Design Guidelines and Standardization Needs for Pavement Energy Harvesting Systems: A Gap-Analysis Review with a Focus on Hydronic Asphalt Solar Collectors

Asphalt pavements offer a large, continuously irradiated surface that can be leveraged for renewable energy and urban thermal management. This study reviews pavement energy harvesting methods, focusing on hydronic asphalt solar collectors (ASCs), and assesses important pavement and energy-system standards. A structured database search and a systematic screening process were employed to select studies that report design and operational parameters together with laboratory, pilot, or field demonstrations. Across the selected ASC studies, reported performance typically includes a 5–20°C increase in outlet temperature, thermal efficiencies of up to 50–55%, and annual heat outputs of approximately 150–320 kWh m−2, with strong dependence on climate, pipe depth and spacing, system placement, and working fluid. Despite these promising energy outcomes, structural and durability aspects are rarely assessed under realistic traffic loading, and few studies translate rutting, fatigue or interfacial integrity results into design criteria. Moreover, most publications do not explicitly reference applicable standards, and no dedicated guideline for coupled structural-thermal pavement design is identified. To bridge this gap, a practical guideline framework is proposed, outlining key stages from site assessment and coupled structural–thermal design to energy-system integration, construction quality control and long-term monitoring.