**6. References**

288 Solar Radiation

Fig. 27. Air velocity distribution on the vertical section at the inlet of VDLP

Fig. 28. Air velocity distribution on the vertical section at the centre of the room

addition, is able to effect the necessary air exchange in the passage room.

In this work the authors show the results of an intense analysis carried out on some innovative devices for daylight transport and natural ventilation in underground areas of buildings or rooms without any direct connection with outside. Starting from the knowhow, achieved in many years of numerical and experimental activity regarding the traditional light pipes, they propose two innovative devices: the Double Light Pipe (DLP) and the Ventilated Double Light Pipe (VDLP). By the DLP the problem of the encumbrance of a traditional light pipe installed in the centre of a two - level underground building is resolved because it illuminates both the passage and the final room, while the VDLP, in

**5. Conclusions** 

