Design guidelines based on the impact of indoor living walls on building cooling energy consumption

Indoor living walls are increasingly recognized for their aesthetic appeal, noise reduction, and improvement of air quality and occupant wellbeing. However, their impact on building cooling energy use remains underexplored. While past research has primarily focused on outdoor living walls, the potential energy savings of indoor living walls have not been fully quantified. This study employs the indoor living wall object in EnergyPlus to evaluate the cooling effects of evapotranspiration (ET) on building energy use across 16 U.S. climate zones.

The study integrates a model that quantifies both sensible and latent loads from the ET process into the EnergyPlus energy simulation software via a Python plugin. The U.S. Department of Energy (DOE) medium-sized office building reference model was adapted to assess the impact of indoor living walls on cooling energy use. A comprehensive parametric study was conducted, analyzing variables such as leaf-to-floor area ratios (LFAR), orientations, and climate zones to determine their influence on the performance of indoor living walls.

Results indicate that indoor living walls can significantly reduce building energy consumption, especially in climates with higher cooling demands. Its effectiveness varies by climate zone and wall size, with larger walls generally leading to greater cooling energy savings. In hot, dry regions, even smaller living walls can provide noticeable savings, while in consistently warm climates, larger walls can substantially reduce cooling energy use. In colder regions, living walls can still lower cooling loads during summer months, though overall energy savings may be less pronounced.

This study will offer practical design guidelines for architects and engineers, highlighting the critical integration of indoor living walls into building designs. These guidelines will underscore the significance of factors such as climate zone, wall size, and building orientation in optimizing energy savings. By considering these elements, architects and engineers can select suitable living wall systems to passively contribute to meeting cooling demands for specific projects. Customizing living wall designs to align with particular climates and building features will enhance their functional role, ensuring they play a meaningful part in sustainable building practices.

Overall, this research highlights the dual role of indoor living walls in enhancing both building aesthetics and energy efficiency. By quantifying their energy-saving potential across diverse climates, it offers valuable insights for integrating biophilic design into buildings to achieve energy reductions. The findings advocate for the strategic incorporation of living walls, emphasizing climate-specific approaches to optimize their energy-saving benefits while maintaining occupant comfort.