Beyond yield: integrating energy, water, cost, and carbon to benchmark indoor vertical farming viability

The interest in vertical farming arises from its ability to ensure consistent, high-quality, and pest-free vegetable production while supporting synergies with energy systems and urban development. While previous studies have assessed energy use and cost-effectiveness in vertical farming using simplified models, this study fills a gap by providing a comprehensive analysis of how individual input parameters affect efficiency, sustainability, and economic viability through a detailed modeling framework with sensitivity and correlation analyses. 162 scenarios were evaluated by combining three levels of temperature, photosynthetic photon flux density, and CO2 concentration across three distinct localities, namely Trondheim, Shanghai, and Dubai regions, which differ from a socio-environmental viewpoint. Two insulation thicknesses were also tested in each scenario. Results indicate that, due to the heating, ventilation, and air conditioning and dehumidification system, crop productivity could be kept optimal regardless of insulation or the external climate. Photosynthetic photon flux density was the dominant growth factor (correlation: 0.85), followed by CO2 (0.36) and temperature (0.22), and also the driver of energy consumption (0.73). The lowest specific energy consumption coincided with the lowest productivity (55 kg/m2). Levelized cost of lettuce identified the most cost-effective setup as 24°C, 250 umol/m2s photosynthetic photon flux density, 1400ppm CO2, with insulation (102kg/m2). Only decarbonized energy systems can support vertical farming without increasing CO2 emissions compared to imported lettuce. These findings guide practitioners and policymakers in selecting cost-effective, sustainable vertical farming strategies and provide validated data for research and implementation across diverse climatic and energy contexts.