Decision Support and Planning Tool to Facilitate Urban Rooftop Farming

Abstract

There is an increasing trend among urban populations to recognize the importance of fresh produce in their diets and its impact on reducing the carbon footprint created by food transportation. Thus, urban farming as a produce source has grown in popularity in recent years. One farming method that is gaining attention is urban rooftop farming, which integrates farming practices into city infrastructure without requiring expensive real estate or large warehouse-type structures with interior grow lighting. Rooftops in American cities represent the largest unoccupied urban space for agricultural purposes, but they remain underutilized. Selection of feasible and safe locations, obtaining permissions, designing and constructing the farm itself, selecting appropriate crops, and projecting farm outputs are all complex issues that impede the adoption of rooftop farming. To address such complexity, this project developed a prototype Decision Support and Planning Tool that assesses rooftop feasibility, supports informed and geographically appropriate rooftop farm design and crop selection, and predicts crop yield. The team implemented requirements analysis and functional decomposition to identify structural, safety and access requirements for rooftop farming. A second phase of the requirements analysis and functional decomposition was performed to identify agricultural methods and farm design. As a result, “square foot farming” was selected as the appropriate basis for farm and tool design. Users are also guided to input their desired level of effort for maintenance, time to maturity, and crop yield to identify crops most suitable to the specific rooftop location. Analytic hierarchy process (AHP) was used to scale and calculate the weights associated with the users’ maintenance preferences. A linear programming model based on knapsack optimization was used to project maximum total yield based on available square footage and crop yield preferences. Two proof-of-concept rooftop farms, generated by the prototype Decision Support and Planning Tool, were constructed in Washington, DC and Los Angeles. Prior to the spread of COVID-19, these farms were intended to validate model results against actual yield from crops produced over a 90day growing horizon. Instead, the farms validated rooftop assessment and crop selection tool functions.