Effective thermal conductivity of hollow bricks with cavities filled by air and expanded polystyrene

Effective thermal conductivity of hollow bricks with the cavities filled by either air or expanded polystyrene is analyzed using a hybrid experimental-computational approach. The experimental setup involves an application of a thermal insulation box and a set of temperature and heat flux probes placed at characteristic positions of the specimen-insulating box system. Using the measured heat fluxes and temperatures, the heat loss of the system is determined. A computer simulation tool based on the finite element principle is then used for modeling the temperature fields and heat losses in the studied system. Finally, the effective thermal conductivity is identified using an iterative procedure. Experimental results show that the application of expanded polystyrene as cavity filler instead of air leads to approximate to 30% decrease in the effective thermal conductivity of hollow brick blocks.