Many public transport companies operate old properties (depots, workshops, stations) with inefficient lighting. This can have a strong impact on energy efficiency, due to long operational hours.
Public transport operators can take advantage of several opportunities for replacing old lighting equipment with more energy-efficient technologies. Retrofitting outdated lighting components with energy-saving alternatives promotes sustainability and offers significant benefits.
Not only can ‘relighting’ improve the overall quality and functionality of light, it can also make spaces safer, easier and less costly to maintain, and more comfortable to work or stay in. Metro and light-rail stations require different types of lighting and more lighting power than consumer market equipment. Nevertheless, the newer and more expensive the lamp, the longer it lasts and the more energy-efficient it will be.
It is therefore recommended that an assessment is carried out on the type of lighting used and the need for replacement.
Light bulbs were the main type of lighting used in Europe before 1990. They are cheap to purchase but are also much less efficient than most other types of lighting. They convert less than 5% of the energy they use into visible light; the remaining energy is converted into heat.
Compact fluorescent lamps (CFL)Since around 1990, compact fluorescent lamps/lights (CFL) – also called energy-saving light – have been available to European consumers. Compared to incandescent lamps producing the same amount of visible light, CFLs use one-fifth to one-third of the electric power and they last up to nine times longer. When directly replacing fluorescent lights with more efficient CFL lights, there is typically no need to replace the light fitting itself. The new, more efficient light bulb can simply replace the old one.
Because this is a relatively straightforward operation, a replacement of this type is highly applicable in light rail and metro stations. CFL’s last much longer than conventional light bulbs, leading to lower on-going maintenance costs and so their whole life costs are much lower.
A LED lamp (or LED light bulb) is a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light. LED lamps offer long service life and high-energy efficiency, but initial costs are higher than those of conventional lights.
LED lighting made a commercial breakthrough around 2010. LED technology is very energy efficient, has low maintenance costs and has a long lifespan. LED lights have high investment costs but have lower whole life costs than most alternatives.
One reason for the high cost of installation is that the light fittings usually may need to be replaced. Since LED lamps have high investment costs, it is recommended they be bought in bulk through public procurement. Following a period of cautious adoption of LED solutions, their deployment has accelerated recently in the public transport sector and their costs continue to fall significantly.
Lighting control systems
In many places, such as stations, interchanges or workshops, lights can be switched off where and when there is sufficient natural light or when nobody is present on the premises. However most traditional systems were not configured to react dynamically to light levels throughout the day. Various lighting control systems are available and their choice will depend on the location:
- Occupancy control12 involves using a sensor to determine when people are in the vicinity, and reducing or eliminating unnecessary lighting if areas are empty
- Daylight responsive13 control uses photosensors that assess the amount and quality of natural daylight in a particular space
- Time clock control allows for the automatic control of lighting depending on the time of day (or night). Time clock control ensures that lighting levels are automatically set correctly for the coming time period.
Metro and light-rail stations are often illuminated for 24 hours a day, even at night when they are not operational and public access is prohibited. During this time, a station does not need lighting except for maintenance, safety and security reasons. Dimming or switching off lights can bring significant energy savings. One critical aspect to do with switching off lights during daytime or at night is that lighting must be kept at a certain level to ensure that security cameras (CCTV requirements) are working properly. This issue needs to be addressed if operators are to get the full benefit of these cameras and to prevent security and safety problems.
In a situation where all the lights are turned off in stations, motion sensors need to be installed: these sensors automatically trigger lighting when movement is detected. Appropriate design of the location of the sensors will ensure that they do not respond to passing trains. Motion sensors are a proven and extremely effective technology, greatly increasing the lighting energy efficiency of metro and light-rail stations.
It should be kept in mind that lighting controls are not always a good investment for minor locations, as their payback times may be long. Training people to turn lights off whenever necessary is still the most costeffective solution in some situations. In a new building or major renovation, it is recommended that a lighting control system be added; the costs of such a system can be rapidly recovered.
Fig. 31 – View of a lighting control system in a metro station, RET
12 Also known as PIR (passive infra-red).
13 Also known as photocells.