Under the global challenge of climate change, the growing awareness of green buildings in China not only bodes well for the environment but also means enormous business opportunities.

With the largest construction market in the world, China's building area has been increasing by 2 billion sq m each year, nearly half of world's total. It is estimated the construction industry will take up 40 percent of the country's total energy consumption by 2020 to become the largest energy user.

This also means a huge potential of the green construction market, with an estimated value of 1.5 trillion yuan, according to Qiu Baoxing, vice-minister of housing and urban-rural construction.

The current market scale of green buildings is expected to grow as the construction industry has introduced a new rating system for energy efficiency.

Issued by the Ministry of Housing and Urban-Rural Construction, the rating system includes regulations on savings in land-use, energy, water and construction materials, as well as inspection of indoor air quality.

Such attention on energy-efficient buildings brings business opportunities to multinationals ranging from those involved in designing them to those supplying environmental friendly materials, building intelligence and air-conditioning systems.

"The new rating system suggests China has raised its construction criteria, which means higher construction costs and correspondingly higher investment by developers. This opens more opportunities for enterprises like Honeywell," said Georgy Ko, general manager of Honeywell Building Solutions.

According to Ko, one of Honeywell's special materials, Enovate 3000, is helping insulate walls for seating areas of the National Stadium. The non-flammable, hydrofluorocarbon liquid is an ozone-friendly blowing agent for foam insulation, which also resists heat better.

Honeywell also offers a full range of automation and control solutions to both commercial and residential buildings, making them more energy efficient and comfortable.

Mammoth China, a supplier of air-conditioning system capitalizing on heat from sewage water and energy at shallow ground, has signed contracts with high-end residential buildings and hotels.

"Such technologies can save up to 40 percent of electricity," said Jack In, vice-president of Mammoth (Shanghai) Air Conditioning Ltd.

American Forest and Paper Association (AF&PA) has been promoting its wood-structure products in China for nine years. Wood is one of the most environmentally friendly building materials as it is recyclable, said Michael Virga, forestry executive director of AF&PA.

A Tsinghua University report shows wood structures use 27.75 percent less energy and save more than 39.2 percent of water over steel construction, while they consume 45.24 percent less energy and save 46.17 percent more water compared with concrete structures.