A cool way to meet energy hunger

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A COOL WAY TO MEET ENERGY HUNGER

By Kota Sriraj
Op-Ed
The Pioneer
http://www.dailypioneer.com
Thursday, June 13, 2013

With economic development taking a heavy toll on
environment, the Government should cultivate and harvest
the potential of systems that cost less in overall set-up
and maintenance

The Indian construction industry can be regarded as the
indicator to the country�s economic growth. The rapid
construction boom and consequent high rises have given
India enviable skylines, but the flip side is that they
have made strenuous demands on the energy resources of
the country as well. The Indian construction industry has
had a compound annual growth rate of over 20 per cent in
the past five years and contributes eight per cent to the
GDP.

The demand for energy to run appliances such as air
conditioners, refrigerators and heating units, is set to
increase substantially along with the living standards.
Add to this the growth in the commercial sector and the
continuing shift from rural to urban living which
translates to increased emissions from the realty sector.
According to the Central Electricity Authority, the
electricity demand is likely to increase to 43.7 per cent
between 2016 and 2017, as compared to between 2011 and
2012; and by yet another 37.5 per cent between 2021 and
2022, as compared to 2016-2017.

On an average, in a typical commercial building in India,
around 60 per cent of the total electricity is consumed
for lighting, 32 per cent for air conditioning, and less
than eight per cent for refrigeration. Whereas, in a
typical residential building, around 28 per cent of the
total electricity is consumed for lighting, 45 per cent
for air conditioning, 13 per cent for refrigeration and
14 per cent for other utilities. The average electricity
consumption for air conditioning in India is around 80
kWh/m2/annum and 160 kWh/m2/annum for residential and
commercial buildings respectively.

Given this scenario, concentrated efforts are required to
be implemented by the Government and the construction
industry to bring down the energy demand and consumption
levels of buildings through various measures.

One such measure is radiant cooling systems for
buildings. Similar to an automobile engine getting water
circulation for keeping the temperature under control, a
radiant cooling system cools indoor temperatures by
maintaining a temperature-controlled building surface
that removes sensible heat and where more than half of
the heat transfer occurs through thermal radiation.

Radiant cooling systems use the opposite effect of
radiant heating systems, which rely on the process of
heat flow from a heated surface to objects and occupants.
The systems are hydronic and use circulating water
running in pipes in thermal contact with the surface. The
circulating water needs to be

2-4�C below the desired indoor air temperature. Once
having been absorbed by the actively cooled surface, heat
is removed by water flowing through a hydronic circuit,
replacing the warmed water with cooler water. Since the
majority of the cooling process results from removing
sensible heat through radiant exchange with people and
objects and not air, occupant thermal comfort can be
achieved with warmer interior air temperatures than with
air-based�cooling systems.

As a result of the high cooling capacity of water, and
the delivery of a cooled surface close to the desired
indoor air temperature, radiant cooling systems
potentially offer reductions in cooling energy
consumption. Furthermore, radiant cooling systems can be
integrated into the building using thermally activated
building systems.

There are several advantages of the radiant cooling
technology that the construction industry can capitalise
on. For instance, the system can be integrated with other
energy-efficient strategies such as night time flushing,
indirect evaporative cooling or ground source heat pumps
as it requires a small difference in temperature between
desired indoor air temperature and the cooled surface. In
addition, according to a research conducted by the
Lawrence Berkeley National Laboratory, USA, radiant
cooling systems offer lower energy consumption than
conventional cooling systems and afford energy savings of
upto 40 per cent.

As compared to air-conditioning systems, the energy saved
in radiant cooling systems is attributable to the lesser
energy required to pump water as opposed to distributing
air with fans.

Furthermore, compared to air circulation in an air-
conditioning system, water is more efficient and can
carry 3,400 times the energy that the same volume of air
can carry. This property of water helps achieve maximum
advantage in a radiant cooling system. Besides this, the
system ensures a healthier indoor air quality as there is
no recirculation of air and occupies just one-third of
the space compared to conventional air-conditioning
system.

With the economic development taking a heavy toll on
environment, the Government should cultivate and harvest
the potential of such systems. Government assistance in
the form of tax rebates and subsidies for those opting
for the technology would help promote an environmentally
responsible culture in the buildings of tomorrow.

More at:

http://www.dailypioneer.com/columnists/oped/a-cool-way-to-meet-energy-hunger.html

Jai Maharaj, Jyotishi
Om Shanti

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