Agro-urban sustainability through rooftop greenhouses, improving cities' sustanibilityEconomic viability and sustainable business models

Resumen

Currently, more than half of the world population lives in urban areas and this trend will reach 68% in the year 2050. The expansion of urban agriculture (UA) systems, and especially their innovative forms of roof greenhouses with integration of flows with the building (i-RTG in English), provides opportunities for sustainable development in cities in three dimensions: environmental, social, and economic. However, most studies have not paid enough attention to the economic aspects when using life cycle costing (LCCA). In addition, research on sustainable business models (SBMs) for the agri-food sector is still limited and for UA systems it is very scarce. The objective of this doctoral thesis is to analyse the economic viability of i-RTGs as innovative ways to contribute to the sustainable development of cities, with the following three specific objectives: (i) analyse the evolution of the use of LCC in UA during 22 years; (ii) evaluate the economic viability of tomato production in an i-RTG and (iii) present a comprehensive characterization and categorization of SBMs for UA, providing recommendations for their selection and subsequent application. The following methodologies are applied: i) literature review, ii) LCC, iii) case study, iv) break-even point (BEP), v) bibliometric analysis using software, and vi) impact analysis on sustainable development goals (SDGs). The findings of the analysis of the evolution of the use of LCC in UA are: i) urban horticulture is the most studied UA practice among the investigations that used LCC; ii) the four main stages of LCC are not properly applied; iii) essential costs such as labour and infrastructure are excluded from the calculations and iv) the use of additional financial tools is very low. The economic viability of tomato cultivation in i-RTG depends on four costs (which contribute 61.8% of the total cost): i) labour (24.7%), (ii) greenhouse infrastructure on the roof ( RTG) (15%), iii) external pest control specialist (EPCS) (12.6%) and (iv) rainwater (9.5%). The reduction of these costs is a basic requirement to achieve economic viability. Some proposals for its reduction are included. The results of the calculation of the breakeven point (BEP) indicated that the combination of high fixed costs together with low production yields could be a significant obstacle to economic viability and profitability. For the comprehensive characterization and categorization of SBMs for UA, a list of 11 archetypes was drawn up, including their relationship with the SDGs, which in the future will be useful for the analysis and development of SBMs for UA (UA-SBM abbreviation in English). Of the 11 identified archetypes, 4 of them are particularly relevant for the deployment of sustainable UA systems due to their greater presence and sustainable potential. The main contributions for the research and practice of UA, LCC and SBMs are: i) recommendations to improve the application of LCC; ii) application of the LCC to tomato production in i-RTG including essential costs such as labour and infrastructure, classifying fixed and variable costs; (iii) calculation of the minimum level of production (BEP) and maximum level of fixed costs at different sales prices; and iv) the comprehensive characterization and categorization of UA-SBMs, including their relationship with the SDGS, to facilitate the expansion of more socially responsible, economically viable and environmentally sound urban food production systems in urban areas.