Get A QuoteShop

What are U-Values and why are they important?

U-values measure how effective a material is as an insulator. The lower the U-value, the less heat is lost and the more insulation the material provides.

You can see that more heat is lost through windows than the same area of wall. You will also notice that Low-E-Plus2™ heat-retaining glass reduces U-values by as much as 80%.

Low-E-Plus2 diagram

Comparing U-Values

The table shows the U-values of the various materials used in a building. Of all these materials, glass is the poorest insulator. You can see that more heat is lost through windows than the same area of wall. See how Low-E-Plus2 reduced u-values by as much as 80%

Material Type

U- value

Roof Without Insulation 2.3
With Insulation 0.4
Cavity Wall Without Insulation 1.6
With Insulation 0.6
Floor Without Insulation 0.9
With Insulation 0.6
Solid Wall (block & plaster) 2.3
Cavity Wall (block/polys/block) 0.58
Cavity Wall (timber frame with above) 0.46
Windows Single-Glazed 5.8
Windows Old Double Glazing(24mm) 2.8
Triple Glazing (24mm) 1.3
New Low-E-Plus2-Glass Only (24mm) 0.9