Unified Glare Rating has long been considered a designer’s metric but now, electricians are discovering why it matters on-site too. Daniel Williamson sheds some light on the topic.

When electricians think about lighting, they usually focus on lumens, colour temperature and energy efficiency. But there’s another metric that often goes overlooked, especially in commercial and educational settings, and it could quietly impact occupant comfort and compliance: Unified Glare Rating, or UGR.

UGR is a metric used to quantify the visual discomfort that can come from luminaires, natural light or reflections. It helps designers, architects and lighting installers understand how lighting will impact occupants. The calculation behind UGR considers luminance of the luminaires, background luminance, viewing angles and room geometry. It’s usually modelled during the design phase by lighting professionals rather than worked out on-site.

In practical terms, a lower UGR value indicates reduced glare and increases visual comfort. The UGR scale typically runs from ten (imperceptible glare) to 30 (uncomfortable glare). Office environments, for instance, often aim for a UGR of 19 or lower, in line with international and local standards like AS/NSZ 1680.1:2006 Interior and workplace lighting, Part 1: General principles and recommendations. The Green Building Council of Australia recommends this for all residential and commercial interiors to support occupant wellbeing.

Glare is important in spaces with screens – offices, classrooms and many contemporary work areas – because screens move and people reposition themselves, changing how glare is perceived.

Experienced lighting designer and consultant Steve Brown says that many components in a workplace can cause discomfort and eye strain due to glare.

“Glare in workplaces, especially those with screens like PCs, tablets and laptops, can lead to significant eyestrain and discomfort,” Steve says.

“One challenge is that screens are not fixed; their position often changes throughout the day, which affects how glare is perceived. That variability makes it even more important to consider UGR during the lighting design phase.”

International Association of Lighting Designers regional coordinator, Gavin Woodford, brings many years of experience in commercial and office lighting, and says that this needs to be clearly understood. Gavin points out that product choices alone aren’t a silver bullet. While installing fittings with sensible glare control is a strong starting point, other design elements like dimming capabilities and tuneable colour temperature can enhance the user experience depending on the time of day or the task being performed.

But UGR isn’t a fixed product spec. It’s location dependent, meaning it can change depending on how a space is used, where an observer is standing and what other surfaces and light sources are present. That’s where collaboration with the lighting installer, typically an electrician, comes into the fold.

“Because UGR is a design consideration rather than a product-only spec, engaging a qualified lighting designer can make a significant difference,” Steve says.

“A designer can assess layout, occupancy, room function, surface finishes and natural light – all of which influence glare.”

The Lighting Council of Australia (LCA) says that electrical contractors should be aware of UGR and know that if they alter a specification to a different product, then UGR could be adversely affected and should be recalculated to ensure compliance. Swapping a fitting on-site for one that looks similar on paper can still change glare performance enough to matter to a client or a rating tool such as Green Star.

“Electrical contractors play a key role in ensuring that fittings are installed as per the intended layout. Positioning and orientation of fixtures can dramatically impact UGR levels in the final environment,” Gavin says.

“Contractors should understand the basics of UGR and coordinate closely with designers to maintain lighting performance and compliance.”

So, what should electricians do whilst they’re on site?

You don’t need to become a photometric modeller, but you should be cautious when substituting fittings without checking whether the change affects glare ratings, follow specified positions and orientations during installation and flag any on-site changes or constraints to the lighting designer or project manager. Asking simple questions, like “will this change affect UGR or glare performance?” before making substitutions can save rework and protect clients from an uncomfortable outcome.

Electrical contractors who take the time to understand how UGR interacts with installation choices become more valuable collaborators. Simple on-site practices like double-checking orientation, avoiding unauthorised product swaps and communicating early about changes help keep the original design intent intact.

Glare may seem like a small aesthetic issue, but in modern lighting design, it affects comfort, productivity and sometimes compliance. Electricians who understand where UGR fits into the bigger picture are helping deliver better, healthier and more usable spaces.