Urban resilience: The impact of green roofs on thermal performance in sustainable building design

Abstract

Urban areas are increasingly impacted by climate change, leading to higher temperatures that cause discomfort and increased energy demands. This study examines the effectiveness of extensive green roofs in reducing heatwave temperatures and improving thermal comfort. We compared the thermal dynamics and energy efficiency of green roofs to conventional roofs during a heatwave in a semi-arid region of Argentina. Conventional roofs reached peak temperatures of 44.5°C, while green roofs maintained around 31°C, showcasing their ability to regulate roof temperatures. Thermal fluctuations on conventional roofs varied nearly 20°C from day to night, while green roofs experienced fluctuations of less than 1°C. Conventional roofs had incoming heat flow values from -3.7 W/m² to 114.4 W/m², whereas green roofs ranged from 26.2 W/m² to 46.2 W/m², with some negative flows indicating a cooling effect. We found an 11% to 16% reduction in cooling energy consumption with green roofs. This study highlights the benefits of native plant extensive green roofs in semi-arid cities for reducing heat, improving thermal comfort, and enhancing energy efficiency.