Toward 2060 Carbon Neutrality Life-cycle Planning and Design of Photovoltaic Integrated Green Roof (PVIGR) Systems for Hong Kong and the Greater Bay Area

To achieve the goal of carbon neutrality, electricity generation from renewable sources needs to be increased substantially. The photovoltaic integrated green roof (PVIGR), where a PV panel is placed over a green roof, is a promising emerging technology that is especially suitable for densely populated cities with hot and humid weather conditions, such as Hong Kong and other mega-cities in Greater Bay Area (GBA), because of its dual carbon emission reduction, the synergy between PV and green roofs, and other environmental benefits. However, since the first study on PVIGR published in 2007, few PVIGR projects have been constructed worldwide, for two major barriers: lack of location-specific design guidelines and high initial costs. To overcome the first barrier, we will develop a first-of-its-kind location-specific optimized PVIGR design toolkit for the GBA. We first plan to develop a reliable solar irradiance database for GBA, based on which to propose a new model to assess spectral Plane-of-array Irradiance (POA) resources using remote sensing, radiative modelling, and deep learning techniques (Task 1). Next, a new heat and mass transfer model will be developed and experimentally validated to investigate the thermal interactions between PVs, green roofs, buildings, and the local micro-climate (Task 2). With the solar resourcing results, we will develop a web-based PV/PVIGR generation potential map that can help to select suitable roof spaces for PVIGR, and decide the optimal PV installation capacity according to the accurate estimates of the life-cycle benefits and costs of PVIGR (Task 3). Based on the analytical and experimental study on PVIGR, we will propose design guidelines to inform optimized installation specifications for PVIGR. To overcome the second barrier, we plan to quantify the life cycle costs and benefits of PVIGR through city-scale building energy and computational fluid dynamics (CFD) simulation (Task 4), and data-driven public health analysis (Task 5), taking Hong Kong as an example. The comprehensive analysis of the long-term benefits of PVIGR can help decision makers to develop proper financial incentives to internalize positive externalities of PVIGR, and to address its high initial costs. To overcome the barriers and to promote the PVIGR adoption in Hong Kong and the GBA in an efficient way, we have formed a team of seven researchers from three universities with diverse but complementary relevant expertise to work on this inter-disciplinary project.

Mengying Li
Assistant Professor