Located on the coast of Cascais, next to St. João do Estoril Fort, the house is a body that creates close relationships with the sea front and the ground. The relationship with the place is reflected in several ways: the relationship of the house with the sun, providing different ways of harnessing solar energy and, simultaneously, different relationships with the landscape; in relation to the topography, by proposing a monolithic body that tries to integrate itself into the landscape; relationship with the ground, which presents itself as an important source of geothermal energy. The first floor, partially buried, harnesses the heat from the ground and, along with a proper solar orientation and openings, give the house a desirable thermal comfort, strenghtened by the use of cork in the entire exterior of the house. A skylight plays a reference role in the spatiality of the house and in the natural ventilation system, which takes advantage of the natural flow of the cold / hot air. Sustainability begins by understanding the place and its energy potential; by a correct site plan and orientation, in order to take advantage of solar and geothermal conditions; and by the use of thermal protection and appropriate materials which, in this case, are used also as a means of integrating the building into the landscape. Co-authorship: Carlos Lima, Gil Silva, Joana Magalhães, Maria João Araújo and Patrícia Rocha (architects).