New Delhi: When the world just celebrated the World Environment Day on 5 June and reaffirmed their pledge to preserve the planet in its God-gifted way, it is time to note how some of us have been benign to mother Earth.
India’s northeast, which is always referred to as a treasure chest of natural resources, has actually set itself as an example when it comes to co-residing with nature. Mostly unknowingly, people in this region have built houses that are suitable to the prevailing climatic conditions, comfortable to live in and above all environment-friendly.
Keeping cool: A mud structure. Photo: Manoj Kumar Singh
“People in the northeastern region have perfected upon the vernacular architecture for their own benefit and the environment,” said Sadhan Mahapatra, a senior faculty member of the department of energy, Tezpur University in Assam. “By vernacular architecture I mean method of construction that uses locally available resources to tackle local needs. This kind of architecture also has cultural and historical implications,” he said.
I met Manoj Kumar Singh, a senior research scholar with the Instrument Design Development Centre, Indian Institute of Technology Delhi, who said, “Environment, social and cultural values are pre-requisites for sustainable solutions. The climate-responsive building design is a solution to reduce carbon-emissions and a smart option for energy-conservation.”
The country’s northeastern region is divided into three bioclimatic zones: warm and humid, cool and humid and cold and cloudy.
“The main problem in a warm humid climatic zone is overheating with high humidity in summer months. For comfortable indoor environment bulk of the cooling is to be done by artificial methods rather than natural ventilation,” said Mahapatra. Same climatic condition persists in the cool and humid zone except the artificial cooling dependence is bit less comparatively, he said. “The cold and cloudy climatic zone has passive solar heating potential of 38% during winter thus needing conventional heating of about 46%,” said Mahapatra.
Conventional heating device use electricity, oil, gas or firewood while passive solar heating technique means use of heat and light energy of sunlight to keep the indoor warm and adequately lit up. “If a house has high thermal mass walls then these walls are exposed to sun so that the thermal energy is stored in the fabric and is radiated to indoors,” explained the teacher. “At times, solar atrium allows the direct entry of sunlight through glazing so that the house is adequately lit up and the heat is preserved,” he added.
“What is impressive in the northeast is the use of locally available materials like bamboo, cane, mud, lime and brick effectively to build a house,” said Singh. “They make a mixture called surkhi which is generally a mixture of lime, brick powder, sand and jaggery,” he said. This is used to fix bricks in the old (more than 70 years) pukka buildings in the warm and humid climatic zone which also uses wooden framed structure traditionally, said Singh.
Local material: Rocks and bricks are used to construct a house thereby cutting cost and fitting it to the culture and tradition of the region. Photo: Manoj Kumar Singh
“Excessive rainfall is another factor that influences the building design in the warm and humid zone. How the vernacular architecture has evolved so intelligently is witness to the fact that the entrances are pulled inside and the external walls cleverly built to minimize rainfall damage,” said the senior research scholar. “When the structure is mud-made the houses are on a raised platform to protect it from rain water pouring from the roof,” he said.
Roofs are steeply inclined and are extended to act as an overhang to protect the wall from rainfall. Wind direction is intelligently used for natural ventilation. “The planting of trees wisely to protect the building from excessive sunlight is another feature of this type of construction. An air gap is maintained in the lower side of the ceiling to reduce heat gain inside the built space,” Singh said.
The northeastern region has found out ways to tackle climatic challenges in the cool and humid zone as well.
Shade theory: Trees are planted around a structure strategically to prevent solar radiation. Photo: Manoj Kumar Singh
“The use of bamboo, mud processed with cow dung, lime, beaten straw or jute are seen in the cool and humid conditions for construction purpose,” said Mahapatra. “Bricks are often used in an urban set up but have no major presence in a rural setting,” he said. “Most of the houses are east-west oriented and south facing to make use of most of solar radiation,” said Mahapatra.
In the cold and cloudy climatic zone, wood, bamboo, cane, cane leaves, stone chips and surkhi play an important role in the construction of a house. Mostly located on hilly terrains stones are easily available and reduces cost. “The cooking space, low ceiling and wooden floors are characteristic in their features to improve comfort conditions in this type of houses,” said the Tezpur University faculty member. “Cane leaves roof are economical and also ensures better comfort in summer months,” he said.
Different ways to make the place of dwelling a comfortable one have led to the development of a unique architecture form in the region called Assam type.
“Assam type houses provide an adequate cultural and social picture. But more research is needed to explore appropriate design solutions to make living more comfortable. This housing design can be commercialized in a big way because it is economical and consumes less energy intensive materials,” explained Mahapatra, when I asked him about the future of the design commercially.
Giving a small background of the Assam type architecture form, he said, “Assam type architecture contains many features that address local climate constraints like heavy rainfall, high humidity and solar heat gain and also blends well with the local tradition and culture.”
The genesis of this environment-friendly cost-effective architectural form can be dated back to the Great Shillong Earthquake of 1897, he said. The British realized the dangers of being in a high seismic zone and insisted upon using light and durable locally available resources thereby making it safe.
“Steeply inclined roof and high floor base are trademarks of this architectural form,” said Mahapatra. “High humidity is taken care of by large number of openings in the form of windows, doors and ventilators,” he said, while, “solar heat gain is minimized by false ceiling and overhang over windows.”
What struck me is the extensive use of wood for every construction and the possible threat of deforestation consequently. Mahapatra was quick to quell those fears though.
“Longevity of the wood once used in construction is same as the life of the house (25 – 30 years). After that the house needs major renovation. But the time required to mature a tree is 15-20 years. So the natural cycle will not be broken if wood is judiciously used,” the faculty member said.
The country’s northeast has embarked upon a bio-climatic design more as need rather than knowledge but it gave the planet what it needs most — low energy consumption, environment-friendly structures and sustainable style of living.