In this sense, this article presents the first results of the research project Fertilecity, which aims to analyze, from a technological and sustainability approach, a new agricultural production system for Mediterranean urban areas through the integration of greenhouses on the roof of buildings. This innovative system is an integrated RTG (i-RTG) that includes energy, water and CO2 flows in the metabolism of the building. Multidisciplinary experts participate in Fertilecity Project using multiple methods such as Life Cycle Assessment and the Integrated Value Model for Sustainable Assessment (MIVES). Their first results are: a review of the main experiences in UA; an environmental and economic life cycle analysis of implementing Rooftop Greenhouses (RTGs) in Barcelona and the construction of the ICTA Rooftop Greenhouse Lab (RTG-Lab) near Barcelona. This project aims to demonstrate the potential of i-RTGs and quantify their environmental, economic and social benefits, as well as study how they can change the image of our cities.