New York Times: By lighting all of the building’s exterior and most of its interior with L.E.D.’s, Sentry Equipment Corporation in Oconomowoc, Wis. spent $12,000 more than the $6,000 needed to light the facility with a mixture of incandescent and fluorescent bulbs. But using L.E.D.’s, the company is saving $7,000 a year in energy costs, will not need to change a bulb for 20 years and will recoup its additional investment in less than two years.