Question

のんき

赤線の箇所の文の意味のとり方がわかりません。教えてください🙇‍♀️🙏

there are recycled-construction
schools for local children. The green elements of this
kind of building are relatively cheap, and over the life of the building, they should provide
a large return on the initial cost. They also function as valuable teaching materials
when educating students about the environment.