Energy Savings from Advanced Lighting Control Retrofits in Federal Office Buildings

摘要

Lighting systems account for a significant portion of the energy consumed by commercial office buildings. Reducing the energy consumed by lighting systems is pivotal in reaching the ambitious energy targets and greenhouse gas reductions set for the next 10-15 year timeframe. Despite the availability of advanced lighting controls, such as occupancy sensors and dimmable ballasts, this energy conservation measure remains largely untapped, primarily due to the lack of understanding regarding the technology and its capabilities. This study presents results from an investigation into installations of workstation-specific lighting and advanced control retrofits in 10 federal office sites, focusing on implementation of institutional tuning and scheduling, occupancy sensing, and personal control. Luminaires in open office areas were centered over each workstation, while in other areas a like-for-like fixture replacement was implemented, maintaining the same layout. Lamps were operated via individually addressable digital dimming ballasts by a central lighting management system. Power use was metered during pre-retrofit and post-retrofit phases starting in August 2010 and continuing through July 2012. This study found that implementing advanced lighting controls resulted in energy savings ranging from 26% to 66%, with an average energy reduction of 46%, even though the retrofits had similar or increased installed lighting power densities. Results from this study indicate that the greatest impact can be seen at sites with variable occupancy patterns and/or high baseline lighting energy consumption. Due to the relatively high cost of installation, results of this study suggest that for retrofit applications, workstation-specific responsive lighting systems are best suited to targeted, rather than universal, deployment. For major renovations and new construction, installation costs would be significantly lower in comparison to conventional ceiling mounted systems and may represent a viable alternative.