Energy-Efficient Lighting Transitions Create a Material-Climate Trade-Off

Energy-efficient lighting transitions are central to energy system decarbonization, yet the prevailing emphasis on operational electricity reduction obscures a critical system-level trade-off. We show that replacing simple incandescent and fluorescent technologies with complex light-emitting diodes (LEDs) creates a material-climate trade-off: operational efficiency gains are accompanied by rising material intensity and material-related embodied greenhouse gas (GHG) emissions. As grids decarbonize, these embodied impacts are expected to become an increasingly important component of lighting's lifecycle footprint. Using a dynamic stock-driven model, we examine China's lighting transition from 2000 to 2060 by quantifying changes in lighting stocks, material flows, and material-related embodied GHG emissions, excluding operational-phase emissions. We assess four decoupling strategies: technology substitution, efficacy increase, lifetime extension, and improved recycling, to decouple service provision from product demand, material consumption, and emissions. Rapid LED deployment generates a structural transition burden through increased material demand and embodied emissions, while recycling of minor metals can increase emissions due to energy-intensive recovery; by contrast, efficacy improvements deliver substantial reductions. These results highlight that energy-efficient transitions require explicit integration of material dynamics to achieve system-wide decarbonization.