Post #2086681

I'm teaching an undergraduate class this semester called "Introduction to Nighttime Lights", and I want to share this (from the EU) because it's absolutely AMAZING how much more efficient lights have become in the last 15 years. For outdoor applications, high pressure sodium had already offered very high luminous efficacies (100 lm/W or better) for decades, but those lights weren't appropriate for indoor use. The last 3 classes I've tried to drive home the point that: "The history of lighting is a history of innovation and technological change".