Sustainable small-scale brick production
Practical Action
efficiency is of crucial importance, rather than energy efficiency or perhaps the long-term
environmental impact. As such, they were quick to grasp the advantages of using boiler waste
in Zimbabwe or sawdust in Sri Lanka and Peru.
SMEs often manufacture low quality bricks; underfiring, to save on fuel costs or due to the
dwindling supply of fuel, is an important factor in this. Their product quality needs to improve
if they are to make the most of the emerging urban markets. Better kilns and firing methods
are one factor in product quality but improvements in other aspects of the production process
also help. Product pricing clearly affects market viability and demand, suggesting that there is
a case to be made for the production of different grades, to suit a range of market segments.
Energy data from brick production are often unreliable and incomparable; a standard method
for assessing energy efficiency is required to make systematic progress and share lessons.
Similarly, there are no standard methods to assess the environmental impact of SMEs, and
Practical Action is developing those in practice. Given that it took some time to develop and
apply the methods, more reliable results are only now starting to come in.
At the SME level, it seems reasonable to aim for a firing energy figure of around 2 MJ/kg of
fired brick of acceptable quality; this amounts to an energy efficiency of around 40%. The
drying energy will have to be added to that. This type of production will release at least 0.25
kg CO2 per kg of brick. What these targets represent in terms of energy savings or reduced
pollution depends on the baseline situation in each case.
A second strategy for the survival of SMEs is fuel substitution. It is possible to use coal in
clamps or Scotch kilns, and there is great scope to use residues, mixed in the brick clay, loose
or briquetted. Use of alternative fuels can have a considerable impact on the commercial
viability of SMEs. As yet, the environmental impact of using residues as fuel is somewhat
unclear, but since their current disposal is often by burning or dumping, it is assumed to be
no worse than burning wood.
So far, there is insufficient reliable data on the comparative efficiency of different kiln types.
The figures provided in Table 1 are at best indicative, but once the standard method is applied
more widely, they will become firmer. The coal-fired VSK (Vertical Shaft Kiln) has proven to be
very efficient in China, but its dissemination elsewhere in Asia has run into problems. A Swiss-
funded project in India, has, however, proven to be more successful in its dissemination of the
technology and has also generated further improvements to the kiln. In theory; bigger kilns are
more efficient.
Finally, improvements elsewhere in the production process, such as better soil selection and
preparation or better moulding and drying, not only help to produce more marketable products,
but also to reduce waste and save energy.
Summary
Building materials production is the greatest single contributor to pollution in the construction
sector. Developing countries are facing an increasing demand for conventional materials, such
as fired clay products. A large proportion of these are produced by SMEs, generating income
but often significant amounts of pollution too. This paper looks at brick production as an
example of a conventional building industry with a substantial environmental impact. The
sustainability of SMEs producing these materials is under threat. A significant factor in this is
their inefficient energy use and reliance on wood as their main source of fuel.
After many years of research and development, supported mainly by the UK's Department for
International Development (DFID), the Intermediate Technology Development Group (now
Practical Action) has concluded that standard methods are required to assess energy efficiency
and environmental impact. Improvements to kilns and their operation enable energy
efficiencies in SMEs to reach at least 40%. Furthermore, it is possible to substitute fuelwood
by coal, charcoal and oil. The use of residues, such as rice husk, bagasse or sawdust, as fuel
also has great potential. Savings on fuel are crucial in enhancing the economic sustainability
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