LEDs are 90% more efficient than modern incandescent bulbs. Their rapid uptake has resulted in measurable cuts in energy demand and emissions. But their plummeting cost over the last ten years is also causing a “rebound effect” where people are using more and more LEDs, not least for outdoor lighting. Lucas Davis at the Haas School of Business believes we must embrace it, even if it’s counter to maximising energy savings. More and brighter lighting for our homes, businesses and public spaces can make us happier, more productive, and safer. Davis presents a fascinating history of the falling price of lumens, going back to the stone age when it took 60 hours of labour to generate 1,000 lumen-hours. Wax candles dropped that to 5 hours of labour for the same lumen-hours. The first incandescents dropped it to 0.01 hours of labour in the 1880s. One study calculates lighting consumption per capita in the UK increased 6,500 fold between 1800 and 2000. If some rebound effects from big efficiency gains are going to happen, this is one worth having, says Davis.
LEDs are great even if they won’t necessarily result in large net energy savings.
LED technology is exploding, enabling entire new categories of lighting. My favourite example is the new “bulbs” that screw into regular sockets (E26/E27), but use multiple LED panels to supersize the total lumens.
One of the best sellers on Amazon is a 120-watt “bulb” that produces 12,000 lumens. Let me pause for a second to let that sink in. An old-school 60-watt incandescent bulb generates 800 lumens, so this is 15x brighter! It is so bright that the instructions warn users to avoid looking directly at the light due to potential eye damage.
Yes, there’s a “rebound effect”
I’m sure it won’t be long before someone cries “rebound effect”. Indeed, these new bulbs are a perfect example of how an improvement in energy efficiency can spur increased use. Replace your incandescent with one of these and your energy consumption goes up, not down.
But even if LEDs don’t result in large net energy savings, they are still creating immense economic value. For today’s post, I want to celebrate all this LED innovation. LEDs are the latest example in a long history of humans finding ingenious ways to consume more lumens. More and brighter lighting inside and outside our homes and businesses, and throughout our communities can make us happier, more productive, and safer.
A history of the falling price of Lumens
LEDs are the latest chapter in a long history of technological innovation in lighting. In a pioneering 1996 paper, Nobel laureate economist Bill Nordhaus traces how the price of light has fallen throughout one million years of human history.
- When light came from open fires, the price of lighting was that you had to gather wood. Nordhaus calculates that it took 60 hours of labour to generate 1,000 lumen-hours.
- The Greeks and Romans had wax candles. A typical wax candle puts out 13 lumens, and, according to Nordhaus’ calculations, wax candles require 5 hours of labour to generate 1,000 lumen-hours.
- Oil, gas, and kerosene lamps were developed in the 1800s, pushing down dramatically the effective price of lumens. Depending on the source of fuel, Nordhaus calculates as low as 0.2 hours of labour per 1,000 lumen-hours.
- Enabled because of the developments in electric power, carbon-filament, and tungsten-filament light bulbs were commercialised in the 1880s and 1920s, respectively. These innovations pushed the price lower still, to 0.01 hours of labour per 1,000 lumen-hours, by Nordhaus’ calculations.
- Even with little additional technological innovation in light bulbs between the 1920s and 1980s, the effective price of lighting continued to drop precipitously as wages increased and electricity prices declined.
- By the time CFLs arrived in the 1990s, Nordhaus calculates that it took only 0.0001 hours of labour per 1,000 lumen-hours, about 600,000 times cheaper than it was for prehistoric man gathering wood for open fires.
Rising consumption of Lumens
At each step of the way, humans have increased their consumption massively. Economists Roger Fouquet and Peter J.G. Pearson calculated that lighting consumption per capita in the United Kingdom increased 6,500 fold between 1800 and 2000.
Over these long time periods, it is hard to perfectly disentangle falling prices and rising incomes, but there is no question that the rebound effect for lighting has been very large. Before the development of modern lighting, it was simply too expensive to consume much lighting so most people lived in near complete darkness except from the sun and the moon.
Thus, these new supersized bulbs and other innovations with LEDs are the natural next step in this long-running human thirst for ever increasing quantities of lumens.
The Department of Energy says that LEDs “use up to 90% less energy” than traditional incandescents. The DOE is not wrong. But, what they have in mind is very short-run: (1) unscrew an incandescent and (2) screw in an LED that puts out the same quantity of light.
Over the long-run, there are countless ways for people to use more lighting, just as they have responded to lighting innovations throughout history.
Just the beginning
My sense is that we are just beginning to see what is possible with LEDs. Yes, LED technology has been around for a long time, but it was not until the 2010s that LED prices started plummeting and consumers started buying them in large volumes.
It has taken time for LEDs to saturate the different lighting categories. Commercial bay lighting, recessed lighting, under the counter lighting, LED strip lights, rope lights, grow lights, ambient lights, flood lights. Across countless categories, there are smart entrepreneurs developing new LED technologies.
It will take time. We won’t all rush out immediately to buy a bunch of LEDs for every possible usage. But, over time, as homeowners, landlords, and business owners remodel their buildings, you can bet that they will add lighting.
Outdoor lighting is particularly ripe for price-induced increases in consumption, despite real concerns about light pollution. Maybe it didn’t make sense to have so many lumens in your backyard before, but now it probably does. And wouldn’t it be nice to have brighter street lighting, particularly in areas with lots of pedestrians and cyclists?
How much farther can this go? I don’t know. But historical precedent shows that humans have an almost insatiable appetite for ever larger quantities of energy services.
Lucas Davis is the Jeffrey A. Jacobs Distinguished Professor in Business and Technology at the Haas School of Business at the University of California, Berkeley
This article is published with permission
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