Double and Triple Glazing : Windows

Double and Triple Glazing


It’s difficult to imagine that less than thirty or forty years ago most of us had single pane windows and endured costly and often uncomfortable heat loss during the winter months. Fortunately, nowadays, we have double or even triple glazing to thank for increases in our energy efficiency, something that saves us plenty of money, as well as keeping us comfortably warm.

As a long term investment with a substantial initial outlay, double glazing is one of the most popular improvements home owners opt for in addition to cavity wall and loft insulation. Without these initiatives, introducing more economical heating systems and energy efficient measures simply don’t work. You might say that double and triple glazing are an integral part of the foundations on which the rest of our home eco-strategy rests.

How Double and Triple Glazing Works

In double glazing, two panes of glass are combined with a layer of gas in between which acts as an insulator. Glass is a pretty good conductor of heat, which is why there is so much loss when only single panes are used in our windows. Introducing that layer of gas makes all the difference.

One of the important part of the window is the seal – if this is not complete then air can get into the gap and cause condensation. Cheaper window designs offer suffer from this problem, looking great in the first few months or years but then developing problems when air gets in.

Triple glazing utilises three layers of glass separated by gas for extra insulation and is popular in colder regions such as Canada and Scandinavia. For most UK homes, double glazing is sufficient but if you want to pay an extra premium, and have more insulation, you can find certain companies who deliver triple glazed windows.

For both double and triple glazing, the glass can be coated with a low emissivity metallic layer that reflects more heat back into a room. Many windows are now incorporating this innovation as a matter of course but it is worth checking with your supplier if they provide this type of window. All windows produced in the UK must comply with European Union legislation which means they should be marked with the CE logo that ensures they are compliant.

The energy efficiency of a particular window design is determined by its R Value. A single pane window may have an R value of around 0.15 whilst uPVC windows will have a level of 0.50 or more. Essentially the higher the R value, the more energy efficient it is.

The Benefits of Double Glazing

  • Double or triple glazing greatly reduces the amount of heat lost through your windows.
  • It not only keeps you warm in winter but cooler in hot summers.
  • Double glazing greatly reduces the amount of noise from outside, particularly important if you live near a busy road.
  • Double glazed windows reduce condensation by keeping the temperature in your room relatively constant.
  • They make your home more secure. It is difficult to break into with the double layer of strengthened glass and the addition of the secure locks used nowadays.
  • They increase the resale value of your house – people are less likely to make a good offer if they know they have to spend money and time on installing double glazing.

Energy Efficiency and Double and Triple Glazing

There are a variety of choices for double glazing and, of course, it pays to shop around to find the one suited to your home. Energy savings for the kind of window you need are measured over A, B and C ratings, with A being the most efficient. The rating will all depend on how your window is made up. Windows also have a U value that shows how much heat they let through – a lower U value suggests greater energy efficiency than a high one (as opposed to a higher R value).

The glass is important in double glazing and if you want the best then you need a product with low emissivity – usually a coating of metal oxide that allows light to come in but then stops the heat escaping to the outside. The gas that is used between the glass panes can also vary. Heavy gases such as argon are less conductive and provide better insulation but are more expensive. The spacers which keep the panes separated contribute to efficiency and non-metallic ones are better than something like aluminium which is more often used in large office blocks.

The material making up your window frames can be uPVC, wood, aluminium or steel or composite. There are pros and cons for each. For instance, uPVC lasts a lot longer and is recyclable whilst wood has a lower environmental impact but needs to be well maintained over the years. Find out about window construction here.

Cost of Double Glazing

More than any other home installation, getting the right price for your double glazing means doing a fair amount of research and getting as many quotes as possible. Prices can vary considerably across types of window and from supplier to supplier. How much you pay can also vary depending on whether you use a national company or a local one. For a 3 bedroom semi you should be expecting to pay between £3,000 and £5,000 and a 4 bedroom detached might cost around £6,500. Find out more about the cost of double glazing.

Paying for Double and Triple Glazing

A number of national companies offer financing for the installation of double glazing but it’s a good idea to look around for alternatives such as using your own savings, taking out a bank loan or increasing your mortgage to find the best rate. The government has now closed down the Green Deal which was a loan scheme for homes that wanted to improve their energy efficiency and there are no plans to replace it with anything else (they cite low uptake as the prime reason for closing the scheme).

Combining Double Glazing with Other Insulation

Once you have had your double glazing installed you can expect to make at least £100 savings on your fuel bills over a year. Insulation measures such as this do not work in isolation though. Other options such as installing proper lagging in the loft and having cavity wall insulation can also make a big difference. Find out more about insulation here.

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