**1. Introduction**

It is known that every human activity is better carried out in the presence of natural light than in the absence of it. This is probably due to the comfortable feeling of the occupants respect to the perception of the flowing of time, which is impossible when artificial lamps are the only light sources in the environment. In many cases the natural light is absent, as in underground areas of a building, or insufficient, as in the case of large plant area rooms, where the windows on the perimeter walls are not able to illuminate the whole environment being too small or too distant from the centre of the room. Moreover the indiscriminate use of electric light even if the daylight is available, due to a deplorable habit of the occupants of the workplaces, is a fairly common practice and it increases the energy consumption in buildings that already covers about 40% of the total energy consumed worldwide.

Many technological devices have been developed with the aim of contributing to an efficacy energy saving by using daylight in buildings, such the light pipes, that are able to transport the natural light away from the collection point, usually on the roof-top of the building, for example in hypogeum environments. There are two different types of light pipes depending on whether they are equipped with fixed or mobile collector. In recent years the authors carried out an intense experimental and numerical analysis with the aim to evaluate the daylight performances obtained by light pipes equipped with fixed collectors (Chella et al. 2006, Baroncini et al. 2006, Zazzini et al. 2006). Moving from the experience gained in the work, the authors developed some innovative devices which improve the performances of the traditional light pipes. The first one is called "Double Light Pipe" (DLP) and it is able to transport daylight into a two floors underground building. It is an evolution of the traditional light pipe. The second one is a further evolution of the DLP, which allows transport of daylight into underground areas of a building as a DLP, and guarantees the necessary change of air by natural ventilation. It is named "Ventilated Double Light Pipe" (VDLP) and it is simultaneously able to introduce daylight and fresh air in underground areas of buildings or rooms without direct interface with outdoor. This device was recently presented at the World Renewable Energy Congress 2011 (Boccia et al. 2011). Through a numerical analysis, the performances obtained by the VDLP and its applicability in architecture are examined. The numerical data allow the examination of the possibility of generating an architectonical space from the availability of daylight and fresh air by natural ventilation.

The main goal of this work is to propose an architectonical space equipped with a certain number of VDLP, in which the geometry is generated by the availability of daylight and the possibility of effecting an efficacy of natural ventilation by the VDLP.
