How it works

The same thermal performance as conventional double glazing in one quarter of the thickness

Conventional double glazing consists of two glass panes placed up to 20 mm apart, with the cavity between the panes filled with either dry air or an inert gas such as argon or krypton. This gas reduces heat transfer through the glass due to its lower thermal conductivity. The wider the gap between the panes, the lower the heat transfer, up to an optimum level above which circulation patterns in the gas reduce the benefit.

This means that the overall thickness of thermally-efficient double glazing is typically 24 mm.

Pilkington Spacia™ is different; the air between the two panes of glass is extracted, creating a vacuum.  It offers the same thermal performance as conventional double glazing in one quarter of the thickness and two thirds of the weight.

A vacuum, even a small one, is much more effective at minimizing conduction and convection heat losses, so the gap between the two panes can be reduced to just 0.2 mm, giving an overall thickness of just over 6 mm. Heat flow through radiation is limited through one of the glass panes having a low-emissivity coating, similar to that used in modern conventional double glazing.