Just because you can build it doesn't mean that you should

Lots of people put LED lights into things that you never knew they could.
Read more at AllEDLighting.com: Not Every Bright Idea Is a Good Idea 

The Hawthorne Effect is alive and well

Research shows that LED lighting generally improves working conditions in the office and on the shop floor. Control over the lighting, however, matters most.
Read the rest on my blog post at All LED Lighting, LED Lighting in the Workplace: Hard to Measure

When cool is too cool

As states, cities, and towns replaced their traffic signals with energy-efficient LED lights, they discovered an underappreciated feature of the old systems : the heat melted snow and ice.
You can read more in my blog post on All LED lighting: Of Light, Snow & Ice