Fossil fuel-powered automobiles have made modern urban life possible, enabling long commutes and widespread sprawl. However, this system has turned cities into major energy consumers, responsible for 75% of global energy use and 70% of greenhouse gas emissions. As urbanisation accelerates, these patterns, along with rising rates of hunger in urban areas, are becoming increasingly unsustainable.

Redesigning urban models provides methods of building safer, more resilient, sustainable, and inclusive cities. Research published in the Open Access journal Sustainability proposes a new model for urban development building on the concept of a 15-minute city, focusing specifically on the localisation and optimisation of urban food systems.

By integrating spatial access to food supply amenities with low-emission distribution strategies and urban agriculture (UA), the study suggests a neighbourhood model capable of achieving 100% annual vegetable self-sufficiency while reducing CO₂ emissions by 98%. This holistic approach advances several key United Nations Sustainable Development Goals, positioning the 15-minute city not just as an urban planning concept, but as a pathway towards a more sustainable urban future.

The 15-minute city and urban sustainability

The 15-minute city concept designs neighbourhoods so residents can access their essential needs within a 15-minute walk or bike ride from home. This reduces car use and supports healthier, more connected communities.

In North America, the average meal travels between 2,400 and 4,000 kilometres from farm to table. Urban agriculture can significantly reduce these food miles, and the associated greenhouse gas emissions, by producing food in unutilised neighbourhood spaces.

This study focuses on implementing food production on building rooftops and facades, which lowers a building’s energy demand and engages urban residents, who increasingly value locally grown food.

Green transportation in cities not only promotes energy sustainability but also eases traffic congestion. Electric vehicles are most effective when powered by clean energy sources, highlighting the need for integrated renewable solutions. Sidewalk photovoltaics offer a promising option, generating electricity from solar energy on pedestrian pathways. Modern sidewalk photovoltaic systems are designed to withstand substantial pedestrian and vehicular traffic, require minimal space, and can support electric vehicle charging, collectively helping to lower the carbon footprint of transportation in dense urban environments.

Building on these strategies, the study’s novel Food Production and Transportation Framework envisions a scalable system for sustainable, liveable neighbourhoods. Dr. Caroline Hachem-Vermette, a leading author of the study, explains:

“We want to see how we can integrate energy, mobility, land use and social functions to bring daily needs closer to residents so they can reduce the number of fossil-fuel-consuming trips. Our broader goal is to design interconnected neighbourhood clusters that share food, energy and amenities, creating a balanced, adaptive urban network.”

Creating communities that foster food self sufficiency

The 15-minute city model was applied to West 5, a net-zero, electric vehicle-ready smart community in London Ontario, Canada. Due to the nature of its design, West 5 offers an ideal environment for applying and evaluating sustainable neighbourhood strategies.

To evaluate food accessibility, the team reconfigured West 5 into a neighbourhood unit and replicated it to form a circular neighbourhood cluster, composed of 10 identical “slices”, much like sections of a pizza. Grocery stores were placed on the centre of each even-numbered slice, while farmers markets were positioned on the outskirts of odd-numbered neighbourhood clusters. A neighbourhood cluster with a radius of 1 km provided each resident with a food outlet within 15-minutes from their house.

Nine urban agriculture scenarios were developed, each using a constant flat roof area and varying amounts of south- and west-facing facades and lot space. Ten different vegetables were grown based on their demand, growth cycle, weather tolerance, and their open-air farming method. A particular focus was given to leafy vegetables, which are responsible for about 20% of total vegetable demand.

When solely one vegetable type was cultivated in each neighbourhood unit, even the scenario providing the most farming area failed to achieve complete food self-sufficiency. After implementing a food production schedule, allowing multiple vegetables to be grown within each neighbourhood unit, food self-sufficiency was achieved in over half of the possible cases.

This collaborative approach, where different neighbourhood units grow different combinations of vegetables, enabled full food self-sufficiency using surprisingly little space: just 13.8% of rooftops, 10% of facades, and 15% of lot areas. The findings highlight how community-level planning can transform urban sustainability, as Dr. Caroline Hachem-Vermette notes:

“Growing food and sharing it with neighbours fosters a real bond… Beyond food, beyond carbon, there is a sense of community.”

Reducing emissions through local food and clean transport

Multifunctional neighbourhoods, coupled with self-sufficient urban agriculture systems and green transportation strategies, reduce the number of food miles and their related CO₂ emissions. Long farm-to-supermarket journeys are eliminated, and the 15-minute city layout ensures residents can reach food outlets by walking or, if preferred, by a short car journey.

Overall, the calculated annual CO₂ emissions fell by 98% from the base case scenario, which included food-truck and automobile emissions based on 2016 City of London traffic data.

The implementation of sidewalk photovoltaics and creation of a fully electric vehicle neighbourhood has obvious initial costs. However, when comparing this to the cost of fuel, it was found that the green transportation system had a payback time of just 2.8 years. Highlighting the benefit of investing in more sustainable, cleaner energy for the future.

Reimagining cities of the future

The work in this study expands the 15-minute city concept by  introducing community-level farming and locating grocery stores or farmers markets within 15-minutes of travel from each resident. This creates a strategy that dramatically reduces emissions while meeting neighbourhood-level vegetable demand.

While this study focused heavily on food-related infrastructure, it represents one phase of a larger ongoing program led by the group. Future stages will apply the same modelling approach to amenities such as workplaces, schools, health, and recreational facilities. The overall aim is to advance future cities, shifting from car-dependent, single-use neighbourhoods to polycentric, resource-sharing ones.

While successful, this study revolved around West 5, a purpose built complete community. Its conditions may not be easily replicated elsewhere. Additionally, CO₂ emissions from growing of food were not assessed or included in the model. Furthermore, the crop growth data was extracted from the Canadian Government. It remains unclear whether community grown crops in urban spaces would achieve comparable levels of growth. These gaps present important areas for future research.

Regardless of whether the model can be directly replicated, the Food Production and Transportation Framework equips planners, policymakers, and communities with a scalable tool for integrating food and mobility strategies into both existing neighbourhoods and new developments. The use of models in scientific research is an important way for researchers to test hypotheses and understand processes that would be difficult to study directly.

More studies on sustainable cities can be found across the Open Access journals Smart Cities and Sustainability. Alternatively, you can access the full MDPI journal list here.