Reduced carbon emissions is just one of the advantages of using LED street lights, says Sandy Patience
That local authorities and even the Highways Agency are planning to switch off swathes of street lighting after midnight is a strong indication the Carbon Reduction Commitment Energy Efficiency (CRC) scheme is beginning to bite. Simply put, the ageing stock of mercury vapour and sodium street lights, estimated at around 7.4 million standards, is too expensive to run.
Environmentalists looking to reduce light pollution support the ‘Big Switchoff ‘, but it plays badly with those concerned with prevention of accidents and crime. An alternative approach could be to adopt the fast-developing LED-based lighting technology.
The technology is not completely unknown on the highways - LED traffic lights are already mature systems - but lighting a road with lots of diodes packed into a container is novel. There is no one-to-one diode-metal halide equivalent at present, so design effort is focused on evolving strategies for directing light from multiple small sources to the roadway below.
For customers, the foremost attraction is reduced energy demand and carbon emissions. One of the first local authorities to commit at a substantial scale has been Birmingham City Council, which intends replacing some 47,000 lighting points installed in residential areas with remote controlled LED lighting, while slashing their energy consumption by more than half of their current rate.
Other attractions include improved vision through the more natural broad-spectrum quality of light - providing relief from the orange glow that cloaks our nocturnal landscape. The familiar ‘hot-spot’ surrounded by dim light will also disappear as a more even distribution of light is provided through integrated optical lenses.
But it all comes at a price. Capital expenditure is higher than for conventional lighting and overall cost of ownership will depend on the veracity of claims of higher LED life expectancy. Though claims of around 100,000 hours abound, most warranties are limited to no more than five years - equal to 20,000 hours of operation.
- Sandy Patience is an architect and editor of www.greenspec.co.uk
The Crossover features LSI’s SmartTec intelligence platform which includes thermal control that continuously monitors and controls the device and driver temperatures. It also incorporates optical systems that enable the setting of light output to maximise the use of ambient daylight systems or equally, the precise light level needed.
Manufacturer LSI Industries
Product Crossover LED Roadway light -Medium (XRM)
LED type 119 Osram Golden Dragon LEDs
Light output 9900 lm
Watts 136.2W (efficacy 72.6 lm/W)
Colour accuracy 70
Correlated colour temperature 5750K
Lifetime Minimum 60,000
Country of manufacture US
Housing L 885mm; W 419mm; H 140mm
The Piano features the LensoFlex photometric engine. The system is based upon the ‘addition principle’ of light distribution. Each LED associated with a specific lens generates the complete photometric distribution of the luminaire. It is the number of LEDs that determines the intensity level of the light distribution.
Manufacturer Urbis Lighting Lamp Piano 2
LEDtype 96 x Cree XP-E
Lightoutput 10,944 lm
Watts 128W (efficacy 85.5 lm/W)
Correlatedcolour temperature 6000K
Lifetime Minimum 60,000 hours at L80 with a maintained luminous flux at Ta=35°C
Country of manufacture Portugal
Housing L 1110mm; W 307mm; H 87mm
Suitable for side-entry, suspended or post-top installation, this versatile luminaire fits every application. Multilayer optics provide uniform distribution and reduced glare, allowing direct replacement of HID solutions without compromising on spacing, mounting height or light quality. The luminaire’s internal architecture makes maintenance straightforward.
Lamp LEDGine City Soul BGP431 GreenLine
LEDtype 112 x LED Lumiled Rebels
Lightoutput 11,760 lm
Watts 130W (efficacy 76 lm/W)
Correlated colour temperature 4000K
Lifetime Lumen depreciation at Ta=25°C @60,000 hours is 86 per cent
Country of manufacture France
Housing L 754mm; W 480mm; H 196mm
Utilising multiple, high-powered white LED chips and an enhanced thermal management system, the Marlin 1000 maintains its efficiency for a much longer period. It also features a robust construction that is more resistant to impact, vibration and vandalism than traditional street lights.
Manufacturer Advanced LEDS
Lamp Marlin 1000
LED type 10 x Cree MCE
Light output 4485 lm
Watts 65W (efficacy 69 lm/W)
Correlated colour temperature 5000 K
Lifetime L70 minimum 110,000 hours
Country of manufacture UK
Housing L 645mm; W 345mm; H 120mm
Warranty 25 years
Independent laboratory testing shows that Stela street lights reduce energy consumption and cut carbon emissions by up to 78 per cent compared to traditional street lighting. Installed by 80 local authorities, Stela installations save more than 50 tonnes of CO2 and 90 megawatt hours of energy per month.
Manufacturer Indal WRTL
Lamp Stela Long
LEDtype 30 x Cree XPG
Light output 4200 lm
Watts 37W (efficacy 113 lm/W)
Colour accuracy 75
Correlated colour temperature 5700K
Lifetime L85 100,000 hours
Country of manufacture EU
Housing L 620mm; W 265mm; H 120mm
Warranty 100,000 hours
Installing lighting points that generate their own power is a logical move. The SunMast integrates solar cells into the body of the mast. The mast is connected to the grid so that during daylight hours it exports electricity to the grid while drawing from it at night.
Standard SunMast WP600
PV type Monocrystalline cells
Number of cells (10m mast) 150
Nominal power output (10m mast) 600Wp
Dimensions H 10413mm; W 200mm; D 200mm
Mast core and flanges Galvanised steel
Luminaire The standard can be used with most types of common outdoor luminaire.
Country of manufacture Denmark