UGR: Choosing the right products for your installation

Poor lighting can have a big impact on employee comfort and health, particularly when it comes to glare stemming from more than one competing light source. That is why the Unified Glare Rating (UGR) exists, which is a measure of glare in any given environment. 

It is important to remember that the UGR value for an area is not dependant on a specific fixture, but rather the room it is located in; its shape, size, the surface reflections of walls, ceilings, floors and so on. 

As such, creating a UGR-compliant installation requires more than just UGR ‘compliant’ products; a lighting design needs to consider how much glare will be produced in the space, based on the above factors. 

Why is UGR important? 

Warehouses, factories, shops, showrooms – whatever the environment, the presence of apparent glare can cause noticeable discomfort to any person subjected to it for extended periods. Glare may affect a person’s wellbeing, such as a lack of focus and concentration, but may even impact visibility, which can be dangerous, dependant on the task in hand.  

There are two types of glare;  

  • Discomfort glare: a luminance contrast imbalance high enough to cause discomfort, but will not necessarily prevent a person from carrying out a task 
  • Disability glare: the impairment of vision, which would therefore prevent or hinder a person carrying out a specific task 

How is UGR calculated? 

UGR is calculated using a formula that takes into account many factors; background luminance, luminaire luminance, the angle of the observer’s eye and the position of the luminaire relative to the line of sight. 

What are the recommended UGR levels? 

This depends on the space and the task in hand. The standard BS EN 12464-1 (Lighting for Indoor Workplaces) provides a list of the maximum recommended UGR values per type of room and type of activity, across more than 280 different applications. 

Office lighting, for example, needs to support reading, writing and data processing. Therefore, a UGR level of 16 to 19 is recommended, which is suited to average eye tasks. For simple eye tasks – for example, an industrial environment with rough machine assembly in operation – the UGR level should be between 22 and 25. A UGR rating above 28 is deemed unsuitable for work lighting. 

This is where the distinction really matters, when considering both the UGR level and how it is calculated. Although some luminaires can be categorised as UGR<19 rated, the UGR refers to the actual installation, not the luminaire. In reality, UGR<19 luminaires are assigned a rating because the products have a light distribution that helps the electrician achieve the required UGR based on the task in hand. 

To summarise, there is no guarantee that solely using ‘UGR<19 luminaires’ in an installation will result in a UGR rating of 19 or less. Luminaires that are not classified as UGR<19 can be appropriate if they are used in the right way. 

Therefore, installers must ensure they have a suitable luminaire and accompanying lighting design for the task in hand. 

What is the key takeaway for electricians? 

Ideally, electricians must ensure that they have the best possible information about the products they are using, the space they are working with and how that space will be used to install lighting that goes someway to meeting UGR recommendations. 

Through Red Arrow’s free lighting design service, we can provide guidance for electricians, supply UGR calculations and select an appropriate luminaire suitable for the task in hand. 

As part of our mission to help electricians conquer some of the biggest lighting challenges, we have opened our brand-new facility, which aims to showcase the latest lighting innovations and provide technical support, guidance and installation advice to contractors across the UK. 

If you are looking for further advice on achieving the appropriate UGR levels or require assistance on your next lighting project, do not hesitate to contact Red Arrow today.