Bio-solar green roofs increase solar energy output: The sunny side of integrating sustainable technologies

Abstract

In urban spaces, localised energy generation through rooftop solar has become increasingly popular, and green roofs are often used for a range of services such as thermal insulation. In recent years, the adoption of Bio-solar green roofs (BSGR) for both thermal insulation and increased solar energy outputs has increased. Here we present two buildings of the same dimensions and location, similar age and construction material, where one hosts a BSGR, and the other a conventional solar roof (CSR) in Sydney, Australia. Each solar array hosted a range of environmental sensors, including ambient temperature and global horizontal irradiance (GHI). The modelled BSGR average hourly energy output was 4.5% higher than the CSR (seasonal trends observed Spring; 4.14%, Summer; 4.16%, and Autumn; 5.21%) with BSGR producing 14.26 MWh more than the CSR, valued at $4526.22 AUD, and equal to 11.55 t e-CO2 greenhouse gas mitigation. Further potential for up to 1.55 t of CO2 could be mitigated by the plant material on the roof, provided the trimming of plant material during maintenance is conducted responsibly. In this instance, the implementation of a BSGR increased the system's solar output by 23.88 kWh per m2 of panel coverage, as well as reducing the e-CO2 emissions by 0.019 t per m2 over the CSR. When compared to the results of previously reported pilot studies and some simulations, it is evident that the implementation of a BSGR is favourable for maximising energy production and the mitigation of GHGs.