light pollution

Good Lighting Advice

Digital photo magazine

by Chasing Stars

To achieve International Dark Sky Reserve status all those responsible for lighting (local authorities, highway departments, businesses and individual residents) are required to ensure that light pollution (light escaping sideways and upwards) is reduced to a minimum.

LEDs are now beginning to appear above our streets and main roads in very large numbers. Sadly, far too many LEDs are very bright, and their excess light reflects from the ground into the sky.

AONB Position Statement & Good Practice Note

The AONB position statements set out its current position on a variety of topics. These include light pollution, and the Cranborne Chase and West Wiltshire Downs Area of Outstanding Natural Beauty derives much of its beauty from its qualities of tranquillity, remoteness and cultural heritage. Light pollution has the potential to erode and destroy that tranquillity and sense of remoteness.

It is, therefore, considered appropriate that all artificial external lighting within its borders, or within the setting of the AONB, should be muted, screened, and the minimum required.  

Position Statement 1 - Light Pollution (PDF, 75Kb)

Good Practice Note 7 - Good External Lighting (PDF 70Kb)

Position Statement 7a - Recommendations for Dark-Sky compliant lighting on new builds & refurbishments - a Developers' Guide (PDF 500kb)

Terms used in describing good lighting, and waste light not directed to the area to be lit.


Task or Useful light – light that fulfils the task for which the lamp was installed.

  • Obtrusive light – light causing a problem of some kind through misdirection.

  • Spill light - falls outside the area where it is needed.

  • Upward reflected light - unwanted light bouncing off the ground.

  • Direct upward light - wasted light shining above a light fitting (not necessarily vertically upwards – it may be escaping just one degree above the horizontal but will eventually end up in the sky).

  • Light intrusion – over-bright and poorly directed light, often going in windows and/or causing glare and discomfort on other premises. Sometimes called light trespass, but this term is normally to be avoided as, in law, trespass is deliberate intrusion and the intrusive light is usually the result of ignorance rather than malice.



Compact LED light directed downwards. This and similar types are recommended for domestic, commercial, farmyard and similar uses: preferably with sensors to switch off when not needed. 
Photo: Auraglow

A halogen floodlight, correctly angled, can light a large area. 
Photo: Martin Morgan-Taylor


An LED floodlight that, even if tilted down, will shine above the horizontal
Photo: ILP

An LED floodlight on a hospital shining into ward windows: its wiring and short fitting bar mean that it cannot be tilted far enough downwards to illuminate the area to be lit. It will always emit upwards as well as down.
Photo: Bob Mizon

Environmental Zones

It is recommended that Local Planning Authorities specify the following environmental zones for exterior lighting control within their Development Plans.

ZoneSurroundingLighting EnvironmentExamplesE0ProtectedDarkUNESCO Starlight Reserves, IDA Dark Sky ParksE1NaturalIntrinsically darkNational Parks, Areas of Outstanding Natural Beauty etcE2RuralLow district brightnessVillage or relatively dark outer suburban locationsE3SuburbanMedium district brightnessSmall town centres or suburban locationsE4UrbanHigh district brightnessTown/city centres with high levels of night-time activitySource: Guidance Notes for the Reduction of Obtrusive Light GN01:2011

Where an area to be lit lies on the boundary of two zones the obtrusive light limitation values used should be those applicable to the most rigorous zone.
NB: Zone E0 must always be surrounded by an E1 Zone.

Lighting Types, qualities and Impacts - Bob Mizon Commission for Dark Skies (CfDS) - March 2016

This paper by Bob Mizon looks at best practice relating to external lighting - Different types of lighting through the years, terminology guide, threats to the environment from blue-rich white lighting, putting light where it is needed, part-night switch-offs and common misconceptions met when discussing quality lighting and good practice...

Download Lighting: types, qualities and impacts (PDF - 1.2Mb)

Institute of Lighting Professionals

The Institution of Lighting Professionals (ILP) is the UK and Ireland's largest and most influential professional lighting association, dedicated solely to excellence in lighting.

The key purpose of the ILP is to promote excellence in all forms of lighting. This includes interior, exterior, sports, road, flood, emergency, tunnel, security and festive lighting as well as design and consultancy services.

Their website contains a wealth of information and advice, and we would recommend the two links below - the first one being a PDF, and the second link taking you to the free resources page on their website:

Guidance Notes for the Reduction of Obtrusive Light (PDF)

Free Resources from the Institute of Lighting Professionals

More Links to useful resources

Universe Today - LEDs: Light Pollution Solution or Night Sky Nemesis? - Article by Bob King

Edison Tech Centre - Find out about the evolution of the Electric Light.

International working group (PDF) - Regional Government of Andalusia - Declaration on the use of blue-rich white light sources for nighttime lighting

Understanding & choosing colour temperature in LED lights (YouTube Video) - David Geldart of Lumicrest Lighting Solutions

Blue-rich LED Lighting — Bright New Future? - The Commission for Dark Skies

Switchoffs - Most UK councils are adopting environmental and economic lights-out policies - The Commission for Dark Skies

Light Pollution

The Good and the Bad

The Good and the Bad


Why do our dark skies need protecting?

The night sky makes up half of our visual environment and yet, unlike historic housing, ancient settlements, resident wildlife and our fantastic landscapes, the night sky has no protection, which explains why in just six years light pollution has increased by 24%.

This is not just bad news for people who can no longer be enthralled by the night sky. The amount of money squandered by ‘wasted’ light is staggering, plus the cost to human and wildlife health is significant. Making just a small low-cost difference to our lighting could bring about massive changes for the better.

Pollution is just that – light that is wasted and not used to light the things that people need. We all need light and certainly don’t want to make the AONB a light-free zone. All we want to do is ensure that we have the right lights in the right place at the right time.

The impacts of light pollution are significant, but small changes can make a big difference.

Is light pollution really that bad?

Even though it doesn’t smell bad, and if you’re used to it, it doesn’t look that bad, light pollution has been proved by experts to be just as bad as air and environmental pollution – it’s just not as obvious.

Here are some facts to get you started….

  • Total of 830,000 tonnes of CO2 pollution is produced from the energy wasted by streetlights alone.

  • The estimated cost of wasted light (that which isn’t shining on the things we need to illuminate) is a staggering £1 billion.

  • Light pollution is directly linked to a decrease in robin, songbird and owl populations.

  • Insects are the basis of many food chains, but one street light can kill up to 150 each night.

  • Lighting at night disrupts our circadian rhythm which has been proved to increase your risk of stress by 52%. It is linked to more serious health issues too.

Let’s look at this more positively…

  • There is increasing interest, wonder and amazement at the incredible array of stars above us. Stargazing is a fabulous educational activity for all and by keeping our dark skies you’ll be one of the lucky 10% of people in this country to enjoy this spectacular show.

  • Dark skies make the Cranborne Chase AONB unique, encouraging people to visit from polluted areas to escape to our pocket of tranquillity. That means more income for businesses through people arriving and staying longer.

  • Saving money. Substantial savings can be made by local authorities, businesses and individuals by turning off or dimming down unnecessary lighting. That means more money for the things that matter.

  • Saving energy. There is no point shining a light into the sky. Energy wastage can easily be considerably reduced – which is so much better for the environment.

All of the above is wasted light.

Easy ways to protect and enhance our dark skies… and banish the pollution

It is often said that if we all do a little, collectively we can make a big impact. In one small area of Wales, angling lights to illuminate the ground and turning off lights when they were not needed reduced light pollution by 10%.

Do you have concerns about street lighting or obtrusive lighting from another property? Let us know. We will not divulge your details but will work with others to install lighting which is a win win for everyone.

If you are interested in finding out more about light pollution, its impacts and some solutions, visit the websites below, both of which have some great resources on this subject: