The Impact of Green Roof Conversion on Energy Efficiency: A Case Study of KTU Kanuni Campus

Refia Güngör Günay; Seda Kalkan; Ayça Akkan Çavdar; Ebru Şanlı Karabak; Nihan Engin

doi:10.15320/ICONARP.2026.353

Authors

Refia Güngör Günay Kilis 7 Aralik University
Seda Kalkan Tokat Gaziosmanpasa University https://orcid.org/0000-0001-8496-2781
Ayça Akkan Çavdar Recep Tayyip Erdoğan University https://orcid.org/0000-0002-3333-8943
Ebru Şanlı Karabak Karadeniz Technical University
Nihan Engin Karadeniz Technical University

DOI:

https://doi.org/10.15320/ICONARP.2026.353

Keywords:

Green roof, Sustainability, Energy efficiency, Carbon emissions, Water retention capacity

Abstract

Green roofs are multi-layered systems constructed on a supporting structure, with the vegetation layer forming the uppermost layer. They contribute to ecological, economic, and social sustainability through functions such as rainwater harvesting, reduction of heat loss, mitigation of the urban heat island effect, and the creation of aesthetically appealing public spaces. University campuses—key environments for implementing sustainability principles—play a crucial role in energy management, circular resource utilisation, and water management. In this context, this study investigates the impact of converting the hard-surfaced roof of the “Surveying Engineering Canteen” at Karadeniz Technical University’s Kanuni Campus into a green roof. Following field surveys and feasibility assessments, three inverted green roof alternatives (extensive, semi-intensive, and intensive) were modelled in DesignBuilder to evaluate energy performance, operational and embodied carbon, construction costs, and the additional structural load resulting from the soil’s water retention capacity. The findings indicate that green roof applications reduce annual heating loads by 36–46%, improve indoor operative temperatures during winter months, and lower operational carbon emissions by 16–20%. However, embodied carbon and construction costs increase relative to the existing roof, particularly for semi-intensive and intensive systems. Structural load analysis revealed that while extensive roofs fall within acceptable limits, semi-intensive and intensive systems may exceed standard live-load thresholds due to their higher water retention loads, requiring reinforcement. Overall, the extensive system emerges as the most feasible option in terms of cost, embodied carbon, and structural compatibility, while still providing meaningful energy savings and environmental benefits.

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Author Biographies

Refia Güngör Günay, Kilis 7 Aralik University

Refia Güngör Günay is a Research Assistant at the Department of Architecture, Faculty of Engineering and Architecture, Kilis 7 Aralik University, Türkiye. Her research interests include micro house, building materials, and performance-driven evaluation of architectural components in relation to sustainability.

Seda Kalkan, Tokat Gaziosmanpasa University

Seda Kalkan is a Research Assistant at the Department of Architecture, Faculty of Engineering and Architecture, Tokat Gaziosmanpasa University, Türkiye. Her research focuses on traditional building patterns, rural settlements, material improvement approaches, and sustainability-oriented architectural studies, including analytical methods for understanding vernacular environments.

Ayça Akkan Çavdar, Recep Tayyip Erdoğan University

Ayça Akkan Çavdar is a Research Assistant at the Department of Architecture, Faculty of Engineering and Architecture, Recep Tayyip Erdoğan University, Türkiye. Her research centers on sustainable architecture, energy-efficient building envelopes, and timber-based solutions, including ventilated façade panels and performance assessment through digital simulation and design methods.

Ebru Şanlı Karabak, Karadeniz Technical University

Ebru Şanlı Karabak (M.Arch.) is an architect affiliated with the Department of Architecture, Faculty of Architecture, Karadeniz Technical University, Türkiye. Her work relates to timber construction and building performance, with interests in contemporary envelope applications, material-based design decisions, and architectural detailing for durable and efficient systems.

Nihan Engin, Karadeniz Technical University

Nihan Engin is a Professor at the Department of Architecture, Faculty of Architecture, Karadeniz Technical University, Türkiye. Her research spans environmental design and building physics, including climate-responsive architecture, traditional housing studies, natural ventilation and passive strategies, and sustainable material-oriented approaches in architectural design and education.

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