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  • Lisa Gardener

Double or triple glazing?

This discusses how this choice could impact on energy performance in your home

It's almost impossible for you not to have heard about how double glazed (2G) windows will save you money on heating bills in comparison to single glazed units, as the former are now standard in new installations.

But as with all technology, we're now onto the next evolution of efficiency, which is why 80% of all windows sold in Europe are now triple glazed (3G). However, very few of these are actually in the UK; in fact, there's been some debate recently about whether triple glazing makes enough difference to be worth the extra cost. So the question is, which solution is best for your project?

Energy Performance

The rate at which heat passes through a window is much greater than a solid wall, so it's important to keep energy transfer as low as possible. Having air or gas-filled gaps between glass panels reduces the amount of heat transfer between inside and outside. This makes the triple glazing setup of three glass panes and two gaps more efficient than the single cavity used in double glazed units. 3G therefore helps to keep the maximum amount of warmth inside and eliminates draughts, in turn saving on energy bills because you don't need to pump as much heating into your home to create a comfortable environment.

Energy transfer through windows is not only about heat loss, as solar gain is another consideration for your glazing. This is the solar radiation from daylight that can increase temperatures inside a room. Solar gain in double glazing is about 62%, but 50% in triple glazing.

While this is an advantage in the summer, reduced solar gains means in colder months you won't benefit from the same amount of free, natural warmth that you would with 2G. However, there are ways around this. For instance, Internorm's Solar + coating enables triple glazing to reach 62% solar gain - the same as double.

Other Considerations

That extra pane in triple glazing can create a sound deadening effect, which can help reduce noise from a busy road, for instance. Performance can be enhanced by choosing variable thicknesses of both glass and cavity, but you'll need to consult with a specialist to get the best result.

Triple glazed units will have a thicker profile than 2G, so this will need to be accounted for at the design stage. More layers also means better security simply because three panes are more difficult to break through than two. The stronger makeup means that they hold better in strong winds, too - great for coastal locations.

Cost & Installation

With bigger windows and more glazing features increasingly being used in houses, windows are likely to be a significant chunk of your overall project budget, so cost is a key consideration. Obviously with more components making up the windows, manufacturing are higher so triple glazing comes in more expensive than double. But don't let this put you off, because you'll be making savings in the long-term with lower energy bills.

As with all building elements, having the product fitted by a specialist who understands how the system works is the only way to guarantee you're getting the best possible performance from the system.


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