The project for the building of 26 Bioclimatic Social Houses in Umbrete aims to define two key concepts at the same time: the standard house and the global image of the intervention, as well as the relation of both with the urban context. Our purpose is to exploit the available surface completely, without leaving any space unused. This with a series of full and empty volumes, establishing a close connection between each other and defining the whole project.

The standard House is repeated always the same, slightly modified only to be adapted to the irregular shape of one side of the plot, generating this way some modifications to the standard model of this social Andalusian houses. The global image is almost not affected by these differences. It allows the formalization of a project where from the outside you just note the different cells by which it is composed, and offers a vision of unity and an image that dialogues with the urban path, living harmoniously with the examples of traditional domestic architecture.

A first reading of the external elevations offers a compact image, almost bi-dimensional: measured windows on the first floor and large openings on the ground floor, veiled with an aluminium mash protecting from external glances. Inside the house, on the contrary, full volumes follow up empty ones. Internal and external at the same time, alternating each others, surrounding and surrounded, playing with lights and shadows which are sliding on the walls.

The entrance to each house is possible passing through a covered space, which can be used as well as a parking, opening towards the road on one side, and on a patio on the other. This first sequence between "full and empty" generates the threshold between public and private sectors. In front of us the living room opens to the first patio. This space separates and limits the second, more private and hidden patio -the lemon tree patio-, to which the kitchen overlooks. The stairs rise up filling a double height area vertically combining the two floors, leading to a walkway that horizontally connects the bedrooms and a sun terrace, located above the living room. The "voids" of the house, internal or external, are essential in the comprehension of the project. Along with "full", both create the space of life in the house.

The main planning effort was directed towards a passive energy operating of the buildings, since the construction costs of only 526,00 Euro/m² and the sale price of 68.355,00 Euro for each house, made impossible the installation of active technology systems. The structure simplicity, and the use of materials easily available on site and well-known by local building workers, have been the central choices; big thermal mass in the foundation, walls and roofs in vaults, allow us to isolate from heat in summer and from cold in winter. The proposed distribution, despite of the unlucky orientation of the plot, allows us to have living rooms and main bedrooms with one side towards the south and the other to the north, as well as taking advantage of a natural cross-ventilation, both fundamental aspects in the climate of southern Spain. Letting the sun come in, taking advantage of the seasonal variation of its angle of incidence, and protecting ourselves with vegetation and typical regional horizontal awnings during the summer, promote a huge quality of the built space.

Starting from the project data and carefully analyzing the context, introducing elements of sustainability, necessary but not sufficient in itself (materials, longevity, energy balance, passive use of environmental, natural light, natural ventilation, orientation, volumes, etc.), we achieve the most advantageous welfare housing, limiting the consumption and waste. The architecture is a great amalgam of elements that must work together (structure, technical installations, economy, passive end active systems, etc.) towards a constructive global act, without forgetting that we have to reach a formal and aesthetical richness too, a fundamental aspect in our work.Promoting and building a sustainable architecture in this century could be a great opportunity for a new revolution in architecture.