Sustainability constraints in techno-economic analysis of general lighting retrofits

Several governmental programs seek the adoption of measures to promote energy efficiency through the substitution of old incadescent light bulbs by CFLs (compact fluorescent lamps). However, fluorescent lamps emit UV, pollute the environment with mercury and rare earths if disposed recklessly. These also present higher performance degradation levels, lower efficiency and shorter lifespans if compared to LEDs (light emitting diodes), which require higher initial investment. We advocate that retrofits shall have a broader scope, pursuing beyond the achievement of short term efficiency and profitability, but the long term sustainability. Thus, selecting which technology to use in a retrofit requires thorough feasibility study comparing alternatives. We propose a framework using equivalent annual costs (EAC) as a metric for comparing substitute technologies in lighting retrofits, considering sustainability constraints as reverse logistics, waste management, performance degradation, lifespan, luminous efficiency and energy prices. The results of a simulated general lighting retrofit comparing LED tubes, CFLs and fluorescent tubulars demonstrate CFL as the highest annual cost and toxic waste disposal in most scenarios, fluorescent tubular as the most economic alternative, but if their lifespans shorten, LED prices drop or achieve higher efficiency LED becomes the most sustainable and economically attractive alternative. (C) 2013 Elsevier B.V. All rights reserved.