Semi-arid cities, often characterized by scarce rainfall, high solar exposure, and low vegetation cover, are particularly vulnerable to urban heat island (UHI) effects and deteriorating thermal comfort for residents. With climate change intensifying these issues, there is a growing imperative to adopt sustainable, adaptive strategies that not only mitigate environmental extremes but also enhance human well-being in urban environments. Urban greenery and solar energy integration present promising, mutually reinforcing solutions that can not only mitigate temperature extremes but also reshape urban microclimates, reduce energy demand, and foster long-term ecological resilience.

Urban Green Infrastructure

Urban vegetation, including trees, green roofs, pocket parks, and vertical greenery systems, plays a crucial role in climate regulation. This research topic explores the multifaceted role of urban greenery in improving microclimates and enhancing livability:
· Evapotranspiration: Vegetation cools the air by releasing water vapor, lowering surrounding temperatures.
· Shading: Tree canopies reduce surface and ambient heat by blocking solar radiation.
· Airflow Modulation: Green corridors can redirect or buffer wind patterns, helping regulate air quality and temperature.
· Carbon Sequestration & Pollution Filtration: Plants absorb CO₂ and trap airborne particulates, improving overall air quality.
· Water-Wise Management: Green infrastructure can contribute to sustainable water management through rainwater harvesting and the promotion of drought-tolerant native vegetation.

Solar Energy Synergy

Semi-arid cities are ideal candidates for photovoltaic (PV) integration due to their high solar exposure. This collection examines the various ways solar energy can work in tandem with urban greenery to mitigate heat and enhance energy efficiency:
· PV Canopies: Provide shade over walkways, parking lots, and public plazas, reducing surface albedo.
· Building-Integrated Photovoltaics (BIPV): Reduce building heat gain while producing on-site energy.
· Energy-Climate Feedback Loops: Solar energy reduces reliance on fossil-fueled cooling systems, mitigating further urban heat generation.

Integrated Design: A Synergistic Pathway

The integration of greenery and solar energy offers transformative potential for climate-adaptive urbanism. The synergistic nature of these strategies presents a path toward climate-resilient cities:
· Agro-solar corridors: Combine farming, shading, and PV harvesting.
· Hybrid green-solar rooftops: Balance biodiversity and energy generation.
· Urban planning codes: Incentivize mixed strategies for cooling, shading, and decentralization of energy.
· Policy frameworks: Developing robust policy and regulatory frameworks that facilitate the integrated deployment of green and solar solutions, overcoming administrative and financial barriers.

Research Focus

This research topic aims to explore the integrated potential of renewable energy systems and urban green infrastructure to improve microclimates in semi-arid regions. By combining the cooling benefits of urban greenery with the energy-producing capabilities of solar energy, this collection seeks to foster resilient, sustainable cities that adapt to the challenges of climate change. These approaches not only mitigate the urban heat island (UHI) effect but also contribute to sustainable energy systems and enhanced environmental quality.

We invite original research, case studies, review articles, and modelling studies that address, but are not limited to, the following themes:

· Integration of renewable energy and green infrastructure in urban microclimate design
· Advanced simulation and performance modelling of hybrid green-solar systems
· Case studies and real-world applications in semi-arid urban settings
· Policy innovation and urban planning frameworks for climate-resilient cities
· Contributions to the UN Sustainable Development Goals (SDGs 7, 9, 11, 13)
· Interdisciplinary perspectives on natural and engineered climate solutions.
· Studies on participatory design, community acceptance, and the role of local stakeholders in the successful implementation and maintenance of integrated green-solar systems.

This research topic invites high-impact interdisciplinary research on how the strategic integration of urban green infrastructure and solar energy technologies can transform microclimates in semi-arid cities. These nature-based and technological solutions offer synergistic benefits that support long-term climate resilience and sustainable urban development. It addresses a gap in current literature by focusing on the synergistic and context-specific integration of urban green and solar solutions for microclimate transformation, particularly in the under-researched semi-arid urban environments. It aims to move beyond theoretical discussions to present actionable, evidence-based strategies for fostering climate-resilient and sustainable cities.

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Harnessing Urban Green and Solar for Microclimate Transformation in Semi-Arid Cities