Ten years of greening a wide brown land: A synthesis of Australian green roof research and roadmap forward

Australian cities have been slow to implement green roofs. This is because there are many potential barriers to their widely acceptance as a nature based solution that can make cities more liveable and help them adapt to, and mitigate, climate change. Due to significant differences in rainfall, temperature, available substrates and suitable vegetation relying on northern hemisphere research and experience is problematic as many of the environmental and economic benefits of green roofs are location specific. This paper aims to 1. Synthesise a decade of Australian green roof research that has sought to overcome these barriers, 2. Assess the current status of the Australian green roof industry and remaining knowledge gaps, and 3. Provide a roadmap for future progress developed in multidisciplinary industry workshops. Many of these insights will be applicable to areas with similar seasonally hot and dry climates or emerging green roof markets. We identified that significant progress has been made in addressing the barriers to green roofs in Australia. Research has focused on developing green roofs for local conditions and quantifying their benefits. Substrate research has investigated the suitability of locally available materials with a focus on how water retention additives and organic waste materials can increase plant available water and therefore survival. By taking a plant physiology approach Australian researchers have gained a strong functional understanding of suitable green roof plants and the benefits they provide, considerably expanding the available palette beyond the succulents commonly used internationally. Research has quantified green roofs’ stormwater retention and building insulation and energy benefits and provided evidence that they benefit well-being and performance, important for employee productivity.