What is triple glazing?
Put simply, triple glazing is 3 panes of glass instead of 1 or 2. The claim is that by having an extra pane, you will increase efficiency and reduce noise. We already know that double glazing makes a significant improvement over single glazing, but even so, upgrading from single to double glazing takes a long time to pay back in terms of energy efficiency. So would making the jump to triple glazing make that much of a difference?
Modern double glazing
As you may be aware, the energy efficiency of windows is measured with a ‘U-value’ and the lower this value is, the better.
Single glazing has a U-value of 5, older double glazing about 3 and new modern double glazing a U-value of 1.6, which is mainly due to improved methods of double glazing compared to older models. These improvements have been made through optimisation of the window cavity, the use of low emissivity coatings, using inert gas to fill the gap, and using aluminium spacers or ‘cold bridges’.
All this has brought down the U-value of modern windows considerably, so does that make triple glazing worth it, if double glazing is now so much better? Well, walls have a u value of around 0.3, so it is clear that windows have a long way to go before they are no longer a weak point in the efficiency of the building.
Does installing triple glazing pay?
In Scandinavia, triple glazing is now pretty much standard, with modern triple glazing taking the U-value of the windows down to around 0.8. This is a considerable improvement on even modern double glazing. Lots of new homes are now being built with triple glazing and it is generally acknowledged as being better, but compared to top double glazing, the payback period is very similar. As we have mentioned elsewhere, on a purely efficiency basis, double-glazing does not pay for itself and triple glazing is no exception. Changing from single glazing to triple glazing, in terms of energy efficiency payback, is very similar to double glazing payback.
Why? Well the cost of triple glazing is a fair bit higher than double, whilst the improved U-value is not very large. If you are getting your windows done anyway, or you are building a new home, triple glazing is not a bad idea, but if you already have double glazing, triple glazing might not be right for you.
Are there other things you can do to reduce your U-value?
Yes. If you are going to have triple glazing, you will need well insulated frames, as this is one of the major heat loss areas in a window. Adding thick curtains, and keeping them closed at night will help reduce your bills also.
Other reasons for getting triple glazing
So triple glazing doesn’t really pay for itself, but are there other reasons for getting it above double glazing? Here I will go through a couple of other reasons why you should consider triple glazing.
Triple glazing offers a significant reduction in noise pollution – so it is ideal for those living in noisy areas.
Double glazing can create cold patches in the house, due to the higher u value of windows compared to walls and doors. This problem is exacerbated by modern insulation – as better and thicker wall insulation means windows become much colder compared to the rest of the house. Triple glazing is an excellent solution to this problem, as it reduces the difference in U-value between the windows and the rest of the building.
Alternatives to triple glazing
The main alternative to triple glazing is to add secondary glazing like Ecoease to your existing windows. This is a removable pane which acts the same as double glazing but at a fraction of the price. While it’s true that you wouldn’t reach quite the same U-values with the kind of option, it certainly has it’s positives; it’s cheaper, better at soundproofing, and helps cut your bills significantly.
So triple or double?
The debate over triple or double-glazing is still raging, so I won’t tell you one way or another what is best for your property. But there are a few main points:
- If you’ve already got good double glazing, don’t bother with triple.
- Triple glazing doesn’t pay for itself, but neither does double.
- Triple glazing is usually more expensive.
- If you want to get rid of cold spots in an otherwise well heated house, or you have lots of noise outside, triple glazing is an option.
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