Algal Photobioreactor Façades Coupled with BAPV/BIPV in High-rise Urban Buildings Improves Indoor Air Quality and Enables Energy Resilience in Race to Net-Zero

In the high-rise urban buildings' use phase, the two critical concerns are improving indoor air quality (IAQ) and the race to achieve net-zero. The IAQ refers to the air quality within and around buildings and structures. The uncontrolled IAQ in high-rise buildings will have severe implications on occupants in terms of health and comfort. So, understanding and controlling common indoor pollutants can help reduce the risk of indoor health concerns. Similarly, the race to achieve net-zero refers to the balancing between energy used by the building occupants and systems associated with them to the energy produced onsite by various means, even in the event of a disruption. So, understanding the patterns of energy consumption and exploring the potential renewable solutions with integrated design can help achieve net-zero and energy resilience. Hence, thinking of addressing the IAQ, and net-zero and energy resilience issues, this paper proposes using algal photobioreactor façades (APhF) coupled with a building attached/integrated photovoltaics (BAPV/BIPV) in high-rise urban buildings. First, a conceptual design for APhF integration with BAPV/BIPV systems without compromising building aesthetics is provided considering a standard high-rise building in Hong Kong. Second, based on the estimates of the building’s occupants, potential indoor pollutants, and energy consumption (including cooling and heating loads), the APhF and BAPV/BIPV capacities are determined. Third, the performance is analysed, followed by sensitive analysis. The sensitivity analysis considers variation in incident solar radiation for APhF and BAPV/BIPV and photovoltaic technologies for BAPV/BAPV. The results include microalgae and solar electricity's co-production potentials, energy demand and supply curves, along with performance indicators. We also provided a critical discussion on possible food, feed and energy-related synergies. Such synergies include the microalgae-biogas-syngas-fuel cell electricity-heat recovery, microalgae-protein powder. Lastly, mapping with the relevant United Nations Sustainable Development Goals (UNSDGs) explores the challenges and future research possibilities in alignment with the SDGs. The APhF coupled BAPV/BIPV system provides the near real-time possibility of removing the indoor air pollutants, thus bolstering the energy resilience in the race to net-zero.