Every year in the UK, hundreds of thousands of homes get double-glazing for the first time or to replace their old set-up. Because it’s such a big investment, it always will pay off well for you if you do as much research as possible before getting an installer in to quote you.

There are three main choices facing homeowners – how much of my house do I get new double-glazing for, what type of frame should I go for, and what type of glass do I want my double-glazing made from?

There are eight main types of glass that manufacturers use in Britain and in this article, we’re going to be looking at the pros and cons of Low E glass, sometimes called “coated glass”.


Introduction to Low E glass

Low E glass, or coated glass, uses a transparent metal coating which does two things to save you money on your gas and electricity bills. First, it reflects heat back into your rooms. Second, it allows heat and light from the sun to pass through from outside.

That means that your rooms will be nice and cool in the summer and warm and toasty in the winter.

All double-glazing has this effect to some degree or other but in Low E glass, it’s the main selling point and an important feature for home owners keen to save money on their household bills.


There are two types of Low E glass

Low E Glass is produced in the UK by two major manufacturers, Pilkington and Saint Gobain. If you choose Low E Glass for your home, your installer will be getting your windows from one of these two companies.

Pilkington uses a “hard coat” method. What that means is that molten tin is poured in a very thin layer onto a sheet of glass while the sheet of glass is still molten itself. The tin and the glass fuse making it virtually impossible to remove the tin from the glass. You’ll be able to recognise these types of window because they’ve got a slight bluey or grey tint.

Saint Gobain use a “soft coat” method. They place the glass in a vacuum and release atomised silver, zinc or tin into the chamber. There’s an electrically-charged gas in this chamber and then the atomised metal is sprayed onto the glass – it’s similar to the way a lot of jewellery is gold- or silver-plated. The coating is delicate to the touch but, in your double-glazing, it’s always on the side of the pane that doesn’t face your indoors or outdoors.

Both of these methods achieve the energy-saving effect you’re looking for.


Low E glass – costs

Low E glass is one of the more expensive options you can choose for your home, costing up to 25% more than standard, annealed glass.

Bear in mind though that, because of saving on your energy bills, the actual cost will work out lower over the years.


If I’m speaking to an installer about Low E glass, what should I ask?

If you want to make your double-glazing decorative by, for example, adding Georgian Bars, you will lose some energy-saving benefit from your Low E glass.

Make sure you know how much of your energy-saving advantage you’ll lose before you make your decision either way.