Dimming Lights have a Bright FutureSouth Ayrshire Council
SUMMARY Advances in modern lighting technology, along with changes in regulations, mean that it is now feasible to
achieve energy savings by means of varying street lighting. A trial on Holmston Road in Ayr proposed upgrades to old equipment, allowing adjustment of lighting levels to 60% of their full value between midnight and 6am. With a projected annual reduction of 19.42 tonnes of CO2, and savings of around £3,250 at current electricity prices, this project has been so successful that five further installations have been completed, and planning is underway for further projects.
BACKGROUND
Holmston Road in Ayr was lit by means of 250 Watt high pressure sodium lamps. These were housed in old, optically inefficient lanterns first installed in the 1980s, and were due routine upgrades/maintenance. A change in lighting standards, BS EN 13201 – Road Lighting, presented an opportunity that was too good to miss.
Why does variable light work?
The human eye has the ability to adjust quickly to different levels of illumination (lux). This can be seen when moving from an overcast day(10,000 lux) to a brightly lit room (500 lux). Considering this change, the shift from full street lighting to 60% dimmed is easily abated by the eyes’ natural response and gives an almost inperceptible difference in light level.
How it was done
The policy development was headed by Bobby Borland, a supervisory engineer in Lighting, and supported by our lighting engineer section. Advice and support from Lorraine Finlayson, Strategic Management Officer on equalities issues, for example in relation to visual impairment, was invaluable in the consultation process, and in acting as a critical friend during the preparation of the Equality Impact Assessment.
Consultation took place with local residents, community council groups, the South Ayrshire Access panel and the local Police. Research from the Scottish Government, the Institute of Lighting Professionals, and the Society of Chief Officers in Transportation, was considered alongside appropriate British Standards. Physical installation of the new technology was implemented over a period of two days. This required the replacement of the old lanterns’ inefficient optical/reflector systems, and fitting electronic control gear which allows varied light levels.
Challenges
One of the main challenges we expected was public dissatisfaction with the reduced light levels during the period of midnight to 6am. In planning the installation and consulting with the various shareholder groups, we explained the reasons behind the project and the scale of the savings achievable, both in terms of finance and the environment. Most of the post-installation feedback received was positive.
LOOKING AHEAD
The trial proved to be widely approved of by local residents with survey responses showing only one negative response on overall lighting quality of pre-dimmed lighting and none on overall lighting quality of dimmed lighting. Survey responses were collected by post and online.
Results
The table below shows the results of this project, illustrating clearly how beneficial this trail has been both to council coffers and to our commitment on climate change. The pay-back time of the project was estimated at five years, although this time scale will decrease proportionally with increasing energy prices.
Since completion, five other sites have been completed and are already making savings. Other projects are planned and will be implemented when resources allow.
Lighting the way
The Council has now implemented a policy of installing variable lighting in all main urban traffic routes where it is appropriate to do so. Trials of variable lighting are currently underway in an industrial estate, a rural village, a rural traffic route and a town centre street. If successful, variable lighting will be rolled out in these types of area throughout South Ayrshire
Plans are underway to replicate this and further trials with differing areas and lamp types, eventually equating to a definite saving both in carbon and money, year after year.
KEY CONTACTS
Lorna JarvieSustainable Development Policy OfficerTel: 01292 612297Email: [email protected] Bobby BorlandSupervisory Lighting EngineerTel: 01292 616256Email:
[email protected] Report to Leadership PanelConsultation results – To be updated
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Annual energy consumption per
unit
Annual energy cost per unit
Annual CO2 emission per unit
Previous Lighting Units
1,154 KWh £120.96 0.63 tonnes
New Lighting Units 505 KWh £49.06 0.27 tonnes
Annual savings over 56 units
36,344 KWh £4026.00 20.16 tonnes
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Our eyes have the ability adjust to different levels of
light
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