This code supports the study titled "Stealth Bio-Thermal Wall Skins: A Multi-Functional Retrofit Strategy for Mould Mitigation and Hygrothermal Performance in Urban Housing". The submission includes GNU Octave scripts for simulating 1D transient heat and moisture transfer through multilayer wall assemblies under five African climatic zones, assessing mould growth risk using the Viitanen model, and estimating annual energy losses. Real-world climate data (.epw files) and material property definitions based on peer-reviewed sources are included. Results generated include temperature and humidity profiles, Mould Growth Index (MGI) trends, and energy loss visualisations (Figures 2–7). The dataset promotes open science and reproducibility in urban building retrofit research.