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Which is better? Double or Triple Glazing?


A much better and more relevant question to ask is which of these 2 very different options is the better product for you and your UK property?

Nowadays, although they do cost more, triple glazed PVCu windows, residential doors and French doors are not massively more expensive than double glazed products, but nevertheless do cost a fair bit more. The extra up-front investment aside, properly installed PVCu triple glazing offers unrivalled value for money when household energy savings are taken into account over a twenty year period.

Double Glazing Windows

There are some genuine pros and cons to consider when comparing double and triple glazing windows, doors and conservatories. Triple glazing obviously has an extra pane of glass, so each triple glazed sealed unit is thicker and heavier than double glazing, putting more strain over time on window hinges. So not only does the extra glass cost at least 50% more, each window and/or door costs more to transport as is much heavier.

Top quality PVCu triple glazing should have a combined U-value of around 1.0 W/m²k, and is usually around 40% more thermally efficient that standard “A” rated double glazing and 60% more thermally efficient than standard “C” rated double glazing. This is a massive potential beneficial energy saving for home owners, bearing in mind that between gas and electricity prices seem to shoot up more and more every year.

Going forward, future window Building Regulations (which currently dictate a minimum combined U-Value of 1.6 W/m²k) are likely to call for windows used in new build homes and replacement windows to have a combined U-value of around 1.4 W/m²k in order to reduce carbon emissions from the UK housing stock. By investing in high quality A Plus energy rated PVCu double glazing, with a U-value of 1.3 W/m²k or A Plus Plus PVCu triple glazing with a U-Value of 1.0 W/m²k, property owners are essentially future-proofing their home.

Triple glazing supplied and installed by Hazlemere Windows is all but identical to their “A Plus” rated double glazing with the main difference being the internal bead, so aesthetically there is little or no difference. The internal bead has been specially developed to enable a wider 36mm unit to be fitted into a standard 70mm profile. By using a 36mm triple glazed sealed unit, as opposed to the 44mm sealed units of other fabricators, Hazlemere’s triple glazing bead blends in with the overall aesthetics of the window and retains its concave form (sloping in towards the sealed unit). Because their triple and double glazed window frames both measure 70mm front to back, both products can be used on the same property, where a client for whatever reason wants one particular elevation to be triple glazed and the rest double glazed.

The extra investment required for triple glazing as opposed to double glazing has to be carefully considered. Here are some pros of triple glazing:

1)    Triple glazing is approximately 40% more thermally efficient than “A” rated PVCu double glazing so energy savings are far higher.

2)    Triple glazed windows and doors will further reduce draughts and cold spots in a room that currently has less thermally efficient windows and doors.

3)    Triple glazed windows and doors can reduce the impact of exterior noise.

4)    A third pane of glass, by definition, makes a triple glazed sealed unit much harder to break than a double glazed sealed unit – especially when the middle pane is made of toughened glass. What’s more, all Hazlemere’s “A Plus Plus” rated PVCu triple glazed windows are internally beaded and the glass unit can only be removed from the frame by a person who is inside the premises.

Now here are some cons of going for A Plus Plus triple glazing windows as opposed to A Plus double glazing windows:

1)    Triple glazing costs more at the outset.

2)    Triple glazing sealed units tend to break down more often than double glazed sealed units.

3)    Triple glazed sealed units cost more to replace than double glazed sealed units once out of guarantee, something worth thinking about.

4)    Triple glazing is only about two decibels quitter than double glazing, and if there are trickle vents required in the windows, there is no real difference.

5)    The extra weight of triple glazing puts more strain on the frames, hinges and opening window and door sashes.

6)    If the middle pane of a triple glazed sealed unit is float glass, this middle pane can be prone to cracking due to the temperature differences between inner and outer panes, so better installers will always use toughened safety glass to reduce the chances of this occurring.

Spending on new windows and doors in the UK proves that the vast majority of property owners end up opting for double glazed windows and doors instead of triple glazing, so their actions are a strong indication that they believe double glazing offers the best value for money and less that can go wrong in the future.


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