As children, we're all taught to turn off the lights behind us as we leave an empty room.
But it seems Norwegians have taken that lesson one step further.
Along a 5.5-mile stretch of road in Hole, Norway, smart streetlights automatically dim when nobody's around—then come back to full power when a car, pedestrian, or other object approaches.
READ MORE: Half of Norway's new-car sales are now hybrids or electrics
The system, called Eagle Eye, is manufactured by a Norwegian company called Comlight. It's one of several technologies Norway is deploying to cut its energy use.
This particular installation in Hole involves some 220 light posts fitted with radar that senses oncoming traffic and pedestrians.
When no object is detected nearby, however, the system dims the lights to 20 percent of total output, saving some 2,100 kilowatt-hours of electricity per week.
Bjørn Nyland, a Norwegian Tesla owner, demonstrated in a YouTube video how the system works by recording a car driving along the road.
The barren road is semi-lit by the lights, but they get brighter—like photon dominoes—as the car approaches.
On New Year's Day, Comlight introduced a new version of the system, called Eagle Eye 2.0, which can be fitted to a wider range of light-pole sizes.
CHECK OUT: Norway's Goal: All New Cars Will Be Emission-Free By 2025 To Cut Carbon
Norway was the first nation on earth to set a goal of ending sales of new cars with combustion engines, which it plans for the year 2025.
Electrified vehicles—both conventional hybrids and plug-in electric cars—now make up more than half of its new-vehicle sales, thanks to an array of incentives on them and penalties on conventional cars.