Mitigating light impacts

NE22: Mitigating light impacts 1. In developments where external lighting is required, all the following criteria must be met: a) The lighting scheme proposed is the minimum required for the security and safety of working activities. b) Light spill and potential glare and the impact on the night sky is minimised through the control of light direction and levels, particularly in residential and commercial areas, areas of wildlife interest or the visual character of historic buildings and rural landscape character (including the National Landscape where there may be significant impact) c) The choice and positioning of the light fittings, columns and cables minimise their daytime appearance and impact on the streetscape, and d) Where possible, in considering development involving potentially adverse lighting impacts to wildlife, the council will require surveys to identify wildlife corridors and ensure that these corridors are protected and enhanced. considering the impact of lighting, especially if they are found to support species known to avoid light. 2. Artificial Light at Night (ALAN) can have negative impacts upon wildlife, most notably bats. Dark corridors should be protected as they are essential for the movement through the landscape which facilitates feeding, breeding and migrating of some protected species. 3. The Council will only support proposals for ALAN in the National Landscape where it has been demonstrated the lighting, including any mitigation, will not detract from the purposes of the National Landscape. 4. A mitigation hierarchy set out below should be followed to ensure the use of lighting is appropriate to the level of impact. 5. Development affecting watercourses, ecological corridors and major developments must ensure that an informed assessment of potential Artificial Light at Night (ALAN) impact on wildlife is made and that ALAN is kept to the minimum level required to ensure health and safety. Where areas are identified as important to be kept dark for wildlife, lighting must be avoided. a) Avoidance - methods might include situating development that requires lighting, away from the sensitive dark area. b) Minimising - methods might include changing the lighting design strategy to reducing the impact (e.g. reducing lux levels, the Kelvin light temperature, or installing baffles or screens, or other interventions). Use best practice techniques for reducing or removing lighting where ALAN could adversely impact on ecological networks. c) Compensation - might include creating an alternative dark corridor which serves the same function. 6. In all instances ALAN should have a clear purpose, be directed to only where it is needed, be no brighter than necessary and be turned off when not needed. ALAN should use warmer colour lights where possible. 7. The ‘Bats and Artificial Lighting at Night, ILP Guidance Note 2023’ (or successor) provides best practice guidance which informs how lighting should be considered in development. 7.259 The Buckinghamshire and Milton Keynes Local Nature Recovery Strategy https://bucksmknep.co.uk/nature-strategy/overview/ notes the importance of dark skies to reduce light pollution. 7.260 There is a need to create dark sky areas and reduce light pollution for wildlife, so that animals and plants perceive day and night correctly. Light pollution has an overall negative impact on wildlife because it disturbs the way animals and plants perceive daytime and nighttime which upsets their natural systems and behaviour including navigate on and feeding habits. All light should have a clear purpose, be directed to only where it is needed, be no brighter than necessary and be turned off when not needed. Use warmer colour lights should be used where possible. 7.261 Measure 99 of the LRNS is linked to the importance of dark corridors. 7.262 At least two thirds of all animal species are active at night and require appropriate conditions to thrive, this includes inverts such as glow worms, mammals such as badgers and bats, fish including salmon and birds such as owls. 7.263 Artificial Light at Night (commonly referred to by the acronym ALAN) is rapidly increasing, distribution nocturnal wildlife behaviour, migration and reproduction and having impacts on ecosystems. 7.264 Examples of Dark Corridors include watercourse corridors, interconnected woodland and hedgerow networks. 7.265 ALAN can detract from the character and openness of the Green Belt through light spillage, light glare and sky glow. These effects can be reduced or removed by using a lower strength light source and a cover which surrounds light to focus light onto a specific area. 7.266 Two thirds of invertebrates are partially or wholly nocturnal and even diurnal species can be impacted by light. The charity Buglife report that light pollution is reducing nocturnal pollinator visits to flowers by 62% in some areas. Caterpillar populations declined by 52% in areas with streetlights. Glow-worm populations are reduced in artificially lit areas and their ability to communicate by ‘glowing’ is reduced. Dung beetles navigate using the moon and stars. Under light-polluted skies, they become disoriented and unable to find their way. 7.267 Birds are also vulnerable to artificial light, causing them to fly toward lit areas. Research shows more birds migrating over urban compared to rural areas, this deviation could have a significant impact on energy levels and lead them to stop in suboptimal habitats. 7.268 Artificial lighting can cause many problems for bats, including disrupting their roosting and feeding behaviour and their movement through the landscape; in the worst cases, causing direct harm. As all bats in the UK feed on insects the loss of food sources is also a considerable threat. 7.269 The Chilterns National Landscape is considered an E1 Natural Zone within the E1 environmental zones defined by the Institution on Lighting Professionals (ILP) where particular care is needed. The Chilterns Conservation Board Lighting Planning Guidance (2025 or as amended) should be used to consider, mitigate and design solutions to impacts in and affecting the Chilterns National Landscape. 7.270 The policy seeks to ensure the protection of dark corridors to be treated equally to green and blue infrastructure. Requirements for Artificial Light at Night (ALAN) should be kept to a minimum required for health and safety. Developers should use current best practice techniques for reducing or removing lighting where ALAN could impact ecological networks that could impact flora and fauna known to be sensitive to light. 7.271 Although appropriate lighting can help to enhance community safety and reduce the fear of crime, caution must be taken to ensure that lighting only illuminates the intended areas or structures and does not negatively impact surrounding areas. This must not compromise a purpose of lighting to encourage the use of public urban areas and green infrastructure as part of a healthy lifestyle. 7.272 Consideration will be given to the impact of the proposed lighting on the natural environment and the effect on wildlife. Lighting within and around any development is expected to respect the ecological functionality of wildlife movement corridors. Certain species of invertebrate and mammal are highly sensitive to inappropriate lighting. In these circumstances, surveys are expected to determine where these wildlife movement corridors are and measures put forward that demonstrate how these will be protected and enhanced.