Moisture Buffering of Hemp-Lime with Biochar and Rape Straw-Lime as Surface Materials for a Stable Indoor Climate

Abstract

An appropriate and stable indoor climate in museums is crucial to guarantee an appropriate preservation of our cultural heritage. Depending on the collection, indoor temperature and relative humidity need to be kept within a certain range. Fluctuations in temperature and relative humidity could cause damage to museum artefacts and may require higher energy needs than necessary. Biochar is a material of which the use is relatively new in building materials. Previous studies have shown that biochar has unique moisture properties with a high surface area, high porosity and therefore high capability of moisture uptake. In Southern Sweden there are several biochar manufacturers that produce biochar from local biomasses such as seaweed, gardening wastes and residues from greenhouses. The aim of this project was to investigate the impact of hygroscopic surface materials on the indoor climate of buildings, focusing on moisture buffering and hygrothermal properties. The building materials that were studied were hemp-lime (with and without biochar) and rape straw-lime. Passively influencing the indoor climate by choosing appropriate surface materials could contribute to lower energy needs and less need for mechanical ventilation in historic buildings and museums without the need for excessive HVAC solutions.