Going Green: Urban Farming is more than a dream


Going green: is it just a hippie dream or could Barcelona’s rooftops really be used for food production?

Revista BCNMES, 09 març 2016, Prithika Nair

The roar of a frustrated lion went unheeded as we tal-ked. Poor creature, trapped on a concrete island for twenty-five years. We ignored the lion, but our attention was caught by a large bee which had just flown over the side of the terrace. He strutted about brazenly, flirting with the lavender, and we stopped, awestruck by this pollinator’s presence, to take pictures. But wait, I can’t start with the happy ending. Yes, this was my idea of a happy ending. You don’t want to know the other endings I considered. Let’s get back to basics first.

You know the story so far, but just in case, here it is in a nutshell: climate change, rising sea levels, crop failure, war and strife, yadda, yadda, yadda; the end is nigh. We can postpone said end by increasing the efficiency with which we use our natural resources, slowing the destruction of the good stuff we have left, and hoping like hell that in the meanwhile some clever clogs will discover a solution to our problem of potentially infinite population growth (about 1.1% annually) on a finite planet. By this viewpoint, going green should follow the twin principles of not wasting resources, and repairing or not polluting what we still have. We were curious then, about where our lovely little city fit into this future of sustainability. Where are we going? When will we get there? And who’s driving this thing anyway?

We found three main players. Four if you include the Ajuntament, although the Ajuntament is a bit like that little cousin who insists they want to play, but when you throw them the ball they drop it, or if they get hold of the ball they refuse to pass it to anyone. The other players were 1) community groups, 2) researchers, and 3) green businesses.

The permaculturists and community gardens

In 2013 the Ajuntament initiated ‘Pla Buits’ a programme under which people could form a community group and apply to use a vacant lot in their neighbourhood. Several groups applied to convert spaces into community gardens to join the pre-existing urban vegetable gardens dotted around the city. Success varies with these gardens.

When they work well, they reap all the benefits of community-led projects. They create a sense of connection within that community. Children get to see for themselves amazing natural transformations such as a caterpillar turning into a butterfly. These things are important. These are fundamentals of life, and as Jiddu Krishnamurti said, if a person loses their relationship with nature they lose their relationship with man (Jiddu who? Look him up, world’s most kick-ass philosopher ever).

The energy, water and CO2 flows between the Rooftop Greenhouse and the offices below, allowing researchers to measure the true potential of the greenhouse to offset the carbon footprint of the building.

Unfortunately, as Alessandro Ardovini, co-founder ofPermaculture Barcelona muses, “I keep hearing about new gardens starting up, but they all eventually suffer from a lack of volunteer hours.” Beginners’ enthusiasm? “People are wildly optimistic about the time they can devote and typically the number of volunteers shrinks quickly after the first few weeks,” says Anna Gurney, president of Boodaville Permaculture Association. And when they do come, people sometimes clash on ideas. Fertilizer versus organic. “Let’s plant only cucumber” versus “Yuck, I hate cucumber!” Such are the joys of community garden politics – well, of politics at large, really.

It takes significant time, money and resources to grow food and the produce from these gardens appears to be token: a salad here, a carrot there, and a little glut of tomatoes and cucumbers for your gazpacho. If you needed to survive off this produce, you’d last one weekend, in the summer. So community gardens seem to be low on resource efficiency but high on educational benefits.

The Boffins

Researchers with the Universitat Autónoma de Barcelona are also having a crack at the problem. They are running the Fertilecity CTM2013-47067-C2-1-R project, a prototype building with an integrated greenhouse rooftop built at a cost of 8 million euros, co-funded by the Ministerio de Economía y Competitividad. The Ministry of Economy and Competitiveness. Hear that? Sustainability is a matter of staying competitive in today’s world.

Fertilecity is an exciting project running from January 2014 until December 2016, consisting of the purpose-builtICTA Rooftop Greenhouse Lab (RTG-Lab). It’s a three-story office and laboratory with an integrated greenhouse on the roof. The energy, water and CO2 flows between the Rooftop Greenhouse and the offices below, allowing researchers to measure the true potential of the greenhouse to offset the carbon footprint of the building. The team director, Dr. Joan Rieradevall is assisted by experts in agriculture, engineering, architecture, chemical engineering and design. They aren’t just measuring the carbon dioxide, energy and water savings, but also doing a lifecycle costing of the environmental impact of the greenhouse structure, comparing it to the benefits of the 0 km food produced, and other qualitative and social benefits.

The Fertilecity team will be using an MCDMA (multi-criteria decision-making model) to create a decision making tree. This tree will have three requirements, 1) environmental, 2) economic, and 3) social. Under each requirement there will be several criteria, which the team is currently working to assign values and weights to, with the aim of then being able to compare everything in one comprehensive assessment. By the end of the project they hope to have quantitative (that’s sexy science talk for ‘hard’) data to indicate the net positive Green Value of a rooftop greenhouse. Green Value is the final environmental benefit of a project after all its environmental costs (energy and resources used to produce and run it) have been deducted.

Dr. Rieradevall and his colleague Dr. Pere Muñoz kindly agreed to show us around the site. The ICTA building lies at the end of the UAB’s Bellaterra campus. Its metal skeleton is covered in adjustable glass panels and the interior walls are bare plywood. A year after construction there’s still a faint smell of sawdust. In the greenhouse there is a strong chemical odour. Tomato plants snake out of rows of plastic grow bags, reaching well above head height. They’re tied to the metal girders of the roof and the branches are heavy with ripening fruit.

Anna Gurney and Alessandro Ardovini had also come along. So what happens when you put two boffins, two permis and one closet nihilist in a room together? Sexy lighting, it turns out. Who saw that coming? First, Dr. Joan demonstrated one of the RTG’s energy-saving technologies, smart LED strip lighting. When switched on, sensors detect natural light and switch off the strips closest to the window, dimming the next set of lights, and leaving only the deepest part of the room with artificially illuminated. Pretty cool.

To date, the project has completed one year and two crop cycles and Dr. Muñoz, the director of R&D for Environmental Horticulture (the science of improving our physical environment with the use of plants), spoke about the growing system. Fertilecity opted to work with hydroponics because it allows greater productivity per square meter and weighs less, which puts less stress on the roof structure. In hydroponics, plants are grown with their roots in an inert material, perlite in this case, while fertilizers are mixed into the irrigation water at regular intervals, to provide all the plant’s mineral nutrition needs. The Fertilecity system uses only harvested rainwater and runoff is collected and reused. Hydroponics use 80% to 90% less water than soil-based growing systems, require fewer fertilizers, and are roughly 11 times more productive than a conventional equivalent. In one study, where a traditional field would have produced 3.9 kg of lettuce/m2/yr, a hydroponic system produced 41 kg of lettuce/m2/yr. It does, however, use much more energy than a soil system: about 82 times more energy per kilogram of produce according to a 2015 study that the School of Sustainable Engineering and the Built Environment at Arizona State University conducted. The majority of that energy was used for heating, cooling and artificial lighting, and perhaps a system not in Arizona which eliminates these energy costs would drastically reduce the energy use. In addition to the benefits of hydroponics, Dr. Muñoz also stresses that greenhouses are much more productive than open-air crops, even in our warm Mediterranean climate. A study by Wachira John Mwangi (Department of Agricultural and Applied Economics at Egerton University) in 2012 on tomato growers in Kenya found the yield for open fields was around 0.95 kg/m2, while the yield in greenhouses was 10.53 kg/m2. That’s about 11 times more productive. Yeah, we learned shit.

The permaculturists were not too impressed with the use of fertilizers and insecticides, or the single-species planting. Cue a little permi-versus-scientist discussion. And when we asked about any quantitative CO2 savings, for example, we were gently told we should probably wait for the research to be completed before jumping to conclusions. Fair enough, this is probably why we didn’t become scientists: no patience. They did go so far as to say that the figures were looking promising, though.

The other points raised were valid, but as a research project, I don’t have a problem with the scientists’ chosen method. This is a prototype they’re testing and, if found to be genuinely beneficial in greening our urban areas, it could be used as a model to influence policies. After that, each building owner could adapt the rooftop greenhouse model to his or her style and goals. This would be choice on a personal level. Do they want to produce organic vegetables? Do they want to produce large quantities? Do they just want a green space? Do they want a year-round growing season?

The Fertilecity model could be applied to both new and pre-existing structures. New structures would be relatively easy and cheap to install, as it would be part of construction plans from the start. Pre-existing structures, however, fall into two categories: easy wins and hard ones. The easy ones would be buildings with large flat roofs and a single owner. Installation is easy, the scale would likely be profitable, and only one person’s permission is needed. The hard wins are buildings with small or uneven roofs and multiple owners – pretty much every block of flats in the Barcelona. So, contain your excitement, the vegetable market isn’t coming to our rooftops just yet.

Dr. Rieradevall listed what needs to happen for a rollout of RTGs in Barcelona. According to him, we need:

  1. Communication with the Ajuntament to plan a roll out, or incorporate it into any on-going greening plans.
  2. Research into different adaptations.
  3. Mapping of promising areas in the city with the help of the Institut Cartogràfic i Geològic de Catalunya.
  4. Consensus on the best course of action.
  5. A way to manage the increase in demand for water and plans for rainwater harvesting and water conservation.

When asked if there was an estimate of how much food the average person in the city consumed and how much of this could potentially be provided by urban RTGs, he quoted an earlier paper he co-authored with junior researcher Esther Sanyé-Mengual: “It’s estimated that if as little as 8% of the rooftops in Zona Franca were turned into RTGs, they could produce enough tomatoes to meet the consumption needs of 200,000 people per year or 10% of Barcelona’s population.” That’s a lot of pa amb tomàquet, my friends.

When asked about the challenges facing the project, Dr. Rieradevall spoke instead about the challenges facing humanity, the imminent dangers of global climate change, and the pressing need to become more sustainable. It became apparent that the boffins and the permis feel passionately about the same topics. They’re all deeply concerned about the fate of humanity. It’s enough to make a nihilist’s heart melt. Just a little.

Many cities around the world have introduced green roof laws, including Tokyo, Toronto, Basel, Copenhagen and Zurich. In Toronto, all commercial buildings built since 2009 have been required to have at least 20% of the covered roof built as a green roof. Rooftop vegetation is a mandate in Toronto’s building bylaws.

In March 2015 France passed a law requiring all new buildings in commercial zones to have either green roofs or solar panels installed over part of the roof. While previously cities have taken the lead, this is the first national law to mandate green roofs and, as such, has been hailed as a trailblazer.

Now, green roofs are not necessarily agricultural spaces. Growing food requires deep containers and more care. Businesses will probably opt for low-maintenance plants which will require a lot less care. But growing plants that don’t produce food still has a huge impact on local ecosystems, specifically on insect and bird populations. A biodiversity study of seventeen green roofs in Basel, Switzerland published by Urban Habitats in 2006 found 78 spider and 254 beetle species. Eighteen per cent of those spiders and eleven per cent of the beetles were listed as rare, and 13 of the beetle species were considered endangered.

Social enterprises

People’s attitudes will change in time, and the idea of a green roof will become normal, but in the meanwhile, we are on the lookout for commercial buildings”, says Lidia Calvo, founder of Eixverd, a green roof company

In Barcelona, there are a few environmentally conscious entrepreneurs trying to set up green roof installation businesses, but with little legislative support they face an uphill battle.

According to Stuart Franklin from Huerto City, they are yet to install a single rooftop garden. “The neighbours can never agree on a project. Some don’t want to spend the money – understandable – then those that do find that the neighbour who lives below the rooftop is worried about leaks and noise and so refuses the plan. Community living!”.

Lidia Calvo, founder of Eixverd, another green roof company, doesn’t focus on residential pro-jects. “People’s attitudes will change in time, and the idea of a green roof will become normal, but in the meanwhile, we are on the lookout for commercial buildings.” We’re standing in the middle of her experimental garden, on the roof of a building at the Ciutadella campus of Universitat Pompeu Fabra (UPF). Nine planters stretch out in front of us. Each one contains different types of substrata and plants. Each mini ecosystem is being measured for its capacity to collect rainwater run-off, its efficiency in insulating the roof below and its plants’ carbon fixing capacities. The cost and weight of each planter will also be noted. Some systems require the roof to have a load-bearing capacity of just 70 kg/m2 while others require 250 kg/m2 but also hold more beneficial plants. For comparison purposes, the load of a person walking on a rooftop is 200kg/m2. So, basically, structural integrity is not the problem. Some roofs have been built to have no access and could have load-bearing capacities as low as 75kg/m2 but they are the exception. It goes without saying that large-scale projects should be carried out with assessment by a structural engineer.

Up on the roof with us is Vicky Collier, owner of Urbaroma, an urban aroma growing enterprise. Vicky and Lidia met at a course on green roofs which was held by L’Era (Espai de recursos agroecològics) in 2014. A chance encounter on the streets of Barcelona brought the two women together again and led to collaboration between the two fledgling businesses. “It’s about trying marry the need to make money with having an ecological benefit,” says Vicky.

One of the planters is now testing different lavender growing techniques. Their aim for the joint venture is to find car parks in the Eixample district which have large flat spaces and are relatively sheltered. They are looking for building owners in the area to collaborate with. (Have a roof? Know someone who does? Contact Vicky aturbaroma.bcn@gmail.com.)

To finance the roofs, they are considering different economic models. One option could be finding a building owner who would let them use the space. Or they could lease the space for production. Or neighbours could invest in a planter for the right to harvest lavender from that tray: real-world crowdsourcing.

“Our main problem is getting those early adopters. Did you know that until the end of 2015 the Ajuntament was offering 50 per cent subsidies on green roofs, and no one claimed them?” Why? First, there isn’t a lot of awareness of what a green roof is. Second, the funds were hidden as a sub-point behind the ‘rehabilitation subsidy’, funds for general work such as façade repairs. A third reason could have been the clause within the subsidy which required building owners to have an ITE, Inspección Técnica de Edificios. This is a comprehensive inspection of a building which notes any and all necessary basic repairs. Some of these repairs could class as urgent and, thus, would need to be completed first. All I.T.E.’s with urgent repairs are required by law to be lodged with the Ajuntament who will then follow up to make sure they are done. Lidia suspects that this may have also played a part in dissuading uptake.

Then that bee buzzed up onto the terrace while we were talking and got treated like a rock star. What about bees? “Oh, we’d love to cultivate bees in the future. Imagine a lavender field and bees making lavender honey on the same rooftop…”

The Ajuntament recently made it legal to keep bees within the city, but keepers need a licence. To date – you guessed it – not a single licence has been granted, despite the fact that we have an Associació d’apicultors de Barcelona (Barcelona Beekeeper’s Association). They confirmed that none of their members have beehives within the city.

According to the London Beekeeper’s Association in 2014 there were 4,218 registered hives belonging to 1400 beekeepers in London. The real number is estimated at 5,000, as keepers don’t always register their hives. They stress the importance of enthusiasts taking extensive theory and practical courses in order to keep the bees and people in their neighbourhood safe. The London Bee Company is the largest single owner of hives within the city, and they are a functioning business, selling honey and candles.

The Future

We asked all the people who spoke to us for this article the same question: what would you like to see in Barcelona’s future?
Alessandro, Permaculture Barcelona: I’d like to see a city where the people are more aware. They understand what it takes to grow food and they make an effort to buy locally.

Anna, Boodaville Permaculture Association: If everyone could just grow a little. They could start with herbs. Just get a pot of herbs and try to keep it alive for a few months and then slowly take on more.

Dr. Rieradevall, Fertilecity (ICTA-UAB): A green mosaic where every rooftop in the city is doing something suited to its structure: green rooftops, greenhouses, solar panels, or rainwater harvesting.

Esther, Fertilecity (ICTA-UAB): Barcelona starts to regulate its tourism for a more sustainable city model and moves towards self-sufficiency in areas such as energy, water and food, through multidisciplinary projects.

Lidia, Eixverd: To stand on Tibidabo and see nothing but green roofs until the sea.

Vicky, Urbaroma: For it to be possible to earn a living from a green business. And to have a distillery for aromatics within the city!

Okay, nihilist or not, one can’t help having a soft spot for those who choose to fight. Although each of them may have a different approach, they’re all committed to our sustainable future.

It looks like a little bit of policy sugar from the Ajuntament is what’s needed to get this party started. If they follow the example of cities like Toronto and make green roofs mandatory for commercial buildings, small businesses like Urbaroma, Eixverd, and Huerto City would suddenly find the owners of car parks and shopping malls very interested in their services. Subsidies would be getting claimed left, right, and centre, and professions based on urban agriculture would become the norm.

Imagine going to a party and speaking to as many people identifying as urban farmers, beekeepers and rooftop gardeners as DJs and musicians. And imagine one day sitting down to your breakfast of rich, lavender-scented Barcelona honey on toast.


Il·lustració by Elisa Munsó


🌿 La clau de l’èxit d’una coberta verda

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Necessites manteniment per la teva coberta verda? 🧤

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🪴 Plantacions de plantes mediterrànies

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Planta plantes mediterrànies a la teva coberta verda, balcó, pati d’interior, pati d’exterior o terrassa 💚

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