possible to put a tiny mechanical damper on a pane (something like a lead bar) as well.
    • CommentAuthorJoiner
    • CommentTimeMay 22nd 2012
     
    :bigsmile: Stick-on lead "cames", a la the upvc "cottage look"? Very classy as well. :cry:
    •  
      CommentAuthordjh
    • CommentTimeMay 22nd 2012
     
    Posted By: SteamyTeaMay be possible to put a tiny mechanical damper on a pane (something like a lead bar) as well.

    Or if you have the famed heated glass - or any other glass with conductive films - you could presumably turn it into noise-cancelling glass. Just need a microphone, digital delay and an amplifier and you could drive two sheets of glass together and apart like an electrostatic loudspeaker to cancel out the sound.
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 22nd 2012
     
    Posted By: djhyou could presumably turn it into noise-cancelling glass.

    You got a patent or copyright on that idea :wink:
    If it works can be put on all houses near a wind turbine :rolling:

    In fact, just make the whole house wobble in sympathy to the noise, make it look like a jelly, put some whipped cream on the top instead of insulation, sit back and relax. Now where have I put the bong :smoking:

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