Passive cooling of residential buildings in tropical climates using user-preferred plant species in green walls

Abstract

This research examines the effect of green walls (GW) on indoor air temperature, utilizing user-preferred plant species as a passive cooling strategy in tropical residential buildings. Epipremnum aureum is a widely preferred plant species due to its adaptability and ease of maintenance in urban settings. Two test cells were installed on the rooftop of a three-story apartment building in Chennai, India—one with a GW and one without. Temperature, humidity, solar radiation, and wind speed data were recorded. The GW significantly reduced indoor surface temperatures, especially on the east-facing wall (3.2 °C). Moderate temperature reductions were observed on the west (2.0 °C) and north (2.8 °C) walls, while the south-facing GW showed a decrease of 1.5 °C. Indoor air temperature reductions followed a similar trend, with the east-facing GW providing a cooling effect (2.9 °C). Regression analysis revealed that ambient temperature and humidity were key factors influencing cooling performance. A simulation was conducted to assess the annual performance using DesignBuilder. In the summer, the GW provided significant cooling, with the west-facing wall achieving the highest reduction in surface (6.8 °C) and air temperature (2.8 °C). In winter, the south-facing walls exhibited significant cooling, with a 7.6 °C decrease in surface temperature and a 2.9 °C decrease in air temperature, whereas the north-facing walls maintained a higher temperature. The chosen plant species enhances indoor thermal comfort and could decrease the energy demand of residential buildings in tropical climates. The study's novelty lies in incorporating user-preferred plant species into real-world experimental analysis and computational simulations to assess annual GW performance thoroughly.