Bright Idea? Shining a Light on Rebound Effect of LEDs.
Light-emitting diodes (LEDs) have been gaining increasing popularity and usage across the globe. Initially, the LEDs were invented almost a hundred years ago in the 20th century [1]. Compared to fluorescent lamps, LEDs offer many more advantages including safety, durability, and energy efficiency. LEDs are safer because of its temperature, its cooler, which reduces the risk of combustion or burnt skin. They are also resistant to breakage due to the epoxy lenses they are made of [2]. The LED lights use just 20% of their energy to generate heat, and the rest 80% is utilized for creating whiter light [3]. While LED advancements existed for long time, it was not popular until the 2010s, when LED prices started declining and consumers started buying them in large volumes [3]. As a result, by 2010, LED lights saw widespread adoption for commercial properties and public spaces because it is initially expected that there would be an increase in cost savings and a significant reduction in energy consumption. However, due to the Jevons Paradox, LEDs have instead created light pollution over the years [3].
Due to its price elasticity, changes in costs of lighting have a significant effect on the quantity of the LEDs demanded. Represented on the chart below, when costs are reduced due to the emergence of LEDs, quantity demanded for LEDs increases more than proportionately. The dramatic decline in costs reflects the same dramatic increase in efficiency. Before the development of LEDs, it was just too expensive to consume much lighting so most people lived in near complete darkness except from the sun and the moon which was long time ago.
For example, in 2000 in the UK, lighting was more than 100 times time more affordable than it was in 1900, considering adjustment for inflation. Moreover, it was 3000 times more affordable than in 1800 as electrical power became more advanced and efficient [4]. As a result, an average citizen of the UK consumed 75 times more artificial light than their ancestor in 1900 [4]. The increase was driven by the outdoor light installations and buildings advancements.
Besides the rebound effect that led to overconsumption, the LED lamps installation caused other environmental issues [5]. While efficient, the LED lights emit more blue light that scatters more in the atmosphere, contributing to a 9.6% increase in ski brightness from 2011 to 2022 [5]. It was proven that before the transition to LED light, the sky was 60% darker. Besides causing human health issues, high emission of artificial lighting impacs animals and their habitats. For example, due to the light pollution, sea turtles and birds guided by moonlight during migration get confused and lose their way [6].
To prevent the rebound effect or the Jevons Paradox, it is recommended to choose LEDs with warmer color temperatures that emits less blue light and use minimum brightness. On the regulations side, what could have been done is setting a maximum lumen output standards for different lighting applications in the commercial areas to prevent overlighting. Another way to regulate it is subsidizing transition to warmer LEDs through utility rebates and tax credits. Finally, requiring outdoor lighting to be shielded and directed downwards to prevent uplight.
