Thermal response of blue-green roof under extreme drought conditions

Žižak, Tej (author), Medved, Sašo (author), Arkar, Ciril (author)

Green building envelopes have been emerging as an important tool for mitigation of urban heat island effects caused by rapid urbanization. The adaptive ability of vegetation to cool itself through evapotranspiration can effectively improve the thermal comfort in urban environment. However, the transpiration mechanism requires water for its functioning. This study focuses on prolonged water shortage periods which are common in dry climates and are even expected to be more and more frequent in other climates due to climate changes. While irrigation offers a solution to water scarcity, it is often not desirable, or in some extreme cases even prohibited, to use drinking water for irrigation. A new design of green roofs with water storage layer (blue-green roof) has emerged in recent years to help with the water shortage periods by storing rainwater. But even this is not adequate for extreme climate conditions. The subject of this research is an extensive blue-green roof with water storage layer and drought resistant sedum vegetation. The experimental results include measurements of evapotranspiration, substrate moisture content and temperatures of the blue-green roof test module. The test module is exposed to prolonged water shortage periods. The ability of vegetation to recover after water stressed conditions is evaluated. The thermal response which includes the temperatures and water content across various layers is shown. Special attention is given to surface temperature at water stress conditions, which is compared to temperatures of conventional roofs. A validated water balance model is used for the purpose of expanding the results to different climates. The typical meteorological year data for various locations is used for year-round simulations, which show the expected duration of water shortage periods. The paper concludes that while performance of green roofs in extreme climates is reduced, positive benefits remain in comparison to conventional roofs.

• Language: English
• Keywords: blue-green roof, surface temperature, water stress, evapotranspiration
• Work type: Other
• Typology: 1.16 - Independent Scientific Component Part or a Chapter in a Monograph
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: Str. 768-776
• PID: 20.500.12556/RUL-180473
• UDC: 502.131.1:620.9
• DOI: 10.5281/zenodo.17643071
• COBISS.SI-ID: 271087107
• Publication date in RUL: 10.03.2026

Record is a part of a monograph

• Title: Comfort at the extremes : investing in well-being in a challenging future
• Editors: Jesica Fernandez-Aguera, Samuel Domínguez-Amarillo, Susan Roaf
• Place of publishing: Seville
• Publisher: Ecohouse Initiative
• Year: 2024
• ISBN: 978-1-9161876-8-9
• COBISS.SI-ID: 270935299

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: modro-zelene strehe, površinske temperature, stresni pogoji, evapotranspiracija

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: L7-4495-2022
• Name: Zelene stene za trajnostne stavbe in mesta prihodnosti

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P2-0223-2022
• Name: Prenos toplote in snovi