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The ecology and ethics of brick kilns

Summary

The production of modern building materials such as bricks can sometimes affect the local economy, architecture and environment more negatively than positively. This article explores this assertion through a study of brick making in Bankura district of West Bengal - one of the poorest districts of India - where the traditional architecture is based largely on construction techniques using local soils.

Brick buildings are generally thought of as being progressive in areas where the traditional architecture is based on unbaked earth. Yet in the case study area, poor production technology has led to less than satisfactory brick quality, caused land and air pollution and affected the local economy by taking away traditional jobs in building, pottery and agriculture. The article raises issues of insensitive technology transfer whilst recognising that the new production methods employed in Bankura seem to have been successful in other parts of India.

History of Brick Production in Bankura

One of the simplest architectural objects, the brick, has survived almost unchanged as one of the world’s most popular building materials for several millennia. Brick has been popular on the Indian sub-continent for many centuries; the evidence is clear in the brick ruins of the Indus civilisation. And Bengal has had a tradition of brick architecture since at least 3000 B C, well before the Aryan invasion of India.

Bankura district in West Bengal has many surviving examples of brick architecture, especially temples. Bankura is situated 200 km north west of Calcutta, just south of the Tropic of Cancer. It has a composite monsoon type of climate, with a flora and fauna adjusted to its harsh climate and poor soils. This region is one of the poorest in India.

Earth in various forms has long been used for building. The most popular local method is cob, in which soil mixed with a little dung is carefully heaped up in thick layers to form walls. Other techniques known in the region include wattle and daub, rammed, laterite and fired earth (in form of bricks and tiles). Given the lack of building stone, more important buildings like temples and palaces were built in brick and laterite while ordinary houses were almost always constructed with cob and thatch.

The Bankura temples, built with the distinctive double-curved ‘Bangla’ style roof, date from the early fifteenth century although there are ruins from earlier periods. The older a temple is, the thinner the brickwork is; sometimes the walls are only 200 mm in thickness.

The bricks were fired in a small traditional kiln, called a ‘Puaan’. This type of kiln is still in use in some places. The kiln is cylindrical, ranging from 1.5m to 3m in diameter and 1m to 2m in depth. It has an opening at the side through which fuel is inserted. Dried vegetation and cowdung are commonly used fuels, although it is considered that tamarind wood is the best for firing. Tamarind wood is supposed to have acidic properties which neutralise the salts in the brick clay, thus preventing problems associated with efflorescence later on.

This method of firing green bricks, which may take several days, usually happens in the summer months. It is particularly labour intensive and slow although there is very little wastage. The technology seems to have been environmentally benign in the past when only a few special buildings such as temples and palaces were made of fired brick. However, new technologies and new aspirations are now changing the situation very rapidly.

The Hoffmann and Bull’s Trench Kilns

These kilns were introduced to India by the British colonial rulers in the late 19th century. They are still found all over India and have remained essentially the same in technology and capacity. They are in the form of an elongated trench measuring up to 10 m in length to 2.5 - 5 m in width. Green bricks are stacked in the bottom with an insulating roof layer made of rejected burnt bricks, ash and earth. A metal tube chimney is moved around and along the kiln as firing proceeds from one end to the other. The fuel used is coal mixed with cinder. In the more efficient kilns, over 70 % of the bricks may be usable while the rest can be crushed to make surki, a cement-like pozzolanic material.

Compared to the traditional puaan kilns this type of kiln is more fuel efficient, can fire more bricks at a time and does not depend on the season for operation. However, they are having a much a larger impact in terms of air pollution, total fuel consumption, space requirement and employment.

Living in a brick house is considered to be proof of upward mobility and progressive attitudes. Official terminology throughout India classifies all buildings made of unfired earth as ‘kutcha’ meaning temporary and weak; while a brick building is called ‘pukka’ meaning permanent and strong. Inevitably, people aspire to modern, pukka homes whilst houses made of unfired earth are associated with poverty and backwardness. Thus, with increasing wealth in some sectors of the population it is not surprising that bricks are in great demand. In recent years new kilns have been built in huge numbers throughout Bankura district.


good agricultural land destroyed by new trench kilns

A case study of Bamundiha village

Bamundiha, on the western borders of Bankura district, is a small village of about 1000 people. It is at the end of an all-weather macadamised road and, being the terminus for the local bus service, is an important point of contact for surrounding smaller villages. Although most of the houses are made of cob, they are being rapidly demolished to make way for brick houses. Until 1991 there was only one brick house in the village. It had been built in the 1960’s. Bricks were hardly made in this area before. But in the past five years, two trench kilns have been built on prime agricultural land just outside the village to cater for the rising demand for bricks. This development has had three important repercussions as discussed below.

Pollution

The pits caused by excavating the soil which is used to make the bricks form the trenches in which firing is done. As these trenches spread horizontally they take up precious agricultural land. And as the firing zone is slowly moved forward and the newly fired bricks are removed a trail of toxic waste is left behind in an exhausted, gaping hole. The inexorable progress of excavation and firing is consuming more and more agricultural land. This is particularly significant in Bamundiha where good agricultural soil is hard to come by. Ironically the soil preferred for brick making is also the most fertile agricultural soil.

There always seem to be land owners needing quick money (and usually a brick house) who are ready to sell or lease their land to brick kiln operators. When the author revisited the village in 1993 she noticed, for the first time, black soot on her bare feet. This is fall-out from the air pollution that is an unwelcome gift of the kilns. The situation is made worse as the pollution level from the nearest kiln is particularly high due to the nature of the fuel being used. As coal prices go up, operators use lower grade coal that they might formerly have rejected, thereby lowering both the quality and quantity of their product and, at the same time, increasing environmental degradation. Another problem is associated with the trucks that come into this village day and night, to transport the bricks. They cause noise, environmental pollution and are too big to travel through the narrow streets of the village.

Employment

Approximately 5 percent of the village population are potters who work on terracotta products and the repair of cob houses. The brick kilns are destroying part of their income. However, the main effect has been on agricultural labourers who mainly comprise the lower and economically deprived castes. As land is swallowed by the kilns, they are losing their livelihood. They have not found alternative work in the kilns because, as one of the kiln operators commented: "I like to employ migrant ‘Biharis’ (people from the neighbouring state of Bihar whose border is 100 km from Bamundiha) as they are more sturdy and work hard for less money". So, with labourers being introduced from afar, the local people are losing out yet again.

Local technology and architecture

Brick making is not a familiar skill locally, nor is building with brick. Sometimes there is almost 40% wastage from the kilns as the soil is not ideal for brick making. Soil is not tested prior to using as this facility is not available in the area. The kiln operators compensate for these losses by paying their labourers less. Most of the kilns such as the ones operating in Bamundiha are not licensed or monitored and so their efficiency and pollution levels go unchecked.

Meanwhile, new buildings are being erected by masons who are not familiar with bricklaying. The result is waste and dangerous structures; several new houses are reported to have collapsed soon after they were finished. The problem of poor quality building is compounded by the low quality bricks which are unlikely to be very durable. Traditional building skills are being abandoned. Whilst a traditional cob and thatch house is not as durable as a high quality brick and tile building, there are many ways to improve both walling and roofing without totally abandoning these familiar and environmentally benign technologies.

The Way Forward

In much of India trench kilns are considered to be a great success. But not in Bamundiha. The reasons lie in the three points mentioned above. There are alternatives. On the technology side a possible answer lies in trying vertical shaft brick kilns. They take up less space and cause less pollution and wastage (5-7%). Or compressed earth block technology may also work here as the region has a rich history of unfired earthen architecture. However for the present what is most needed is a way of monitoring and controlling the existing trench kilns, closing down the ones that cause most pollution and wastage and licensing kilns only after the appropriate soil testing and fuel resourcing have been conducted. The problems connected with local employment could be addressed by the village council or district authorities. But at present no-one is dealing with any of these issues.

By Sumita Sinha

Bibliography:

- Spence R J S and Cook D J. 1983, Building Materials in Developing Countries (Chichester: John Wiley & Sons Ltd)

- Mukherjee A N. 1971, Poramatir Kaaj of Panchmura (Government of India Census - 1971)

- Dasgupta P. 1971, Temple Terracota of Bengal, Crafts Museum (Ministry of Foreign Trade, Government of India)

Note: Sumita Sinha is an architect and environmental consultant. She received a UNESCO award in 1987 for the design of a housing project for artisans in West Bengal. Her concern has been taken up of very recent by Development Alternative and Swiss Development Cooperation, c.f. page 29