Site: Barisan mountains in Sumatra (Indonesia) Climate: Tropical humid. Temperatures between 22º and 34º and very high humidity constant throughout the year. Wind coming from the South in summer and from North/ North-West in winter, at a speed of 7 m/s. Position of building: on the peak area of the mountain, where the wind is most fluent, so as to optimise ventilation. Trees may be used around the South, East and West façades to block direct sun. The house is elevated by a series of pilotis, so as to be protected from humidity from the floor or even inundations. Materials: Timber. As in tradicional Indonesian dwellings, slabs are displayed vertically with an inclination such that the rain and sun can’t come in, but the air can flow through the holes accross the house in every direction. Blocks of granite are used at the ends of the timber pilotis, as this material is more resistant to water than wood. Timber is the optimal material for this climate because it has no thermal mass. Besides, wood is an autoctonous material, it is cheap and local people are used to working with it.