Low Energy House - Vacuum Glazing - Energy Saving Glass
The world’s first commercially available vacuum glazing offers the thermal performance of conventional double glazing, with the same thickness as a single pane of glass. Vacuum glazing introduces improved thermal performance to older buildings and opportunities for thin glazing the windows of energy efficient buildings
What is Vacuum Glazing?
Vacuum glazing provides a similar level of energy efficiency as does modern double glazing by the use of a glazed unit that is typically only a quarter of the thickness of conventional double glazing. Advances in vacuum glazing technology have made windows a significant contributor to the energy efficiency of old and new homes.
Vacuum glazing offers an attractive solution to the problems of resolving building conservation with modern comfort, as well as fulfilling environmental requirements.
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. Vacuum glazing offers replacement windows that can maintain the character of the original building design. It may even facilitate the re-use of the original window frames, if these are in a reasonable or repairable condition.
Vacuum Glazing - Modern Applications
Vacuum glazing is also suitable for applications where the use of thinner, lightweight glazing is desirable, e.g. in sliding box sashes, secondary glazing, or as one pane of a high performance double or triple glazed windows
Conventional Double Glazing
Conventional double glazing consists of two glass panes positioned 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. The the use of inert gas reduces heat transfer through the glass due to its lower thermal conductivity. The wider the gap between the panes, the lower the level of transferred heat heat. This means that the overall thickness of conventional double glazing is typically 24 mm.
How Vacuum Glazing Works
During the course of vacuum glazing manufacture, the air in the space between the two panes of glass is extracted, creating a vacuum. Even a small vacuum is effective in reducing conduction and convection heat losses, so the gap between the two panes can be reduced to just 0.2 mm, giving an overall unit thickness of just over 6 mm. Heat loss through radiation is further limited by treating one of the glass panes with a low emissivity coating, similar to that used in conventional double and triple glazing.
Vacuum Glazing Construction
A vacuum glazed unit consists of an outer pane of low emissive glass and an inner pane of clear float glass, separated by a micro spacer grid of small pillars each measuring just 0.5 mm diameter and set 20 mm apart. This grid ensures that the two glass panes are kept a fixed distance apart. The edges of the unit are welded to achieve an airtight seal. Air is extracted to create a vacuum via the extraction point, instead of filling it with air or gas. The result is an excellent thermal performance from a unit that is only slightly thicker than a single pane of glass.
Vacuum Glazing - Air Extraction
The vacuum creation process in vacuum glazing results in an extraction point in one of the panels, located 50 mm from the glass edge. This point is covered by a small permanent cap (12 mm diameter), which must remain on the glass surface and should be glazed towards the inside of the building. You can choose to have the cap positioned in any corner of the pane providing this is made clear prior to the order being placed.
Vacuum Glazing Performance
Vacuum glazing provides a similar energy efficiency performance as a standard double glazed unit. It contains a low emissivity glass, such as Pilkington K glass but in much thinner profile. It is therefore perfectly suited for use in building conservation refurbishment or new thin profile frames.
Vacuum Glazing – Cost Effectiveness
Advanced Pilkington technology has produced the world’s first commercially available vacuum glazing. It provides a cost effective method of improving the energy efficiency of older properties where glazing choice is restricted, or where the original frames are a desirable feature.
By fitting vacuum glazing, cold spots close to the window are reduced and occupant comfort is much improved. Acoustic performance is greatly enhanced, improving the living and working environment. Heating bills are lowered as vacuum glazing offers four times better thermal insulation than single pane glazing
Vacuum Double Glazing - Low Energy Windows