We don’t see many tiny houses with green roofs, but Austria’s Wohnwagon (translated as “living wagon”) demonstrates that it can be done. Outfitted with distinctive, rounded ends and round porthole windows, the solar-powered tiny home also boasts its own water filtration system that cleans greywater for reuse — using marsh plants on its roof.

Source: Green-roofed, off-grid Austrian microhome filters greywater for reuse : TreeHugger