**4.2.1 Daylighting simulation**

278 Solar Radiation

Fig. 9. Qualitative air circulation in an inlet and outlet VDLP

Fig. 10. Basic square modular form

**4.1 The modular square form equipped by four Ventilated Double Light Pipes** 

A certain number of VDLP can be installed in order to generate a modular architectural structure, by which more complex buildings of various geometrical forms may be obtained.

In Figures 11 and 12, the numerical illuminance distribution on June the 21st under Clear Sky, and on December the 21st under Overcast Sky respectively are shown, while in Figures 13 and 14 the internal luminance distribution in analogous conditions is shown. (Boccia et al. 2011)

Fig. 11. Internal Illuminance distribution on June the 21st – Clear Sky

Fig. 12. Internal Illuminance distribution on December the 21st – Overcast Sky

Fig. 13. Internal Luminance distribution on June the 21st – Clear Sky

Fig. 12. Internal Illuminance distribution on December the 21st – Overcast Sky

Fig. 13. Internal Luminance distribution on June the 21st – Clear Sky

Fig. 14. Internal Luminance distribution on December the 21st – Overcast Sky

In summer condition, under CLEAR SKY, an average value of about 800 lux is obtained in the environment with maximum values of about 2700 lux in positions close to the tubes. The illuminance spatial trend is not symmetric due to the influence of the reflections coming from the devices and coming also particularly from the intense direct solar radiations. In winter conditions, under OVERCAST SKY an average value of 150 lux is obtained with maximum illuminance values of about 500 lux. A similar situation is obtained regarding the asymmetric distribution of illuminance with peak values close to the VDLP. The images regarding the luminance distribution in the room (Figures 13 and 14) show how the luminances are all over comfortably with some areas on the walls that appear particularly bright with respect to the surrounding environment, as already evidenced in the picture of Figure 1. Only the upper portion of the tube is characterized by luminances so high that the risk of glare is present. In this case the adoption of a diffusing film applied on the internal surface of the transparent pipe is an appropriate antidote.

Starting from the results about daylighting the influence area of the VDLP has been determined in order to assure daylight comfort for the occupants. A centre distance between the VDLPs of 7 m has been chosen and on the basis of this geometric data the basic square modular form was designed.
