The "tube house" in Ahmedabad is a model of contemporary sustainable design. It is shaped such that cool air is naturally drawn through it, leaving via a vent close to the apex of the roof. It's a prototype of low-income housing, and cleverly minimises the number of windows, which are relatively expensive items, while creating a humane and livable interior. It uses readily available building materials and techniques. It shows the sort of thinking for which architects such as Chile's Alejandro Aravena are being lavishly praised.