Transition Culture

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14 Feb 2014

Zenrainman on the rooftop paddy fields of Bangalore

I was recently in Amsterdam at an event at which one of the other speakers was S. Vishwanath, better known as Zenrainman.  He spoke of his work in Bangalore, where he is working to get the city to look at its resources in a very different way.  Could the city of Bangalore really become a net exporter of rice, just from its rooftops?  It was a fascinating story, one I knew had to be shared here.  So a couple of weeks later we hooked up on Skype, and here’s our conversation:

“My name is Vishwanath, I also call myself Zenrainman. I’m a civil engineer and an urban planner by qualification. I’ve worked for the Government of India for about 14 years and after that have been trying to work on sustainable water and sanitation systems and a bit on ecological architecture and groundwater management systems. That’s all happening in the city of Bangalore in India. A lot of the work happens in other states of India also.

I run a small company called Biome Solutions and that is the professional ecological architectural firm which designs and implements earth architecture and earth buildings. And there’s a Biome Trust which works with schools and helps them access better water, sanitation and education.

When I saw you speaking in Amsterdam, a month or so ago, you were talking about the work you’ve been doing in Bangalore trying to get the city to look at its rooftops in a different way. Could you tell us a bit about that?

The city’s a bit uniquely placed in an Indian context. It sits on a ridge line, so it’s very far away from water systems. Water has to come from over 100 km and has to be pumped 300m. And similarly food also has to come from a long distance to get into the city. There’s a physical ceiling to the water availability of the city, we can only draw about 1,500 million litres per day from the river, and we’ve already drawn, that so there is no more water in the river for us as a city.

Rice on the roof

The city has to look at alternatives and one obvious one is to look at local resources. Rainwater harvesting was one way the city could start to supplement its water requirements, and what better place to start rainwater harvesting than the rooftops? Once you start looking at the rooftops of the city you start to examine many more possibilities and potentialities. Not only can it harvest rain but we can also start to capture solar energy.  Luckily the city has the largest number of solar water heaters of any city in India. So can we then start capturing solar energy for water heating, for cooking, for lighting? That was obviously the next step.

The third step was that we can actually use the rooftops for growing food for ourselves. Since South Indians love a lot of rice, one experiment was to grow rice on the rooftops to see how that would perform. And then to look at creative ways with water and what we call ecological sanitation toilets, composting toilets and using the nutrients from the toilet for the rice paddy. The experiment turned out pretty well, so we have been trying to push that too in the whole system of designing and implementing smart roofs.

What one found out of course was that a roof could also become an absorber of all the waste streams that come out from the house, be it the water from the toilets or the kitchen compost or the grey water from the bathroom.  The paddy crop was excellently designed to do all that absorption and convert it into food, and stock of course. Paddy, the grass that feeds half the world, is my favourite wetland crop.  That’s been the experiment around smart roofs for smart cities.

So all of the toilet waste, liquid and solid from the house can be cycled around the rooftop paddy field?

Completely.  What we figured out was that urine can be easily absorbed by the paddy almost on a daily basis, so there’s no surplus available. Solids can be composted for 8-10 months or slightly longer if necessary, and that compost can also be added to the rice on the roof. Everything is absorbed by the rice plants.


And it doesn’t smell?

Well, fantastically, what it does is if you separate number 1 and 2, the smell quotient drops dramatically. If you were to cover it well, the solids especially, with ash that comes from a biomass boiler or a cooker which is there on the rooftop as well, then there is no smell at all from the loo.

How does that work in multiple occupancy buildings, when you have a number of apartments in one block? Can it work there too?

Rice on the roofThat’s the trickier part. What one realises in this experiment is that everyone deserves their piece of sky. In the context of Bangalore, you actually should have about 35 square metres of roof land in your area. If you have that 35 square metres beaming up to the sky, then that patch of land or that patch of roof can then receive rainwater, can receive solar energy and so on and so forth.

In a multi-story building obviously, you do not have such a large parcel of land for you to live. Therefore my questioning now, internally and as my friends and professionals say, should not cities plan to be self-sufficient with a right to land or a right to sky?

How long have you been promoting this idea and how has it been received, how has it taken off?

For example, rainwater harvesting is now the law in this city, so there are more than 100,000 buildings – I worked on the policy aspect of it, worked with the government on setting up the by-laws for buildings. We’ve got about 100,000 buildings doing rainwater harvesting in this city alone.

As I said, solar water heating now is becoming very common and it’s done almost de rigueur. Everyone picks up solar water heaters and install them for themselves, because it saves a lot of money and energy. The rooftop cultivation is now becoming quite popular too. People don’t grow rice, they find it a bit strange and difficult to wrestle with this idea, but rooftop gardening is exploding all across Bangalore. It’s not me alone. There are many, many people who are part of the movement and who are doing wonderful work.

What’s your sense of what needs to happen in order to scale up the rice growing part of it?

The rice was just an example, sort of like a metaphor because rice is seen as extremely water intensive. If you’re a water harvester or a water conserver, it was automatically assumed that you would be against rice, that you would grow other local crops like millet or other things. But what one could show was that rice a) did not need a lot of water and b) was a very nice plant that could transform waste into nutrients. That idea slowly but surely is spreading and people loved the idea. People don’t necessarily grow only rice but they do grow a whole bunch of things that can take care of waste water on the rooftops.

 It must potentially open up potential for employment, particularly for people who’ve moved to the city from the villages and who’ve struggled to find work, but who bring those skills with them?

Absolutely. The construction sector is one of the greatest employers of unskilled village workers in typical cities of India. These village workers are not permanent migrants, many are temporary migrants who come during the non-agricultural season in the rural areas. When they come to the city and, for example, the rice on the roof was such a nice thing that they liked, they almost participated for free. That’s at one level.

However, with their skills of gardening, their ability to take care of plants and vegetables, urban gardening and urban rooftop cultivation would potentially be of great help to them for employment.


What does this project and your work teach us about what, conventionally, our city authorities would think of as resources, and actually what with a more imaginative approach we could think of as resources?

So far the city authorities in India, perhaps for historical reasons, have seen themselves as providers of services and products, so the city utility looks at itself as providing water and providing the sanitation system to take it away.

Now I think they must and surely there will be a slow shift to where they see people providing it for themselves, and they being just managers and making sure that things are alright, and that there’s no negative externalities. It takes a lot of dialogue and a lot of convincing to do that. The city governments and city utilities are generally a bit suspicious about it. At scales below a certain level, they don’t see it as threatening. But one has to wait and see how the dialogue will develop.

From outside India, it seems like the rush, the push for economic growth means that concerns about the environment or concerns about climate change are really at the bottom, or any kind of questioning of economic growth as a model is being pushed to one side. You’re promoting something which is about bringing food production very much to the forefront in urban areas. How do those two things sit alongside each other? Do you see that there’s an openness to thinking beyond the current economic model, or are you very much having to work within it?

People generally don’t see the economic potential of all this. Even such a thing as rainwater harvesting, how much money can come into the sector, how much livelihood and employment can be provided?  How much innovation can be postured, people designing wonderful systems of filtering rainwater, separating the first rain and so on and so forth?

But when the numbers are stacked up, it really starts to show you that you could tap into what’s called the green economy more, very easily. Productivity need not necessarily be sacrificed at the cost of the environment.

The fact remains that in India there is a really huge water crisis. So climate and climate change is seen more through the lens of water a lot more by the population. If you’re able to figure out solutions for people and demonstrate it, I think the government would necessarily come in line with it and not necessarily be in conflict with it.

When I saw you speak in Amsterdam, you talked a bit about the potential of growing rice on roofs in terms of feeding the city. Could you give us a taste of the potential of this, or what would be your vision of how far this could go?

 The total city area of Bangalore is about 800 square km, of which about 60% is roofs. There’s something like 1.8 million properties.  If all of them started to grow rice on the rooftop, the city can actually be a net exporter of rice, that’s the potential at the ultimate end.

One doesn’t see that happening, but one definitely sees smart roofs, growing roofs,  productive roofs, harvesting grain, using solar energy, absorbing waste streams and nutrient streams as a distinct possibility for the city.

What are the obstacles that you need to overcome in order to move towards that?

Seriously, it’s just a question of small groups starting to spread the work as it’s already happening and a bit of a skillset. If you just want to grow rice on the rooftop, that’s possible, but if you want to put in grey water systems or put in eco-san systems as nutrient flows for the rice then it needs a lot of skills to be able to do that and that is not available enough in Bangalore right now.  Growing that would be important.

In terms of selling the idea, is the most persuasive argument around climate, around the environment, around public health, around saving money, around biodiversity – what catches most with people?

I think it’s the simpler ideas, not the more complex ones like climate change. It’s about growing your own food and having fun doing that, and being able to do it with limited resources and limited money, not really needing big money to do it. Having fun on the way. I think that’s the best hope, and it especially resonates with a lot of the younger people who populate Bangalore a lot, people from the IT sector who participate for the fun and the knowledge that growing your own food gives them.