Energy Conservation Strategies |
Building construction is an energy intensive activity. A large number of buildings are constructed with bricks. Brick is manufactured either in kilns or traditional clamps using firewood and the efficiency is very poor. A number of studies by Engineering Colleges and the National Productivity Council have been done to find out energy consumption in brick manufacture. As seen from Table 16 the consumption varies from 167 kg to 700 kg (the kilns use coal and clamps mostly firewood). This study definitely shows that brick industry uses an estimated million tons of firewood per year. Hence it is essential to find out methods of reducing the energy used in this industry.
One solution to this problem is use of unburnt compacted dense soil blocks in place of burnt bricks. Such blocks have been tested and it has shown that their strength is equal to that of burnt blocks for right composition of clay in soil. Further improvements are possible if a small percentage (2-5%) is added to the soil. ASTRA, IISc. has used this principle and constructed a number of buildings. The compression is done in a manually operated machine. ASTRA has designed a simple inexpensive block making machine called ASTRAM. Similar machines have been developed by National Institute of Engineering, Mysore and other Engineering Colleges as part of the KSCST's programmes.
The technology has many advantages;
i) Normally a poor person, who has a mud house, would like to construct a brick house; with this machine, he can compact soil and construct a house which has a good appearance, has the same strength as a conventional brick house and is inexpensive;
ii) Energy consumption - especially firewood - is considerably reduced;
iii) Compaction of soil to make blocks means employment. This generates employment for people in rural areas. Hence this idea has become popular. Currently a large number of persons are using compressed soil blocks to construct houses, schools etc in Bangalore, Mysore and other places.
Another alternative to the problem of wall construction is being studied at S.J.C.E., Mysore - rammed wall construction. This constructs a wall in situ by ramming mud in panelled formers. The panel can be removed later. Such a construction increases strength, reduces the number of joints, uses locally available resource, is inexpensive, uses a simple technology needing minimum skills and is one of the energy saving technologies.
Another area where there is a large scale use of energy is in roofing. Mangalore tiles used for many houses for roofs, needs an energy input of nearly 0.5 kg/tile of firewood (or about 0.33 kg/tile of coal). Some projects are under progress to devise manually operated devices for some aspects of tile making - like pug making extrusion etc. Alternate panelled roof designs - with 2' x 2' steel reinforced tile panels - are being experimented with to be an economical alternative to sloping concrete roofs. This design reduces consumption of cement, another energy intensive material. Already a few buildings - both public institutional and private houses - have adopted this design which gives an architecturally aesthetic, inexpensive and a sloping functional roof to a building. S.J.C.E., Mysore is also working on the design of similar panels for roofs.
Another way of energy conservation in brick and tile industries is to study the process of burning and find out ways of improving efficiency thereby reducing firewood consumption. The State Department of Science and Technology identified this problem and funded a project to National Productivity Council. Their findings are;
i) Use of an improved high draught kiln in brick production will result in 50% savings of fuel;
ii) If the waste heat is used to dry green ones or for preheating in another chamber, about 15-20% of fuel can be saved;
iii) Good housekeeping practices like regular measurements of temparatures, control of dampers, cleaning of ash pits etc can save upto 5% of fuel usage and
iv) Increase of fire travel distance can reduce fuel consumption.
The study has calculated thermal efficiencies for these kilns; (for intermittent kilns=13.7%; continuous kilns=34.2%) specific fuel consumption varies from 300 kg to 1000 kg per 1000 tiles. This shows that as cost of energy is about 48% of production cost and the fuel mostly fire-wood is used inefficiently, the large number of tile and brick manufactures in Karnataka (more than 140) should be educated and encouraged to adopt better practices and go in for continuous kilns.