Differences between triple and double glazing

Thursday, 18 March 2021

What a funny question! Of course, double glazing has two panes of glass and triple glazing has three - next question? Well, as with all of these things, perhaps the question is in fact more complex than it first appears. What are the implications of two panes of glass as opposed to three? What processes must the glass undertake to construct these products? And which is better for your home? Understanding how these two apparently similar types of glazing work should help to clear all of this up.

Mind the gap

It’s not just about the extra pane of glass, you see. With the third pane of triple glazing comes an additional air pocket buffer. This pocket typically contains an inert gas such as argon, which is heavier than the air around us. It’s this which makes it so effective at muting noise and retaining heat. This feature is so important to the performance of multiple glazed products.

Energy

Conserving heat in your home is probably the biggest factor that most people consider when looking at glazing. In fact, Building Regulations now insist that any window you install today should have a U value no higher than 1.6. As a result, all newly installed windows will be at least double glazed. On the large scale, there are huge implications to energy consumption and environmental impact of housing. But for the average consumer this is the aspect which most immediately impacts your outlay on energy bills. So how much does energy efficiency improve with each additional pane of glass?

Single Glazing

The measurement of heat loss from a home, or U-value, of single glazing varies since single glazed products range depending on when they were manufactured and installed. However, The U-value tends to sit somewhere between 5 and 5.6. As you can see, this is a huge difference to current requirements for new window installation.

Double Glazing

Glass engineering has come a long way since the first double glazing products were introduced. While on average, double glazing used to perform at a U-value of around 2.8, current products can now achieve up to 1.4. This is all down to the coating and tinting of glass, improved engineering within casements and superior composition of the gas that sits within the panes.

Triple Glazing

So it follows that the U-value of triple glazing is still lower. With an average of 0.8 and some manufacturers achieving as little as 0.5, this is clearly the most energy efficient option for glazing a home.

It’s worth remembering that heat isn’t only lost through the windows of your home. So while you’re tackling your glazing, don’t forget to also look at your loft insulation, flooring and external doors.

Noise

Next on the checklist of the benefits of multiple glazed windows is noise reduction. With building sites, roads, motorways, railway lines and flightpaths to consider, there are more places than ever that need to counteract noise pollution. So if reducing the intrusion of outside noise is a priority, then surely triple glazing is better than double glazing? In theory, yes. The additional gas pocket and pane of glass will certainly better reduce noise disturbance. However, the acoustic performance of a window is actually more to do with the construction of the window casement itself. Interestingly, if the panes of glass are all of the same thickness, triple glazed windows only offer a small increase in sound insulation when compared to double glazing. The key here is that one pane of glass should be thicker than the other to offer superior sound protection. This is true for both double glazed and triple glazed product options.

Light

Could adding an extra pane of glass limit the quantity of natural light that enters your home? It may be true that the UK is not the sunniest of locations, but when the sun does come out, we all want to make the most of the light and heat that it offers. It is true that triple glazed windows let less sunlight through than double glazed windows. This won’t be visually noticeable, but can work as both an advantage and disadvantage when it comes to harnessing or reflecting the heat of the sun. It really depends on the time of year!

Coating

The key to light is really in the coating of glass panes within a casement window. Low emissivity, or Low-E, coatings can allow a window to perform in a very specific manner depending on where the coating is applied. This is where bespoke services can offer you the best solutions that optimise the positioning of your home.

Ventilation

When double or triple glazed casement windows are so high performing, it’s vital to the health of your home to consider ventilation. Trickle vents may feel like they are undoing all of the thermal benefits of multiple glazing. However, without these features, your home can become prone to damp and condensation. This in turn can impact your health as fresh air flow becomes restricted. In fact, ventilation which may come in the form of trickle vents, is required under Building Regulations. These little features of both double and triple glazing provide regular air circulation into your home without compromising security. It can feel like this requirement counteracts the decision to add a third pane of glass. However, remember that both double and triple glazed casement windows often require a trickle vent or other ventilation solution. The thermal benefits more than withstand the impact of air flow.

Cost

If budget is a consideration, then this is a major difference between triple and double glazing. Triple glazing technology is still in relative infancy and the price tag is certainly more hefty. Before you decide on triple glazing over double glazing, it is worth checking which improved features are your priority. Do the gains offered in these areas warrant the increased price tag? Or are there additional features such as glass coating or treatment that you could add to a double glazing spec? This is where the expertise of a specialist can save you money. With the knowledge and experience that we hold at Bill Butters Windows and Doors, we strive to ensure that our customers make the best choices for their circumstances.