BENCHTESTS
What the Victorians did for us…

…was give us awkward wrappers in which to put state-of-the-art LED engines. But one Oldham-based manufacturer of heritage lanterns has successfully fused Victoriana with the latest in solid state lighting technology. Ray Molony reports

Formed in 1983, Oldham-based Metcraft Lighting is your classic heritage lantern manufacturer, full of skilled craftsmen using time-honoured skills learned over generations in the fabrication and foundry industries.

The challenge for companies such as these is to integrate the LED technology into a wrapper designed for a totally different technology: gas. Easier said than done, especially when it comes to optics.

Cleverly, the company has worked closely with Philips to develop the range and has decided to base its LED offer around the Dutch giant’s Fortimo LED engine.

‘It’s very difficult to create lenses with individual LEDs, especially ones that are going to give you a perfect batwing distribution,’ says Metcraft chief Phil Carr. ‘The Fortimo works more like a lamp, so it’s much easier for us to harness optically.’

The company developed a six-piece variable optic to get the distribution it wanted.

The company has been keen to ensure the fittings are future-proof. ‘You can spend huge amounts of time bringing an LED fitting to market and then discover six weeks later that is has been superseded by another luminaire,’ says Carr.

‘We do a lot of private finance initiative schemes, and we always get asked how long the LEDs will last. But we reckon in about eight or nine years, local authorities will want to upgrade the light engine to the latest version of the Fortimo. In the future you’ll be able to change the modules from 33W to, say, 20W so we have designed the heatsink with this in mind.

‘We anticipate Fortimos with 8,000, 12,000 and maybe 16,000 lumens.’

Carr says the company hasn’t been chasing a hero number for its lumens-per-watt rating. The creation has been more about balance. Still, the efficacy is respectable considering the awkward shape of the heritage luminaire. We tested two versions: one using the 3,000 lumen Fortimo and one with the decidedly more pokey 4,500 lumen package.

Our results show that from the 3,000 lumen version, some 2,349 lumens (an LOR of 78 per cent) get out to do some useful work. That’s an efficacy of 63.6 lumens per watt, not groundbreaking but something a street lighting engineer could live with in a conservation zone.

The 4,500 lumen version performed proportionally worse, with 2,968 lumens, or 66 per cent, escaping the post-top design. That’s an efficacy of just over 60 lumens per watt. To put that in context, we’ve recently tested LED downlights with 9 lumens per watt. If you can’t manage the heat well, you’re in for a disaster with LEDs. The good news with heritage lamps of course is that there’s plenty of space for slabs of metal to drain away the lumen-sapping heat.

Because it’s white light, the fitting lets street lighting engineers drop a code, and the luminaire will work up to the S2 class.

 

POWER (NOMINAL) 33W/55W
POWER FACTOR (NOMINAL) 0.95
CRI 74
LED ENGINE Philips Fortimo 3,000lm or 4,500lm
EFFICACY Up to 63.6lm/W
OUR VERDICT ★★★★
We really like this. An elegant marriage of Victoriana with a state-of-the-technology LED engine. The heat is managed well, the efficacies are good and it’s upgradeable to future versions of the Fortimo. What more do you want?

 

HOW WE DID THE TESTS

The benchtest took place at Lux magazine’s official test house, the highly respected laboratories of 42 Partners in Wolverhampton. The tests were conducted in a 3.5m integrating sphere, one of the largest in the UK, and all measurements were taken in accordance with EN13032. The photometric centre of the luminaire was taken as the geometric centre of the front face of the white panel. The photometric nadir was taken to be perpendicular to the base of the luminaire. The luminaire has been treated as though it has one plane of symmetry through the 90°/270° plane. The lumen output and power consumption of the luminaire were determined at 25°C after 100 hours of pre-conditioning.

42 Partners
21 Woden Road
Wolverhampton
WV10 0AU
UK
Tel: +44 (0) 1902 453650 richard@42partners.com ian@42partners.com

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