Why LEDs haven't yet cut energy use for lighting

Waterford, Ireland's Altitude bike shop owner Eamon Barrett advises lighting up a bike to sell it. In brilliant light, the technicolour paints, chrome, and fresh spokes shine.

Mr Barrett started to dislike having fluorescent lighting on all day to promote a green mode of transportation.

Three years ago, he switched Altitude's showroom, workshop, canteen, and back offices to LED lighting for efficiency.
Some rooms now have motion sensors that turn on lights when someone enters. Partially powered by modern solar panels and a battery.
"It's a win-win," says Barrett. "The quality of the lighting is better." He claims a 35% reduction in his annual electricity bill. Mr. Barrett says that saving would be even higher without Russia's invasion of Ukraine, which skyrocketed energy prices.
LED lighting is decades old, but few businesses have installed it. Upfront switchover costs contribute to that. Mr. Barrett paid €10,000 (£8,800; $10,900) on new lighting for his 6-7,000-square-foot home. He expects it to take seven years to repay this and the solar panels and battery costs.

LEDs reached a milestone last year.

They represented 50% of global lighting sales, per the International Energy Agency. Since more individuals are installing electrically-powered lighting than ever before, lighting energy consumption is rising. Latest LEDs are ultra-efficient, yet we may need to do more to reduce lighting energy use.
"The number of lights used in each household is increasing," says Imperial College London's Grantham Institute's Shivika Mittal. "That is offsetting switching to LED."
She believes many Western homes have LEDs. Commercial buildings take longer to convert. Government policies may encourage business switching. Lighting with smart systems like Mr. Barrett's motion sensors saves even more energy, she says. This could reduce world lighting energy use.
Picnic tables are made from recycled plastic by Marmax Products in County Durham. The company switched from incandescent bulbs to LEDs in its warehouse and offices last year. "We felt like we were helping because of our product range," explains general manager Dave Johnson. An energy reduction assessment suggested LED lights. "You can always do more," says Johnson.

Electric lights are efficient if they emit lumens per watt of energy.

Paul Scheidt, senior product marketing manager at Cree LED, a prominent lighting producer, says white LEDs had 20 lumens per watt in the early 2000s.Cree LED introduced 228-lumen-per-watt white LEDs in March. LEDs use most of their energy to produce photons, while incandescent lamps spend 90% to heat.Warm-toned LEDs have lower efficiency, but warm white luminaires with a colour temperature of 2,700 kelvin can still produce 160 lumens per watt, according to Mr Scheidt. However, additional improvements are predicted. Dr. Mittal estimates these lights' efficiency might increase in 20 years.
In some places, updating old lighting is difficult. Gemma Lighting was consulted on exterior and street lighting for London's Stamford Hill Estate earlier this year.

We found 10% of the original lights functional when we surveyed the site.

Marketing manager Piers Lowbridge believes it generated several dark patches. The ancient lights were SON lamps. All over 100 fittings are now LEDs.
Mr. Lowbridge believes the old lights would have consumed 341,000 kWh per year if they had all worked, enough to power more than 120 average British houses. The new LEDs use 36,000 kWh yearly, a 90% savings.
The switchover cost £34,500, but Gemma Lighting estimates that the previous bulbs would have cost £115,000 per year to run, including maintenance overheads, if they were all working.
The business has announced a grid-free solar-powered street light. It has a motion sensor and light sensor to turn on only at night. This raises the light fitting's brightness from 30% to 100% when a vehicle or human passes.
LEDs emit blue light, which can cause sleep disturbances and disorders. Even warm-toned luminaires emit blue light. According to Dr. Karolina Zielińska-Dąbkowska of Gdańsk University of Technology, our eyes feature blue-sensitive photoreceptors.