Improvement of the thermal inertia of building materials incorporating PCM. Evaluation in the macroscale

Abstract

The energy demand by the private sector for buildings HVAC systems has increased significantly, driving the scientific community to find different alternatives to reduce this high energy demand. Phase change materials (PCMs) are presented as materials with high thermal energy storage (TES) capacity due to the latent heat stored/released during phase change, able to reduce the energy demand of buildings when incorporated to construction materials. The analysis of the construction materials and their thermophysical properties are a key step in the building design phase. Even though the thermal characterization of real samples might be helpful, it is not always possible and it is usually costly. Therefore, the authors have developed two devices able to characterize effective thermal conductivity of real materials at macroscale and to register the temperature–time response curves produced by the inclusion of PCM in the constructive system for thermal inertia increase. The materials tested have a gypsum or Portland cement matrix which incorporates 5wt% and 15wt% of microencapsulated PCM (DS5001 Micronal®). Comparing the results, it was demonstrated that the PCM addition produces a reduction in the thermal conductivity of the samples. Furthermore, to incorporate 5wt% PCM in Ordinary Portland cement matrixes is more beneficial than to add this PCM amount in gypsum matrixes, from the thermal properties point of view. However, the benefit from extending the PCM addition up to 15wt% is better for gypsum samples than for Ordinary Portland cement matrixes.