Barrier laminates for insulated glass units: The Problem
Window bar spacers are used to keep glass panes separated in insulated glass units (IGUs) – also known as double/triple glazing.
These spacer systems perform a variety of functions. The air/gas space serves to reduce heat transfer across the building envelope, helping to save energy and money, improve comfort within a building and provide sound insulation.
However, with spacers being a critical component to the overall integrity of IGUs, they themselves need to harbor the right characteristics in accordance with four key considerations. They must…
- Be able to accommodate stress induced by thermal expansion and changes in pressure.
- Reduce heat loss while at the same time prevent the formation of interior condensation.
- Provide a moisture barrier that prevents the ingress of water and vapor that would fog the glass.
- Provide a gas-tight seal that prevents the loss of any special low conductance gas in the airspace.
Various technologies and materials are used in window bar spacers that offer different advantages, and disadvantages. In today’s market, there are three key types:
● Metal spacers, typically made of aluminum, galvanized steel or stainless steel.
● Hybrid spacers, typically made of a combination of plastic materials and thinner metal components.
● Non-metal spacers, typically made of composite, foam or thermoplastics with a barrier film on the exterior.
The chosen material for the window bar spacers will have a significant effect on the overall characteristics of the system. Metal spacers, for example, perform well in accommodating stress in the IGU and act as efficient barriers (points 1 and 4), but offer poor insulation value (point 2) due to the high thermal conductivity of the metals.
Meanwhile, non-metal spacers based on polymeric materials have much better insulation properties by avoiding a cold bridge (point 2), but have a too high permeability for gases (point 4) and water vapor (point 3).
Finding a system that can address all 4 points can be a challenge.
Barrier laminates for insulated glass units: The Solution
Here lies the strength of non-metal or warm edge spacers with high performing barrier films.
In essence, it combines the desirable properties of both metal and non-metal spacers to develop the best possible solution. Where non-metal warm edge spacers are permeable to gases and water vapor, this is solved with a barrier film on the exterior of the spacer.
The extremely high barrier performance of these films are combined with an extremely low thermal conductivity, thereby removing the drawback of high thermal transfer that you experience with spacers that are entirely made of metal.
To ensure that such performance levels are achieved, these IGUs undergo rigorous testing according to specific industry norms in order to evaluate them for their long-term effectiveness. This includes intense temperature cycles, as well as tests to evaluate moisture penetration and desiccant capability and gas chromatography to evaluate gas leakage.
As a result, we’re able to ensure our barrier films work highly effectively, providing:
● Low water/vapor and gas permeation through the laminate skin.
● Excellent adhesion to a range of sealants with special surface treatment.
● Resistant to mechanical damage and/or degradation of the films.
● Low thermal bridge.
With the market for glazing insulation growing amid tightening insulation regulations and requirements around the world, it is vital that such systems are made up of the most effective components – that includes the best performing spacer solutions.
