Wednesday, 17 June 2015

Norfolk Light Pollution Conference, UEA June, 2015



Amber LED
LED luminaire
Lighting is a major issue in our urban centres these days. There is so much pressure to provide more and brighter lighting but  at a huge environmental cost. There are  many measures that can be undertaken with new technology to  limit the toll on species and habitats (see previous posts: Kingston University Lighting). Light that causes the most pollution is that travelling horizontally (10 degrees) as it  goes unchecked for miles through atmospheric dust particles, pollen and salt from the sea.

Modern LED lighting is very easy to control and a site can be lit without spilling onto areas  that should be kept dark for wildlife. This is called the 'surround ratio' so that there should be no 'surround ratio' or ' light tresspass' onto abutting areas. There are good examples of this along the Crane Corridor and Warren Footpath in Twickenham. Here  LED's can be switched on or off to create a narrower cone of light, mounted on PIR sensors, dimmed to emit lower lux levels or switched off entirely (or alternate columns) after midnight.  Amber LED lights (pictured) are currently installed by the Dutch Highways Agency on major roads, where there might be an impact on bats or insects as 'warmer' wavelengths have less impact  on certain taxonomic groups.

It is a myth that lights are required for Health and Safety reasons and this is insisted upon by the police. In fact the police position is clear and there are publication such as 'Under Lock and Quay' (British Waterways Board) which states that there should be no lighting where people should be discouraged at night, especially where misdemeanors will go unobserved. This was was expounded recently by members of the Norfolk Constabulary at a CPRE conference on Light Pollution. 200 Local Authorites are now switching off with a crime reduction rate of  up to 36% as criminals also require visibility. 11% of councils  reported that residents had not even noticed dimming or switching off and Essex County Council has saved £1,000,000 by introducing part-night lighting with a measurable crime reduction of 18%.

Secured By Design‘Secured By Design’ (SBD) refers to a set of national police guidelines for developers that aim to reduce opportunities for crime in housing estates, commercial premises and car parks. By designing in security from the outset and considering issues such as locks, fencing, landscaping, CCTV and lighting, it is hoped that crime can be minimised. Nevertheless, evidence frequently shows that security lighting is not actually a useful tool in crime reduction and CPRE Norfolk argued that new developments should not necessarily have to adopt security lighting (especially dusk to dawn lights) to achieve SBD status.

This was first exemplified in a small housing scheme in Burston which was awarded SBD status in 2010 without a requirement for permanent dusk to dawn site lighting. Instead, accreditation was given with the only lighting on the development being movement controlled (PIR) lights. These only illuminate when approached and stay on for a short period of time. Soon afterwards (2011) Norfolk Police authorised the replacement of dusk to dawn bollard lighting by PIR movement sensor lights at another SBD small housing scheme in Denton (South Norfolk). This did not affect the development’s SBD status. The Secured By Design Officer called the change “another success story” adding, “the amount of time the area will be illuminated has been significantly reduced”.
Insects caught in metal halide lighting
Prey seeking dead bat caught by hot lights
This is particularly important where housing is built in close association to areas of good habitat, particularly along the rivers including the Thames. Insects, attracted to lights, can be 'vaccumed' out of an area by inappropriate lighting and become unavailable as prey species for birds and bats. As Bob Mirzon (CfDS) remarked in  the opening address 'you wouldn't light your guinea pig all night'!

3 comments:

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