Responsible partners: Ensap Bordeaux and Xylofutur (France)

Description: The experiment carried out by ENSAP in Bordeaux consists of studying the impact of adding thermal mass behind the external face of the thermal envelope of a building whose construction method is wood-frame.

Two types of thermal mass are considered:

  • A 3 cm layer of Rubitherm RT21 paraffin phase change material with latent heat of 150kJ/kg and density of 800kg.m3.
  • A 7.5 cm layer of earth molded in a plastic state (molded raw earth brick : adobe)

The envelope elements, enriched with these thermal masses, were tested on the western façade of a positive energy wood-frame building on the Bordeaux campus.

These tests show that in summer, the presence of one or other added thermal mass has a temporary “thermal barrier” effect:

  • A temperature jump across the thermal barrier, consisting of the added thermal mass, whose value is between 12°C and 14°C
  • A time lag between the incident thermal wave (thermal solution from the building environment) and the thermal wave passing through the thermal barrier of 4h to 6h

Thus, in SudoE regions, this temporary thermal barrier is sufficient, for vertical envelope elements, to ensure summer comfort, by drastically limiting the attack of the thermal insulation by the thermal wave generated by the summer environment.