Thermal Resistance Measurement of Green Roof Layers with Coarse Artificial and Recycled Materials

Substituting the natural coarse aggregates with recycled coarse aggregates within substrate and drainage layers of green roof contributes to decreasing the burden on the environment by saving natural resources. Moreover, there is actually a need for evaluating the thermal resistance of green roof layers with recycled materials: do they can provide the nearly same thermal resistance as classical natural materials? Therefore, in this study, different types of coarse granular aggregates, including Natural Coarse Aggregate (NCA), Recycled Coarse Aggregate (RCA), Incinerated Municipal Solid Waste Aggregate (IMSWA), and Lightweight Expanded Clay Aggregate (LECA) were separately used for the drainage layer, when coarse recycled materials were used for the substrate layer. The thermal resistance of dry substrate and drainage layers was measured separately and together in accordance with ISO 9869-1 standard. According to the results, LECA had the lowest density and the maximum thermal resistance among the coarse granular aggregates as drainage layers. For green roof systems, the presence of air-voids among dry media particles resulted in greater heat resistance than the presence of water in soil particles. Among all suggested green roof systems, the specimens with a 20-cm substrate layer and a 5-cm LECA drainage layer had the lowest weight and maximum heat resistance. Consequently, they were known as ideal rooftop arrangements.