Controlled Environment Agriculture (CEA) is gaining momentum as a viable strategy for addressing food security in urban areas while mitigating the environmental pressures associated with conventional agriculture. However, the environmental sustainability of these systems remains under scrutiny due to their high energy and resource demands. This study presents a comprehensive Life Cycle Assessment (LCA) and operational scenario analysis of hydroponic lettuce production within a growth chamber using a nutrient film technique (NFT) system. By integrating experimental measurements, plant growth modeling, and LCA methodologies compliant with ISO 14040–14044 standards, the study evaluates environmental trade-offs under five different lighting scenarios ranging from 200 to 1000 µmol m⁻² s⁻¹ photosynthetic photon flux density (PPFD), while keeping temperature and CO₂ constant. A mechanistic plant growth model was utilized to simulate fresh biomass yield under varying PPFD conditions. Model predictions closely aligned with experimental data, yielding R² values of 0.95–0.98 for both fresh weight and leaf area across light scenarios. Water consumption was estimated by establishing linear relationships between plant biomass and evapotranspiration rates, while electricity usage for lighting and HVAC was continuously monitored using a Fluke 1735 Power Logger. Results indicated substantial increases in yield, water use, and energy consumption with increasing light intensity. For example, yields ranged from 1.69 kg at 200 PPFD to 14.06 kg at 1000 PPFD, while electricity usage increased from 257 to 361 kWh per growth cycle. The LCA adopted a cradle-to-gate system boundary and a functional unit of 1 kg fresh lettuce, covering inputs including lighting, climate control, water, nutrients, system materials, post-harvest processing, and transportation. Impact categories were assessed using ReCiPe 2016 midpoint (H) indicators: global warming potential (GWP100), terrestrial acidification potential (TAP), fossil fuel potential (FFP), freshwater and marine eutrophication potential (FEP, MEP), and water consumption potential (WCP). Environmental impacts showed strong inverse relationships with light intensity up to 600 PPFD, beyond which impacts plateaued. GWP100 decreased from 69.09 kg CO₂-eq at 200 PPFD to 12.87 kg CO₂-eq at 1000 PPFD, primarily due to increased yield efficiency. Across all scenarios, the lettuce production stage was the dominant contributor to environmental impacts, followed by system manufacturing, with minor contributions from post-harvest processes and waste management. Optimal light intensity for balancing yield and sustainability was identified between 400–600 PPFD. Notably, the integration of dynamic plant modeling enabled scenario-specific inventory estimation, enhancing the robustness of the LCA compared to conventional top-down methods.
