Urban lighting: upgrade or replace?

Uneasy choice between high short-term costs and long-term savings

By Morand Fachot

Lighting for the residential, commercial, industrial and public spaces is undergoing a radical transformation with the introduction of new lighting solutions. Users are often faced with an alternative: buying new systems, upgrading or adapting existing installations. Several IEC TCs (Technical Committees) and SCs (Subcommittees) are preparing International Standards for many components used in lighting installations to ensure these get more energy-efficient.

Illuminating city landmarks with LEDs (Tower Bridge, London, Photo: GE) Illuminating city landmarks with LEDs (Tower Bridge, London, Photo: GE)

Different environments, multiple needs

Until the emergence of entirely new types of energy-efficient lighting systems and public policies aimed at cutting the growth in energy consumption, homeowners, businesses or public authorities had little choice but to rely on long-standing and tested solutions.

Homes mainly used very inefficient incandescent bulbs, of the tungsten or halogen sorts. They are now shifting to more energy-efficient CFLs (compact fluorescent lamps) or LED lamps as incandescent bulbs are being phased out.

In office, commercial, industrial or public spaces fluorescent tubes, incandescent bulbs and HID (high intensity discharge) lamps are used, as well as other light sources such as incandescent, halogen or CFLs for task lighting.

HID lamps are also used in warehouses, outdoor areas, parking lots, pathways, etc.

Public institutions also manage extensive lighting assets for outdoor use.

These are large consumers of electricity and many authorities are looking at ways of cutting their energy and life-cycle maintenance bills. The choice they face is between refurbishing, renewing or replacing parts of, or whole installations, with the decision down to costs, and sometimes taken according to short-term constraints rather than long-term considerations.

IEC TC 34: Lamps and related equipment, and its four SCs prepare International Standards for all kinds of lamps and associated gear, such as lamp caps and holders, and for auxiliaries like ballasts and luminaires. Their work makes lighting equipment interchangeable and safe to operate.

Street and city lighting – a power-hungry environment

In addition to operating lighting installations for offices, buildings for emergency services or indoor sports facilities, public institutions have to manage extensive and complex urban lighting networks and equipment. These are necessary for city and street lighting, traffic lights and signage for roads, bridges and tunnels, as well as for public spaces.

The resulting operating costs for the energy consumed, servicing and maintenance of urban lighting installations may represent a significant burden in the long term and authorities everywhere are looking at ways of cutting these.

Operating costs, rather than initial capital costs, are often the deciding factor in the refurbishing, upgrading or replacement of lighting assets.

As regards office space or other premises the replacement or upgrade of energy-inefficient lights can be adopted to cut energy bills. The same easy solution does not apply to urban lighting which is a demanding and power-hungry environment, in the US, for instance, it consumes 8% of all the energy generated in the country.

Urban lighting is complex as it must meet many needs such as helping pedestrians and road users find their bearings and move around safely, illuminate architectural landmarks or outdoor areas, such as parks or sports grounds, provide light at entrances and all around buildings, etc. To fulfil these needs different types of fixtures are needed, such as recessed or low and high column or catenary luminaires for orientation or road lighting, spots or floodlights to illuminate facades, wall luminaires, traffic lights, etc.

As public institutions in many countries are looking at meeting sustainability targets and at providing the proper level of services expected by local residents with more limited resources, street lighting installations, that may account for as much as 40% of their electricity bill are seen as opening possibilities for long-term savings and good returns on investments. LED-based lighting solutions in particular offer radically new prospects not just by saving operating costs, but also as they may transform completely public outdoor lighting by introducing tailor-made and smart solutions.

Smart lighting for smart cities

Outdoor urban lighting, for streets and paths, and other applications still uses mainly HID lamps like low- and high-pressure sodium vapour lamps and metal halide lamps. These lamps present the advantages of having long service lives when properly powered and high luminous efficacy, but present a number of shortcomings in terms of light quality, power consumption and flexibility. Low- and high-pressure sodium vapour lamps have poor colour rendering as they appear bright yellow or intense pink orange when warm. Metal halide lamps provide a whiter light and are used for wide area overhead lighting of commercial, industrial and public spaces.

However HID lamps cannot be dimmed and may see their service life more than halved if switched on and off frequently. A number of cities and local authorities are looking at phasing out these lamps and replacing them with LED-based solutions. Key drivers for the change are the dramatic fall in the price of LED lamps, public policies pushing energy efficiency and investments in smart city infrastructure that will integrate smart street lighting systems.

 Smart street lighting systems are equipped with control nodes that, in combination with various sensors, allow for the remote on/off switching and some level of dimming control.

IEC SC 47E: Discrete semiconductor devices, prepares International Standards for components used in a variety of sensors. As for IEC SC 23B: Plugs, socket-outlets and switches, it prepares International Standards for HBES (home and building electronic systems) switches that can be used for the operation of lamp circuits and dimmers. Pike Research, a market research and consulting company that provides analysis of global clean technology markets, estimates that more than USD 100 billion will be spent in the next 10 years to support smart city development and that "the power and communications ability of a smart street lighting system can provide the backbone for many smart street applications".

The company forecasts unit sales of LED street lights to grow by 24,9% a year between 2012 and 2020, from fewer than 3 million to more than 17 million units.

Balancing tight budgets and saving needs

A number of initiatives, at a city level or grouping several urban communities, sometimes in different countries, are looking at the opportunities and costs of introducing LED street lighting and smart lighting projects.

The US city of Pittsburgh, Pennsylvania, published its LED Street Light Research Project report in September 2011. The city operates some 40 000 street lights at a yearly electricity and maintenance cost of approximately USD 4,2 million. Replacing these mainly HID lights fixtures with LED systems is expected to save an estimated USD 1,7 million a year in reduced energy and maintenance costs and to cut CO2 (carbon dioxide) emissions by 6 818 tonnes a year.

However, following a pilot project it appears that switching from the current system to the more advanced LED lights, even if smart solutions are not introduced, is a complex procedure. Unlike luminaires found in households and many offices, which allows CFLs or LED lamps to replace incandescent light bulbs, LED systems cannot be installed in existing street fixtures designed for HID lights, as they require electronics and ballasts of a different kind. Furthermore, luminaires for current lamps do not have reflectors or lenses that can control glare from LED lamps or provide the right beams and must be replaced. Therefore, the whole conversion appears quite costly.

However, an important factor to be taken into account is the extremely long life of LED-based street lighting solutions. AmberGreat Electronics' LED street lights of the Aries series, for instance, have a lifetime of 60 000 hours, equivalent to being on 12 hours a day for over 13 years without dimming. Reduced maintenance, replacement and power costs make LED street lights attractive solutions in the longer term. The choice between high short-term capital expenditures and long-term maintenance, operating and energy savings may not be an easy one for many public institutions that manage very large urban lighting assets as they also try to keep their budget under control. Whether the introduction of energy-efficient and smart lighting appears sooner or later, the IEC’s work will ensure its components will be as interchangeable and as safe to operate as possible.

Illuminating city landmarks with LEDs (Tower Bridge, London, Photo: GE) Illuminating city landmarks with LEDs (Tower Bridge, London, Photo: GE)
LED modules are now used in traffic lights (Photo: OSRAM) LED modules are now used in traffic lights (Photo: OSRAM)
LED Street lighting used with sensors helps cities cut electricity bills (Photo: Philips) LED Street lighting used with sensors helps cities cut electricity bills (Photo: Philips)