I remember my first trip to Paris, The City of Lights. But, because I’m a lighting nerd, I couldn’t help finding the yellow headlights on automobiles particularly striking. Probably because it was so different from the headlights I was used to in the United States at the time. Today, however, I’m seeing more and more headlights in the blue range as opposed to the standard incandescent halogen range of about 2900K. Do we see better under cool light, or is it simply a function of the electric source generating the light? Up until the 1940’s or thereabouts, ‘white light’ for interior architectural applications has had a predominantly warm cast to it, mostly because it was generated by candles or incandescent sources. Since World War II and the widespread use of fluorescent sources, we’ve seen our interiors take on cooler color temperatures. With the advent of LED light sources, it is more efficacious to generate light in the blue range than in the warm range. Are we looking at an even ‘cooler’ future in architectural lighting?