We report on an experimental case study of personalized lighting controls built on top of an infrastructure designed to enable rapid development of applications in commercial buildings. Our personalized lighting controls (PLC) use an existing standard commercial building lighting automation system and require no new hardware to deploy. PLC presents occupants with a "shared virtual light switch" accessible online and easily viewable on smart phones by scanning a QR code. It embodies three important design principles: individual empowerment with localized human-centered resolution, token effort for energy consumption and return to a low-power state when inactive. After deploying our lighting controls on two new floors of a large research building on campus, we show a sustainable reduction in lighting energy of 50% to 70% on both floors over 12 weeks, continuing to this day. These savings are found to come from a combination of reducing brightness and keeping lights on less often, especially during evenings and weekends.