By Cass Jacoby.
We lose “more than 50 acres of American farmland to urban development every hour and in that same amount of time the human population grows by 240 people,” according to James Kauffman, director of the commercial tower garden division of Agritecture. With less land to grow food and more mouths to feed, it doesn’t take much to see how the way we use land is creating a problem. However, across the country, and even globally, farms are taking back the land. Albeit, they are cropping up in a rather unexpected place: the roof.
Urban rooftop farms are present in Paris on top of supermarkets, on the industrial roofs of Chicago and Brooklyn, right on top of a car park in Singapore, and even more locations across the globe. More than just a growing trend, rooftop farms can be found from Australia to St. Louis as a way to feed communities, supply grocery stores or restaurants and as a general way to make cities greener. Rooftop farming is the best solution for smart urban agriculture, a growing movement which aims to address the diverse goals of urban sustainability, including food security and equity, efficient food supply chains, stormwater management, mitigation of urban heat island effects and waste management.
The green-roof movement has slowly been gaining momentum in recent years, and it is no surprise when you look at the benefits that come out of utilizing the previously deemed “unusable space” of the city roof. Outside of helping meet demand for food production, food roofs additionally offer:
Plenty of studies have told us that exposure to nature and vegetation provides an array of psychological benefits, from decreased anxiety to increased productivity. By making our cities literally greener, we make them a better place to live.
Obviously planting more vegetables on the roof is a greener practice, but there are additional factors about food roofs that benefit the Earth. Bare roofs in cities absorb and then radiate heat — a phenomenon known as the urban heat island effect — which in turn increases energy usage and contributes to the poor air quality that often plagues big cities. But rooftop farms help cool buildings, ultimately reducing carbon emissions. Plus, by growing food in the communities they serve, rooftop farmers lessen the environmental impact of food transportation.
The city is, unfortunately, often a site of food deserts, where access to clean, fresh and healthy food is limited. “St. Louis has huge disparities in food access between certain areas where grocery stores are located and accessible to folks and where they are not,” Jamie Wallace with Urban Harvest STL tells 5 on Your Side. “With our rooftop farm we are able to donate the majority of the food that we grow to nonprofit partners. We are able to grow across our sites about 5,000 pounds of food.” In growing food literally atop the city, more people have access to affordable and wholesome food than ever before.
Rain is free water and energy we get from the environment, and rooftop gardens are primed to make the most of it. Living Roofs reports that green roofs absorb up to 75% of rainfall, thus reducing the runoff dramatically, and lowering the risk of flooding.
Green roofing can extend a roof's lifespan by over 200%, according to an article in the Journal of Environmental Management. By covering the waterproofing membrane with growing medium and vegetation, the plants shield the roof from ultra-violet radiation and physical damage. In most cases, farming on the roof can be a great way to maintain the roof while making use of the space.
As more rooftop farms are created, the movement’s viability is further validated. Food roofs are increasingly shifting from a drop of water in a bucket to a tidal shift as more people are agreeing that a food roof is a necessary change to address the growing issues of climate change and diminishing agricultural space.
“It is a clean, productive and sustainable model of agriculture that can in time make a real contribution to the resilience – social, economic and also environmental – of the kind of big cities where most of humanity now lives,” Pascal Hardy an engineer and sustainable development consultant tells the Guardian. "And look: it really works.”
The benefits rooftop farms provide are made possible through innovations that make these farms easier to install, advantageous to the roof and designed to make green roofing more accessible than ever. From modular to build-on-site vegetated systems, products like SOPRANATURE offer flexibility to the green roof design, providing a green roof that can be tailored to the roof’s needs. SOPREMA’s semi-intensive systems are mid-light green roofs are even preferred for urban rooftop agriculture.
Head grower of the iconic grocery store rooftop farm in Saint-Laurent on the Island of Montréal, Pierre-Antoine Jacques tells SOPREMA, “I was skeptical that a rooftop farm could be productive given the very shallow depth of soil. It turns out that there are many advantages to a rooftop farm. Amongst others, perfect light exposure, the absence of deer and other small mammals, and near-perfect ‘field’ conditions very early in the season.”
As the benefit of green roofs becomes more and more undeniable and the food roof revolution continues to grow, the future of urban agriculture is clearly the rooftop farm. Increasingly, we can look up for our food supply.
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Photo credit: SOPREMA
Cass works as a reporter/writer for RoofersCoffeeShop, AskARoofer and MetalCoffeeShop. When she isn’t writing about roofs, she is putting her Master degree to work writing about movies and dancing with her plants.
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