Dynamic Modeling of Living Walls for Enhanced Building Energy Performance
Integrating natural ecosystems into building envelopes has emerged as a promising strategy to improve energy efficiency and environmental sustainability in urban contexts. Living Walls (LWs), as vertical green systems, offer both thermal regulation and ecological benefits. This study introduces a dynamic numerical model designed to accurately capture the complex thermal and moisture interactions between living walls and building façades, addressing current limitations in conventional Building Energy Simulation (BES) tools.
Development of the Dynamic Living Wall Model
The proposed Living Wall model was developed in the MATLAB® environment with a structure specifically designed to represent sensible and latent heat exchanges within the vegetation layer. Careful management of inputs and outputs enables seamless coupling with TRNSYS®, allowing the LW system to interact dynamically with the building fabric. This integrated approach facilitates whole-building energy simulations that account for plant–building thermal behavior.
Coupling with TRNSYS for Whole-System Evaluation
By interfacing MATLAB® with TRNSYS®, the study enables comprehensive simulations of the combined building–plant system. This coupling allows for dynamic assessment of façade-integrated vegetation under real climatic conditions, considering both heat fluxes and moisture transfer. Such interoperability represents a significant advancement over static or simplified green façade modeling approaches.
Model Validation Using Experimental Data
Validation of the dynamic model was conducted using experimental measurements, including temperatures at two LW layers, inner surface heat flux, and growing medium water content. Statistical indicators such as Root Mean Square Error (RMSE) and coefficient of determination (R²) demonstrated excellent agreement between simulated and measured data over a five-day period with variable climatic conditions, confirming the robustness and reliability of the model.
Energy Performance Assessment and Scenario Analysis
Following validation, the model was applied to a case study to evaluate the influence of façade orientation and irrigation rate on building energy performance. TRNSYS simulations based on real climatic data revealed notable cooling energy savings compared to a baseline building with a bare wall. With irrigation rates exceeding 0.0004 kg/s·m⁻², cooling energy savings reached 8 kWh/m² for south-facing façades and 6 kWh/m² for east-facing façades.
Seasonal Strategies and Sensitivity Analysis
To mitigate the negative effects of latent cooling during winter, irrigation was limited to the summer season. As a result, winter energy performance remained unaffected by irrigation rate, while heating energy savings of 10 kWh/m² (south) and 6 kWh/m² (east) were achieved due to the added green layer. A sensitivity analysis further highlighted how vegetation parameters influence overall energy performance, reinforcing the importance of accurate plant characterization in Living Wall simulations.
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