Study of a new capillary active bio-insulation material by hygrothermal simulation of multilayer wall

[Display omitted] •A new bio-based capillary active insulation material was developed.•Mould risk of walls containing capillary insulation material was reduced.•Capillary insulation material reduced the heat loss through the wall.•Uninsulated reference wall showed the higher risk of condensation. This paper studies the influence of a new bio-based capillary active insulation (CAI) materials (corn stalk based vegetal derived concrete namely CS-1 and CS-2) and two traditional insulation materials (aerated autoclaved concrete (AAC) and aerated insulation brick (IB)) on the hygrothermal properties of multilayer wall. The reference wall consists of solid brick masonry plastered on the internal and external sides. Walls based on CAI materials consist of an extra layer of insulation and weather-resistive barrier (WRB) on the façade surface. Simulations were performed under the natural climatic condition of hot-humid and cold regions. Optimum thickness for the bio-based CAI materials to be used as internal insulation was 100 mm beyond which higher insulation thickness triggered the risk of mould growth. All walls based on CAI insulation materials (CS-1, CS-2, AAC, and IB) showed the mould index (MI) within the acceptable range. Bio-based CAI materials showed considerable improvement in the temperature and relative humidity at the interior surface. CAI materials reduced the heat losses through the wall by 58–69% as compared to the reference wall. Drying behavior of the wall was significantly improved with the combination of CAI and WRB and no risk of condensation was observed in the walls.