Farms on roofs

Developing urban areas into more pleasant and sustainable environments to live in is on the agenda of many cities.

There are many approaches and ideas to how this can be done. One of them is urban agriculture. Urban agriculture has many benefits to offer to cities and their inhabitants. For example, on the environmental side it helps reducing the distances foods travel from producers to consumers and on the social side it can help educate the public of how food is produces and where it comes from. Urban agriculture is not a new phenomenon, throughout history and today in developing countries, growing food in cities is common practice. In recent years it has become again somewhat of a trend and has gained popularity in western cities and communities. This trend can also be seen in Tampere. (Pulliainen, Virtanen 2022)

At the same time as citizens wish for more opportunities to grow food in cities and entrepreneurs establish small urban farms, a whole new high-tech industry of controlled environment agriculture (CEA) is reshaping the way food is grown and delivered, especially in and close to cities.

Since I have a background in agriculture and moved recently to Tampere city, I started to explore urban agriculture to see what opportunities is holds. The topic is vast and there are many different approaches and ways to grow food in cities.

This essay looks specifically at soil-based roof top farming, which uses rooftops in cities to grow food in soil, it’s natural way. This essay tries to answer if it has real benefits or if it is just a trend. Additionally, it will explore if it can be a profitable business and what the practical steps of creating a farm on a roof are.

Urban gardening vs. urban farming 

Urban agriculture can be subdivided into different fields. One division can be made between urban gardeningand urban farming. (McEldowney 2017a) Urban gardening includes for example backyard gardens, community gardens, school gardens and focus often on social, environmental and food security benefits. Urban farming additionally focusses on the economic benefits and tries to implement business models to make growing food in the city profitable. Urban farming includes outdoor urban farms, rooftop farms, controlled environment agriculture (CAE) like vertical farms, indoor farms. CAE often does not use soil as a growing medium but rather others for example water/ hydroponics.

Examples and different ways to farm a rooftop

There are typically four aspects of how urban agriculture benefits cities: social, food security, environmental and economic. (McEldowney 2017b) Each of those varies a lot from project to project and typically businesses/ organizations have a specific focus and vision for their urban agricultural project. Rooftop farms come in all shapes and sizes, in the following are two examples.

Brooklyn Grange:

Brooklyn Grange, located in New York City, is the largest soil-based rooftop farm in the world. They grow their produce on three rooftops in the open air across the city. With farming as the backbone of their operation they also use additional income streams which are based on the farm to make profit. They host events, speaking appointments, photo, and film shoots, install green roofs, provide education, farm visits and more.

As a soil-based farm, they “transform bare roofs into ecosystems, and (we) employ natural farming practices which help those ecosystems thrive with as little human intervention as possible… (and) Healthy ecosystems start with healthy soil” (Brooklyn Grange 2023)

Their farming practices are based on organic market gardening practices.

Brooklyn Grange runs as a social enterprise. In the book “The farm on the roof” Anastasia Cole Plakias, one of the cofounders says “The farm is all about interaction and fostering community. It is, we all realize, the most special thing about it, and gives us our greatest chance to make a socially significant impact… At the same time, we have a business to run…” (Cole Plakias 2016a)

The budget for their first rooftop farm which was established in 2010 was 200.000$. (Cole Plakias 2016b) They broke even the first year of operation and became profitable in year three. (Brooklyn Grange 2023)

Dakakker:

Dakakker is the largest open air rooftop farm in the Netherlands and one of the biggest ones in Europe. Located in Rotterdam, Dakakker hosts a variety of projects and businesses on their 1000m2 rooftop. They grow a variety of vegetables for restaurants, keep bees, produce compost, they host guided tours and are a test site for the “smartest roof of the Netherlands” – a rooftop water storage system that helps to relief the cities sewer systems during times of heavy rainfalls.

Dakakker served as an inspiration for many other rooftop farms in Europe and acts as an example of how “smarter cities” of the future can be build. (Dakakker 2023) Farm Manager Wouter Bauman says that a normal black roof in a city heats up to 80°C whereas a green roof, like at the Dakakker, heats up to a maximum of 30°C. At a scale this can make life in cities much more pleasant. (Bauman 2023)

The farm has full time employees and a lot of dedicated volunteers.

Benefits:

Social benefits:

The social and community aspect is a big part of many rooftop- and urban farming projects.

Rooftop farms often function as social enterprises or non-profit organizations.

„Research (also) highlights the potential social impact of urban agriculture, whether for recreation and leisure time, for education or health issues, or for disadvantaged people in the form of specialised-care farming. There are examples of urban agriculture projects that include target groups, such as drug addicts, juvenile offenders and immigrants, who are at risk of social exclusion.“ (McEldowney 2017c)

“Urban agriculture’s most significant benefits center around its ability to increase social capital, community well-being, and civic engagement with the food system” (Santo, Palmer, Kim 2016a) states research of John Hopkins Center for a livable future.

Those statements are written about urban agriculture in general. In the context of rooftop farms these statements can still be true but apply probably slightly less since a rooftop comes with more restrictions and is not as easily accessible for the public as ground level urban agriculture projects. Brooklyn Grange or Project EATS, another urban/ rooftop farm, demonstrate that it is possible to bring huge social benefits to cities via rooftop farms. They provide among other things, jobs to the community, immigration and work training and programs that make quality food available to people with low income. (St. Germain 2017)

Environmental benefits:

Beyond the social benefits that urban farms bring to cities there are several others. Cities like Toronto, Canada or New York, USA have extensive programs and grants to support and encourage green roofs on buildings. This shows that there are measurable benefits for cities. One of them is storm water management. Brooklyn Grange in NYC received a grant of $600.000 to install their second green roof. (Cole Plakias 2016c) On the cities webpage it reads “We offer green roof retrofit funding for private property owners in New York City. The goal is to incentivize private property owners to retrofit their roofs with green roofs to manage stormwater runoff” (City of New York. 2023) In 2009, the city of Toronto decided that all new buildings that have a gross floor area larger than 2000m2 need to install a green roof. Depending on size it needs to be at 20-60% of the roof space. (City of Toronto 2023)

Storm water management is a serious challenge that big cities face, green roofs/ rooftop farms are one way to aid that challenge.

The “heat island effect” mentioned already in the context of Dakakker rooftop farm is another challenge cities face. Due to the concentration of buildings and roads, and the materials they are built with, cities absorb more heat than natural landscapes such as forest, fields, or water bodies. Temperatures in cities are usually higher than in rural environments.  This effect is called the heat island effect. Green roofs help to reduce that effect.

Other benefits rooftop farms add to cities are improving air quality, increasing habitat and biodiversity, carbon sequestration and others. It is important to mention that those are benefits that can play a part in a bigger solution but considering the limitations of scale of rooftop farms, it is not a solution in and of itself.

All types of urban agriculture, including CEA, have the benefit of reduced carbon emission when it comes to transport since the produce travels only a short distance from producer to consumer. But only soil based, open air urban agriculture provides the other above mentioned environmental benefits to cities.

Economic benefits:

Economic advantages for rooftop farms are their proximity to market and their visibility.

The food is grown where the consumer lives. Delivery and marketing are easier and less cost intensive. Rooftop farms often get a lot of attention because of all the above-mentioned benefits and since it is looked upon as new and innovative. This helps their marketability and opens the door for many additional income streams that those farms need to be financially viable. Considering the costs of installing such farms and the high value of the real-estate they are established on, it is hard to turn a profit from selling seasonal vegetables alone. Through partnerships or by their own effort rooftop farms often add many different income streams. Examples of this are educational programs, restaurants, events, tours, and cooperation with social services.

Comparing their soil-based rooftop to an CEA hydroponics rooftop farm, Anastasia Cole Plakias writes “Sometimes it all seems incredibly complicated. There are days when we envy our colleagues at Gotham Greens, the hydroponic rooftop farming business that only grows, packages, and sells lettuce, basil and, as of recently tomatoes. They have no wedding to set up for, no rental companies wheeling dollies through their grow labs. They don’t have prospective clients taking photos of them as they harvest. We didn’t choose that route because our business, unlike theirs, is seasonal, and we’d be broke if we had. But we’d also be downright board… Because among the other things the branches of our business afford us is the almost constant interaction with our community. At the end of the day, it is the time we spend with the people on the farm that we love most. Money is not the only metric by which we measure our success” (Cole Plakias 2016d)

It is hard to get detailed insights into the finances of those businesses, but it seems clear that additional income streams are crucial to the success of soil-based rooftop farms. Great that those farms also offer a good foundation for additional business and entrepreneurial creativity.

Food security:

„Urban areas rely heavily on a multitude of food systems to meet their food needs. This makes them vulnerable to any crisis in the food supply chain.“  (McEldowney 2017d) With a constant increase of world population comes an increase of people living in cities. There is a general concern of how our current food system will provide food for everyone, especially in times of challenges or crisis. Historically urban agriculture has played a significant part during wars to provide food to nations under wars strains. The “Victory Gardens” in the US during the second world war show how the public relieved the strain of food shortages to some degree by growing more of their own food in backyards, community gardens and other vacant spaces such as sport fields or green strips in cities.

Urban agriculture can help to make cities more resilient to food challenges. Looking specifically at rooftop farms it is again the case that they can be seen as a small part of the solution, but their contribution is going to be limited since they are limited in scale and the ratio of input to output of resources does make other options like ground level urban agriculture more effective.

Conclusion of benefits:

All things considered soil-based rooftop farms bring real benefits to cities. Their biggest strength seems to be helping cities with water and heat management and their potential as a creative social enterprise that builds the community. Their social impact is hard to measure but there are many examples which show that an urban rooftop farm can be the foundation of amazing social initiatives and impact. Especially if there are grants available to establish them, they can become financially viable businesses. They do provide food right where people live. But when considering only the question of food security in an urban context, and weather the input of resources in establishing is worth their output of food, soil-based rooftop farms are not very efficient since the cost of establishing is much higher than on ground level. Raychel Santo, program coordinator at Johns Hopkins Center for a Livable Future says, “While urban agriculture alone will not solve the many dilemmas of our food system, it can be part of a constellation of interventions needed to transform the food system into one that is more socially just, ecologically sound, and economically viable.” (Santo, Palmer, Kim 2016b)

What it takes to establish a farm on a roof:

When it comes to establishing a farm on a roof there are many things to consider. Given one has a team, the first consideration and challenge is to find a landlord. A cities legislation can either help or make it more difficult to find landlord for the farm. As mentioned above, for example New York or Toronto have grants available for green roofs, such incentives make is easier to find landlords. Some European cities also have grants available. Berlin, for example, gives grants to cover some of the costs for normal green roofs and for roofs that act as a “green roof lab” the city covers the entire installation cost and 100% of the planning cost up to 40.000€. A green roof lab is a roof that has experimental- and role model- character. A soil-based roof farm would qualify. Having grands available firstly helps immensely with the startup costs and, secondly gives a good basis when approaching potential landlords since they know that the city is supportive of such projects. On the other hand, if there is no support from the cities legislation it will be more difficult to sell the idea to potential landlords and get the project approved.

Anastasia Cole Plakias describes Brooklyn Granges’ search for a suitable first roof and calls it searching for a “needle in a haystack” since it is difficult to find a roof that ticks all the boxes. Step one in the process is looking at the cities’ roofs with the help of for example google maps. If location and size fits, the next step is looking at the building’s structural integrity. Generally, roofs suitable for a rooftop farm should be able to hold around 400kg per square meter but that may vary due to for example soil type. Some visible indicators for the roofs holding capacity are the age of the building, the building material and if the structure columns are spaced not further than 6 meters apart. Often, buildings that are built in the first half of the 20^th century are built very solidly. To make the final decision whether a roof can bare the weight of a farm with all its soil and additional loads one should consult a structural engineer.

When it comes to the landlord type, Anastasia Cole Plankias says “as we would realize later, this was the attribute we should have been seeking all along. Acumen (their landlord) needed to attract tenants. And not the low-density, low-paying manufacturing tenants that occupied so many of the warehouses and industrial sites we’d visited over the last several months. They wanted high density tenants who are accustomed to paying a greater amount per square foot: tech companies, design firms, etc. Perhaps better than we did that time, Acumen saw the potential for us to draw these tenants in. A green roof- let alone a rooftop farm which operate a farm stand in the lobby where folks could pick up fresh veggies on their way home at the end of their day- would be a huge amenity. In fact, Acumen had planned on paying for the green roof themselves…” (Cole Plakias 2016e) A landlord who wants to develop their real-estate and sees the value a rooftop farm brings to their business is better than landlords who need to be convinced into a deal.

If the right place is found and the deal is made there are two ways to create the rooftop farm. Either the farming business establishes it oneself or, and often landlords or grants require that, is must be established by a 3^rd party company that specializes on green roof installations. In any case there must be several layers of materials between the roof and the soil to ensure the safety and integrity of the roof and building underneath. Firstly, there is need for a waterproofing membrane to keep water out of the building. This layer every flat roof should have but it might need to be improved or exchanged since there is more ware on rooftop farms.  Secondly one needs a root barrier mat since, like water, roots are incredible strong and can destroy the building easily. Then comes a drainage layer since part of the job of the farm is to keep water longer on the roof if there is storm but also to drain it eventually. The next layer is a filter fabric because soil particles or any other debris should not be washed down the city’s sewer systems.

The final layer besides the plants themselves, is the soil. As mentioned before, weight is an important consideration when establishing a rooftop farm. For that reason, one needs to choose soil that light weight and has good drainage capacity.

Creating such a rooftop is cost and labor intensive. Depending on location and capacity of the elevator there is a need for a crane or blowing machine to transport the soil onto the roof and a team of workers to distribute it quickly since it cannot be kept in one place because of weight distribution.

As the roof is established, the farming operations are similar to ground level mixed vegetable farms. There are financially viable small vegetable farms and those methods of growing and operation can be used alike on a rooftop.

Conclusion of establishing process

Establishing a farm on a rooftop is not an easy task. It is more costly and there are more boreoarctic hurdles then there are when establishing a farm on ground level.  In my experience it is already quite hard to find a suitable landlord on ground level. Finding the right landlord that will provide a rooftop is even more difficult. Especially if one is the first one in a certain city and especially if there is no clear support in the form of grants given by the city. Having said that, it is possible to do it. There are many examples of well-run rooftop farms that bring many benefits to cities and are financially viable. One key ingredient for the success of such a project seems to be a dedicated and talented team with both a good vision of how they want to impact the community and entrepreneurial skills.

References

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https://www.youtube.com/watch?v=CwGzr3kuuA8&t=114s

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https://www.brooklyngrangefarm.com/farming-practices

https://www.brooklyngrangefarm.com/faq

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Cole Plakias, A. 2016b. The farm on the roof. Penguin random house. New York. 63.

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https://www.toronto.ca/city-government/planning-development/official-plan-guidelines/green-roofs/green-roof-bylaw/

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https://dakakker.nl/site/?lang=en

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https://www.europarl.europa.eu/thinktank/en/document/EPRS_IDA(2017)614641

McEldowney, J. 2017b. Urban agriculture in Europe: Patterns, challenges and policies. European Parliamentary Research Service. 9.

https://www.europarl.europa.eu/thinktank/en/document/EPRS_IDA(2017)614641

McEldowney, J. 2017c. Urban agriculture in Europe: Patterns, challenges and policies. European Parliamentary Research Service. 12.

https://www.europarl.europa.eu/thinktank/en/document/EPRS_IDA(2017)614641

McEldowney, J. 2017d. Urban agriculture in Europe: Patterns, challenges and policies. European Parliamentary Research Service. 9.

https://www.europarl.europa.eu/thinktank/en/document/EPRS_IDA(2017)614641

Pulliainen, E. & Virtanen, M. 2022. Tamperelaiset toivovat lisää mahdollisuuksia kaupunkiviljelyyn. Read on 10.02.2023. https://www.fusilli.fi/uutiset/tamperelaiset-toivovat-lisaa-mahdollisuuksia-kaupunkiviljelyyn/

Santo, R. Palmer, A & Kim, B. 2016a. Vacant Lots to Vibrant Plots: A Review of the Benefits and Limitations of Urban Agriculture. Read on 12.03.2023  https://clf.jhsph.edu/about-us/news/news-2016/vacant-lots-vibrant-plots-review-benefits-and-limitations-urban-agriculture

Santo, R. Palmer, A & Kim, B. 2016b. Vacant Lots to Vibrant Plots: A Review of the Benefits and Limitations of Urban Agriculture. Read on 12.03.2023  https://clf.jhsph.edu/about-us/news/news-2016/vacant-lots-vibrant-plots-review-benefits-and-limitations-urban-agriculture

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