Urban farming with rooftop greenhouses: A systematic literature review

The environmental impacts of food systems will increase in tandem with rapid urban population growth, which calls for alternative solutions, such as urban agriculture, to reach the United Nations Sustainable Development Goals. Among several urban agriculture systems, rooftop farming and its subset, rooftop greenhouses, are promising technologies. They optimize land use, increase profitability for building owners, deliver good yields per unit area, increase water use efficiency, and reduce the energy use of both greenhouse and host buildings while mitigating the urban heat island effect. A systematic literature review of the rooftop greenhouse technology was carried out to examine the benefits and challenges associated with this technology. This review was based on 45 articles, covering themes such as the impact of rooftop greenhouse technology on yields, energy use, water use, environmental impacts, and life-cycle costs; some benefits identified are the symbiotic heat, water, and CO2 exchanges between the rooftop greenhouse and its host building, and the possibility of delivering year-round production. The additional investment, operational costs, limited availability of flat roofs, and various regulations were challenges to overcome. The relevance of symbiosis between rooftop greenhouses and buildings to enhancing sustainability, and meeting the SDGs was explored. This review also outlines that rooftop greenhouses are increasing in scale, system diversity, societal acceptance and popularity among commercial operations in large cities. The future of rooftop farming lies in customizing the right technology for selected building typologies globally, where food production is fully integrated into the urban landscape.