The landmark of Yeouido, LG Twin Tower, was transformed into an environment-friendly office building after extensive remodeling that lasted for a year and four months. The most noticeable change was the replacement of inner lighting fixtures with LED and the introduction of a touch screen automatic lighting control system that adjusts the intensity of lighting according to the external luminance automatically, thereby greatly reducing energy consumption. It was designed to maintain the existing distinguished image and the characteristics of LG Twin Tower. An effective plan was selected through a mockup work and the emphasis was laid on improving the working environment.