Pilkington Spacia™

Pilkington Spacia™


Pilkington Spacia™ is the world’s first commercially available vacuum glazing. It offers the thermal performance of conventional double glazing in the same thickness as single glass (6 mm).

Pilkington Spacia™ provides a real solution to the problems of balancing historical preservation with modern comfort and  environmental requirements.

How It Works

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.

Click here to see video on Pilkington Spacia™


Pilkington Spacia™ has low overall thickness (6 mm) and good acoustic performance, making it ideal for use in historic buildings, offering replacement windows more in keeping with the original design. It may even allow the use of the original frames if these are in a reasonable or repairable condition.

Until now, the only choices were to sacrifice thermal performance and comfort, or to compromise the appearance of the building by using bulkier modern frames with double glazing.

Pilkington Spacia™ is also suitable for other applications where the use of thinner, low-weight glazing is desirable, for example in sliding box sashes, secondary glazing, or as one pane of a triple glazed “super-window”.


  • Substantially improved thermal insulation compared to conventional double glazing; U value of 1,4 W/m2K in 3-0,2-3 vacuum glazed construction.
  • Thermal performance of modern double glazing in the same thickness as single glass, offering the opportunity to improve energy efficiency in older traditional buildings.
  • Minimum disruption, can be retro-fitted into existing frames designed for single glazing.
  • Cost-effective method of improving the energy efficiency of older homes where glazing choice is restricted or where the original frames are a desirable feature.
  • Significantly improved acoustic performance over single glazing, enhancing the living and working environment.
  • Has been successfully used in Japan for over ten years and is a proven solution.


Project references

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