The Department of Defense (DoD) has around two billion square feet of existing building space, with an annual electric energy use of about 30 million megawatts per hour (MWh). Because lighting accounts for 18% of electricity use in a typical commercial building, energy efficient lighting retrofits can have a significant impact on DoD’s building energy use and expenditures. Many existing interior commercial lighting systems use inefficient lamp and fixture technologies, provide too much or too little light, and allow little or no control for changes in occupancy, availability of daylight, or user preferences. These systems waste energy and reduce productivity by leaving occupants dissatisfied with their work environment.
Cree's SmartCast Technology system, by incorporating integrated controls and automated commissioning, significantly reduces the complexity of holistic lighting system retrofits. The objective of this project, EW-201722, is to evaluate the SmartCast system as compared to typical existing lighting systems. The project team will work with staff at several military installations to select facilities and monitor energy use and light levels of existing lighting systems over a period of several months. The SmartCast retrofit system, designed to meet applicable requirements of the Unified Facilities Criteria, will then be installed and monitored for several additional months. Analysis will include evaluation of the savings attributable to luminaire technology and to controls. A survey of occupants pre- and post-retrofit will probe satisfaction with the new system. The study will include an evaluation of the installed cost and life cycle economics of the replacement lighting system.
The SmartCast system uses Light Emitting Diode (LED) luminaires with a typical efficacy of 120 lumens per Watt and the addition of wireless controls, integral sensors for occupancy and daylight harvesting, and automated commissioning. The fully integrated controls and commissioning process assures intended energy savings performance and persistence. In contrast, prior research has shown that many add-on lighting control systems suffer from unidentified functional errors and do not operate optimally. The wireless networking built into the SmartCast system allows straight-forward installation with little or no re-wiring, and great flexibility in placement of new light switches. In addition, it enables automated formation of lighting groups, and permits users to easily modify groups and adjust control settings.
This holistic retrofit lighting solution has the potential for significant, persistent energy savings with wide applicability across DoD facilities. Projected annual energy savings from replacing T8 fluorescent fixtures in a typical facility are 3.1 kWh/ft2, with cost savings of $0.31/ft2. Estimated payback for the SmartCast system installed as a retrofit is about eight years. Economics will vary across facilities, based on characteristics of the existing lighting, operating hours, and other factors. Extrapolated to just 1% of DoD facility space (about 19 million square feet), total energy savings would be about 60,000 MWh annually, with cost savings of roughly $6 million. Additional benefits include increased satisfaction with lighting quality, reduced maintenance and disposal costs, and reduced environmental impact.