How (better) Windows make better Walls

A 90mm timber framed wall with R2.5 insulation achieves an overall performance of R2.17. When we add a window this effectively derates the performance of the entire wall as even high-performance triple glazed windows are only half as good as the wall in avoiding heat loss.

If you choose a locally manufactured thermally broken Aluminium frame with double glazing and use a window that is 10% of the wall area it achieves an overall performance of R1.57.

If you choose a locally made uPVC window with triple glazing you can have a window that is 40% of the wall area and achieve exactly the same performance.

Want to understand why this is the case and how it is possible, then read on.

How Better Windows make Better Walls.pdf

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