Green roof substrates influencing the provision of ecosystem services: A review

Green roofs are among the ideas of sustainable growth. However, there is a lack of knowledge of the substrate layer, especially its composition. Thus, this paper aims to review the substrate compositions of green roofs used in literature in the last ten years. The main green roof substrate components include inorganic matter (perlite, vermiculite , crushed bricks), organic matter (compost and peat), and alternative materials such as recycled ones, biochar, and mushrooms. Compost was the most used material for plant growth, with 10 %. Peat was the most mentioned component for runoff quality, with 30 %. For thermal performance, sand was the major material utilized with 10 %. Moreover, compost is the major substance used in making substrate, with 38 out of 62 papers reviewed. Out of 38 papers, including compost, only 16 mentioned the type of material used. In fact, the compositions used till now mainly focus on the plants. Therefore, more studies must be conducted to establish new substrate compositions for not only the vegetation but also for the ecosystem services provided by green roofs, such as thermal and acoustic insulation . • There is no definite composition for green roof substrates. • Generally, a mixture of organic and inorganic matter is used. • Compost and peat were among the organic content. • Sand and crushed brick were frequently used as mineral part.