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Purpose: Rooftop greenhouses (RTGs) are agricultural systems that can reduce the food supply chain by producing vegetables in unused urban spaces. However, to date, environmental assessments of RTGs have only focused on specific crops, without considering more long-term impacts resulting from seasonality, combinations of crops, and non-operational time. We analyze the production of an RTG over 5 years to determine the crop combinations that minimize yearly environmental impacts while diversifying the food supply. Methods: The system study consists of an integrated RTG (i-RTG) with hydroponic irrigation in Barcelona (Mediterranean climate). By using life cycle assessment (LCA) with the ReCiPe hierarchical midpoint method, we evaluated the environmental performance of 25 different crop cycles and seven species cultivated during the 2015-2018 period. Two functional units are used: 1 kg of edible fresh production and 1 unit of economic value (€) in the wholesale market. The system boundaries consider two subsystems: infrastructure (greenhouse structure, rainwater harvesting system and auxiliary equipment) and operational (fertilizers and their emissions into water and substrate). In addition, we perform an eco-efficiency analysis, considering the carbon footprint of the crop cycles and their value at the wholesale market during their harvesting periods. Results and discussion: Spring tomato cycles exerted the lowest impacts in all categories, considering both functional units, due to the high yields obtained. In contrast, spinach and arugula had the highest impacts. Regarding relative impact, the greenhouse structure presented a large impact, while fertilizer production had notable relative contributions in tomato cycles. Moreover, nitrogen and phosphorus emissions from fertigation exerted the majority of the impact on freshwater and marine eutrophication. Growing two consecutive tomato cycles was demonstrated to be the best alternative with the functional unit of yield (0.49 kg CO 2 eq./kg), whereas a long spring tomato cycle combined with bean and lettuce cycles in the autumn was the best scenario with the functional unit of economic value (0.70 kg CO 2 eq./€). Conclusions:The present study has demonstrated that increasing the diversity of the system leads to better environmental performance of greenhouse urban agriculture if suitable crops are selected for the winter season. The functional unit involving the economic value and the eco-efficiency analysis were useful to demonstrate the capability of the framing system to produce added-value vegetables under harsher conditions, while categorizing and classifying the crops to select the most suitable based on economic and environmental parameters.

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