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Environment
Eco-friendly
Habitats to Combat Climate Vicissitudes
by VK
Joshi
India has a number of historical buildings, palaces, mausoleums
memorials etc. One factor is common amongst all of them. They are cool
in summers and remain warm during winters. The houses of the yore were
constructed with climate in mind. For example Lucknow's Imambara
constructed by Nawab Asif-ud-daula (1775), it is said that it has empty
pitchers placed over- turned on the roof under the layer of lime and
coarse sand. The air space of the pitchers acted as an insulator. The
walls of small 'lakhauri' bricks are almost three feet thick and keep
the building insulated from the vagaries of weather.
The advent of the British added European grandeur and style to Moghul
Architecture of the yesteryears with innovations. For example, Claude
Martin, a Frenchman who combined the functions of trader, military
adventurer and architect was recommended to Nawab Asif-ud-daula in 1776
by the Resident John Bristow, writes Rosie Llewelyn-Jones in her book,
'A Fatal Friendship'. Martin erected a residential building for himself
in 1781. Located on the right bank of Gomti River, the building had
Martin's living rooms at three different levels. During the summers when
the water level in the river went down Martin lived in the basement
which was at level with the river surface. During the rains as the river
level rose Martin ascended another story and when the weather cooled
down he shifted to the bedroom on the top floor which had a huge terrace
part of which was erected on piers sunk in the river. It seems the
arrangement of natural 'air-conditioning' kept Martin's house cool in
the summers and warm in the winters! After his death in 1800 the house
was taken over by Nawab Saadat Ali Khan and named 'Kothi Farhad Baksh'.
Later the building came to be known as 'Chattar Manzil' and presently
houses the famous Central Drug Research Institute.
Cost was no consideration to these builders and owners it was the
climate that mattered for them.
In the post colonial era the styles of architecture changed. The rising
cost of land, housing materials and population explosion forced people
to consider smaller houses with thinner brick walls.
 Climate is once again in the saddle now and the architects are coming
forward with eco-friendly, cost effective housing techniques to meet the
challenge of global climate change. Nilanjan Sengupta of the forum of
scientists, Engineers and Technologists, Kolkata, quoting the report of
the Intergovernmental Panel on Climate Change (IPCC) says in his recent
paper published on the issue in the Current Science 'WARMING of the
climate system is unequivocal, as is now evident from observations of
increases in global average air and ocean temperatures, widespread
melting of snow and ice, and rising global average sea level'.
As Green House Gases (GHGs) keep accumulating in the atmosphere the
phenomenon of global warming will keep going. Global cooling and warming
has been going on since the earth came in to being. At present we are in
a warming phase. Whether we want it or not the nature is at work to keep
the atmosphere warm. But as inhabitants of this Globe our contribution
towards GHGs has been more than positive. It is something like hacking
the branch of the tree on which you are sitting! In every filed of
technology there is a rush to check the emission of GHGs. At least on
paper everything is trying to become green they say.
 The population boom on the other hand has caused a boom in the
construction activity. With the availability of wood getting scarcer
there is demand for bricks, cement and mortar, steel etc. for
construction of dwellings. That is why the construction industry is one
of the major sources of pollution says Nilanjan. Modern buildings
consume energy in a number of ways, he says. The manufacture of
construction material itself is a great polluter. Construction related
activities account for a large chunk of carbon dioxide emission in the
atmosphere. Energy consumed in the construction activity like in the
manufacture of construction materials, transportation of these materials
from plants to sites, energy used in the actual construction work,
running of the building after occupation and later even the demolition
of a building consumes energy.
Nilanjan claims that at the Forum they have developed techniques to
reduce the quantity of construction materials and also substituted them
with low-energy consuming materials thereby making the buildings cost
effective and eco-friendly. The manner in which the urban habitats are
becoming a concrete jungle, technologies tried by Nilanjan's forum
appear to be the need of the time.
 Knowing the actual quantity of carbon dioxide emissions in the
manufacture of construction materials is important says Nilanjan. The
ingredients for a 'pucca' building are steel, cement and brick.
Production of one ton of crude steel emits about 2.75 ton of carbon
dioxide. It is natural that conversion of crude steel to processed steel
emits higher quantities of carbon. Similarly cement manufacture releases
about 0.9 ton of carbon dioxide for each ton of cement produced.
Nilanjan has not taken the environmental degradation due to extraction
of sand in his paper because sand is a natural product obtained from the
river beds. However, one must remember that despite being freely
available, removal of vast quantities of sand leads to degradation of
river banks causing water-logging in the post monsoon periods and
indiscriminate extraction causes extensive bank erosion. Similarly in
the large cities like Chennai and Bangalore the thickness of sand
available is very little and it is a major source of ground water. The
author had reported extraction of sand from tube-wells which had stopped
yielding water. Such extractions cause large scale sinking. Even
over-exploitation of tube-wells leads to 'caving in' and the sand grains
after losing the film of water, just collapse. Due to this reason, in
Agra in U.P. reports of houses collapsing due to sinking of ground were
in the news two years ago. Therefore despite sand being naturally
available ingredient for construction activities, it needs to be mined
with caution. It may not add to carbon dioxide in the atmosphere but
haphazard mining does leads to land degradation and misery for the
common man.
The most important unit of a building is the brick. Nilanjan says that
brick production is carried out in a big way and the kilns guzzle large
quantities of coal. He records that 38 tons of carbon dioxide is
released in the atmosphere for every 100,000 bricks manufactured. Brick
manufacture has another serious implication which Nilanjan has not taken
in to account as his discourse is mainly about carbon emission and ways
to control it. Brick manufacture needs lots of clay. On the outskirts of
any township in the alluvial planes of north India one can find
innumerable brick kilns dotting the landscape. Well these planes as we
know have been formed by the painstaking efforts of the rivers which
have deposited all the sands the richest vaults of ground water. In
addition there are layers of clays, which are now the source of the
bricks. One can see degraded land around the brick kilns where the clays
have been removed and converted to bricks. These depressions lead to
water stagnation and alkalinization of the soil. Finally even the area
surrounding the brick kiln becomes infertile. Very few people realize
that it will take another 1000 years for the nature to get back what has
been removed.
 Nilanjan recommends use of various cost saving technologies like
Rat-trap bond in wall construction, which involves laying bricks on
their sides with a cavity of 4" in between. The plain surfaces of bricks
make the outer surfaces of the walls. This bond has strength equal to a
250 mm solid brick wall yet consumes 20% less bricks. Total cost of 26%
is saved by this technique. The air gap of 4" provides a good insulation
to keep the rooms cool during summers and warm during the winters. The
plain surfaces of brick walls need no plaster hence save the cost of
cement and sand, labor and are aesthetically pleasing. This technique
was popular in England for buildings up to three stories till the turn
of the 20th century. Laurie Baker (1917-2007) an English architect came
to India in 1945 as a missionary and settled here in Thiruvananthapuram.
Houses constructed by him using this technique stand firmly even today
after more than 40 years.
The other techniques that cut costs of material and construction are
Brick arches in lieu of traditional RCC lintels. These cost about 30-40%
less than the lintels. Similarly Filler slab in roof composed of bricks,
tiles etc consumes much less steel as the roof becomes lighter in
weight. Costs of such roofs are reduced by about 23%. Additional 40%
saving is obtained by this technique as it needs less steel and cement
says Nilanjan. Yet another technique is use of compressed earth blocks
made of a mixture of cement, gypsum and lime. Because of uniform shape
bonding them is faster and construction is naturally faster. It is
overall cost efficient technique. However, in high rainfall areas such
blocks need a layer of plaster.
Rise in population has increased the need for more and more dwellings.
The government's programme of constructing two million houses each year
since 1998-99 is a fall out of spurt in population only. Nilanjan says
that if each dwelling is of 20 sq m a total of 40 million sq m per year
will be constructed. If cost effective technologies recommended by his
group is used carbon dioxide emission can be reduced by 16.80 metric
tons per year and in terms of money it will save Rs. 24,000 million.
Carbon credits worth Rs 1200 million can thus be achieved.
Presently many architects in the country are working on energy efficient
housing. Nilanjan's work has added another dimension of energy and cost
efficient housing which is eco-friendly too. Such technologies need to
be given a wider publicity as they give other brighter ideas to the
architects and create an environment for sustainable development.
Image 1: Filler slab roof of Dhakuria Railway Station, Kolkata
Image 2: A double storied building with Rat-trap bond wall
Image 3: A brick arc
Image 4: Rat-trap bond wall under construction
( All images curtsey Chief Editor, Current Science, Bangalore, India)
June 15, 2008
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