Although double and triple glazing can use the same types of glass and have many similarities, the main differences are between the enhanced performance and efficiency:

Heat retention

Double glazing works by having an air gap that reduces the thermal transmission of hot and cold air.

Having an additional pane of glass in triple glazing creates another air gap to increase the efficiency of heat loss or solar gain. Effectively, it’s a double, double glazing unit.

Noise reduction

Although standard triple glazing can dampen noise when replacing single glazing, the middle pane of glass can actually increase sound vibration and amplify sound transference. For the best results in sound reduction, a glazed unit needs to disrupt the soundwaves transmitted through the glazed unit. This can be achieved by adding a pane of glass with a specialist laminated layer.

A triple glazed unit with specialist noise reducing glass will reduce noise transmission better than double glazing. However, if you have more than average noise levels, we recommend that you will need to make other changes to your house to get the best results of noise reduction.

Security

Laminated glass has a polyvinyl butyral (PVB) layer of thin plastic between two panes of glass. If laminated glass should break, the glass is fused to the PVB layer and stays in place. For this reason, it’s used in skylights or glass ceilings to avoid glass shattering and falling from above.

Adding a layer of laminated glass to a glazed unit will make it more difficult for an intruder as the PVB layer makes it harder to break open.

Triple glazing also has an additional pane of glass making it even more difficult to break than standard double glazing.

Depth of frames

One important point of difference between double and triple glazing is the depth of the glazing units, making it a problem for fitting in existing windows. The standard width of a double glazed unit is 28mm and the standard size of a triple glazed unit is 36mm. That extra depth on the triple glazed unit means that triple glazing cannot always be retrofitted to existing frames.

Double glazing Vs. triple glazing an experiment

To visually see the difference between double glazing and triple glazing we conducted an experiment.

To demonstrate the thermal efficiency of windows, we used a thermographic camera that shows the heat loss from two sets of windows.

We chose identical houses next to each other. Woodbrook Cottage on the left has standard double glazing, Briar Cottage on the right has Everest Triple Glazing fitted.

We used an independent specialist who measured the windows early in the morning. The results above clearly show the difference between double and triple glazing. Heat loss is shown as red and yellow, with red being the most heat lost.

Woodbrook showed greater energy loss through window panes, frames, and doorways. Briar Cottage had only slight energy loss from around its window frames, with little to no thermographic differentials shown in the centre of the panes.

The survey was performed to provide a qualitative thermal performance comparison between two adjacent properties; Woodbrook House, with standard double glazing and Briar Cottage, with Everest A++ Triple Glazing.

Understanding the difference between thermal images:

The darker colours on thermal images represent colder surfaces, and the lighter colours represent hotter surfaces where heat is being lost.

You can see the full report here.