Insulating glass units, or double-glazed units, are one of the most common types of glass used today for building applications. Patented as far back as 1865, IG units were implemented in architectural applications after the World War II. Due to their excellent thermal and acoustic properties, they have almost completely replaced basic monolithic windows.
Over the decades IGU?s thermal performance has been upgraded with the introduction of low-emission coatings and gases with a low thermal conductivity. Attention was then turned to the edges to further reduce thermal losses caused by highly conductive material.
Today the most common type of IG unit is composed of two pieces of glass and a hollow aluminum spacer around the edge of insulating glass. The hollow spacer contains a moister-removing desiccant agent. The major benefits of aluminum pacers are: lightweight, durability and relatively low cost. The dawn back of this spacer is aluminum conductive properties, which sometimes cause that the edges of the glass could lose more heat than the center of the glass.
To overcome this limitation, the glass industry developed so-called low-conducting spacers or warm-edge spacers. These are designed to improve the thermal performance of the windows, reduce condensation, and with the appropriate machinery, permit faster and easier assembly of insulating glass units. There have been several attempts to place these products on the market. However as it turns out the anticipations were too big as the warm edge spacers are more expensive and have in comparison with classical aluminum spacer a very small IG U-value improvement.
When new discussions were held regarding energy-saving legislation in Europe in 1997, interest in low-conductive spacers increased. There are several low-conductive spacers on the market today, however due to the above mentioned fact the classical aluminum spacer remains the number one choice for IG applications.