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Triple glazed windows or not?

If you are considering triple glazed windows for your project - here is a few answers to the most common questions.

Idealcombi Futura+ with 53 mm aluminium profile, triple glazing and Idealcore™ thermal break.

Energy performance of triple glazed windows

The big difference in energy performance, when you replace double glazing with triple glazing, is down to the extra layer of insulating air, or in most cases gas.
Energy performance of a window is highly dependent on the sash and frame surrounding the glass. That is why Idealcombi is using Idealcore™ in our windows. With twice the thermal properties of timber and traditional composite materials, Idealcore™ is the ideal choice of thermal break for energy efficient windows.

Considerations before installing triple glazed windows

If you are considering triple glazing you are already in an “energy efficiency” state of mind, and you would probably already have considered an air-tight envelope and a heat recovery system(MVHR).
All Idealcombi windows are very air-tight and will therefore minimise the natural airflow in your building.
Due to the additional weight of the glazing, some of the opening sizes/functions of the windows could be restricted in size, when compared to double glazed frames.
The Idealcombi team will help you through any considerations regarding your project.

Triple glazing in renovation projects

Triple glazed windows require the same amount of work as double glazed windows. All Idealcombi windows are bespoke and made to measure – your new windows will fit your structural opening perfectly.
Adding air-tight windows to an old house may change the natural air-flow. You might have to change your habits and regularly ventilate your house manually - to make sure you get the damp air out and fresh dry air in.

Additional weight of triple glazed windows

The additional weight of triple glazed windows does not normally require additional structural support, however there may be additional installation costs due to the additional weight of the triple glazed units. And as mentioned above, larger units may be restricted in size, due to the overall weight.


For Idealcombi Futura+ and Futura+i windows the average u-value for a complete top-guided or tilt-turn sample window is 0.74 W/m²K. Depending on opening function and size of the window the u-value can be lower than this reference value.

Triple Glazing Costs

Idealcombi triple glazed windows cost from £400m2 which is about 10-15% more than regular double glazed windows. Going from double to triple glazing means you jump from 1.31 W/m2K to 0.74 W/m²K –  however the change to triple glazing does not affect the look of the windows.
Triple glazing has become a lot more common, meaning window and door suppliers are able to reduce manufacturing costs etc. - hence the low difference in cost.

Idealcombi Futura+ triple glazed sliding door