"Improved lighting efficiency has long been a major strategy to reduce the energy use in buildings. These savings have traditionally come from improved efficiency of lamps and ballasts. Today, deep energy reductions and Zero Net Energy (ZNE) are possible by continually controlling each of these efficient fixtures in response to varying details within the space. This guide provides an overview of luminaire-level lighting control (LLLC). The full LLLC approach provides controllability at each fixture with real-time energy tracking and data collection."