one for each sample), two thermo hygrometric devices and a
domestic heater device were adopted as the main equipment. Each
heat flux meter transfer system included two heat flux sensors (detail
f, Fig. 6b), four superficial temperature sensors (detail e,
Fig. 6b), a data logger and a computer. The heat flux sensors make
it possible to measure the heat flow across a sample. A heat flow
occurs when there is a significant thermal gradient between the
two surfaces of a sample (i.e. indoor and outdoor surfaces). In this
case, this gradient results from the existing thermal gradient between
indoor and outdoor temperatures. The superficial temperature
sensors were used as a complement and as reference of the
heat flux measurement sensors, and in order to evaluate the inner
surface temperature of the samples. Two superficial temperature
sensors by heat flux sensor were adopted as Fig. 6b shows. One
thermo hygrometric device was placed indoors and another one
was placed outdoors. The heat transfer and the superficial temperature
sensors were fixed on the inner face of the samples by adhesive
tape, Fig. 6b. This procedure is extremely important taking
into account the rugosity of the surface of the two tested samples
types, which were corn cob concrete samples (ratio 6:1:1, aged
60 days) and expanded clay concrete samples (ratio 6:1:1, aged
60 days). It is imperious to guarantee a perfect contact between
the surfaces of the heat flux sensor and the inner face of the samples,
and to avoid any possibility of the sensors coming off during
the test performance. According to [14], the test duration is related
to the thermal inertia of the building component under study. For a
high thermal inertia building component a minimum of fourteen
days test duration is recommended. On the other hand, for a low
thermal inertia building component a minimum of 3 days of test
duration is recommended. In this case, five days test duration
was considered assuming that both types of lightweight concrete
samples under study had low thermal inertia.
In the Portuguese context and, in particular, in the northeastern
region of this country, it is convenient to perform this test
during the winter or the summer because it is easy to ensure the