Gurgaon (Haryana): Prince Charles today (Oct 31) commended the efforts of Teri Energy and Resources Institute (TERI) for coming out with energy efficient technologies, which he said would help India achieve its target of 10 per cent of total energy coming from renewable sources by 2010.

The visiting royal said the institute's inventions in energy efficiency devices for reducing the fuel consumption in the country was laudable.

"These achievements are all the more important in a nation where more than 16 per cent of the world's population has to be supported from the resources of about 2.5 per cent of world's surface," Charles said in his address at the "TERI Retreat".

The Prince of Wales also expressed interest in the underground earth tunnels installed at the institute, which insulate buildings by keeping them cool in summers and warm in winters.

The concept is based on the observation that underground cellars are usually cooler in summer and warmer in winter.

Four tunnels each 70 metres long and with a diameter of 70 cm have been laid at a depth of four metres below the ground in the building.

During his address at the institute, Charles said energy efficiency in buildings is a prime example of how a "problem shared can be a problem halved".

PTI