I read a neat article recently that talked about the "Dubai Lamp". They're lightbulbs that Philips makes for Dubai that are twice as efficient as their standard LED bulbs. The difference is simple: LEDs are more efficient when run at lower power, so by increasing the number of LED elements in the bulbs and reducing the voltage across them you get 600 lumens for 3 W. For reference, California requires lightbulbs to operate at 80 lumens per watt or higher.

https://hackaday.com/2021/01/17/leds-from-dubai-the-royal-li...

Looks like they're bringing this idea to the rest of the world:

https://www.lighting.philips.co.uk/consumer/p/led-bulb/87195...

The one that's the most neglected is natural lighting. Light pipes, solar collectors, and microprism window treatments are all available.

The second thing is white paint. You need less outdoor lighting if the built environment absorbs less light.

It's the most efficient option we have, but that doesn't mean it's good.

In the 1800s the steam engine was the most efficient way of producing work from heat, but that still didn't make it objectively efficient.