Growing Innovation: Can Locally Sourced and Recycled Materials be utilized in Engineering an Industry Alternative Extensive Green Roof Substrate?

Abstract

The objective of this study was to develop a more sustainable and lower cost green roof substrate using locally-sourced and recycled materials. The hope is that these substrates can supplement or replace the mined and energy intensive heat expanded slate, shale, and clay- based substrates that are the current industry standard. The main inorganic, locally derived, and recycled components chosen for this study include: ceramic pottery shards, T-shirt and bike intertubes. During the experiment, measurements of survival and growth were recorded along with the soil properties of each substrate in comparison to the FLL guidelines for a green roof. An Economic Input Output Life Cycle Analysis (EIOLCA) was run to compare a recycled and locally sourced substrate with the industry standard in term of energy use and cost of production. Finally, a good educational model was produced in order to both show the layers of a green roof to public audiences in a educational setting and to accurately represent a testable green roof without the availability of a full-scale installation. Although it was reported that none of the substrates met every parameter for compliance to the FLL guidelines, all three substrates reported the growth on average of 1.4- 3.9 new stems during the six- week growing period. According to the LCA model, the sand, gravel, clay and refractory mining process sector represents 59.4% of the total cost of manufacturing inorganic industry substrate components and truck transportation represents 34.2% of the total cost respectively. Therefore, this study has established the principle that locally sourced recycled materials can provide economically affordable and sustainable alternatives to traditionally mined substrates and can support Sedum growth. Reformulation of these substrates in light of FLL guidelines and the observation seen in this study is needed to further implement these substrates.