GREEN
STRUCTURES AND SMART MATERIALS
The need for Green Building
People and building are as intrinsically infused with nature as bees and
their hives are with honey. Unfortunately the effects of our building industry
are far less sweet. Due to the non-ecological structure of building industry
and historical lack of environmental awareness of many building professionals,
the way buildings, built environment and the process of building have been
created, has played major role in the decline in Earth’s ecological health.
For the construction of a building or a structure we need a lot of
energy, and for the requirement of this energy, fossil fuels are burnt in a
large quantity so that it can meet our needs which are growing exponentially.
This results in disturbing the ecological balance and pollutes the environment.
The most effective solution for this destruction of earthly resources is the
new concept of construction, that is, green structure or green building
concept.
Buildings worldwide consume about 40% of the
planet’s material resources and 30% of its energy. The construction of
buildings is estimated to consume 3 billion tonnes of raw materials per year,
and generates between 10% and 40% of the solid waste stream in most countries.
For every tonne of cement, the world’s most used material, about two tonnes of
raw material must be mined, and nearly one tonne of CO2 and 6 kg of
NOx green house gas is produced.
Concept of Green Building
A green building is a building that produces net
zero or less carbon footprint or the other harmful emissions. Advanced
technology and the efforts of brilliant scientists throughout the world has
made it possible for humans to harness energy from sun, wind, water and other
renewable sources of energy. Deriving energy from these sources produces less
or negligible unwanted gases or waste which harms the environment.
A green building does not produce a negative impact
on the environment as it generates its own energy from renewable source and
then use that energy efficiently and effectively and then the waste is again
reused or recycled for further use. This is the simple concept of green
structures. In today’s generation, most people are not aware of this concept
and are not concerned with the deterioration of environment caused by us by
constructing buildings which are just built to shelter the humans and not the
environment.
To observe the concept of green building in
practice, I went to see a green building which has been constructed in my
hometown, Bhopal, M.P. by an Indo-German company, Omega-Renk.
My visit helped me to understand this concept very
well. Some of the features or specialities of green buildings which I came to
know about are:-
· A green
building runs on energy produced by an adjacent power plant, which produces its
own energy from a renewable source of energy i.e. sunlight. The green building
is thus, run by this derived energy. A sizeable quantity of waste
produced by the building is ultimately treated, recycled or is reused. The
building which I visited produced its own energy from a solar power plant
situated just adjacent to the green building.
It had
2 two large panels fitted with many solar cells. It produced maximum of 75kw.
Installation of a wind mill was also in progress so that a steady supply of
electricity is maintained throughout the year, even in rainy season, when
sunlight is not enough to produce required solar energy output.
·
That
building had LED lights which consumed very less electricity as compared to
cfl’s and tube lights. These LED lights were installed with motion sensing
technology so that when no one is there in room, it switches off automatically.
·
The
materials used for the interiors and for the furniture were recyclable. Almost
95% of the furniture used in that building was recyclable.
·
It had
efficient air conditioners(AC). The AC’s used in that building consumed only
50% electricity compared to the electricity consumption by normal AC. The
harmful gases emitted by those AC’s were treated first before disposing them in
the atmosphere so that they don’t harm the environment.
·
The walls
and roof of the building were insulated so that the temperature inside the
building is maintained and there is minimum use of air conditioners.
·
The
liquid and solid waste produced by humans was also collected and then treated
for using the liquid waste again for watering the gardens and the solid waste
for making soil fertile. Therefore, there was negligible amount of waste
generated from the building.
·
Rain
water was also collected by practicing rain water harvesting. The rain water
which was collected was then used for various purposes. One of the main uses of
that water was to increase the underground water level.
Two or three holes were drilled in the land just like
boring is done to extract underground water. The rain water which was collected
was allowed to pass in
those holes through pipes because of which the
water flows deep down the surface and increases the underground water level.
·
The paint
used for painting the roof of the building reflected the sunlight falling on it
which maintained the temperature of the building to some extent.
This building was certified with platinum rating by
LEEDS, which is the highest
rating by it. Leed was established in 1998, in US. Since then it has been
adapted for use in India, Canada and Italy.
There are many organisations and associations which
assess buildings and have their own protocols, rules and laws like the US
Green Building Council, the UK’s Association for
environmentally conscious builders, Kyoto Protocol and the Australian
building Energy Council etc.
Now this concept of green building has gained
attention of many builders and contractors and some are even interested in
building houses by following this
concept but a big question arises:
Will eco friendly homes find buyers? Naturally it is new concept, but if
established with proper implementation, will find takers!
SMART MATERIAL:-
What are smart materials? How are these materials
different from normal materials? Basically, a smart material is a material
which responds to an action by the environment in a predictable way. For
example, photo chromatic glass. When light falls on this type of glass, it gets
darkened. This reduces the intensity of light entering through that material.
So these glasses can be used in windows during summers so that the temperature
is cool in the room.
Smart materials have appropriate and predictable
responses, whereas, normal materials have limited responses.
Smart
materials are the result of development of material science due to which many
new and cost efficient materials are now being used in civil engineering to
deal with the deteriorating infrastructure. With two crystal structures called
Austenite and Martensite under different temperatures, smart material exhibits
two special properties different from ordinary steels. One is shape memory, and
the other is superelasticity. Both of these two properties have applications in
civil engineering, such as prestress bars, self-rehabilitation, and two-way
actuators, etc.
Smart materials are the materials that have the
intrinsic and the extrinsic capabilities, first, to respond to environmental
changes and, second to activate there functions according to these changes.
This is the general definition of smart materials.
CLASSIFICATION OF SMART MATERIALS
Smart materials can be classified further depending
on its properties. They can be grouped into the following:-
·
Piezoelectric: - These are the materials which undergo some mechanical changes when
subjected to electric charge or a variation in voltage. For example, Quartz.
·
Electrostictive: - These materials have the same properties as that
of piezoelectric materials but the mechanical change in these materials is
proportional to the square of the electric field. For example, silicone
polymers.
·
Magnetostrictive: - These types of materials undergo an induced
mechanical strain when these materials are subjected to magnetic field. So
these types of materials are used as sensors or actuators. For example, iron,
cobalt, nickel etc.
·
Shape memory alloys:- Types of materials like nickel, aluminium, zinc
etc. undergo large strain, while recovering their initial configuration at the
end of the deformation process spontaneously or by heating without any residual
deformation .The particular properties of SMA’s are strictly associated to a
solid-solid phase transformation which can be thermal or stress induced.
Currently, SMAs are mainly applied in civil engineering specifically in seismic
protection of buildings.
·
Optical fibres: - Fibres that use intensity, phase, frequency or
polarization of modulation to measure strain, temperature, pressure and other
measurable quantities. They are excellent sensors.
The material used for making
bricks is the top layer of soil which is very fertile and is used for
agricultural purposes. But for making bricks it is dug out resulting in the
infertility of soil. So another material which can be used in some percentage
for making bricks is fly ash. Fly ash is a fine powdered material which is of
no use and it harms the environment if it is not disposed efficiently. So it
can be used for making bricks. It also increases the strength of bricks. Fly
ash can also be used for making concrete.
LED lights are also an example of
smart materials. They consume less electricity and can be used for lighting
purpose in buildings. LED lighting is also considered as ‘green technology’ as
it is efficient than any other lighting material.
Conclusion
The concept of green building, if implemented at an international and
national level, will help greatly in alleviating environmental pollution, which
in turn shall help overcome even more immense environmental problems like
global warming. The need to adopt this concept of green building at a more mass
level is ever increasing.
Since these sources of
energy will soon exhaust, if we will use them rigorously as we are using them
now then we will fall prey to various problems and difficulties. So, to
overcome this situation we have to think of the other sources of energy which
are renewable like solar energy, wind energy, tidal energy etc so that our
future generation doesn’t have to face problems for their survival.
Let me tell you, there is a
new concept for constructing a building which is known as green building. A green
building is perfect for sustainable development as it uses negligible amount of
energy from exhaustible sources and produces minimum amount of waste so that
there is no major problem for the disposal of the waste which could harm the
environment.
These were some of the ways in which a civil engineer can
contribute for sustainable development.