INVIS160 tweed | Idea
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To convince you of the benefits of our solutions, let us introduce the phenomena occurring in the space between the panes, which are the main determinants of the insulating properties of insulated glass units. The transfer of heat within an insulated glass unit is the sum of radiation, i.e. the exchange of energy by infra-red and visible radiation, its conduction by the gas and spacers, as well as convection, i.e. the circulation of masses of gas of various temperatures and densities within the inter-pane space. In general, the undesirable transfer of heat by radiation can be limited by applying low-emission coatings to the internal surfaces of the insulated glass unit to reduce thermal radiation in the far infrared. Conduction is minimised, in practice, by using a gas of lower heat conductivity than air to fill the space between the panes. It would seem that using a thicker insulated glass unit filled with a gas of good insulating properties would form the ideal solution, but then, unfortunately, the intensity of gas circulation increases dramatically, leading to large convection cells forming in the inter-pane space. These considerations lead to important conclusions: air, and in particular other gases with low thermal conductivity, are great insulators, but only if convection is eliminated. For such an “immobilised” gas, large gaps between panes would produce outstanding heat insulating properties of the entire glazing! |
Based on this assumption, our search for window solutions with extremely good heat-insulating properties led to a model of an insulated glass unit of increased thickness – INVIS160tweed.
As a result of increasing the thickness of the glass unit to 160 mm, losses caused by conduction were cut significantly. The use of a technologically advanced thin polymer film and/or sheets of very thin glass, invisible to the eye, to split the large inter-pane space into cells allowed us to radically limit the development of convection.
In the INVIS160tweed model of an insulated glass unit, the inter-pane space is partitioned with perfectly transparent, thin polymer film layers and/or sheets of glass which separate a number of cells inclined at a 45o angle to the external panes. This unusual positioning of partitions brings about a stable thermal and density stratification of the gas inside the glass unit, which does not just dampen convection, but blocks it completely.
This solution makes it possible, regardless of the significant thickness of the glazing, to achieve a Ug even lower than 0.05 W/m2K. What is more, irrespective of such a large number of partitions, the weight of our insulated glass unit and its optical parameters (including the g value) are close to a standard double glazing unit.
