The food-water-energy nexus and green roofs in Sao Jose dos Campos, Brazil, and Johannesburg, South Africa

This paper develops a generalizable methodology and framework for analyzing the food-water-energy nexus of green roofs in data-sparse cities. The framework integrates environmental costs and benefits of green roofs with food-water-energy systems, tracing footprints across city boundaries. Applying the framework to São José dos Campos (SJC), Brazil, and Johannesburg, South Africa, reveals that green roofs are essentially carbon neutral and net energy consumers. SJC benefits from a net water gain, while Johannesburg experiences a net water loss. Rainwater utilization saves irrigated water but requires more energy. The study suggests that SJC and Johannesburg should prioritize green roof development for local food production and energy saving, respectively.

Fanxin Meng, Qiuling Yuan, Rodrigo A. Bellezoni, Jose A. Puppim de Oliveira, Yuanchao Hu, Rui Jing, Gengyuan Liu, Zhifeng Yang, Karen C. Seto