Amidst the urban energy transition towards clean and renewable energy, distributed photovoltaic (PV) systems are emerging as critical infrastructure. However, the evolution of PV rack and mount systems has lagged, particularly in addressing cost efficiency and fire safety This study focuses on the high-temperature mechanical properties of basalt fibers (BFs), a key component of basalt fiber-reinforced polymer (BFRP), to establish a foundational understanding for future BFRP applications. The experimental results demonstrate that basalt fibers retain approximately 150 MPa residual tensile strength at 600 °C (30–40% of room temperature strength of Q235B steel) and 94 MPa at 800 °C, outperforming steel under similar conditions. Furthermore, the decomposition of wetting agents and Fe²⁺ oxidation at 600 °C was observed to stabilize after 100 min, maintaining structural integrity. These findings validate the high-temperature performance of BF, paving the way for subsequent studies at the BFRP composite level, which will address structural optimization and fire-resistance strategies for PV rack and mount systems. This research provides a critical step toward improving the safety and sustainability of urban PV systems.

Free-form grid structures offer both aesthetic appeal and structural efficiency in long-span roof design and application, yet the potential of morphological design to optimize thermal performance has been long overlooked. This study proposes a multi-objective synergistic optimization framework which can improve the thermal environment and mechanical performance simultaneously for the roof. Focusing on public buildings in hot–humid climates, the research investigates the impact of roof geometry on indoor temperature under extreme thermal loading conditions and long-term thermal loading conditions. Furthermore, the evolution of thermal performance during mechanical performance-driven surface optimization is systematically analyzed. Subsequently, a dynamic proportional adjustment factor is introduced to explore the performance of the optimized results under different performance weights, with thermal and mechanical performance serving as the optimization objectives. Results demonstrate that thermal performance-driven optimization generates saddle-shaped free-form surfaces with alternating peak–valley configurations to achieve self-shadowing effects, reducing indoor temperature by approximately 2 °C but significantly compromising structural stiffness. Conversely, strain energy minimization yields moderate indoor temperature reductions, revealing a positive correlation between strain energy decrease and thermal performance improvement. In the multi-objective optimization considering thermal and mechanical properties, when the strain energy ratio is 0.5–0.7 (optimization balance zone), the indoor temperature decreases, while the structural stiffness and stability bearing capacity increase. This study provides a morphological–structural–environmental synergistic design reference for low-carbon long-span building roofs.

This study proposes a cross-disciplinary computational framework to advance the sustainable design of free-form grid roofs in hot climates, integrating architectural geometry with building thermal performance to enhance climate adaptability. Numerical analyses systematically explore the impact of thermal objectives, initial configurations, shape control strategies, and boundary constraints. The optimization results demonstrate that targeting indoor temperature under extreme heat yields saddle-shaped, self-shading morphologies, which achieve a measurable improvement in thermal comfort by reducing indoor temperatures by approximately 2 °C. A key practical finding is that symmetric-point control outperforms full-point control. While full-point control may generate forms with complex central depressions that complicate drainage, symmetric-point control consistently yields morphologies that are inherently more regular, symmetric, and constructible. This results in a superior balance among thermal performance, practical design attributes (e.g., drainage feasibility and construction simplicity), and geometric coherence—a combination that aligns closely with real-world engineering requirements. Furthermore, directional boundary constraints are proven to be effective tools for regulating passive shading performance. The proposed framework provides engineers and designers with a systematic and automated method for the climate-responsive and low-carbon design of free-form architectural morphologies, contributing to the development of more sustainable and resilient building infrastructure.