The triple layer sealed units cost more than double glazed ones as these are more expensive to make. A lot of extra things are needed including extra argon gas, extra toughened glass pane, and extra spacer, as well as additional transportation due to additional weight and size. When comparing the cost with a double glazing unit, each extra square metre of the unit costs around £100. It simply means that a typical 4 square feet window unit has around a square metre of glass. Simply put, you can expect to pay around £100 more for a triple layer sealed unit as compared to the average size double glazed units.
Triple Glazed Window – Cost
KJM Group offer a wide variety of windows in terms of systems and material choices but when it comes to the cost, you should know that the standard white uPVC window system (double glazing and a couple of openings) has an installation cost of around £465 including VAT. This price is correct as of July 2019. A triple glazed window equivalent in size will have an installed value of around £565, which means an increase of around 22%.
Heat Loss through Windows
It is estimated that up to 20% of heat loss in UK households happens through the windows. If you are already planning to replace your windows, it is probably sensible to replace those with the best insulated windows you can find. If you want to do a little maths, consider the extra money you will have to pay for a triple glazed unit and compare it with the expected savings on heating bills. Needless to say, you won’t expect that extra cost to be recovered in the form of lower heating bills within a month or two. Having said that, triple glazing is the right choice in case you want to live as comfortably as possible and a few extra pounds don’t really matter in the long run, though the choice is completely yours.
Triple Glazing Benefits
Triple glazing offers a variety of benefits and its biggest advantage is better heat insulation. However, you also need to remember that all the triple glazing units you can buy are not the same. There are a wide variety of triple glazed sealed units available in the market. The most efficient are those where the gap between glass panes is 16 mm and this gap between the panes is filled with an inert gas such as argon. Argon is a neutral gas and it helps in minimising heat loss through glass panes. Reducing the gap in the glass panes adversely affects the thermal performance of the sealed window unit. If the gap is reduced, you can still get similar thermal performance but you will have to use a more expensive gas such as krypton.
For optimum efficiency, the glass pane should be 4 mm thick and the unit should have a 16 mm gap between glass panes. This is the reason, a triple glazed unit is often known as a 4/16/4/16/4 unit in the glazing industry. If you combine all these widths, it comes to 44 mm in total which means a single triple glazed unit will ideally be 44 mm thick.
In terms of extra insulation, you’ll find that there is a huge difference between the u-values which represent heat losses of the glass when you compare a 44 mm triple glazed unit and a 28 mm thick double glazed unit. The u-value of the centre pane of the 44 mm unit comes to 0.62 whereas the u-value for a double glazed unit with 28 mm thickness is 1.1 which means you get 40% improvement with a triple glazed unit.
You have various options when choosing a window unit, such as choosing it on the basis of number of glass panes. However, you’ll be better served by first checking the Window Energy Rating (WER) of a unit. It gives you a much better idea of the thermal efficiency of the windows when installed.