The Role of Plant Species Diversity in Green Roofs for Energy Optimization: A Case Study of Shokouh School in Babol

Document Type : Original Article

Authors
Rouhollah Rahimi 1
Fatemeh Firozmandi Bandpi 2
1 Associate Professor, Department of Architecture, Faculty of Arts and Architecture, University of Mazandaran, Babolsar, Iran.
2 MS.C in Architecture, Department of Architecture, Faculty of Arts and Architecture, University of Mazandaran, Babolsar, Iran.
10.22034/usd.2026.2068767.1375
Abstract
With the increasing energy consumption and depletion of non-renewable resources, optimizing energy use in educational buildings has become a critical challenge. Green roofs, as a sustainable solution, offer significant potential to reduce thermal loads and carbon dioxide emissions. However, the crucial influence of plant species diversity on the energy performance of green roofs—particularly in temperate and humid climates characterized by high relative humidity and abundant rainfall—remains underexplored. This study specifically investigates the extent to which selected plant species on a green roof can optimize energy consumption patterns and CO₂ emissions in a school located in the temperate and humid climate of Babol, Iran. To address this question, the performance of four native and well-adapted plant species—Sedum album (white stonecrop), Thymus serpyllum (creeping thyme), various Sedum species, and Frankenia laevis—was simulated using Design Builder software and compared to a baseline scenario (conventional roof without green cover). The results clearly indicated that all species reduced energy consumption, but Sedum species achieved the highest overall performance, with a 17.7% reduction in total energy use (25.651 kWh), 17.8% in cooling load, and 17.4% in heating load. This species also lowered the average roof surface temperature to 20.11 °C and reduced CO₂ emissions by 7.5% (29/984 kg). In contrast, Frankenia laevis, with a remarkable 28.7% reduction in heating energy demand, proved particularly effective during the cold season. By filling an existing research gap for temperate and humid climates, this study provides practical guidelines for green roof design in educational buildings and identifies Sedum species as the optimal choice for maximizing energy efficiency and environmental sustainability in such climatic conditions.
Keywords
Green roof
Energy optimization
Plant species
Temperate and humid climate
Subjects
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Journal of Urban Sustainable Development
Volume 7, Issue 22
Spring 2026
Pages 109-129