Use of Natural Building Materials From a Sustainability Perspective
Many of the naturally available and local building materials may not be sustainable in the long run. Dr. Benny Kuriakose discusses about natural building materials such as earth, granite, laterite, lime, timber etc. from a sustainability perspective.
The traditional Kerala architecture, as elsewhere, had developed according to the climate, local materials, and socio-economic relations. Bamboo, earth, lime, timber, leaves etc. were used in the warm humid climate of Kerala.
The most prominent feature of traditional buildings is the sloping roof with 'roof ears'. The carpenters considered the roof design as the most. The important and difficult part. It comes down very low and protects the walls from rain and sun, thus keeping the interior cool.
Illustration 1: A view of the Padmanabhapuram Palace Complex in Kanyakumari District. This is an example of the traditional Kerala Architecture with prominent roofs.
The traditional architecture of Kerala was modest. Houses never attained the brilliance of the places of North India; they were simple, small, but refined. The rich lived in buildings built with laterite blocks, lime, timber and clay tiles. The poorly constructed buildings with less permanent building materials such as earth, bamboo and coconut leaves. But the predominant features are visible in these houses as well.
Natural Materials Vs Local Materials
There is a difference between local materials and natural materials.Traditional Kerala architecture has used local materials. Gandhi ji has said that architecture shall use materials which are available within a radius of five miles.
Natural materials such as marble etc. may not be available locally. They may not be sustainable because of the extra distance in transportation.
In this article, we are looking at some aspects of achieving sustainability to the maximum extent in building construction in Kerala.
In many large buildings, the earth was used. The sun-dried mud bricks may be used for the second storey of a two-storey building, laterite being used for the ground floor. They may also be used for the less important part of buildings. The use of earth blocks (without ramming or sun-dried bricks) was common only among the poor. Mortar using earth is also used in many buildings constructed with laterite so as to reduce the cost of construction.
Mostly, the stone used in Kerala for buildings is granite. We do not have deposits of limestone or sandstone. Granite is very hard and used in the foundations. It was rarely used for the superstructure until the present century, except in temples.
The foundations were usually built with laterite blocks. They are dug out from the earth. Laterite is a hardened earth layer formed due to the weathering of acid rocks. The compressive strength can be higher than that of burnt bricks. It is very porous and cannot hold water. Usually, they are found in layers of 3 to 15 metres below the ground. The top one to two metres will be soft. Towards the bottom, it merges with the clay layer. Laterite can be called the “Blessing of Kerala” since 80% if Kerala’s surface is covered with it. It was widely used for the superstructure. The use of burnt bricks was rare except in the case of few palaces.
Illustration 2: Temple tank in Peralassery Temple in Kannur. The district built with laterite blocks.
Illustration 3: A building with lime.
Lime made from shells was used as mortar for the superstructure shells were burnt in kilns. Lime produced by adding water was beaten thoroughly. Special tanks were constructed for beating lime with a special tool made of wood. This has been found to increase strength. The beating up process increases the workability, thereby reducing the amount of water to be added. Lime gains strength by air drying and less amount of water is good for attaining strength.
Illustration 4: In Kerala, the main source of lime is from shells.
Illustration 5: There were many local techniques of using lime within Kerala itself. Many organic items were added to increase the strength of the lime mortar.
Timber is the most predominant building material. It was widely available and many varieties are very durable. Teak, jack wood, anjali and thembavu were commonly used. In the typical traditional architecture, timber was used for walls, doors and windows, intermediate floors and roofs. Buildings with timber walls were built in Travancore till about 100 years ago.
Timber was getting scarce toward the end of the 19th century as a result of the advent of the railways. Although there were many private forests, in course of time, the Government wanted to have the monopoly of the kinds of timber generally used for house building. Laterite came to be used for walls instead of timber.
Because of the prominence of the timber in traditional Kerala construction, the carpenter was the head craftsman. Since there was little masonry work, masons were of negligible importance in the case of building the timber walled buildings (Arayum Nirayum).
Climate change is happening and many of the building materials are becoming scarce. Hence it is very important to look at the sustainability of the different building materials.
Although a lot of people call it mud, let us call it earth. An architect in England said that “give me a hat and a roof, I will last forever.
If the earth from the site where the building is used, then it becomes very sustainable. But if the earth has to be transported over a distance, then the embodied energy will go up. But one has to remember that even burnt bricks have to be transported, so why not earth.
Illustration 7: A House-made with interlocking earth blocks without the use of any mortar. This is designed by Benny Kuriakose.
Illustration 8: A close up of the interlocking earth blocks.
If cement is used for strengthening the earth blocks, then the sustainability the aspect will be less in such a case depending among the amount of cement being added. If interlocking earth blocks are being used, then the sustainability will be more since no cement mortar is being used for the construction of the superstructure.
The general impression among the public is that if you have a building with earth blocks, then it is very sustainable, but in many cases, it need not be. The cost of the superstructure of a building is only 15-20 % of the overall cost of construction, while the rest of the building units need not be sustainable at all.
There was a time when I thought granite was a sustainable building material, but things are quite different now. There are many quarries from different parts in Kerala. In the olden days, it was very much a local material, but now big quarries have come in the western ghats, many of them invulnerable and fragile areas. Granite which is being quarried from these places is not sustainable, because of the harmful effects it causes on our environment in the form of landslides and other natural disasters.
When my father constructed a house in my village, the laterite was quarried from the site itself. When I was a child, I used to see this land, but over a period of time, it is completely filled up and nobody sees the quarry any more.
Nowadays, the laterite which is being used can be the machine cut. The advantage is that the blocks have much higher compressive strength. The disadvantages are that these are transported over a long distance, the process involves more energy and the big quarries cause lot of environmental issues.
Lime is very sustainable as binding material and a lot of studies have shown that it is much less energy-consuming when compared with cement which is used in the present days. In our textbooks, we learn more about the disadvantages of lime such as it is slow setting, not having enough strength etc.
Cement is a high energy consuming and limestone is one of the main ingredients in its manufacture. If cement is used as mortar in making a wall, then the bricks cannot be recovered for future use when the building is demolished. If lime is used as the binding material, then the bricks can be reused, which makes the use of lime mortar in buildings more sustainable.
According to me, timber is going to be the future building material. Unlike earth, burnt bricks, granite etc., this is a material which can be renewed. It is a material which can easily be recycled. Timber was used in Kerala for building walls and roofs.
Illustration 9: Wayanad House designed by Benny Kuriakose having timber roof, ceiling and
The biggest advantage of timber is that by using them in our buildings, the carbon gets locked. Also, trees are the only things which can convert carbon dioxide in the atmosphere into oxygen. If timber is allowed to decay or used as firewood, then the carbon is released back into the atmosphere, thereby completing the carbon cycle.
If more and more timber is used in buildings, then the carbon in the atmosphere will get reduced. We should grow more and more trees which will reverse global warming. There are a lot of lands available across the world which are not cultivated. The forest fires in Amazon forests or in Australia is contributing to global warming and climate change in a big
Illustration 10: Timber ceiling of the Wayanad House.
I have seen many buildings with cross-laminated timber in London. They are made by glueing the timber planks together in layers at right angles to each other using a non-toxic adhesive. Generally, there will be 3, 5 or 7 layers of timber each one approximately 22mm thick.
Ho Ho Tower is a 24 Storied high building taking shape in Vienna, which will be completed this year. Once completed, it will be the tallest timber building in the world. As much as 76 percent of the building is built with timber. It will house a hotel, apartments and offices. Protective coatings have been given on top of the timber elements which have been exposed.
We have to keep open our eyes to see what is happening across the world. The West has committed many mistakes and it is important that we do not commit the same mistakes. Timber and its byproducts will become common in the coming years as a building material.
Social and Economic Sustainability
Every timber that we use in our buildings need not be sustainable. If the source of the timber is from cutting down a virgin forest, then it is less sustainable. Is the process of cutting the timber, sustainable in the long run? In the processing of timber, if there is an exploitation of labour, then it is to be questioned.
The best is to use recycled timber (from demolished buildings). Now the usage of recycled timber is much less and they are used by the poor in constructing small houses. The prices are also cheap for recycled timber. I use them in my buildings and the price is less than half (teak is a bit more expensive).
We have to look at the manufacturing process of plywoods. It the processing involves the use of the chemical formaldehyde, then it is not sustainable. Formaldehyde is used in resins that as a glue between different layers. Research has shown that formaldehyde is a carcinogen that causes cancer. In the west, formaldehyde-free plywoods are available. We shall be
concerned about our health and living.
Reusing an Existing Building is the Greenest Thing
Reusing an existing building, (instead of demolishing it and replacing it with a new one), is very green and a good way to conserve energy. Conservation uses 40% a lesser amount of materials and is usually labour intensive.
Illustration 11: Vishram on the Sea designed by Benny Kuriakose using the recycled timber rafters, ceiling and the stone columns for an energy-efficient new home to recover the carbon expended in constructing it.
Rehabilitation of 2-3% of our housing stock means perpetual employment in building trades. Infrastructure investment is reduced and the greenfield is preserved. A study done by US Energy Information Agency says that buildings constructed before 1920 are more energy-efficient than those put up between 1920 and 2000. A study done in the UK shows that it takes 35-50 years.
No matter how much greener technology is used, still, it makes an impact on the environment. The greenest building is one that already exists.
It is time that we do not use any building material as such; we have to look at the process and the transportation when sustainability has to be practised. It is important that we ask all these questions before we use many materials. In India, it is very difficult to know most of these details, but it is time that we start demanding this information.
We have to look beyond the lifecycle assessment in finding out what is sustainable and what is not sustainable.
The whole world is thinking about ecology and the environment. The relationship between the architecture that we do and the ecology has to be studied in detail so that the design of the built environment cause less harm, so that future generations can live more comfortably in this earth.
Earlier, we could think that ecology is to do with forests and dams and lakes. No, it is to do with architecture and what we should be doing is to explore a symbiotic relationship with ecology and the architecture. We have to find an equilibrium in these aspects.
When we look at ecology in a broader context, two things become very important. Firstly, reducing the number of materials to be used. This is what Laurie Baker said more than 40 years ago. “If it is not necessary, then don’t use it.” The second thing is to reuse old materials so that we conserver the resources. This is what the poor people who cannot afford to build houses with new building materials do. What they are doing is very sustainable.
We have to think about architecture in a different way. I am not talking about getting designs inspired by nature. I am not talking about having some greenery in our buildings, of course, we should have them. But a much larger relationship with many dimensions. That is what will make our architecture and design more sustainable.