Life Cycle Assessment of Rooftop Hydroponic Production Systems: A Case Study of ComCrop in Singapore

Population growth, limited land, and water scarcity threaten urban food security and the environment. Rooftop farming has emerged as a sustainable way to develop urban roofs, reduce food miles, and increase food access. High-density, land- and water-scarce Singapore has prioritized high-tech farms such rooftop hydroponics to improve self-sufficiency and reduce the environmental impacts of importing food. Research indicates rooftop farming has environmental benefits, including lower CO2 emissions compared to conventional farming, yet we lack a comprehensive understanding of environmental performance. This study applied a life cycle assessment (LCA) to evaluate ComCrop, a pioneer of rooftop hydroponic production in Singapore, using basil as a commonly consumed import. Results showed that 1 kg of basil emitted 0.30 kg of CO2. A sensitivity analysis showed renewable energy (e.g., solar) could substantially reduce emissions. Results were compared to conventionally grown USA basil (Singapore’s main source), adding transportation to the LCA. Results showed 1 kg of rooftop basil emitted 0.59 kg CO2 while 8.90 kg CO2 was emitted in conventional production. Transportation had the greatest impact. We conclude that rooftop hydroponics is the more sustainable production method based on land, water, packaging, and transportation. However, sustainability can be improved with recyclable materials, water nutrient filtration, and renewable energy sources.