The experimental set-up, shown in Fig. 1a, was designed
to simulate a one-story building, with a part of its roof
exposed to direct solar irradiation. It is a box of which the
overall inner length, width and height are 60, 24, and 30 cm,
respectively. The box is made of two layers of cardboard,
with a 20 mm layer of thermal insulation between them, and
the box cover is made of pressed wood, as described in the
previous study [6].