desirable uniform high thermal gradient between indoor and outdoor
spaces. A uniform high thermal gradient between indoors and
outdoors is desirable because it corresponds to the ideal condition
to allow a significant heat flow across the sample. During the winter,
this condition can be achieved by using a simple domestic heater
device placed indoors and able to keep the room constantly
warm. In contrast, during the summer, an air conditioner can be
used to keep the room constantly cool. In this case, the test was
performed during the winter, namely, in February of 2011. Therefore,
a uniform high thermal gradient between indoors and outdoors
was achieved by placing a common domestic heater device
in the confined test room.