The government is promoting a shift from reinforced concrete to wood for school buildings because of the favorable educational and health effects.

"Surrounded by wood, I feel comfortable and can improve my concentration," said Riku Kubota, a 12-year-old sixth-grader at Itako Elementary School, a municipal school in Itako, Ibaraki Prefecture. The school was rebuilt with wood last April.

Wooden structures accounted for 20 percent of buildings or gymnasiums at public kindergartens, elementary schools, junior high and high schools, and special schools newly built or renovated in fiscal 2012, up 5 percentage points from the previous year, the education ministry said.