Effect of temperature on thermal and hygric properties of hemp-lime plasters

Abstract

This study investigates the effect of temperature on thermal properties (conductivity and thermal diffusivity) and on Moisture Buffer Value (MBV) of two types of hemp-lime plasters. These plasters differ from their kind of hemp shiv: one is made of Chanvribat defibered hemp shiv (CHLP) and the other one is made of Terrachanvre defibered hemp shiv (THLP). The investigations are based on experimental measurements and are performed at 14°C, 17°C, 20°C and 23°C for thermal properties and at 11°C, 14°C, 17°C, 20°C and 23°C for MBV. The measurements of thermal properties are made at 50% Relative Humidity (RH). To limit the problems of water migration, the measurements are performed with transient state methods. Hot disk is used at all temperatures; it provides both thermal conductivity and diffusivity. Hot wire is used at 23°C, it provides thermal conductivity only. Over the considered temperature range (14- 23°C), the impact of temperature on thermal properties is very low while it is more sensitive on moisture buffer value. It is shown that the moisture buffer value decreases by about 54 % for Terrachanvre Hemp Lime Plaster (THLP) and by about 59 % for Chanvribat Hemp Lime Plaster (CHLP) when the temperature decreases from 23°C to 11°C.