Sep 06, 2018   |   Energy Efficiency

Not all glass is created equal

Whilst there is no sole determining factor on window performance – frame, glass, seals, climate and orientation all contribute – what is clear is that not all glass is created equal. Choosing energy efficient windows and glass doors can make your home feel more comfortable, reduce energy costs and help create a brighter and healthier space. The Australian Window Association (AWA) suggests up to 40% of a home’s heating energy can be lost through windows and up to 87% of its heat gained through them.

Low-e (or low emissivity) glazed products have a near invisible, microscopic layer of metal bonded to the glass. They are spectrally selective, meaning they target specific elements within the solar spectrum. Specifically, infrared and ultraviolet heat transmission is affected which results in lower U-values (better insulation) and reduced SHGC (Solar Heat Gain Co-efficient). Low-e coatings are best encapsulated within an IGU (Insulated Glazing Unit) and toughened into grade-A safety glass to minimise any risk of thermal shock.

High gain low-e glass encourages passive winter heat gains as the SHGC is similar to uncoated glass, whilst the insulation (U-value) is greatly improved. A slight ‘hazing’ may be viewable when direct sunlight is on the glass, which is a function of the pyrolytic (hard) coating.

Low gain low-e glass minimises summer heat gain by intentionally lowering both SHGC and U-value. The coating is referred to within industry as ‘soft’ and has a tendency to be clearer than the ‘hard’ version, resulting in little or no hazing.

Window performance must always be referenced as a total system, where glass & frame are considered together. Rylock’s TB Series thermally broken awning with 4mm Viridian LightBridge™ clear IGU (low gain) generates a U-value of 2.5 & an SHGC of 0.41, vs. a 4mm clear IGU which results in a U-value of 3.3 & an SHGC of 0.51.

Low-e glass

Improved window seals and draft proofing dramatically aid the overall insulation of any window to deliver even greater energy savings. Your highly trained and experienced Rylock Sales Consultant will advise you on the best product and glazing for your individual project’s requirements.


By Emma Truong Back to posts