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Is your building making the sky glow?

Lighting Design By Hannah Murphy, Senior Lighting Designer – 21 March 2023

Cityscape with the buildings illuminated with a red light reflected in water


Hannah in a cream jumper and collared shirt, smiling to camera in front of an exposed brick indoor wall

Hannah Murphy

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Light pollution is a global environmental change – a change that has been in the making for decades through the improper use of light. The evolving state of artificial light and the transformation of LED lighting is significant in its effect on our darkness. The ever-popular application of LED cool white light can often create bright landscapes and harsh urban cities – tinged with an unnatural blue hue. Now more than ever, we cannot help but notice how external lighting is dominating our surroundings.

Some may ask, what is light pollution? It exists as obtrusive light into the night sky. There are generally three components to light pollution.

  • Spill light – light emitted by a lighting installation that falls outside of the boundary area being lit
  • Sky glow – the brightening of the night sky
  • Light trespass – a form of light spill that leaks onto surrounding property

For the many developers/clients/architects that still do not have light pollution on their radar, there are those few that are now beginning to understand the detrimental effect light pollution has on their environment and their own wellbeing, from affecting our sleep and mental wellbeing to disrupting nocturnal wildlife. New site developments require light pollution studies and lighting manufacturers are developing products in keeping with darker skies.

The application of lighting against architectural façade’s is usually a grey area when it comes to light pollution. Many times, a client may want their building to stand out against other buildings which in their eyes can mean the brighter, the better, however we as lighting designers, have the opportunity to guide against overly lit façades and buildings and light where is necessary, providing a narrative of light against shadows creating contrast and depth.

There are currently several documents featuring regulations, standards and guides that are relevant to light pollution and ways it can be reduced. However, there is limited discussion regarding buildings and their façades. Whilst building façade luminance has a recommended maximum permitted set of values, viewable in the CIE 150:2017 Guide on the Limitation of the Effects of Obtrusive Light from Outdoor Lighting Installations and the ILP Guidance Note 01 The Reduction of Obtrusive Light 2021 publications there is no mention of sky glow cross referenced with building façades. This means there is no guidance to stop developers and designers solely uplighting a building façade with floodlights which would impact the night sky.

Whilst many of the light pollution guides discuss the issue of light pollution and provide guidance on minimising it, there is information lacking on sky glow and the relevance architectural façades have on its abundance.

As with the excessive use of all the world’s resources; we are now experiencing the impacts of our application of light and lighting from the years gone by. The way we design our lighting solutions is more important than ever – as lighting designers, part of our passion is lighting that reacts to the general design aesthetic. For internal lighting that can sometimes mean forging away from guidelines and standards, externally that means keeping in-mind the importance of the latest guidelines on light pollution and uncontrolled light even if further work is required from the official bodies of light.