The last part of the tube is finished with an aluminium multi-layer film with high reflectance (over 99% as reported
in the specifications of the producer (Solar Project, 2003)). It transports the daylight from the dome to the diffuserthrough multiple specular reflections. The diffuser is shown in Fig. 2a and b. It has a convex shape to distribute the light evenly. The surface of the polycarbonate dome is micro-corrugated but other finishing touches are available.
A test facility has been installed in an open area near the campus of Monte Dago University (Ancona, Italy). A light-pipe has been mounted on the roof of the windowless test room. The tubular skylight has a diameter of 0.25 m and is 1 m long. The ratio length/diameter of the pipe is 4 (see Fig. 3).