Light pollution: the good, the bad and the ugly
August 2017
Current estimations indicate that we waste over £100m of energy in the UK every year. £100 million!!
That’s enough money to buy two luxury mansions in central London, 1,000 Aston Martins, or if you fancy yourself as a bit of a Richard Branson; a private island in the Caribbean.
Wasted light, also known as obtrusive light or light pollution, is just one contributory factor.
But what is light pollution and what we can we do to prevent it?
Wasted Light: Wasted Energy: Wasted Money
Light pollution is spill light or upward light which is ‘unused’ and generally unwanted.
Examples include sky glow; the brightening of the nights sky by spill upward light and glare; which can be broken down again into two types, discomfort and disability (more on this here).
We’re more concerned with discomfort glare; the type so bright that it makes you want to look away (disability glare effects your ability to see caused by an intense light source).
Why is it a problem?
Since the introduction of the Clean Neighbourhoods and Environment Act 2005, unwanted artificial light trespass is classed as a statutory nuisance. This means that a local authority has a legal duty to investigate light pollution breaches, in the same way that it would with a noise or air pollution issue.
Don’t over light. As the ILP explain in Guidance notes for the reduction of obtrusive light GN01:2011 (a comprehensive read!).
Good design = Good lighting
How-to reduce the amount of unused light
Part-night switching or dimming is an energy-efficient and money-saving option that should definitely be considered during the design stage. For example, if an area is unused after a certain time every night, is there any need for the same lighting levels required as at peak times?
Anti-glare light shields minimise unwanted light spill and put light where you need it. They are another simple consideration for the design stage of your project – but can also be retrofitted to a scheme already installed. Shields can be discreet, so there’s no need to worry about ugly lighting.
Finally, consider appropriate mounting heights and inclinations of the luminaires. Generally speaking, a higher mounting height or an increase in the tilt angle could generate more spill light than one mounted lower with a zero-degree uplift. Floodlights are one of the biggest contributors to unwanted spill light when positioned incorrectly.