Energy conservation is one of many technique applied to reduce the global warming effect. Sepuluh Nopember Institute of Technology (ITS) contributes to encourage energy conservation by ITS Eco Campus programs. It has so many activities, one of them is audit energy as one way to get energy efficiency in educational area. ITS central library is most accessable building both student and other academics community with total area more than 400 square matres and high occupation rate approximately 90% everyday. Energy audit techniques were carried out by an energy audit team to identify any energy conservation opportunities (ECOs). walk-through assessment and data analysis were conducted over all building zones. These levels of assessments proved that the building and its mechanical and electrical systems were improperly maintained and inefficiently operated. So that, ITS Central Library will be redesigned to be smart building by improving light intentensity level, humidity, and room temperature appropriate with ASHRAE 90.1-2005. Thus exterior building like wall, glass, roof and floor will be redesigned to emphasize minimum total load. Replacement single glass to double glass reduce the load conduction and radiation through glass, approximately 2,7%.