This review is about luminaires that operate at an ambient temperature of 50ºC. Before you say it is never 50ºC at night, consider the temperature the body of the luminaire will be when it is first switched on – after it has been in direct sunlight all day.
We looked at some of the best floodlights and streetlights for these conditions. The manufacturers all provided good, solid technical data to support their claims.
Unshaded metal, such as floodlights and streetlights, can reach very high temperatures during the day. A luminaire body temperature of 70ºC is commonplace in the summer in the Middle East. A professional engineer I spoke to has measured over 100ºC in Saudi Arabia.
Night-time temperatures of 35-40ºC are common – I know, I’ve lived there. As the luminaire ‘cools’ in the evening air, the light source switches on and generates heat, and so there is only a very gradual reduction to the operating temperature.
If you are specifying equipment to be used in these temperatures, there are several things you should check.
One of the most basic is to get data sheets that show suitable operation at 50ºC. The light output of LEDs drops as the temperature increases. This reduction should be stated somewhere on the data sheet. Alternatively, some manufactures limit the drive current (in effect, the wattage) for high ambient temperatures. This is quite common. There may be a reduction in the rated life. Again, this should be checked.
The next would be to see if there are any case studies of identical or very similar luminaires in the same environment. Do remember the importance of wattage. A 10W streetlight may work fine but a 50W version in the same body might not.
Get a sample and use your professional judgement to decide whether there is a clear, unobstructed heat path from the back of the LED to the outside air. Large heatsinks are always a good sign but only if free air can flow over them. A heatsink in a sealed enclosure won’t cool nearly so well. Active cooling – a fan, for example – is a good way to remove heat. People I have spoken to are split as to how reliable fans are. Some say a motor is inherently less reliable and others ask: ‘When have you ever known a fan to fail?’
Finally, always take a good look at the driver and its position in the luminaire. Many people say the driver is the weakest link in the system. If you can mount the driver remotely and away from direct sunlight (not inside the column), it should run much cooler. Most LED drivers have a thermal sensor that will reduce the power to the LEDs if they get too hot.
CU Phosco FL800R
This floodlight has a series of LED modules that can be run at different outputs from 45 to over 500W. It is the most powerful of the luminaires tested in this review. Each module has eight optical distribution options and a range of elevation angles so you can build almost any kind of photometric output you require. A useful feature is the large cowl on top that cuts off the light at five degrees below the horizontal to prevent light pollution.
Its main application is for high-mast lighting and the sales literature says the FL800R is suited for 10-50m mounting heights. The maximum delivered light output (at 25ºC) is over 67,000 lumens. It would be ideal for airport aprons, sports stadiums and large road junctions. This floodlight is currently used at the Airbus A380 stands at Dublin and Heathrow airports.
CRI is >70 and the standard CCT is 5700K.
A lot of work has also gone into the design of the gear box. As well as being able to accept four LED drivers, there is space for a range of photo-cell, CMS (central management system), Dali and other control methods.
DW Windsor Zeppa
This is a new LED streetlight from DW Windsor and ranges in wattage from 7-144W so it can be used anywhere from small residential streets with 4-6m columns to dual carriageways and motorways where 8-12m columns would be used. There are three different optical distributions, all designed for road lighting (P, C and M Classes) and car parks.
The three body sizes can be either side-entry or post-top mounted and DW Windsor has made a special effort to make installation and maintenance easy. This is especially important where work must be done quickly during lane or road closures.
The CRI is >70 in the 4000K version and >80 in the 3000K version. This last one would be ideal for residential areas.
The control gear is in a separate compartment from the LEDs and has a range of control options.
iGuzzini has a huge base in the Middle East with four divisional offices and seven commercial agencies/partners in other countries. Product testing is also done locally. Unsurprisingly, they have several complete ranges of products suitable for the Middle Eastern weather.
I chose the Wow streetlight because it is one of the few luminaires approved by Ashghal, the public works and roads authority in Qatar. This standard requires >100 lm/W at 52ºC.
The Wow is designed principally for residential and traffic route lighting. There are three power ratings and light output is in the range 14,000-17,000 lm. CRI is >70 and the standard CCT is 4000K. There are four road lighting optics and two for applications such as parking areas, roundabouts, public squares. The lantern can also be tilted ±20 degrees in five-degree steps.
Kingfisher AEC Italo 1
This, also, is mainly designed for residential and minor traffic route lighting. There are several power ratings and light output is in the range 2,000-10,000 lm. CRI is >70 and the standard CCT is 4000K (3000 and 5700K are also available).
There are six road lighting optics depending on the proportions of the road relative to the column height.
What I like about Kingfisher’s data sheet is that it gives correction factors for lumen output, life and power at different ambient temperatures.
Osram Siteco floodlight FL20
Siteco is now part of the Osram group. The Floodlight 20 comes in three variants, Micro, Mini and Midi. Typically, the Micro is 3,000 lm and 29W; the Mini is 6,000-12,000 lm, 56-107W; and the large Midi 18,000-27,000 lm, 163-238W.
Although described as a floodlight, some of the optical distributions can be used for traffic route lighting. The Midi can also be used for sports lighting.
In effect, the FL20 comprises two sections. One is the IP66 lighting module containing the LEDs, and the other is the driver section that also houses any control systems and the mounting brackets/clamps.
CCT is available from 3000-5000K with CRI from 70 to >80.
All these packages come in a Basic and Plus version. The former simply switches on and off. The Plus version can have a built-in factory preset and programmable timer for output reduction in two steps. It can also be integrated into existing digital control and CMS systems.
There are already installations of this streetlight in Abu Dhabi. The SpeedStar has been specifically aimed at municipalities for energy-efficient, functional, low-maintenance streetlighting. It is said to be CO2 neutral. The LEDGINE driver and LED module is easily replaceable, so future increases in efficiency can be incorporated without changing the whole luminaire.
There are five road lighting optics and wattages from 27-256W with 16-80 LEDs. CCT ranges from 3000-5700K and CRI from 68-84. Lumen output is from 2,400-28,700 lm (at 25ºC).
Like many modern, up-to-date streetlights, one of SpeedStar’s strengths is the compatibility of its driver with almost any control system.
Urbis Schreder Ampera
One of the biggest transformations LEDs have made to the lighting market is that a single luminaire design can contain a wide range of LED modules with different optical distributions. Whereas an HID lamp might be available in 70, 100, 250 and 400W versions, a modern LED streetlight can have many more intermediate versions that can also be fully dimmed.
The Ampera is a good example of how a traditional HID roadlighting manufacturer can make the best use of the possibilities LEDs offer. There are three versions: the Mini, Midi and Maxi. The nominal LED flux, which will drop depending on the temperature and other factors, ranges from 1,000-31,000 lm in the Maxi. This represents about 10 to 279W across the whole range.
As well as the usual range of streetlighting optics, which cover anything from a cycle path to a motorway, the Ampera has an optic designed for pedestrian crossings called the Zebra. This has a focused light beam that creates a true contrast between the pedestrians and the surroundings.
- High temperature fittings will be dicussed and exhibited at this April's LuxLive Middle East 2016 exhibition and conference at the Abu Dhabi National Exhibition Centre on Wednesday 13 April and Thursday 14 April 2016. Entry is free if you pre-register here.