Since 1997, several ministries in Japan have collaborated on an eco-school programme, which applies to both newly constructed and renovated school buildings, in an effort to make its schools more environmentally friendly. The programme equips school buildings with ecological features such as photovoltaic cells, solar thermal collectors, other new energy sources, wood, roof-top gardening and rainwater recycling. It also promotes using environmentally-friendly designed buildings as practical teaching materials for environmental education.