Replaceable GU10s ‘may be better for environment’, says Arup
A luminaire with replaceable GU10 lamps may have a lower environmental impact than one with an integrated LED module.
That’s the surprising finding of a survey prepared by Arup for a client.
The practice compared a downlight with a fixed LED to one with a GU10 lamp. It worked out that over a lifespan of 27 years, the lamp option had a total global warming potential (GWP) of 26 kilograms while the one with an integrated source had an impact of 33.5 kilograms.
While the use phase carbon impact was similar, at around 15 kilograms, the big difference was the additional driver in the integrated downlight. This had embodied carbon on 7.3 kilograms.
The survey assumed a lifespan of both fittings of 50,000 hours, luminaire use at five hours a day, a similar light output and a carbon factor of 0.15 for the location of the proposed building.
The GU10 lamp lifespan is 10,000 hours so the life cycle assessment assumed that five lamps would be required in the 27 year period. It was also assumed that all five lamps would be recycled.
The LED driver has a life span of 100,000 hours with a 10 per cent failure rating, so 1.1 drivers would theoretically be consumed in the same period.
Natalia Duffy, senior Lighting Designer at Arup, said she was ‘surprised’ by the findings.
The embodied carbon of both luminaire bodies is the same for both options.
‘Even changing the lamp five times, you’re still better off from a carbon perspective,’ she said.
‘This is because the carbon footprint of the lamps is small compared to the luminaire.
‘The client still has to make a decision if they’re happy with having a lamp-based installation that requires maintenance’.
Duffy was speaking at a meeting about sustainability organised by the International Association of Lighting Designers.
Commenting, Duffy says ‘the issue isn’t black and white. In this case, replaceable lamps turned out to have a lower environmental impact, but it won’t necessarily be for all cases.
‘It’s worth challenging your assumptions on every project, as results like this can be surprising.’
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