# Life Cycle Assessment of Land Use Trade-Offs in Indoor Vertical Farming +
## 3 Results and Discussion
### Environmental Footprint Results
The highlighted sub-processes are as follows: Cleaning procedures, Equipment electricity consumption, LED lighting, Clothing for workers, Substrate production and transportation, Seeds production and transportation, Water consumption, NPK fertilizers production, Treatment equipment production and Composti  
Figure 2: Values for the EF v.3.1 results presented as relative contributions from the five life cycle processes as shares to the total impact per category per scenario. AC = Acidification; CC = Climate Change; FE = Freshwater Ecotoxicity; EuF = Eutrophication Freshwater; EuM = Eutrophication Marine; EuT = Eutrophication Terrestrial; HTc = Human Toxicity, cancer; HTnc = Human Toxicity, non-cancer; IR = Ionizing Radiation, human health; LU = Land Use; OD = Ozone Depletion; PM = Particular Matter; POF = Photochemical Ozone Formation, human health; RUf = Resource Use, fossils; RUm = Resource Use, mineral and metals; WU = Water Use. Figure 3 shows that LED lighting dominates contributions to energy-related impact categories such as CC, (70-80%); RUf, (60-70%); and WU (60%), driven by the energy intensive nature of microgreen production in the IVF system. This outcome reflects the work of [PERSON] (2019) [45], where they discuss the high energy demands and associated environmental costs in urban farming systems. The PV scenario shows reduced contributions in these categories compared to GM, reflecting the benefits of renewable energy (e.g., 27% reduction in CC, Table 1), while material-related sub-processes like Equipment electricity and Treatment Equipment contribute significantly to HTc, HTnc and RUm in both scenarios. Notably, Composting showed significant negative contributions (i.e., avoided impacts) in the LU category, highlighting waste reduction benefits. The benefits of composting can be supported by findings from the literature outlining its advantages in sustainable waste management systems [46; 47]. In accordance with the PEF methodology, a hotspot analysis was carried out to identify the most relevant impact categories contributing to the overall environmental performance. This analysis is based on the normalized, weighted, and aggregated results, with the aim of determining which impact categories account for at least 80% of the total score. The total scores were 8.36 \(\times\) 10\({}^{-4}\) for the GM scenario and 6.26 \(\times\) 10\({}^{-4}\) for the PV one. The hotspot analysis for both scenarios is reported in Figure 4, where the most relevant categories were CC, accounting for 24% (GM) and 23% (PV), followed by RUf, 15% for both scenarios, WU, 14% (GM) and 8% (PV), and RUm (9% and 11%, respectively). In order to arrive to 80%, Particular Matter (PM; 7% for both scenarios), Acidification (AC, 6% and 7%, respectively), Photochemical Ozone Formation (POF; 5% for both scenarios) and Eutrophication Freshwater (EuF; 5% for the PV scenario) must also be added. Figure 3: EF v.3.1 relative contributions from sub-processes involved within the Cultivation. AC = Acidification; CC = Climate Change; FE= Freshwater Ecotoxicity; EuF = Eutrophication Freshwater; EuM = Eutrophication Marine; EuT = Eutrophication Terrestrial; HTc = Human Toxicity, cancer; HTnc = Human Toxicity, non-cancer; IR = Ionizing Radiation, human health; LU = Land Use; OD = Ozone Depletion; PM = Particular Matter; POF = Photochemical Ozone Formation, human health; RUf = Resource Use, fossils; RUm = Resource Use, mineral and metals; WU = Water Use. The results show differences in the percentage contributions to the total impact score between the two scenarios. While in the GM scenario the three main impacted categories are, in order, CC, RUf and WU, in the PV scenario, they are CC, RUf and RUm. Interestingly, the contribution of WU to the total impact decreases by 4% when moving from the GM to the PV scenario, highlighting the potential benefits of photovoltaics' energy use to improve one of the weaknesses of IVF systems, as in their water consumption [5,41].