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Choosing Energy-Efficient Windows

Windows are one of the ways in which heat will be lost from your home, but with improved technology, energy-efficient windows can reduce the amount of heat lost as well as the amount of noise that enters into your home. This can be achieved with secondary glazing, double or triple glazing or more simply, by hanging heavier curtains in front of your windows.

The benefits of having energy-efficient windows are numerous, with the most obvious one being that they will save you money on your energy bills. Upgrading to B-rated double glazing from single-glazing could reduce your energy bills by an average of £165 per year. By using less energy to heat your home a reduced carbon footprint will follow and you could potentially be reducing the generation of carbon dioxide by 680kg per year.

With more energy-efficient windows will also come a quieter home, which is great if you live near a busy road or town. It will also reduce the number of cold spots and draughts that you may find within your home, alongside a reduced amount of condensation that you may have building up on your internal windows.

Upgrading to double glazing will cost various amounts depending on the size of your home and the number of windows you have, as well as who is installing them and what materials you are using. However, the average lifespan of double glazing is around 20 years.

How do energy-efficient windows work?

When your window is double-glazed, this means that there are two sheets of glass in your window with a space in the middle of around 1.6cm. This gap acts as insulation and a barrier that will help keep the heat within your home; sometimes this gap is filled with gas to make it more energy-efficient.

If you opt for triple-glazed this follows much the same principle as double-glazing but with three sheets of glass installed in the window. It is important that you do your research when choosing double or triple glazing as triple glazing isn’t always the most efficient compared to double-glazed, so always check their ratings and reviews.

The effectiveness of the window will also depend on several other factors, such as, how much sunlight will be passing through the glass; how efficient the windows are from letting heat pass out of the window; and how much air is able to leak in/out of the edges of the windows.

Choosing your energy-efficient windows.

The Window Panes

  • The more efficient of windows will use gases between the glass sheets, including xenon, argon and krypton.
  • Look for Low-E glass, which means it has low emissivity due to it having a coating of metal oxide that allows light to pass through but reduces the amount of heat that can escape. This layer of metal oxide is often unnoticeable and will be coated on an internal pane on the side facing into the gap.
  • Between the two pieces of glass there will be what are called ‘pane spacers’ which will keep the panes of glass apart. For more efficiency, it is recommended that these contain little or no metal.

Window Frames

Just as with the window pane materials, your window frames can also make a big difference on the energy efficiency of your windows, and they are available in various different energy ratings.

  • Wooden frames are often much more environmentally friendly, but they will require a lot of maintenance on your part.
  • uPVC frames have the ability to be recycled and they will last you a long time.
  • Composite frames use wood for the inner frame work, which is then coated in plastic or aluminium to make the frame weatherproof and to reduce the amount of maintenance that is required.
  • Steel or aluminium frames can also be recycled, they’re slim and they will also last you a long time.

Energy Ratings

You will find that with some window manufacturers they will have an energy rating on their window products, using an A to G scale, like the one you may find on your electrical appliances in the home. Both the frame and glass will have been assessed on how effective they are at heat retention. The British Fenestration Rating Council runs this scheme, so always check for their best rated products.


While you may be installing energy-efficient windows in your home that are much more airtight than your previous ones, it is important you check the ventilation in your home. Poor ventilation could lead to a build up in the amount of condensation you find in your home if you install these more energy-efficient windows. A good way to eliminate this problem is to install windows that have trickle vents that will allow a small amount of air in to help ventilate your home.

If you have noticed a build up in condensation around your windows, this could signify a damp issue within your home. This can be caused by inadequate heating, ventilation or insulation, or all of these factors. However, if you do start to notice that there is condensation building up in your double glazing between the two panes of glass, this could indicate that the seal inside has broken and this window will need replacing.

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2 Comments to Choosing Energy-Efficient Windows

  1. John's Gravatar John
    January 20, 2016 at 1:03 pm | Permalink

    Great article! you have lots of good information on this site about energy saving,

  2. January 20, 2016 at 4:26 pm | Permalink

    People tend to put off things like upgrading their windows because it seems like a lot of hassle and money but what they don’t seem to realise is how much it will save them in the long run! If your windows need replacing it tends to be really obvious and to me it seems like a crazy thing to ignore. It’s true that if you live in a conservation area or in a listed building there may be restrictions on what you can do to your windows. However there are a number of non-intrusive window insulation options available for historic homes such as heavy lined curtains, shutters, secondary glazing and sealed blinds.

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