Energy Conservation Potential of an Extensive Green Roof in Iran for One Year Duration

Document Type: Original Article


1 PhD Student, Department of Horticultural Science and Landscape, Ferdowsi University of Mashhad, Iran

2 Professor, Department of Horticultural Science and Landscape, Ferdowsi University of Mashhad, Iran

3 Assistant professor, Department of Horticultural Science and landscape, Ferdowsi University of Mashhad, Iran


The temperature of cities continues to increase because of the heat island phenomenon and the undeniable climatic change. The observed high ambient temperatures intensify energy problems in cities, deteriorates comfort conditions, put in danger the vulnerable population and amplify the pollution problems. There are some suggested ways to reduce these issues, among them vegetated roofs are shown to be promising. This study describes energy consumption performance of an extensive modular type green roof with different plant selections using a randomized complete design in Mashhad, Iran. Nine species from three major taxonomic and functional plant groups (grasses, ground covers and sedums) namely (Agropyron cristatum, Festuca aurundinacea, Festuca ovina, Potentilla sp., Frankenia thymifolia, Vinca minor, Sedum acre, Sedum spectabile, Carpoboratus edulis) were selected. Temperature fluctuations during four seasons were recorded with three replicates. Experimental trials with growing beds without plants (bare roofs) were also used as controls. Small hand manual thermometers were placed in each module (box) and air temperature was also recorded. The results showed very significant temperature differences between the green and bare roof modules. Larger plants with higher biomasses kept temperatures more stable. Thermal comfort and energy saving was achieved using green roofs in this research and it could be well used in a large scale for growing cities and population energy requirements.


Significant differences were observed between green and bare roof energy conservation potential considering temperature.

Larger plants and higher biomass kept temperatures more stable in both warm and cold seasons.

Thermal comfort and energy saving can be maintained with application of green roofs in a large scale for growing cities and population energy requirements.

The presence of plants in green roofs on top of a building showed major beneficial temperature reduction and subsequently energy saving.



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