Comparison of three different devices available in Spain to test thermal properties of building materials including phase change materials

Thermal properties of materials used in building envelopes must be analysed in order to evaluate the thermal response of the constructive system. This thermal characterisation is a key point during the design phase of a building. However, thermal characterisation of constructive systems at laboratory scale is difficult to be carried out under real environment conditions. In this paper, three devices developed by three different research groups in Spain were used to compare in an inter-laboratory test the performance, capabilities and thermal properties of construction systems at lab scale. Tested materials were gypsum blocks containing phase change materials (PCMs) and made by three different ways: using microencapsulated materials Micronal® DS5001, a suspension water/PCM and impregnation with RT21. The effective thermal conductivity, the total amount of heat accumulated, and the specific heat were measured using these homemade devices. k results followed same trend but there was a drift between them due to the samples porosity and thickness. Moreover, the k decreased when adding PCM but this behaviour was not followed by impregnated samples; due to the PCM filling gypsum pores instead of air. The Cp results followed same trend CpBlank < CpSuspension < CpMicroencapsulated < CpImpregnated but a gap between results was observed due to different amount of incorporated PCM.

► Thermal properties of building envelopes were analysed in an inter-laboratory test in Spain.
► Tested materials were gypsum blocks containing PCM and made by three different ways.
► The effective thermal conductivity, the total amount of heat accumulated, and the specific heat were measured.
► The conductivity and Cp results were Blank < Suspension < Microencapsulated < Impregnated.
► The conductivity did not decrease with impregnated PCM due to the PCM filling gypsum pores.