Deepak Goel

New Delhi, July 23

THE energy bill in residential or commercial buildings could be reduced by almost half if buildings are designed keeping energy efficiency in mind.

The saving in energy requirement of a building could be achieved first at the design stage and then at the selection stage of the HVAC (heating, ventilation, air-conditioning) and lighting systems of the building.

In a study conducted by The Energy and Resources Institute (TERI), it was found that 35 per cent energy saving was achieved by efficient lighting and HVAC systems. These measures typically have a payback time of one to three years. Energy saving measures can also be taken up for existing buildings and can be achieved up to 20 per cent.

They would be primarily targeted at HVAC and lighting systems, with an even shorter payback time.

For instance, a building in a cold climatic zone needs to adopt measures to maximise its solar heat gains by embracing strategies such as maximum exposure to south, windows to capture heat, dark coloured surfaces, high thermal mass and insulation to retain the captured warmth of the sun or use of design elements such as trombe wall and sun spaces, among others.

On the other hand, a building designed for a hot climate should use measures to reduce solar gain such as smaller window sizes, shaded walls, minimum exposure to west and east or use of design elements such as solar chimneys and wind towers, among others, to maximise ventilation. Use of building materials like energy efficient glass could reduce heating or cooling demands by 8-10 per cent.

Further, hard paved parking lots, pathways, and courts could be minimised as they generate a heat island effect that causes a sharp temperature rise. Lighting accounts for 20-50 per cent of the electricity requirements of a building and several measures could reduce the consumption of energy. For instance, motion sensors could be installed for security purposes instead of constant lighting.

TERI advocates `green' design principles for construction of buildings and is currently conducting studies on commercial buildings to make them energy-efficient.

(This article was published in the Business Line print edition dated July 24, 2005)
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