We Made Lighting Cheaper, So We Used More of It

In We’re Squandering LEDs’ Potential to Save Our Night Skies, Paul Bogard examines how cities turned an efficient, controllable technology into another source of excessive light.

“The more bad light we add, the more bad light we think we need.”

LEDs can use up to 90 percent less energy than incandescent bulbs, last for decades, and give cities precise control over brightness, color, direction, and operating schedules. Instead of using those capabilities, many municipalities simply replaced old streetlights with brighter, blue-heavy LEDs that remain fully illuminated throughout the night. (IEEE Spectrum)

Because the light is cheaper to produce, we have also found more places to put it. The expected energy savings are partially lost as buildings, bridges, parking lots, signs, and public spaces become progressively brighter. It is another example of making something more efficient and then consuming more of it.

More light does not automatically produce more safety. Excessive brightness creates glare and harsh shadows that can make it harder for people and cameras to see. Blue-rich light also scatters more easily through the atmosphere, worsens sky glow, disrupts nocturnal wildlife, and interferes with the biological expectation that nighttime should be dark. (IEEE Spectrum)

The better approach is surprisingly straightforward: illuminate only where light is useful, point it at the ground, use warmer colors, keep brightness low, and dim or switch lights off when spaces are empty. Networked LED systems can even adjust individual fixtures by time, traffic, neighborhood, season, or bird migration. (IEEE Spectrum)

This is what bothers me about most public LED projects. We installed programmable, directional, energy-efficient lighting and then operated it as though our only choices were completely dark or aggressively bright.

The goal should not be to remove light from public spaces. It should be to stop treating darkness as a design failure.

Read Paul Bogard’s full article, We’re Squandering LEDs’ Potential to Save Our Night Skies.