How to Choose the Right Glass for a Commercial Office Block

It's not just about how the building looks from the outside. Commercial glazing has a direct impact on comfort, energy efficiency, glare, natural light, and the overall performance of the building.

For office environments, the challenge is finding the right balance. You need to help keep heat inside during winter, reduce unwanted heat gain during summer, manage glare, and still allow enough natural light to create a bright, productive space.

That is where understanding the Solar Factor becomes important.

What is Solar Factor?

Solar Factor is also known as SHGC, or Solar Heat Gain Coefficient.

Put simply, it measures how much solar heat passes through the glass and into the building.

The lower the Solar Factor, the less solar heat passes through the glass.

This matters because commercial office blocks often have large glazed areas. While this supports natural light and modern design, it can also increase heat gain, glare, and pressure on the building’s HVAC system if the wrong glass is specified.

Why Solar Factor matters in office buildings

Standard double glazing typically has a Solar Factor of around 77%.

For many office buildings, that level of solar heat gain may be too high, especially where there are large windows, exposed elevations, or areas that receive strong sun throughout the day.

In a commercial office environment, too much solar heat can lead to:

• Uncomfortable indoor temperatures

• Increased glare on screens and workspaces

• Higher demand on HVAC systems

• Reduced energy efficiency

• Difficulty maintaining consistent comfort levels

This is why stronger solar control glass is often recommended for commercial office blocks.

Commercial glass options for better solar control

For office blocks, glass options such as Low E Xtreme, SunX Grey, and SunX Reflect can help reduce solar heat gain while still supporting natural light and energy performance.

Here are some example Solar Factor ratings:

SunX™ Reflect Low E Double Glazing

Solar Factor: 22%

SunX™ Reflect Low E Double Glazing provides strong solar control, helping reduce heat gain in commercial spaces with high sun exposure.

This can be useful where comfort, glare control, and HVAC load are key considerations.

SunX™ Grey Low E Double Glazing

Solar Factor: 24%

SunX™ Grey Low E Double Glazing also offers strong solar control, with a low Solar Factor that helps limit unwanted solar heat.

It is a practical option for commercial office blocks where reduced heat gain and a more controlled internal environment are important.

Xtreme™ Low E Double Glazing

Solar Factor: 40%

Xtreme™ Low E Double Glazing offers improved solar control compared with standard double glazing, while still supporting good levels of natural light.

It can be a useful option when the project requires a balance between daylight, comfort, and thermal performance.

How glazing affects HVAC performance

The wrong glass choice can place extra demand on heating, ventilation, and air conditioning systems.

If too much solar heat enters the building during summer, the HVAC system has to work harder to cool the space. If the building loses too much heat during winter, heating demand increases.

Better glazing choices can help reduce this load.

By selecting glass with the right Solar Factor, Low E performance, and thermal properties, project teams can support a more energy-efficient office block and improve comfort for the people using the building every day.

That is a brighter way to save energy, and a smarter way to approach commercial glazing.

When should you choose glazing for a commercial office block?

Commercial glass should be considered early in the design process.

At UNO Windows & Doors, we recommend engaging an H1 engineer early to model building performance. This helps identify what the building needs before the project reaches specification, consent, or construction.

Early modelling can help your team understand:

• Which glazing options support the building’s performance targets

• How different glass types affect heat gain and comfort

• What kind of solar control is needed

• How glazing decisions may affect HVAC requirements

• What aluminium joinery solution best suits the project

Bringing UNO into the conversation early also means we can work with your design team to test different glazing options and help confirm what is practical, efficient, and achievable for the project.

How UNO supports commercial glazing decisions

UNO Windows & Doors provides efficient end-to-end window & door solutions for light commercial and multi-residential projects across New Zealand.

Our team can work alongside architects, developers, builders, and H1 engineers to help identify glazing and aluminium joinery solutions that support performance, compliance, and buildability.

This includes support with:

• Commercial aluminium windows and doors suggestions

• Low E glass and solar control glazing options

• H1 construction R-values

• Practical specification support

• Shop drawings and detailing

• PS1 documentation when required

• Efficient manufacturing and project delivery

By bringing together glass selection, aluminium joinery, documentation, and manufacturing support, UNO helps create a more seamless process from design through to delivery.

Talk to UNO early about commercial glazing options for your next office block.