Monitoring and performance evaluation of a green wall in a semi-arid Mediterranean climate

Green walls are gaining popularity as a sustainable cladding solution for buildings, offering various advantages for the built environment and human well-being. However, there is a lack of research on plant selection guides and field data in semi-arid Mediterranean climates, limiting our understanding of green wall potential. To address these gaps, this study assesses the hygrothermal and sound insulation performance of a modular living wall in a semi-arid Mediterranean climate and develops a plant-selection guideline for green wall applications. The experiment involves a comparative assessment between the modular living wall and a bare-wall-reference facade. Measurements of air temperature, relative humidity, and sound pressure were taken, along with thermal imaging, to record the surface temperatures of the experimental facades. Results reveal that the modular-living wall significantly decreased dry-bulb air temperature (up to 8 °C) and reduced sound pressure by up to 5.1 dB. Additionally, relative humidity in the air cavity behind the modular living wall consistently increased by 6.6%, with a maximum absolute humidity differential of 8.6 g/kg. Thermal imaging showed a surface temperature difference of up to 27 °C, with foliage having a higher leaf-area-index proving more efficient in reducing the surface temperature of the green wall. Overall, the modular living wall effectively protected building walls from high solar radiation and temperatures, resulting in reduced energy requirements for space cooling. However, proper irrigation and plant health maintenance are necessary. This study fills important research gaps, providing valuable insights into the potential benefits and performance of green walls in semi-arid Mediterranean climates.