Increasingly, our cities and residential areas are looking like cloned habitats, thanks to the way we are stacking up our homes and offices. Colourless, lacking character or depth, these buildings stick out like sore thumbs in a landscape that has its uniqueness.
One of the reasons for this lackluster appearance is also the reason why these edifices burn a deep hole in the buyer’s pocket. At the heart of it, all are two aspects – building materials and building technology. Here I would like to concentrate on the former and examine some of the pressing needs of the hour.
The mistake we have been committing is to apply a one-size-fits-all in the way we build, heaping steel, cement, glass and wood anywhere and everywhere, in aping the west blindly. Simply throwing in a few vertical green towers cannot relieve the monotony. Not only are these materials unsuited for certain climates, they can push up costs simply because they have to be sourced from a distance. Besides being heavy and incurring high transportation cost, materials such as steel and cement sourced from distances lower the sustainability profile of the building as one has to count for extraction, manufacturing and transportation practices. This includes the quantity of energy and water input into the process – two resources that come at a premium.
According to LEED, the global green building standard, the ideal materials are regional ones that have been extracted, harvested, or recovered, as well as manufactured within 500 miles of the project site for a minimum of 10 percent or 20 per cent (based on cost) of the total materials value. On that basis, most of our buildings would fail to qualify as model buildings.
India is a geographically and climatically diverse country spanning from deserts to cold ice-bound climes, temperate to tropical regions. Luckily, we also have an equally rich range of locally available building materials that allow us to utilise their benefits for our comfort. Be it the varied species of timber, clay bricks, lime mortar and mud plaster, many of these have been traditionally used but are gradually being replaced by steel and concrete.
In the southern coastal regions there is laterite mud, clay, red mud and timber of rubber, teak, coconut, palm, eucalyptus and pine. The construction materials created from these materials include clay tiles, laterite blocks, glazed tiles (eg: terracota Mangalore tiles) and laterite stone among others. The southern states have large deposits of granite, limestone and slate which are ideal for building structures and have been in use for years.
Central India is abundant in clay, red mud, granite, marble, sandstone and limestone which have been used in the construction of a wide variety of structures. The practice has been to blend different materials to attain the strength required. For instance, it has been common to mix mud, clay, rice husk, dried grass strands to build homes in villages; in some regions wooden beams and bricks and stones are used for load-bearing walls.
If you look at the state of Karnataka, different regions here use different local materials. If Mangalore is famous for its laterite stone and the tiles that use red mud clay, it is Redwood that is found in Chikmagalur that is favoured there. Ilkal is famous for granite, Bijapur for slate and Mysore for eucalyptus wood. Adobe (sun dried mud brick), granite stone, mud mortar, arecanut trunks, coconut palm trunk, granite stone, bamboo, thatch using coconut leaves, pine wood and rubber wood are all popular in various parts of Karnataka. Each region has its characteristic style. This is being slowly replaced.
The regional construction materials are being phased out simply because the setting process often takes time, not allowing for a fast construction pace. You need to look at the whole picture rather than be influenced by one aspect of speed, however the important speedy execution is, local construction materials come with the advantage of lower costs and reduced carbon footprint but also are suited best for the local climate. Rather than sweat it out in steel and concrete structures, or incur large expenses on HVAC systems, you can opt for cooler earthen structures.
While setting time may weigh against lime mortar as against cement mortar, some amount of research can help bring this down. Using some advancements suited for our construction techniques, we have managed to improvise on the shape and strength of hollow clay blocks. These are made similar to the way clay bricks are processed in kilns. We also source regionally sourced granite for high footfall areas such as staircases, lobbies that can then take higher loads.
The trick is to look around. There is no wisdom in importing costly wood from elsewhere if the region is lush with bamboo. It has a very good tensional strength compared to any other type of woods and bamboo fibres are finding their way in blends with concrete to increase tensile strength.
Local mud or clay can turn out to be very effective in strength by simply mixing and stabilising with suitable complementary materials such as sand, rice straw or iron ash. By using local manpower, it is possible to eliminate some costly construction tools and along with reduced transportation, the overall costs can be as low as 30 percent of the standardised building. Adobe, bricks from the local earth with a good percentage of clay, when mixed with straw or dung, makes for good walls and floors, while reducing energy expended in the process.
The Earth Overshoot Day has been advancing every year, coming faster than before. This marks the time in a year when we start using resources faster than they can be regenerated, be it food, water or forests. After the date, we are using from reserve socks meant for the future. There can be no over-emphasising the need for using locally available construction materials in a resource-constrained planet.