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May 24, 2018



KJM’s Managing Director Mark Pearce gives his personal views on Triple Glazing

In an age when energy prices are only heading in one direction, fitting your home with new KJM Veka 44mm Triple Glazed Windows can offer additional savings compared to standard ‘A’ rated double glazing. Well that’s the selling bit over and done with!

Triple glazed windows are still a relatively new concept in the UK. But in colder countries like Scandinavia, where homes endure extreme winter weather, they have been a standard fitment for many years. While we might not get the same severity of conditions, the UK does still suffer from harsh winters and of course increasing energy prices.

There are other ways to insulate your home like the roof, walls and floor, but neglecting your windows can result in cold spots and condensation. Personally I installed 44mm triple glazing in to my own home around three years ago and I have never looked back since then.

Some from within KJM would describe me as “KJM’s Triple Glazing King”, as I passionately believe in the product. I was even asked to speak at our national trade show about the benefits of triple glazing, but declined as it was over three days and in Telford, a long way from our base in Andover in Hampshire.

There are many benefits to installing triple glazing in your home but the important thing to remember is that all triple glazing is not the same. There are many systems available but to really get the maximum benefit then the gaps between the panes of glass should be 16mm and filled with argon gas.

Argon is an inert gas that reduces the heat loss through the panes. If the gap is reduced then the thermal performance is reduced, unless you start to use an expensive gas like krypton. So generally speaking the optimum size of a triple glazed sealed unit should be 4mm glass, 16mm gaps, so in our industry it’s called a 4/16/4/16/4 unit and that equals 44mm in total. You then need to factor in the number of chambers within the frame, the fewer chambers the less insulated the frame. The Veka system uses thermal inserts within the frame to improve the insulation further.

Are there any down-falls I hear you ask? The biggest problem I’ve encountered with my own windows would be external condensation on the glass. This happens because the external pane of glass is not being heated so well by your house, so if the glass drops to less in temperature than the outside air, then you reach “dew point” and condensation forms. It’s the exact reason that you get dew on your car windows. It will generally happen after a cold clear night and it would best be described as a light misting that forms from the centre of the pane, actually it’s in the complete opposite place it would form on the inside. This is because the glass in effect is being heated through the frame and spacer bar, so the outer edge of the glass is warmer than the centre.

When you get internal condensation it’s the opposite way, because in reverse the outer perimeter of the internal glass is the coldest. You can find that ‘A’ rated double glazing will suffer from the same problem, but the effects are much less. As I told my wife when she first spotted the external condensation “It just goes to show how well insulated our windows are”. They usually clear fairly quickly in the morning, so it certainly does not bother me. Further information on this can be found on this technical document from our glass supplier.

Light? Having three panes of glass, with two of them having a low e coating, there would be a drop in the natural light coming through the window as the low e coatings darken the glass slightly. Back to my own experience of my windows at home, from the old double glazing to the new triple glazing I did not notice any difference, so I expect this would only be detected with some some good light monitoring equipment.

Security? Three panes would have to be more secure than two, so there is an obvious difference. The middle pane of a triple glazed unit should be toughened especially if the glass faces a sunny elevation, at KJM we toughen all middle panes regardless of elevation. This helps with the stresses that occur with the heat build up within the sealed unit.

The next thing you might find on the internet about triple glazing is sound insulation. There is a lot of misinformation out there and many claim it improves sound insulation because they believe three panes are better than two. Scientific tests would show that if all three panes are the same thickness of glass then the benefit to sound insulation is very marginally better at best.

If you introduce one different thickness of pane, say one pane of 6mm glass and two panes of 4mm then this would improve the sound insulation more, because the different thicknesses will change the wave length of the sound as it passes through the window, thus reducing the sound transmittance. It would be worth pointing out at this stage that an open window will stop nothing and then there is my other pet-hate “trickle vents” that are notorious for leaking sound. That is a subject for another blog as there are better quality trickle vents on the market.

Extra weight from the glass is another problem, so oversized opening windows and doors are generally a “no-no” but traditional British casement window sizes have not produced a problem for KJM over the last few years, so we are confident in what we sell.

Finally did you know that you can buy the mainly recycled PVC system Veka Infinity in our triple glazing range? So if you really want to protect the environment then you can specify this system. Up to 80% of the core (the bits you don’t see) are made from recycled PVC, the important outside is manufactured from Virgin PVC in a very clever co-extruded process.

In summary I love triple glazing and I can see no reason why if you were changing your windows that you did not consider the option. Yes it costs more, but it will “future proof” your home and in the long term you will recoup your extra costs through the energy savings. It should also make your home much more attractive to potential buyers, if you decided to sell. At KJM it costs nothing to get a quotation and of course we can price for both ‘A’ rated double glazing and provide an additional upgrade cost to triple glazing.


If you have a comment to make or any information relating to this article please contact the GGF

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