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U.S. Department of Energy Energy Efficiency and Renewable Energy

Spectrally Enhanced Lighting Economics Validation Study

The U.S. Department of Energy (DOE) conducted a study to determine the cost effectiveness of utilizing spectrally enhanced lighting (SEL). On this page, you'll find information about the Economics Validation Study which looked at the cost of implementing SEL and the resulting energy savings in three different sites.

Purpose

The 2004 University of California, Office of the President (UCOP) feasibility study demonstrated that the high correlated color temperature (CCT) color of lighting used in SEL was not objectionable to building occupants, removing a significant barrier to widespread implementation of SEL. The UCOP study compared two similar floors of an 11-story building and found equal occupant acceptance for the commonly used 835 lighting and the 850 SEL lighting, even with the SEL light levels reduced by 20% as calculated using the SEL Design Method.

All previous SEL field studies by the DOE and Pacific Gas & Electric Company (PG&E) had used dimming ballasts due to the uncertainties about whether the lowered illuminance would be acceptable. The Economics Validation Study was specifically designed to determine whether SEL could be used as a cost effective lighting retrofit strategy, including assessment of design method risk using standard lighting equipment instead of dimming ballasts, assessment of compensatory task lighting, and further assessment of occupant satisfaction.

Description

In 2006, the DOE, AfterImage + Space (AI+S), and Pacific Northwest National Laboratory (PNNL) completed an extensive study involving three California buildings where the lighting was completely retrofit using SEL strategies.

The demonstrations were conducted at the following facilities.

  • PG&E Santa Rosa Service Center Building: 57,000-sq ft, one-story office building located in Santa Rosa, California
  • U.S. Forest Service, Mare Island, Western Regional Headquarters: 119,000-sq ft, four-story office building located in Vallejo, California
  • Port Hueneme Military Base, Building 1000: 67,000-sq ft, two-story office building located in Oxnard, California

Learn more about the demonstration facilities, measured results, and economic analysis by reading the Economics Validation Study Overview.

The Economics Validation Study focused on evaluating the economic validity of SEL, plus quantifying energy savings, occupant acceptance, ease of implementation, task lighting usage, and visual effectiveness. The demonstrations were designed to decrease lighting power loads in the three buildings by 22-50%, depending on the existing installed lamps and ballasts, using the same design method as the UCOP demonstration.

Each building owner hired their own lighting retrofit contractor, and all work was completed outside of business hours, with no disruption of office activity or productivity. All three buildings had similar pre-retrofit lighting systems consisting of three-lamp, 18-cell parabolic luminaires, although each building had different pre-retrofit lamp colors. In one building, the pre-retrofit lighting system contained T-12 lamps and magnetic ballasts, while the other two buildings had T-8 lamps and electronic ballasts. The project team conducted pre- and post-retrofit lighting measurements to validate the design process calculations, as well as before and after surveys to determine occupant satisfaction. The team measured overhead lighting electrical loads, light levels in the workspace, task lighting usage, and occupant ratings of satisfaction with the lighting.

Results

The results included measured energy savings between 19% and 46%, with no measured difference in occupant satisfaction. The normalized economic analysis (using electricity costs typical for California) show that installation costs for SEL retrofits are no greater than typical retrofits, yielding 19-27% energy savings as a no-cost added benefit when compared to otherwise similar fluorescent lamp/ballast installations with non-SEL lamps. In addition, there were no differences in occupant satisfaction between the pre-retrofit lamps and the 850 SEL lighting, nor was there any increase in the use of task lighting, in spite of the fact that the overhead light levels had been reduced.

Overall, the study concluded that SEL can be cost effectively implemented using standard fixed output ballasts without risk to the building owner or occupants, and that building owners can confidently use SEL to reduce lighting energy costs.

Reports

Learn more about the study by viewing the following reports.