In most cities, street lights stay on all night long, even if no one's around. One Barcelona neighborhood is getting around this power suck with an effective system of LED lights that are controlled by sensors, GOOD reported. Their street lamps remain off until they detect when someone is walking by and automatically switch on. Depending on how close the person is, and what time of year it is, they also adjusts the amount of light emitted. The system has reduced the neighborhood's power consumption by 30 percent and makes you wonder, why haven't we been doing this all along?
WATCH GOOD's look at Barcelona's street lamps: