Blow hot and cold

  • 30/08/2007

Air conditioning and energy efficiency

The International Energy Agency has estimated that the global building sector, which consumes roughly half the electricity generated in the world, can be 70 per cent more energy efficient. It estimates that energy spent on lighting, roughly a fifth of the building sector's energy needs, can be easily cut with the introduction of energy saving lights like cfls. In India, there are few estimations of the energy use in buildings but everyone agrees that they should be more energy efficient.

The Union ministry of power's research points out that about 20 to 25 per cent of the total electricity utilised in government buildings in India is wasted due to unproductive design, resulting in an annual energy related financial loss of about Rs 1.5 billion. The annual energy consumption per square metre of floor area in Indian commercial buildings is about 200 kWh. This can be brought down to 120-160 kWh by shifting to efficient design alone.With the June 2007 announcement of Energy Conservation Building Code, 2006 (ecbc) by the Bureau of Energy Efficiency (bee), the government aims to save 1.7 billion units in the first year of the code's implementation. Its energy audit of government buildings shows that much can be done to save energy and so save money, even in current constructions. The point is why, if all this is so easy (and makes economic sense) is so little happening.

Face the sun
The best way to save energy is to move away from fossil fuels and use renewables. But there are constraints, especially with solar power, which is very expensive and does not make business sense. "We have installed solar panels worth 25 kW capacity at a cost of Rs 65 lakh at gbc, but it is for demonstration. Solar power is not economical. We sell about 100 units per day of green electricity to state grid at a rate of Rs 1.50 per unit. But in turn, we buy power from them at Rs 5.50 per unit. Also, the pay back period for solar power is more than the life of solar panels themselves,' says Srinivas.

Passive energy
There are various ways of reducing a building's energy consumption. Use of energy efficient materials and technologies, and appropriate design and architectural features are among them. Passive architecture in plain terms is design that does not require mechanical heating or cooling for thermal comfort and artificial lighting for visual comfort. Homes that are passively use natural energy flows such as sun, wind, plantation and existing site conditions to maintain thermal comfort.

This is where modern architecture can learn from traditional science. Indian architecture also made use of passive design principles to keep homes and buildings cool or hot, as per local weather conditions. For instance, the fort, havelis and streets in Jaisalmer, where mercury touches 50

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