4th August 2023

‘Bats and Artificial Lighting at Night’ ILP Guidance Note update released

The Institution of Lighting Professionals (ILP) has launched the latest practical guidance on considering the impact upon bats when designing lighting schemes. Artificial Light at Night (ALAN) is increasing at an alarming rate, estimated to have risen over 49% in the last 30 years. This has negative impacts on bats, other wildlife and people as well as wasting precious energy. While recognising the importance of ALAN, it is also essential that we use it responsibly to reduce or mitigate the negative impacts it can have. Bats, as nocturnal specialists, can be excellent indicators of the negative impacts of light pollution. For this reason, a panel of experts with representatives from an ecological consultancy, a highways department, lighting designer and manufacturers, a local planning authorities and the ILP has developed the guidance, chaired by the Bat Conservation Trust (BCT).

This free guidance is now available on the ILP website as a Guidance Note GN08/23.

The new guidance (GN08/23) supersedes the 2018 guidance and was previewed at an event run by BCT to highlight key changes in February 2023, with hosts Arup and sponsored by Kingfisher Lighting. Online content from this event is available here and comprises the steering group experts guiding the attendees through the main changes and reasoning behind them.

Since 2018 there has been an increase in the knowledge on how many of the UK’s 18 bat species are impacted by lighting, through updated research work, but also an increase in knowledge on how this impact can be reduced.

Many of the UK’s bat species have declined significantly over the last century which is why they are legally protected. International and domestic legislation protects all species of bat and their roost sites (whether bats are present at the time or not). This protection has helped some species begin to start their journey to recovery although four of the 11 mammal species native to Britain classified as being at risk of extinction are bats. Legal protection means it is illegal to kill, injure, capture or cause disturbance that affects bats, obstructs access to bat roosts, or damage or destroy bat roosts. The Wildlife and Countryside Act 1981 (as amended) protects all bats from ‘intentional’ or ‘reckless’ disturbance. Lighting in the vicinity of a bat roost could constitute an offence since it causes disturbance and potential abandonment of the roost, It can also prevent bats from emerging which leads to entombment and death.

New development projects can further reduce negative impacts of lighting on bats by utilising the updated guidance along with advice from suitably experienced ecological consultants and lighting experts from the start of a project. The 2023 edition has a strong focus on avoidance as a key tool to mitigate impacts from lighting on bats, as well has having a range of case studies to demonstrate principles (such as a truly collaborative approach) outlined in the document. The benefits this approach brings are ultimately for bats and other wildlife as well as people and the overall quality of our environment.

The 2023 guidance note considers bats roosting, foraging and commuting needs in greater planning context than ever before. Some bat species have been shown to be impacted by significantly lower lighting levels than others, certain colour temperature environments also play a factor in the level of impact. However, all bats require dark roosting areas, corridors through the landscape and habitats to feed.

The ILP and BCT intend this document to be read by lighting professionals, lighting designers, planning officers, developers, bat workers/ecologists and anyone specifying lighting.

Although we will continue to learn more about how lighting impacts on bats, other wildlife and people, this guidance note is an important tool for industry on how to avoid or reduce them. This work emphasises that ecologists and lighting engineers must be brought in to collaborate with a project team at the start and communication throughout the project is key to finding positive solutions for all concerned." Jo Ferguson, Built Environment Manager, Bat Conservation Trust.

Cody Levine, Ecology Team Leader, Worcestershire County Council on the steering group said “like place-shaping itself, GN08/23 is the result of multi-disciplinary collaboration; it casts a light on current scientific evidence and demonstrates how to put principles into practice: GN08/23 highlights the need to understand lighting impacts earlier in the design processes, to ensure that the mitigation hierarchy is applied effectively, and encourages us to think ‘bigger, better and more-joined-up’ when we consider bats in lighting schemes."

Stuart Morton, Professional Head of Highways Electrical Design at Jacobs on the steering group said The document will enable cross-industry conversations and help practitioners make evidence-based decisions that consider bats and wider biodiversity issues in lighting schemes. Additionally, as we progress towards achieving genuine biodiversity net gain, it’s hoped that the processes set out in this document will help enable solid policies and decision-making to reduce lighting impact, not only on bats, but on biodiversity more broadly.

The ILP and BCT would like to thank everyone involved in producing GN 08 / 23 and the technical symposium event for all their hard work and considerable expertise which made this possible.


The Institution's mission is to support and develop lighting professionals and their global contribution for the benefit of society and the environment.

The Bat Conservation Trust is the leading NGO solely devoted to the conservation of bats and the landscapes on which they rely. We work closely with many organisations including developers, industry bodies, researchers and over 100 bat groups across the UK. Bats are unique and play a vital role in our environment but during the last century bat populations suffered severe declines. We are working to secure the future of bats in our ever-changing world by tackling the threats to bats, from persecution to loss or roosts and changing land use. As the authoritative voice for bat conservation we work locally, nationally, across Europe and globally.

Please click here to download the document.

Contact Guy Harding, Technical Manager for ILP, for further details on info@theilp.org.uk.