Xiongyi Guo

Achieving long-term urban sustainability requires energy subsidy frameworks that evolve with changing technological conditions and system needs. Renewable energy subsidy regimes have played a decisive role in accelerating building-integrated solar photovoltaic deployment, but many were designed for an earlier expansion phase focused mainly on increasing generation capacity and reducing technology costs. As electricity systems move toward an integration phase characterized by higher renewable penetration, flexibility constraints, storage needs, and cross-sectoral coordination, generation-centric subsidy architectures may become increasingly misaligned with system-level requirements. This study conducts a structured comparative analysis of subsidy design in Hong Kong, Chinese Mainland, and Australia, examining legal foundations, target scope, incentive structures, and technology orientation across expansion and integration phases. Despite major differences in governance systems and market organization, the findings show a common pattern: Principal subsidy instruments remain anchored in output-based performance metrics, while storage, hydrogen, and hybrid technologies are generally supported through supplementary rather than core mechanisms. The study argues that this policy layering may limit technological inclusiveness and reduce alignment between subsidy design and evolving system needs. It therefore proposes a system-value-oriented comparative framework for subsidy redesign that recognizes flexibility, reliability, and integrated clean energy performance in the built environment.

Road transport systems are central to sustainable mobility and the energy transition because they account for a large share of final energy use and remain heavily dependent on fossil fuels. With more than 90% of transport energy still supplied by petroleum-based fuels, improving energy efficiency and reducing emissions in road networks has become a strategic priority. This review compares Australia, Hong Kong, and the United Kingdom to examine how road-design standards and emerging digital technologies can improve energy performance across planning, design, operations, and maintenance. Using Australia’s Austroads Guide to Road Design, Hong Kong’s Transport Planning and Design Manual (TPDM), and the UK’s Design Manual for Roads and Bridges (DMRB) as core reference frameworks, we apply a rubric-based document analysis that codes provisions by mechanism type (direct, indirect, or emergent), life-cycle stage, and energy relevance. The findings show that energy-relevant outcomes are embedded through different pathways: TPDM most strongly supports urban operational efficiency via coordinated/adaptive signal control and public-transport prioritization; DMRB emphasizes strategic-network flow stability and whole-life carbon governance through managed motorway operations and life-cycle assessment requirements; and Austroads provides context-sensitive, performance-based guidance that supports smoother operations and active travel, with implementation varying by jurisdiction. Building on these results, the paper proposes an AI-enabled benchmarking overlay that links manual provisions to comparable energy and carbon indicators to support cross-jurisdictional learning, investment prioritization, and future manual revisions toward safer, more efficient, and low-carbon road transport systems.