Experimental analysis of insulating materials using Guarded Hot Box – Preliminary results

The containment of energy consumption in the construction sector strongly depends on the envelope, which is mainly responsible for heat loss in buildings. Thus, great attention should be paid to the selection of thermally-performing materials. In this work, preliminary results of three different configurations of walls in real size have been compared, conducting the analyses with the heat flow meter method inside the Guarded Hot Box apparatus, capable of guaranteeing repeatable and controlled conditions. The analyses were carried out with two types of heat flow meters, characterized by different sensitivity. The side of the wall facing the hot chamber has been insulated with rock wool for all the experiments, while the other side has been insulated first with expanded polystyrene (EPS) with graphite, then with hemp, and finally with cork. The results showed that the sample with the best thermal behaviour is the first one, i.e., the wall with EPS with graphite, characterized by a transmittance value between 0.148 W/m2K and 0.153 W/m2K. The other two configurations, characterized by the use of natural materials, showed worse performance with conductance values about 20% higher than EPS. The percentage differences between the two heat flux sensors for the experimental campaigns ranged from 2.8% to 4.4%.