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Implementing energy-efficient street lighting

A close review and monitoring of the current conditions of the public lighting system can produce surprising results. Several actions can greatly improve the energy efficiency of the whole system.

Street lighting meets several societal needs, including the safety of road users and security of citizens at night, and is a very important service, provided in most cases by local municipalities. It is extremely important that the lighting system can effectively perform its function with the most efficient energy use while providing security during the hours of darkness.

Street lighting accounts for a small portion of energy consumption for an entire country. However, it has a greater impact on the energy bill of each municipality, where the energy consumption of the street lighting system can be a substantial portion of the total energy consumption in medium-sized towns.

Interventions in street lighting systems are easy, particularly in small to medium cities where the system is under the direct control of the city or city contractors. The potential for energy savings can be considerable while producing a reasonable return on investment.

The following actions contribute to a more efficient and less impacting lighting system:

  • Audit the whole system by collecting aerial data (this may be expensive) to check the effectiveness of different solutions implemented in different areas, check the system’s reliability, uniformity of light, colour of light and its directionality.
  • Maximise the usage of light and avoid directing any light to less useful areas/directions. ‘Useful light’ can be greatly increased by improving the directionality of the luminaires and eventually repositioning them.
  • Avoid overlighting and reduce lighting levels to actual needs. This is an effective option to maximise energy saving in the long term. Consider standards and applicable laws, and work with the public to agree to real needs.
  • Select lamps with high energy-efficient technology. Consider cost-efficiency with regards to durability, colour of light, need for replacement, general maintenance and luminous efficacy.
  • Implement night dimming by reducing lighting late at night.
  • Use sensors, like motion sensors, weather sensors and others, to reduce light and energy consumption in times of low presence. An ‘intelligent street lighting’ system includes measures that increase energy effectiveness by adapting the light output at each point of the installation according to needs over time and other defined criteria, such as switching on or off to a pre-set schedule (for example, seasons, days of the week).

These actions will also contribute to a decrease in light pollution, an environmental issue frequently ignored, due to the veiling effect of light emitted upwards from luminaires on the ground, onto buildings or infrastructure.

All public administration bodies can implement these strategies, directly or through private contractors managing the lighting network. This does require some investment, but it will produce a great benefit in energy savings as the effects of a one-time investment may last for several years.

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