ATLASEN provides a real-time IEQ (Indoor Environmental Quality) monitoring and diagnostic system, through air, thermal, lighting, and acoustic sensing, as well as user satisfaction. IoT multi-sensor modules collect IEQ real-time data, which is then analyzed, and presented in a user-friendly score and graph format. This solution provides occupant comfort and about 5~15% energy reduction compared to conventional building management systems through customizable zone-by-zone assessments. Overall, this system continuously utilizes and builds big data to manage building operation, as well as optimize IEQ and energy consumption.