Laboratory Evaluation of DC Lighting Systems

Most building power distribution systems use alternating current (AC). This significantly influences the design of connected, direct current (DC) appliances including light-emitting-diode (LED) light sources and digital controls.  With the proliferation of DC devices as standard design elements across many building technology categories, the interest in DC power distribution systems has also increased significantly. In theory, direct-DC power distribution can increase overall electrical system efficiency by eliminating losses associated with multiple AC-to-DC conversions. This increase in efficiency translates directly to reduced energy use and increased operational cost savings.

The goal of this study was to evaluate the electrical performance of commercially available DC lighting products for commercial interior lighting as compared to traditional AC lighting products. Manufacturers boast energy-efficiency improvements and ease of installation as benefits of DC lighting systems. In some configurations, DC systems may also be powered directly from on-site, renewable energy sources, which may eliminate the need for multiple DC to AC power conversions. This study was aimed at quantifying DC lighting system performance, validating these manufacturer claims, and documenting benefits and/or challenges under typical and worst-case design scenarios.