Towards accepting biobased variability to upscale robust construction assemblies through stochastic hygrothermal modelling

Biobased materials such as straw and lime hemp offer strong potential for reducing emissions in the building sector through carbon sequestration, rapid growth, valorisation of residual streams and local availability. Yet their heterogeneous and anisotropic nature challenges current standardisation, modelling practices and regulatory acceptance. Moisture risks require long-term durability assessment, yet limited technical data and validation hinder reliable hygrothermal evaluation. As a result, their application remains largely confined to low-rise, experience-based practice.

This research aims to enable upscaling of straw and lime hemp to mid-rise buildings in both new-build and retrofit contexts. Hygrothermal and self-bearing material properties are leveraged to develop monolithic, vapour-open and simplified sufficiency-based construction assemblies with demonstrable robustness. A stochastic, validation-driven framework is developed, explicitly incorporating material variability, moisture load uncertainty, and degradation risks.

The methodology combines material characterisation, two-tier validation based on lab and in situ monitoring data, and large-scale stochastic hygrothermal batch simulations. The outcome is a set of robust probabilistic application ranges for biobased assemblies and an assessment of moisture-dependent thermal performance at building scale. The methodology is reproducible for future-emerging biobased materials, as a pathway for robust implementation.

Project Info

Research group: Building Physics
Duration: from 01-09-2024 to 31-08-2030
Researcher: Ruben Van den Bossche
Academic supervisors: Nathan Van Den Bossche and Marijke Steeman