Watch Your Tone

In this blog, we’re going to discuss toned glass—a design choice that has experienced its fair share of peaks and troughs over the years but has never completely disappeared. When its use is restricted or overlooked during the design process, it can lead to real disappointment for the end user.

Before we explore the emotional side of choosing a glass tone, let’s first understand what toned glass actually is.

In the glazing industry, grey is the most commonly selected tone, although bronze and green options are also available. Grey toned glass is what most people refer to as “tinted glass”, as it has an appearance similar to tinted car windows. However, unlike many car windows, the colour is not created by applying a film.

Instead, a colourant is added during the manufacture of clear float glass, creating a consistent tone throughout the glass itself. Depending on the application and relevant safety requirements, the glass may remain annealed or undergo further processing, such as toughening or laminating.

Grey toned glass is commonly selected to create a darker external appearance, reduce the amount of solar heat and visible light entering a home, and provide a subtle level of daytime privacy. It is often this darker appearance and added sense of privacy that appeals to homeowners and leads them to request grey glass during the quoting stage.

This AI-generated image provides a visual comparison between clear and grey toned glass. Please note that the appearance of grey toned glass can look lighter or darker depending on lighting conditions, reflections and the viewing angle.

Unfortunately, this is also where disappointment can begin.

Most new homes and major renovations now require an energy assessment to be completed as part of the building approval process. The selected window frames and glass types are included in this assessment and contribute to the overall energy performance of the home.

All too often, I see energy reports that have been completed using clear glass, even though the client wanted grey toned glass. I am then left to explain that we cannot simply substitute the specified clear glass for grey glass without the change first being reviewed and approved.

Understandably, the response is often confusion, disappointment or frustration—particularly when the homeowner believed glass colour was purely an aesthetic choice.

Just like the architectural plans, the approved energy assessment forms part of the project documentation. These documents may be checked during inspections and again when the building is completed. If grey toned glass has been installed but the approved documentation specifies clear glass, the project may not comply until the discrepancy has been assessed and resolved.

So, why can’t grey toned glass simply replace clear glass?

Grey toned glass has different performance values because it reduces the amount of solar energy passing through the window. This affects the glass’s Solar Heat Gain Coefficient, commonly referred to as its SHGC.

A lower SHGC can be beneficial when the goal is to reduce unwanted heat from direct sunlight. However, in a heating-dominated climate such as Tasmania, an energy assessment may rely on beneficial winter solar heat gain to help the home achieve its required rating. Substituting grey glass for clear glass can therefore change the home’s calculated energy performance.

This does not mean toned glass is automatically a poor choice—it simply needs to be considered from the beginning.

If you have your heart set on grey, bronze or green toned glass, discuss it with your building designer and energy assessor before the report is finalised. Your preferred glass can then be modelled correctly, allowing any necessary adjustments to be made before your plans are approved, your windows are ordered and disappointment sets in.