City-wide BIA systems could meet 35–77% of a city's vegetable demand
Using our existing building stock, this crisis can be evaded in the environments that have long contributed to the problem.
35-77%
This broad range does not indicate unreliable data, rather the weight that this outcome depends on building typologies.
80%
of the food cities currently consume is imported
90%
of the food miles can be reduced through BIA
Mechanism
Modeling cited in the report—drawing on Orsini (2014), McDougall et al. (2020), Astee and Nirmal (2010), and Haberman (2014)—indicates that deploying rooftop greenhouses and vertical farms across a city's existing building stock could meet between 35% and 77% of local vegetable demand.
Consequence
Currently, cities import over 80% of their food, leaving urban populations highly vulnerable to supply chain disruptions. Achieving this level of localized production represents a meaningful structural hedge against that fragility, rather than just a marginal improvement.
Nuance
The broad variance in the 35–77% range does not indicate unreliable data; rather, it reflects how heavily outcomes depend on building typologies, local climates, and policy frameworks. Echoing a Policy Blind Spot, the technical potential exists, but reaching the upper end of this range requires regulatory follow-through that most municipalities currently lack.
Design Implication
When powered by waste heat and renewable energy, BIA can also cut "food miles" by 90% and reduce agricultural sector emissions by 50% compared to traditional farming. Consequently, the baseline vegetable-demand metric understates BIA's full potential to simultaneously advance both urban food security and broader climate goals.