Die originale Warme Kante

What is a warm edge?

Die originale Warme Kante

The term warm edge describes the glazing edge of a mutli-pane insulating glass unit, in which the spacer bar between the panes of glass is made from a material with low thermal conductivity. That helps to reduce the thermal bridge from inside to outside – thus saving energy and avoiding the formation of mould on the glass edge.

Why you should opt for a warm edge in a window instead of aluminium products

A small but effective component of every modern window is a so-called warm edge spacer bar. The spacer bar creates the physical contact between the panes of an insulating glass unit and is therefore decisive for a window’s thermal performance as a direct connection between indoors and outdoors.

In contrast to products made from aluminium, warm edge spacer bars like Swisspacer are made from a highly insulating plastic composite material that minimises the loss of heat. Although the choice of spacer bar has an enormous impact on the energy efficiency of a window, aluminium spacer bars are still in use. That has a fatal impact on heating bills because metal is just about the best conductor of heat there is.

Did you know that you can save up to 8.6% on heating energy and 340 kg of CO2 per year if your window contains Swisspacer?

SWISSPACER - Der Abstandhalter ist das Herzstück eines jeden Fensters

Modern insulating glass units with warm edge

To achieve high thermal performance, multi-pane insulating glass units are used in windows as a rule. At the glass edge, spacer bars maintain the distance between the panes. The spacer bar thus defines the width of the so-called cavity between the panes. This is frequently filled with noble gas, in order to further improve the energy efficiency of the insulating glass unit.

If this spacer bar is made from materials with a low thermal conductivity, it is referred to as a warm edge. The warm edge is therefore optimised in terms of its thermal insulation, in order to minimise heat loss across the edge of double or triple glazing.

As the thermal imaging camera shows: in a window with aluminium spacer bars and decorative bars (left), the heat is lost precisely in the area of these connecting elements (blue). The window with Swisspacer plastic spacer bars and decorative bars shows much warmer edges.

Keep the cold at bay

If it is cold outside and warm inside the building, heat flows outside via the spacer bar or the glazing edge of the window. This causes the edge area to cool much more than the centre of the glazing. To compensate for this heat loss, heating energy has to be consumed. In addition, the temperature gradient on the surface of the glazing causes thermal air movements, which can lead to unpleasant draughts appearing near the window.

If there is a large temperature gradient between the indoor and outdoor temperature, the edge area of the glass can even cool as low as the dew point temperature. Moisture in the indoor air then precipitates on the inside of the window in the form of condensation. This in turn can lead to the growth of mould and bacteria. Over the long term, the window frame is damaged by condensation and the possible growth of mould, posing health hazards for the occupants.

Unlike aluminium spacer bars, warm edge spacer bars like Swisspacer are made from a highly insulating plastic composite material which minimises the loss of heat. They therefore prevent cold bridges and heat loss around the edge of insulating glass panes – meaning that condensation, mould and the resulting health hazards cannot happen in the first place.

Scientifically proved: 
Less heating energy. More living comfort.

These results are also confirmed by a study of the independent Passive House Institute in Darmstadt. For the first time, the impact that spacer bars in the insulating glass unit of windows have on the total energy requirement of buildings was investigated. Compared to aluminium spacer bars, high-efficiency plastic spacer bars lead to much lower energy consumption, CO2 emissions and heating costs for buildings: the three building types investigated in the study save up to 340 kg of CO2 on their respective 156 m² of living space in different climate zones and per year – when high-quality plastic spacer bars are used in the windows instead of aluminium spacer bars. The saving on building heating energy is up to 8.6% for the triple-glazed low energy house, up to 5.6 % for the double-glazed lower energy house and up to 22% for the Passive House.

With aluminium spacer bars: due to the metal’s high conductivity, heat can escape to the outside more easily – to the detriment of the environment and your wallet.

Ohne SWISSPACER, mit Aluminium

With spacer bars from Swisspacer: thanks to the plastic spacer bar, the cold bridge is minimised – the heat remains inside, the cold stays outside.

Mit SWISSPACER

But what if the heat ought to stay outside?

Not only in tropical, but increasingly also in what used to be temperate climate zones, gradually rising temperatures mean that the insides of buildings need to be cooled. And where cooling involves high energy consumption, Swisspacer and its highly insulating properties work in the opposite direction: now, Swisspacer ensures that the flow of heat from outside to inside is reduced so the air-conditioned interior of the building cannot heat up so quickly.

The inside of the windows, especially the edges of the insulating glass unit, therefore remains cooler than without the use of Swisspacer. Hence the term “Cool Edge”. In this case, the air conditioner does not have to work so hard at cooling the interior of the building. So SWISSPACE also ensures a reduction in energy costs in this case, too.