Aluminium window frames are light, strong, durable, and easily extruded into the complex shapes required for window parts. Aluminium frames are available in anodized and factory-baked enamel finishes that are extremely durable and low-maintenance. However, these frames suffer from exposure to salt water environments lessening the life of the windows.

The biggest disadvantage of aluminium as a window frame material is its high thermal conductance. It readily conducts heat, greatly raising the overall U-factor of a window unit. In cold climates, a simple aluminium frame can easily become cold enough to condense moisture or frost on the inside surfaces of window frames. Even more than the problem of heat loss, the condensation problem spurred has development of better insulating aluminium frames (see Aluminium with Thermal Break). In hot climates, where heat transfer is the major is a major issue Aluminium windows would have the highest U-factor making these frames some of the most inefficient on the market.

UPVC Windows

Plastics are relative newcomers as window frame materials in Australia. Upvc, also known as polyvinyl chloride (PVC), is a very versatile plastic with good insulating value. Upvc window frames do not require painting and have good moisture resistance. Because the color goes all the way through, there is no finish coat that can be damaged or deteriorate over time the surface is therefore maintenance-free. Some vinyl window manufacturers are now offering surface treatments like laminates (wood veneer, paintable/stainable, maintenance free) and coatings. These products increase color selection and surface appearance options. Recent advances have improved dimensional stability and resistance to degradation from sunlight and temperature extremes.

In terms of thermal performance, UPVC frames are comparable with wood, while there are minor differences, depending on the frame construction. Small hollow chambers within the frame reduces convection exchange, as does adding an insulating material.