Structural and Environmental Assessment of Rooftop Hydroponics in Baltimore

Abstract

As city centers grow and expand, so does the threat of climate change and unstable food chain production. Urban Agriculture has been proposed as a solution to increase healthy food availability and introduce redundancy in the food chain for cities. Specifically, rooftop farming has been studied due to the large availability of rooftops within a city. These proposed rooftop farms would be best suited for hydroponics due to their lightweight. Hydroponics replaces the soil medium with a nutrient solution that has a water base. These farms have been studied in comparison to traditional agricultural methods, in terms of their environmental impact and economic feasibility. These farms reduce water usage and produce more than traditional agricultural methods. However, the implementation of rooftop farms and their impact on the underlying structure has not been studied.

This study focuses on remedying that by analyzing the structural impact of the underlying structure with two cases of rooftop hydroponics: a commercial farm or a community garden. To study this, a theoretical model of a typical warehouse was designed in Tekla Structural Designer to analyze the loads and the resulting member reactions. It was then retrofitted to support the theoretical farms and the resulting change in materials in the model was used to calculate the embodied energy and subsequent environmental impact. The results of this study concluded that both cases of hydroponic farms required the change of 1/3rd of the rooftop supporting members in the warehouse with the commercial case using approximately 100,000 kilograms or 120 tons less steel than the community case. The embodied energy between these two farms had a difference of 8.9%, but both cases required approximately 12-13% less embodied energy compared to demolishing and rebuilding a modified warehouse. This study found that the commercial farm and community garden are similar in structural members and that retrofitting an underlying structure is environmentally friendlier than rebuilding a structure.