OTSU, Shiga Pref. -- One of the pavilions at World Expo 2000, slated to run from June to October in Hannover, Germany, is made mostly of bamboo.

While the pavilion, which was constructed using traditional Japanese techniques, received final approval from the German government last week, bamboo buildings are not allowed in Japan.

Gunter Pauli, director of the Swiss-based Zero Emission Research Initiative Foundation, says Japan should approve bamboo as a construction material because it is cheaper, stronger and more environment-friendly than concrete and steel.

The foundation advocates reforming industrial activities to make full use of all resources by recycling waste for application in other processes.

"Japanese technology was employed in the construction of the pavilion. Bamboo structures, however, are not allowed in Japan, though it has lots of bamboo," said Pauli, who visited Japan last week to attend an environmental forum here.

Bamboo was widely used to build houses for ordinary citizens from the 15th century up to the Edo Period. More than 30 percent of the building material in Kyoto's Katura Rikyu villa, which was erected in the early 17th century, is bamboo.

Today, however, bamboo is not included in the list of authorized construction materials under the Building Standards Law, according to the Building Center of Japan, which is affiliated with the Construction Ministry.

The main reason is that two kinds of bamboo native to Japan are not as strong as overseas varieties, said Etsuzo Uchimura, head of the Kyoto-based citizens' group Take Shigen Foramu (Bamboo Resources Forum).

Uchimura, however, said advanced processing technology has increased the strength of bamboo, and it is now being used in interiors for purposes including flooring.

About 200 countries and international organizations are expected to participate in the Hannover exposition, which has the theme "Nature, Mankind and Technology."

The bamboo pavilion to be presented by ZERI uses 4,000 pieces of 9-meter-long bamboo. The two-story complex is 17.5 meters high and 40 meters in diameter.

A prototype was built in Colombia last year, since German authorities required ZERI to build a similar structure outside of Germany first to get test data.

It was designed by Colombian architect Simon Velez, Pauli said.

To strengthen the bamboo piece joints that are put on the roof, cement was poured inside the bamboo.

The plates laid on the roof -- made of cement and bamboo -- are the products of Japanese firm Taiheiyo Cement Corp.

By adopting traditional Japanese preservation techniques, bamboo sections were treated biochemically using bamboo extracts that make them immune to insects and fungi.

The various tests conducted on the building showed that bamboo is a desirable construction material due to its strength and flexibility -- it can withstand major earthquakes and can support large amounts of snow on the roof, he said.

Another merit of bamboo, Pauli said, is that the plant absorbs 40 times more carbon dioxide than pine trees, mainly because bamboo grows much faster.

He is urging the Japanese government to introduce bamboo house building projects in developing countries in line with the "Clean Development Mechanism" mentioned in the 1997 Kyoto Protocol to reduce greenhouse gases to combat global warming.

Pauli launched ZERI in 1994 at the United Nations University in Tokyo.

Serving as an adviser to the UNU, Pauli introduced several research programs to seek ways to achieve zero waste.

About 50 projects are currently in the process of being undertaken around the world.

For instance, in Colombia and Brazil, a program uses waste from mushrooms to feed cattle, and cattle manure is in turn used to produce biogas with which the substrate is pasteurized.

Breweries in Namibia, Sweden, Canada, Germany and Japan are using waste protein and fiber from the brewing process to produce mushrooms and feed chickens and fish. Some 10 of these projects will be presented at the World Expo.

Pauli said some Japanese architects and Shiga prefectural officials expressed interest in bamboo buildings.

"Much more pressure on the Japanese government," Pauli contends, "is needed before the construction of bamboo buildings will be allowed."