Lessons in environment

If schools are about laying the right foundation,Aman Setu seems to have got it right. With its classrooms made of mud...

If schools are about laying the right foundation,Aman Setu seems to have got it right. With its classrooms made of mud,bamboo,straw,husk and cowdungeven discarded cement sacks,barbed wire,plastic bottles,advertisement hoardingsthis school on the outskirts of Pune,in Wagholi,has managed to teach its children their most fundamental and unforgettable lesson in ecological conservation.

This building technique,called Earth bagging is nothing new. It has been around for a few thousand years. Only we have so completely forgotten it that today professionals and architecture students refer to it as non conventional technology, says Saurabh Phadke,the architect of these classrooms.

Earth bag construction is a technique where bags are filled with an appropriate earth mix,sealed and stacked like conventional masonry with barbed wire acting as Velcro mortar between layers and consolidated by tamping. This also makes the structure quake resistant.

The technique has been used worldwide for varying purposesfrom constructing military bunkers to making water retention structures. The idea that dirt-filled bags can be used to construct a permanent shelter was first introduced in the mid 80s by architect Nader Khalili. Incidentally,then it was not introduced as a low cost sustainable technique but as a solution for lunar housing! says Phadke.

It was during a NASA symposium that was exploring ways of colonising the moon that Khalili proposed that moon dust could be filled in bags to build a structure.

At Aman Setu,once the concept was cemented the design took in suggestions from children Phadke carried out several tests with different materials and mixes before starting with the construction. The selected area was cleared of grass and the area to be excavated was marked on the soil. Trenches were dug,the top soil was segregated and not used for construction,while the rest was retained for using in the earth bags.

A 450 mm deep trench suffices for non load bearing walls. This depth is adequate for bamboo column foundations. A level base for earth bags can be prepared by simply tamping the trench base. If heavy loads are imposed on the earth bag wall,a simple concrete base should suffice. Generally,the fill material should be 30 per cent clay and 70 per cent sand. Stabilisers such as cement can be added to the mix to endure better bonding of all constituents. Bags should be filled to 80 per cent of their capacity, explains Phadke adding that they used discarded cement sacks from nearby construction sites.

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The earth bags were then stitched with a flat plastic thread and laid along the trench,leaving space for the bamboo footings. They were then tamped with a home made tamping rod till compacted properly. On completing a course,two strands of barbed wire about six inches apart were placed on top and the procedure repeated. Door opening and windows were spanned with conventional lintels or earth bag arches with bamboo supports. The earth bag courses were corbelled to create a conical roof or a dome shaped structure. Finally,chicken mesh was stretched over the earth bag wall to provide the rough base for the plaster to hold on.

While externally,regular plaster was applied for surface finish and to ensure the durability of the structure,internally,the team tried out different natural mixeswheat flour,cowdung,paneer,whey,paper-mache etc for the walls and the floor. Old hoardings were used on the roof for waterproofing.

Even as the rust brown structure with its green roof elicited much excitement,the toilet vied for attentionthe children call it funny toilet. It is technically known as a Urine Diversion Dehydration Toilet. It works on the simple principle of source separation and sanitisation. Hence the urine and the faeces are both sanitised and used as a fertiliser. This sort of a toilet uses only about 1/10th the amount of water consumed by most modern systems. Discarded plastic bottles act as vent pipes, says Phadke.

These bottles were also put to use in the reception area,with one wall made of coloured plastic bottles with their bases cut off and arranged to look like flowers in a cement bed at the entrance of the classrooms.

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The science lab of the school is located in a discarded bus of the Pune Municipal Corporation that was bought for Rs 70,000 and then given a makeover. The classrooms took just over a month to build. They are about 500 sqft in size and cost Rs 2.25 lakh. Hence this kind of construction costs about Rs 450 per sq ft and is cheaper than most other technologies, says Phadke.

Madhavi Kapur,founder of Aman Setu says,By creating a learning space like this,we are living up to Gandhijis direction to BE the change. Not only is the structure kinder to the earth,aesthetically satisfying,cool and comfortable,it is also a dynamic learning space.