What is Double Glazing?

What is double glazing

What is double glazing, and what are the advantages?

What is double glazing? Double-glazed windows consist of two panes of glass separated by a layer of air. Double glazing has many benefits over single glazing (where there’s just one pane of glass and no air layer):

  • Keeps warm air in, meaning your property is better insulated.
  • This results in fewer draughts and cheaper heating bills.
  • Keeps noise out – you’ll hear far less noise from outside with double glazing.
  • Reduces the amount of condensation on the inside of your windows.
  • Heightens security – double glazed glass is more difficult to break than single glazing.

Having explained a few of the advantages of double glazing lets explain in greater detail what double glazing is and how it keeps heat in…

Sage Windows and Doors what is double glazing

A single pane of glass provides very poor insulation because glass is a good conductor of heat. So much of the heat in your room literally goes out the window (excuse our pun). 


Sage Windows and Doors what is double glazing explanation

Install double glazing and you have a layer of air trapped between two panes of glass. Because air is a poor conductor of heat, much less heat is lost through the window since it would have to go through the layer of air before the second panel of glass. 

Your home’s double glazing operates just like fibreglass batts and woollen clothing. It traps a layer of air between two panes. Air is a very poor conductor of heat, so the trapped layer sets up a blanket of protection between cold air on one side and warm on the other. Glass itself is a very good conductor. So in a home without double glazing, heat is going straight out the window.

How much cheaper will my energy bills be if I install double glazing?

If you were to replace all of the single-glazed windows in a three-bedroom, semi-detached house, the Energy Saving Trust says that you’d save between £85-£110 per year with A-rated glass which all of our windows are.

As double glazing should last for at least 20 years, that’s a saving of between £1,500 and £2,200 over 20 years.  The picture below is a thermal image showing the difference in heat loss between single-glazed and double-glazed windows. The house on the left has a single-glazed window where we can see more heat escaping – indicated by the red colours.

Losing Heat without Double Glazing

What types of double glazing frames are there?

The most common type of window frame for double-glazed windows is uPVC – or, to give it its full name, unplasticized polyvinyl chloride. Not only is it up to three times cheaper than traditional wooden frames, but it’s also recyclable, durable and the most energy-efficient frame type.

uPVC window and door frames are available in a variety of colours and finishes. uPVC is easy to keep clean, too, requiring little more than a wipe down with a soft cloth and a spot of washing-up liquid every now and again. Alternative options to uPVC include aluminum frames. Using our online quoting system allows you to take a look at a range of options giving you a price and a clearer understanding of whats on offer, making sure you make the best decision for your style and home.


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