Rooftop farms: integrating agriculture into our green roofs

In Yale-NUS, where I live, rooftops can be quite a contested space. A few years ago, several Environmental Studies (ES) students advocated for the installation of solar panels on the College’s un-used roof spaces. The months of back-and-forth resulted in an impasse, and some unfortunate tensions between the Infrastructural Office (Infra) and the students. Ultimately, no solar panels were installed, and the proposal has gone to rest. More recently, environmentalists in Yale-NUS have come to request for rooftop space from Infra once again. But this time, the urban farming collective successfully earned the trust of Infra and received permission to expand their farming space to our rooftop space.

The pressures of urbanization has resulted in intense concentrations of skyscrapers in Singapore (A. K. Wong and Yeh 1985). Rooftops are now some of the only spaces left to be further utilized. As we move towards the #30by30 goal, rooftop farming appears to be one of the key pathways forward. While rooftop farming has many ostensible benefits, and is an attractive idea in this small city, there are also many trade-offs associated with maintenance and the additional structural load. Personally, I was most concerned about the embodied energy associated with buildings that bear a heavier load (due to the soil and relevant infrastructure necessary for agriculture). I was interested in whether the emission costs are actually offset by other benefits of rooftop farming, and hence if rooftop farming should be continued. Thus, in this blogpost, I investigate the dis/advantages of rooftop farming and affirm that it is necessary and beneficial in the future of Singapore’s urban agricultural operations. Additionally, I argue that rooftop farming can be integrated into generic green roofs, which are becoming a staple in Singaporean architecture, in the future.

First, it must also be noted that green roofs to refer to any building with rooftop which accommodates all forms of greenery. Green roofs can then be subcategorized into extensive green roofs and intensive green roofs. NParks defines extensive green roofs as those covered in a thin vegetation layer, ‘typically not designed for public access or recreational use, and access is strictly for periodic maintenance (NParks n.d.).’ Meanwhile, intensive green roofs are covered in a variety of vegetation species, ‘usually designed to be accessible to the public. It is often utilised as a communal rooftop space for recreational purposes (NParks n.d.).’ In that, rooftop farming typically falls under the latter category of intensive green roofs.

Green roofs are attractive to the relevant government agencies in Singapore because they provide many benefits. According to Wong et al (2003), ‘NParks is aware of the many other benefits (environmental, social, aesthetic and economic aspects) roof gardens have brought and thus, hopes to motivate the developers and builders to landscape Singapore’s skyline.’ Indeed, the benefits of green roofs are aplenty.

Chiefly, green roofs reduce surface temperature of roofs and decrease the heat transfer into the rest of the building. They mitigate the urban heat island effect and reduce energy consumption of buildings by up to 14.6%, thereby reducing the life cycle costs of buildings (N. H. Wong, Chen, et al. 2003). One study found that the maximum temperature of a hard surface roof in Singapore could peak at 57°C (wow!) – demonstrating the strength of the urban heat island effect in Singapore. Meanwhile, peak temperature of roofs with bare soil was much lower at 42°C, while areas covered in vegetation were below 35°C, depending on the species and their foliage density. Green roofs also enhance other aspects of building performance including air quality, acoustic insulation and the durability of water-proof barriers (NParks n.d.). Additionally, they may provide ecosystem services in the form of carbon storage (Orsini et al. 2014).

However, green roofs come with an additional structural load. It is also unclear much additional embodied emissions are associated with increasing the structural capacity of buildings to accommodate a typical intensive roof garden. When it comes to rooftop agriculture, simplified hydroponic systems may be preferred due to their low weight (Rodríguez-Delfín et al. 2017). That said, the emissions costs of accommodating additional load in new buildings is likely to be sizeable given that default embodied emissions occupy around 30-40% of lifetime emissions of a building (Singapore Green Building Council n.d.). As such, the environmental benefits, in terms of carbon emissions, of green roofs may be mitigated.

Wong et al (2003) also highlight that green roofs are met with resistance by developers in Singapore because of high initial costs and structural loading capacity. Indeed, green roofs can cost up to six times as much compared to conventional roofing systems (N. H. Wong, Tay, et al. 2003). Buildings that were not designed for green roofs may also not be adequately retrofitted to hold additional structural load. This is especially so for intensive roof gardens with greater soil depths to host varied plant species (NParks n.d.). As such, existing buildings’ loading capacity must be carefully studied before any initiation of rooftop farming practices.

Beyond these engineering considerations, green roofs also hold the potential of creating space for recreation and social cohesion. Rooftop agriculture, just like urban agriculture in general, can be a space for community and social justice with the right policy design (Specht, Reynolds, and Sanyé-Mengual 2017). This may be especially applicable in Singapore, where community rooftop agriculture is being introduced to accessible spaces like HDB roofs (e.g., Jurong Community Garden). Rodríguez-Delfín et al (2017) highlight that, “for low-income families, soil-based and simplified hydroponic systems represent a promising approach to tackle poverty and food insecurity.”

In Singapore, rooftop farming is a relatively recent practice. The first tender for HDB carpark rooftop sites for urban farming was launched in September 2020 by the Singapore Food Agency (SFA), signaling a marked shift towards encouraging the use of underutilized space to improve the nation’s food security (CNA 2020). Since then, the SFA has continued to release more tenders for rooftop farming sites (CNA 2021). These are conventional roofs that can be converted for rooftop agriculture. Since it appears that at least some existing buildings in Singapore are able to take the weight of additional roof loads, there is much potential to follow through without additional engineering costs.

Beyond intensive green roofs, extensive green roofs are already being strongly encouraged in Singapore for non-agricultural reasons. Additionally, due to their lower weight demands, they can be more easily introduced to existing buildings compared to the retroactive fitting of intensive green roofs. This holds much possibility as vegetable and herb production is possible and productive even despite the limitations of extensive green roofs (i.e. low soil depths) (Whittinghill and Rowe 2012; Baudoin et al. 2017). Thus, beyond what Singapore is currently doing with the rooftop site tenders, we can also look towards expanding production in extensive green roofs to maximize the use of land area. In such cases, one potential area of contention in this conversion may be the reduction of perceived aesthetic value by building owners. However, it may be a necessary trade-off in Singapore’s vision to improve food security. Even though the Singapore government has established the need to keep green spaces aesthetically beautiful and orderly, perhaps green spaces must now be re-framed to be a space of communal responsibility and practical utility (Neo and Chua 2017).

In all, existing literature affirm the growing trend of rooftop agriculture in places like Singapore. While they may not be the best for mitigating climate change, the host of other benefits they bring, including improved food security, are aligned with the nation’s goals. Additionally, resources supporting rooftop agriculture are extensive and even include details on species of vegetation most suited for rooftop farming and how to cultivate them. Their potential, especially if we include extensive green roof farming, is sizeable and can be applied to the majority of Singapore’s rooftop spaces.

Bibliography

Baudoin, W., Y. Desjardins, M. Dorais, U. R. Charrondière, L. Herzigova, U. El-Behairy, N. Metwaly, C. Marulanda, and N. Ba. 2017. “Rooftop Gardening for Improved Food and Nutrition Security in the Urban Environment.” In Rooftop Urban Agriculture, edited by Francesco Orsini, Marielle Dubbeling, Henk de Zeeuw, and Giorgio Gianquinto, 219–33. Urban Agriculture. Cham: Springer International Publishing. https://doi.org/10.1007/978-3-319-57720-3_13.

CNA. 2020. “Tenders Awarded for 9 Rooftop Farming Sites at HDB Multi-Storey Car Parks.” CNA. September 30, 2020. https://www.channelnewsasia.com/news/singapore/tenders-awarded-rooftop-urban-farming-sites-hdb-car-parks-13163850.

CNA. 2021. “SFA Launches Tender for Rental of 7 Sites at HDB Car Park Rooftops for Urban Farming.” CNA. February 23, 2021. https://www.channelnewsasia.com/news/singapore/urban-farming-hdb-car-park-rooftop-sites-tender-sfa-14262834.

Lambourne, Wendy, and Vivianna Rodriguez Carreon. 2016. “Engendering Transitional Justice: A Transformative Approach to Building Peace and Attaining Human Rights for Women.” Human Rights Review 17 (1): 71–93. https://doi.org/10.1007/s12142-015-0376-0.

Neo, Harvey, and C. Y. Chua. 2017. “Beyond Inclusion and Exclusion: Community Gardens as Spaces of Responsibility.” Annals of the American Association of Geographers 107 (3): 666–81. https://doi.org/10.1080/24694452.2016.1261687.

NParks. n.d. “Rooftop Greenery – The Horizontal Dimension.” National Parks Board. Accessed May 7, 2021. https://www.nparks.gov.sg/skyrisegreenery/explore/rooftop-greenery.

Orsini, Francesco, Daniela Gasperi, Livia Marchetti, Chiara Piovene, Stefano Draghetti, Solange Ramazzotti, Giovanni Bazzocchi, and Giorgio Gianquinto. 2014. “Exploring the Production Capacity of Rooftop Gardens (RTGs) in Urban Agriculture: The Potential Impact on Food and Nutrition Security, Biodiversity and Other Ecosystem Services in the City of Bologna.” Food Security 6 (6): 781–92. https://doi.org/10.1007/s12571-014-0389-6.

Rodríguez-Delfín, Alfredo, Nazim Gruda, Christine Eigenbrod, Francesco Orsini, and Giorgio Gianquinto. 2017. “Soil Based and Simplified Hydroponics Rooftop Gardens.” In Rooftop Urban Agriculture, edited by Francesco Orsini, Marielle Dubbeling, Henk de Zeeuw, and Giorgio Gianquinto, 61–81. Urban Agriculture. Cham: Springer International Publishing. https://doi.org/10.1007/978-3-319-57720-3_5.

Singapore Green Building Council. n.d. “Bringing Embodied Carbon Upfront.” Accessed May 7, 2021. https://www.sgbc.sg/latestnews/749-bringing-embodied-carbon-upfront.

Specht, Kathrin, Kristin Reynolds, and Esther Sanyé-Mengual. 2017. “Community and Social Justice Aspects of Rooftop Agriculture.” In Rooftop Urban Agriculture, edited by Francesco Orsini, Marielle Dubbeling, Henk de Zeeuw, and Giorgio Gianquinto, 277–90. Urban Agriculture. Cham: Springer International Publishing. https://doi.org/10.1007/978-3-319-57720-3_17.

Whittinghill, Leigh J., and D. Bradley Rowe. 2012. “The Role of Green Roof Technology in Urban Agriculture.” Renewable Agriculture and Food Systems 27 (4): 314–22.

Wong, Aline K., and Stephen HK Yeh. 1985. Housing a Nation: 25 Years of Public Housing in Singapore. Brook House Pub.

Wong, Nyuk Hien, Yu Chen, Chui Leng Ong, and Angelia Sia. 2003. “Investigation of Thermal Benefits of Rooftop Garden in the Tropical Environment.” Building and Environment 38 (2): 261–70. https://doi.org/10.1016/S0360-1323(02)00066-5.

Wong, Nyuk Hien, Su Fen Tay, Raymond Wong, Chui Leng Ong, and Angelia Sia. 2003. “Life Cycle Cost Analysis of Rooftop Gardens in Singapore.” Building and Environment 38 (3): 499–509. https://doi.org/10.1016/S0360-1323(02)00131-2.

What have I learned about taking care of my own UA plot: Responsibility, care and nuance

I’ve learned a fair amount of technical knowledge in the course of taking care of my plot. As detailed in my previous blogpost, the workshops we’ve attended have helped me understand farming techniques and knowledge. Over the course of this semester, I’ve tried to use some of them in my own UA plot However, I suspect it is the values and principles I’ve learned about that will stay with me beyond the class.

I was once asked, in an interview about my relationship to the environment, what I would change about my childhood. My response to that was: my relationship to food (waste). I’ve always been more comfortable with wasting food than I should be. I suspect that this is influenced by the distance that I feel: as a Singaporean, born and raised here, I’ve never really known about where or how my food is grown. And I never really cared too much, either. Narratives about farmers breaking their backs for a grain of rice have always felt like mythical exaggerations I should ignore.

But now, I have immense respect for people who grow food! I am so much more aware of exactly how difficult it can be. My entire batch of kalian have unfortunately been decimated by leaf miners, for example.  Farming is truly a long-term, iterative project. Even while some crops are extremely hardy (e.g. the Malabar spinach I’ve been growing), harvests truly need to be earned. One must always listen to the crops and the environment and respond appropriately!

Especially in an extremely sedentary and privileged environment like Yale-NUS, I feel very humbled by the urban farming experience. I am glad to literally get close to the soil and connect to the practice.

I’m also consistently inspired by my peers who are so careful and committed to the health of their crops. Even practices like green manuring – where legumes are planted in the plot at the end of a planting cycle – are new to me! And it’s heartening to know that regeneration can occur as long as we’re intentional with the way we treat the soil.

Beyond personal reflection, this experience has shifted my view on UA practices on broader levels.

From a reading we did in class, we learned about Neo and Chua (2017)’s heuristic scale of responsibilities in a community garden and the spectrum stretches from “garden-centric” to “community-centric” (674). “Garden-centric” would refer to more technical things like prioritizing yield, upgrading skills and expertise. “Community-centric” refers to sharing common spaces, sharing harvests, running workshops. In principle, I have always strongly favored community-centric approaches. For example, I used to be quite harsh in my judgment against what I saw was exclusionary practices like fencing community gardens. I thought they were antithetical to community-centrism. However, I have a much more nuanced perception. After struggling with my own plants, I can appreciate why farmers who spend so much time on their plots would not want people to steal their harvests! There is certainly much room for empathy all around.

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Left: hardy malabar spinach doing great and ready for harvest soon! Right: Kailan, attacked by leaf miners 😦 They died shortly after.

References:

Neo, H., & Chua, C. Y. (2017). Beyond inclusion and exclusion: Community gardens as spaces of responsibility. Annals of the American Association of Geographers, 107, 666–681.

Health

In the past few weeks, our class has had the privilege of visiting the Jurong Community Garden, as well as farms in private and public school campuses. We attended a masterclass on permaculture with Chingwei from Foodscape Collective, and one on soil health by Mr Tang. Through these sessions, I’ve learned quite a lot about plant and soil health!

Perhaps the most important lesson is that plants and soils are all dynamic, living beings. With soil, especially, it can be easy to forget that it is an active composite of bacteria, nutrients, decayed/decaying organic matter, humus, etc. In that, we need to recognize that plant and soil health are ever-changing and exist within the ecosystem that it is in. As such, plant and soil health are dependent on one another, as well as the health of other plants and animals in the area.

For example, the use of organic pesticides ensure the health of pollinators that, in return, promote the health of plants.  We learned from Mdm Kamisah at the Jurong Community Garden two solutions that have worked for their garden. The first is a mix of 1 tsp sulfur soap (grated), 1 tsp vinegar and 1.5 litres of water. This creates an organic pesticide that can be sprayed onto plants to prevent pests like leaf miners (I’ll get into leaf miners in a bit!). The second is to use diluted milk to spray onto plants with powdery mildew.  

Some gardening solutions were more controversial also exactly because of the independence of a garden’s health. For example, Mdm Kamisah taught us about solarizing: a practice where soil is left exposed for an extended period of time between cropping, to get rid of bad bacteria. While this seemed like an easy and effective preventive measure against pests, Chingwei and Mr Tang advised against the technique because it also gets rid of the good bacteria and other micro-organisms in the soil. Instead, the two of them prefer a more holistic, ecological approach where it’s about finding specific ways to restore healthy balance to the soil. For example, Mr Tang shared an example when his crops did poorly because he put too much fish guts, causing too much nitrogen to result in aphids. After these crops failed, he then adjusted what he added to the soil accordingly and let it reach a new plant-healthy balance. It seems that these techniques require more patience, but protect the good micro-organisms that are beneficial to plant growth.

Additionally, we learned about the principles of permaculture, which were immensely helpful in understanding how we can maintain plant and soil health. Simple acts like ‘observe and listen’ imbue farming with a sense of humility. Combined with creativity and the principle of ‘integrate rather than separate,’ we can find solutions that maximise health with minimal input.

Principles of Permaculture, as shared by Chingwei. Photo by Ziyang.

For example, when chickens were interrupting composting efforts at Chingwei’s farm, she built a ‘chicken playground,’ (i.e. a small site that attracted chickens and was suitable for digging) such that their energy could be channeled into something positive and away from disruption. This benefited the chickens, the compost, and in turn, the plants and soil.

I was truly impressed by such resourcefulness and creativity! Another example that I enjoyed learning about was the use of tapioca as a pioneer crop which can grow easily under harsh conditions and, in the process, return some nutrients to the soil such that it can be later used for other crops. This was done in extremely difficult conditions, where Chingwei and Foodscape collective had to dig a 1m deep trench in very compact and gravelly soil and filled it with branches and organic material in an attempt to bring new life to the soil. The tapioca seemed to be doing well.

Farming is truly such a complex practice, and I’m impressed by the creativity and commitment of these community gardeners who are so willing and happy to share their knowledge!

An update on my kailan: sadly, it’s been having a rough time due to leaf miner infestations. Within a few weeks, they’ve been completely taken over (pictured: start of leaf miner infestation on 26 feb, and serious infestation even after cutting heavily infected leaves on 18 mar). Neem oil, however, seems to be helping …

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Planting seeds for social justice :)

from 6 Feb 2021

From tackling the climate crisis to social justice, UA can be hailed as a wonderful solution for people in cities (which is most of us, after all). I’m eager to support UA as a justice movement the most! That said, we must be cautioned against overstating the scale of UA’s tangible impacts.

I find it very exciting, and frankly quite poetic, that resistance against corporate power and oppression can be found in the gentle act of tending to plants. While urban farmers, especially non-commercial ones, are unlikely to achieve complete self-sufficiency, UA remains a way for people to resist the conventional food system. Quantitative studies have also found that urban farming is associated with dietary diversity, which is closely related to caloric adequacy and positive physical outcomes, especially in the global south (Zezzo and Tasciotti 2010).  This is especially significant given that conventional food systems are often not sustainable or regenerative, both in biophysical and social ways (Rhodes 2017).

Beyond the physical, UA has strong social elements to it. UA can also support marginalized communities strengthen community bonds and resist cultural oppression, as Reynolds and Cohen (2016) put it. For example, UA can be a way to assert agency and refute the image of victimization for marginalized communities (Reynolds and Cohen 2016). 

Meanwhile, we witness the political outcomes of UA in spaces like New York City. There, the UA movement has come to represent ‘self-determination and political agency – the ability to effect political change in one’s community – especially in the face of “racial and economic apartheid (Reynolds and Cohen 2016).”

I find these ideas very appealing partly because of the potential I see in the Singaporean context. There is ideological alignment because UA fits very well into the government’s 30-by-30 plans. Beyond that, Singapore is a dense city with a very high rate of income inequality. In this social context, it would be quite cool for UA and community gardens to be a way to empower communities and support food justice (although we might have to frame it differently to suit the local context). 

Additionally, UA can close the distance between Singapore’s diet and the source of our food. Merely recognizing how much effort goes into growing a single vegetable could perhaps shift perspectives about the conventional food system and promote a greater consciousness about the structural transformations we need to promote climate justice.

Transplanted baby Kailan! They’re my favourite veggies, and I’m learning to appreciate them (and the farmers behind the delicious kailan I’ve had) even more.

That said, I acknowledge that these visions are idealistic, and far more difficult to materialize.

Furthermore, I am not as eager to support the entrepreneurial urban farmers whose main motive is profit. I fear that it may undermine the grassroots and community-based spirit of UA which I appreciate the most. After all, it no longer becomes resistance if it reproduces the capitalist system associated with the very things some UA movements set out to resist. That said, my hesitation is tempered when these farmers come from marginalised identities – after all, the success of historically oppressed people is a good and necessary step towards social justice. In addition, I believe that localization is generally a good thing (for food security + minimizing carbon footprint from transportation). Scalable, entrepreneurial urban farms may be the way to go about that in cities or countries like Singapore.

In all, I’ve been learning much about UA across various contexts and look forward to continue doing so!

why urban agriculture?

My gardening journey begins with the Covid-19 pandemic: being indoors so much meant that I had to come up with more ways to keep physical environment more exciting. With some encouragement from my peers, I was inspired to acquire some houseplants for my college dorm.

Around the same time, NParks launched gardening campaign where they offered seeds to Singaporean residents to bolster their 30 by 30 goal. I signed up on a whim – at the time frankly not knowing if the seeds would even ever leave their packaging.

As it happened, the opportunity to germinate my cucumber seeds arose when my housemate brought a bag of soil to the suite. And thus begun my journey with my dear cucumber plants, who now occupies the entire corridor outside my suite. They have since been named Ahurok – Belarusian for cucumber, as shared by my Belarusian neighbor.

I’m happy to say, a few months down the road, that I’ve taken to the role of plant caretaker quite well! Nurturing this cucumber plant has been both exciting and meditative for me. It holds me accountable to being intentional and practicing care every day. It fosters my appreciation for non-human life. It allows me to bring something new to the heavily-curated common spaces of Yale-NUS. It’s also nurtured a community spirit amongst my sky garden mates who occasionally come by to chat while I water the plant. While I was recently asked to remove them, I’m holding out and trying to let them stay there for a bit longer — they are reaching the end of their lifespan, after all.

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[A zine I made for the National Gallery Singapore’s upcoming youth festival: The condensed story of Ahurok.

This experience was certainly part of what compelled me to take a class in urban agriculture (UA).

Borrowing McClintock and Simpson’s (2017) framework, I might categorize myself as a DIY secessionist urban agriculturalist: someone who is motivated to engage in UA for the sake of recreation, community-building and the reclamation of the commons. The other five motivational frames include sustainable development, radical, educational, ecocentric and entrepreneur.

Six motivational frames behind UA (McClintock & Simpson 2017, p26)

I personally am also interested in the radical motivational frame, where UA can be a reclaimed space for justice, food sovereignty and anti-capitalist exchange. This is especially so in a city like Singapore where land is immensely scarce and heavily policed, and where capitalist logic pervades much of daily life.

In the past, I’d assumed that (small-scale) urban agriculture was merely a hobby for the privileged who had the time and energy to tend to a garden.

This has since changed after exposure to the radical potential of UA as a movement. I am reminded of what Bill Morrison said:

Hence the futility of revolutionaries who have no gardens, who depend on the very system they attack, and who produce words and bullets, not food and shelter.

Here, UA becomes a way to resist the corporate agriculture, democratize land, and empower people beyond concerns about profit. This, of course, is not to insist on any one path towards climate justice. I believe that revolutionaries without gardens are doing good work, too! But gardens are certainly important — and I look forward to see what further understanding of UA emerge from my 13-week journey with this class.

References:

McClintock, N., & Simpson, M. (2017). Stacking functions: identifying motivational frames guiding urban agriculture organizations and businesses in the United States and Canada. Agriculture and Human Values, 1-21.