Evaluating the impact of a living wall on the heating and cooling for a single-storey commercial building

This study evaluates the thermal performance and transient heat transfer characteristics of an experimental modular living wall (LW) compared to a bare control wall (CW) on a single-storey, uninsulated commercial building in Adelaide, South Australia. A full-scale 7.2 m 2 vertical greenery system (VGS) was retrofitted onto a 220 mm west-facing solid double-brick facade and monitored continuously for over 12 months. To ensure high-precision data collection, the experimental setup was instrumented with post-calibrated Type K thermocouples (with a relative error of ± 0.5 °C) to measure surface temperatures, alongside DS1923 iButtons housed in louvred radiation shields placed at distances of 400 mm, 700 mm, and 1000 mm to monitor ambient dry-bulb temperature and relative humidity. To bridge the gap between raw surface temperature reductions and actual building energy performance, a one-dimensional (1-D) transient finite-difference unsteady conduction model was developed to solve conductive heat flux (Q) at iterative 7.5-minute timesteps. Statistical analyses using independent sample T-tests confirmed significant ( p < 0.05) seasonal thermal buffering. During an extreme heatwave day (ambient 46.4 °C), the LW reduced peak external surface temperatures by 26.6 °C and delayed the thermal peak by 1 h and 45 min. Thermodynamic modelling demonstrated that the VGS physically reduced cumulative summer heat gain by 48% (saving 19.5 kWh/m 2 ) and winter heat loss by 21% (saving 2.5 kWh/m 2 ). These empirical and numerical findings provide robust quantification of vertical greenery as a passive building envelope retrofit, offering critical validation data for modern dynamic energy modelling and urban microclimate simulations.