The future of thermal glazing

Modern double thermal glazing with metallic insulation coating already provides quite good insulation values. Latest legislation, however, will require additional product innovations in future.

In autumn 2007 the German Federal Government decided on a drastic increase of heat insulation requirements for buildings. As a first step and under Energy Savings Regulation 2009 improvements of 30 per cent are called for. In the context of the next measure, called Energy Savings Regulation 2012, another increase of 30 per cent shall have to be implemented.
Since these rules have been published, German glass manufacturers have been involved in intensive debates on how these new standards can be met for window and facade glazing.

Close to a physical barrier

Over the past few years the performance characteristics of thermal glazing have seen a steady improvement. Meanwhile, insulation results have been achieved that can hardly be bettered without another glazing structure. A heat transmission coefficient of
k 1.0 W/ square metre means that leading double glazing brands provide significantly better insulation than earlier thermal glazing generations. A significant improvement resulted from the use of high-performance, low-emission metal coatings (low-e), inert gas in the gap between individual panes as well as the use of energy-optimised so-called warm edges for glazing edge seals.
These types of thermal glazing will be sufficient to meet the requirements of the Energy Savings Regulation for 2007, they will, however, no longer be sufficient for the next stage.

Mature triple-glazing

Being aware of these needs, intensive debates are taking place already now, whether triple glazing should replace the present standard double glazing in future. This extra pane means that top insulation k values of 0.4 W/square metre may be reached. Triple glazing has already been in use for some time, mainly in passive housing. Disadvantages of this highly-functional type of glazing are its considerable thickness and weight as well as reduced light transmission. A reliable uptake of such heavy-weight panels calls for very solid frame profiles with greater thickness. As a result of this higher material input and more expensive manufacturing, unit prices are considerably higher than those for double glazing. From the point of view of technology, however, the thermal glazing sector does not see any problem in manufacturing these high-performance insulating types of glazing already today.

Vacuum glazing

Vacuum glazing appears to hold great promise, on the other hand. Using such types of glazing would involve quite considerable benefits for manufacturing sashes and supports. Because of a gap of less then one millimetre, vacuum glazing reaches a thickness of less than one centimetre. In an optimised version this type of glazing still achieves insulation values at levels normally reached by triple glazing. Intensive research efforts are going in many places to achieve production status for this new technology. The same problem comes up again and again. As there is a vacuum in the gap between panes, spacers must be provided at short intervals. But those spacers impair transparency. Also, it is still very expensive to make the glazing-edge seals. On account of high manufacturing cost, this type of glazing is not competitive at present.

Glasstec 2008 will show how glass coaters and thermal glazing manufacturers have prepared to meet the challenges of the future and what products they think will be the best for the future. Between 21 und 25 October glass processors from all over the world will present their latest developments at this international fair for the sector.