Warm edge spacers vs. Aluminum spacers

Spacer Position

Are Warm Edge Spacers better?

Today the most common type of double glazed window or IG unit is composed of two pieces of glass held apart by a hollow aluminum spacer around the edge of the insulating glass.

Because of its excellent structural properties, window manufacturers started using aluminum spacers in the 1960's and 1970's.

Unfortunately, aluminum is an excellent conductor of heat and the aluminum spacer represented a significant thermal "short circuit" at the edge of the double glazing, which reduces the benefits of the improved glazing.

Aluminium Spacer 2
In addition to the increased heat loss, the colder edge is more prone to condensation.

To address this problem, low conducting spacers have been developed. They are designed to improve the thermal performance of the windows and dramatically reduce condensation.

With Green Energy Windows the aluminium spacer is replaced with an Intercept® Warm-Edge Spacer System featuring a unique, one-piece, U-channel design, sealer, and desiccant in a thermoplastic compound that contains a blend of desiccant materials and incorporates a thin, fluted tin-plated or stainless steel metal shim.

Warm Edge Spacer1
The U-shaped design allows the spacer to flex with the window during temperature changes instead of the sealant. This reduces sealant failure and loss of insulation ability.

For purposes of determining the overall window U-factor, the edge spacer has an effect that extends beyond the physical size of the spacer to a band about 65 mm wide.

The contribution of this 65mm wide "glass edge" to the total window U-factor depends on the size of the window.

Glass edge effects are more important for smaller windows, which have a proportionately larger glass edge area.

For a typical residential-size window of 900mm x 1200mm, changing from a standard aluminum edge to a warm edge spacer will dramatically reduce the overall window U-factor .

A more significant benefit is the rise in interior surface temperature at the bottom edge of the window, which is most subject to condensation. With an outside temperature of 0°F, a thermally improved spacer could result in a temperature increase of 3-4°C at the window sightline or
2-4°C at a point 25mm in from the sightline, which is an important improvement.

As new highly insulating multiple layer windows are developed, the improved edge spacer becomes an even more important element.

Warm edge spacers have become increasingly important and have allowed Green Energy Windows to provide a switch from conventional double glazing to higher-performance glazing for all our double glazed windows.

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