Higher education institutions (HEIs) primarily serve as centers of knowledge, capacity builders, and policy influencers and choose to voluntarily engage with the United Nations Sustainable Development Goals (UN-SDGs) as they are not mandated to implement them. In this paper, we examine the role of Saudi Arabian higher education institutions (HEIs) in sustainability efforts through their participation in the Times Higher Education Impact Rankings (THE IR) from 2019 to 2024. Also, the strategic alignment of HEIS with sustainability frameworks is assessed, emphasizing their contributions beyond ranking participation. Using the European University Association (EUA) and the UN-KSA Cooperation Framework (2022–2026), this study identifies both achievements and strategic gaps in HEIs’ contributions. Additionally, a comparative analysis with the Saudi Arabian Sustainable Development Report (SDR) of 2024 explores HEIs broader contributions. Hierarchical Cluster Analysis (HCA) is applied to classify HEIs based on SDG engagement, identifying leading, partnering, and supporting HEIs for potential collaboration. The findings reveal a significant increase in HEI participation, rising from 4% in 2019 to 49% in 2024. However, persistent gaps exist, particularly in SDGs 1–2 and 12–15 (addressed by fewer than 10% of HEIs) and SDGs 7, 9–11, and 16 (targeted by fewer than 25% of HEIs). This study highlights the need for a structured strategic alignment beyond rankings, positioning HEIs as enablers of sustainability driven education, research, and institutional governance.

In this paper, a compact design and new structure of bowtie antenna with dual-band characteristics for the 5G and public safety bands in intelligent transport systems (ITS) is presented. The antenna consists of a double-sided bowtie radiating patch with partial ground plane. A triangular complementary split-ring resonator (TCSRR) metamaterial (MTM) structure was etched on the radiating patch, to develop a dual band and a single notch band between 3.85 and 4.65 GHz. The proposed antenna had an overall size of 36 × 36 mm² and was fabricated using a FR4 substrate with a thickness and dielectric permittivity (ε_r) of 1.6 mm and 4.3, respectively. CST microwave studio software was used for the design of antenna. The measured frequency results show impedance bandwidths of 3.45–3.85 GHz and 4.65–5.4 GHz, for a voltage standing wave ratio (VSWR) less than 2. The proposed antenna operates at 3.5 GHz and 4.9 GHz, providing bandwidths of 400 MHz and 750 MHz, respectively, which cover the 5G and public safety bands. A prototype was fabricated and measured based upon optimal parameters, and the experimental results showed consistency with the simulation results. The proposed antenna provided a simulated/measured gain of 5.64 dBi/5 dBi and 4 dBi/3.7 dBi at 3.5 GHz and 4.9 GHz, respectively. The enhanced bandwidth and better gain results of the proposed antenna make it an ideal candidate for an ITS operating in the 5G and public safety bands.

This study presents an activity-based mathematical model to assess daily per capita and regional water consumption in Saudi Arabian households (8.17 million, as per the Saudi Census Statistics, 2022). The model compares two scenarios: (a) the current scenario with standard fixtures and (b) the proposed scenario with efficient fixtures. Water consumption is analyzed based on daily activities and house zones. Under the current scenario, showering is the highest water-consuming activity, using 209-551 liters (23–29%), while the bathroom is the highest water-consuming house zone, using 436-1151 liters (48–60%) with current scenario. Regional water consumption is assessed based on average household size, with Riyadh, Makkah, and the Eastern Province exhibiting the highest daily per capita water consumption of 328-330 liters. These three regions contribute a cumulative daily water demand of 6.763 million $${m}^{3}$$ m 3 , more than double the water demand of the remaining ten regions, which totals 3.171 million $${m}^{3}$$ m 3 . This variation highlights the limitations of nationwide assessments and emphasizes region-specific water management strategies to address water security challenges in Saudi Arabia. The study further analyzes water savings under the proposed efficient fixtures scenario, achieving a reduction of 83-93 liters per capita, resulting in a nationwide daily water saving of 2.806 million $${m}^{3}$$ m 3 . The mathematical model developed is flexible, enabling forecasts of water consumption based on hybrid scenarios combining standard and efficient fixtures. The findings have significant implications for the sustainable management of water resources, contributing directly to Clean Water and Sanitation (Sustainable Development Goal 6) by informing strategies for efficient water use and conservation in Saudi Arabia.

This paper presents Water-Efficient Aerators (WEAs) as a practical, scalable, and cost-effective solution for reducing freshwater consumption during ablution. These aerators, available globally (US, EU, Australia), feature low flow rates (1.0–1.5 GPM) and achieve high water efficiency (30–55%) at an affordable cost ($6–12 USD). Endorsed by the Environmental Protection Agency’s (EPA) WaterSense program, the proposed WEAs have undergone certified laboratory testing to ensure performance under varying pressure conditions and offer a retrofit-friendly, maintenance-free solution compatible with most standard faucets. Rather than relying on experimental trials, this study focuses on broad implementation using a mathematical model specifically developed for ablution, based on empirical benchmarks such as an average ablution duration of 1.04 min from prior field studies. To ensure credibility and practical relevance, the reliability of mathematical model is supported through scenario-based validation with prior experimental studies for water consumption using range of tap types and time utilized for ablution. The model assumes full compliance with daily prayer requirements to estimate maximum potential savings, while remaining adaptable to user-specific compliance levels and practices. Findings demonstrate that combining WEAs with water-saving behaviors particularly the practice of turning off the tap during ablution can substantially enhance conservation outcomes, reducing per-person water use from 2.29 to 0.54 gallons (8.66 to 2 L), enabling up to 76% reduction in freshwater consumption. This aligns closely with the sustainable water use practiced by Prophet Muhammad ( صلى الله عليه وسلم ), who performed ablution with approximately 775 ml (0.2 gallons), serving as an exemplary benchmark for efficient water use till to date. The proposed solution contributes to Sustainable Development Goals (6, 12, and 13), underlining the synergistic impact of both technological interventions and behavioral change in achieving water sustainability.

Saudi Arabia has launched a nationwide Smart Water Metering (SWM) initiative addressing the critical challenge of water scarcity directly supporting the water sustainability goals of Saudi Arabian Vision 2030. This study develops a mathematical model for estimation of water consumption along with associated carbon footprint nationwide, across regions and demographic (Saudi and non-Saudi household) segments. Also, it demonstrates that water savings and carbon emissions reduction potential depends on two interdependent parameters such as user adoption rate and water system efficiency. The results reveal that conservational gains are mainly concentrated in regions of Riyadh, Makkah, and the Eastern Province accounting for 56% of total for Saudi households and 72% for non-Saudi households. Consequently, uniform nationwide rollout is identified to be extremely inefficient. Sensitivity analysis of scaled adoption rate from 25% to 100% shows that nationwide monthly water savings triples from 5.71 to 22.85 million m ³ for Saudi households and from 2.19 to 8.76 million m ³ for non-Saudi households respectively with proportional tripled carbon emission reductions. Similarly, increasing system efficiency from 70% to 90% results in a 42% conservational potential for both segments, highlighting the importance of quality water infrastructure. Finally, the Strategic Impact Matrix (SIM) combines these findings and shows that only the synergistic combination of high adoption rate and high system efficiency unlocks full conservational potential yielding around 4.6 times the water savings of the worst-case scenario. Also, it is found that partial strategies achieve only 8-72% of the full conservational gains. Consequently, a prioritized phased rollout of SWM is recommended. Phase 1 should target Saudi households in three high-impact regions covering Riyadh, Makkah, and the Eastern Province to achieve rapid and scaled outcomes. Phase 2 should target non-Saudi households covering same three regions leveraging population density for additional scaled impact. The approach of this study provides a replicable framework for maximizing water security, financial viability, and climate resilience for other regional contexts. Also, this study directly contributes to United Nations Sustainable Development Goals (UN-SDGs) Targets of 6.4 and 13.2.

Introduction: This study presents the first comprehensive evaluation of the CO₂ mitigation potential of the Haramain High-Speed Railway (HHR) system in Saudi Arabia. Focusing on the 450 km Makkah–Madinah corridor, it addresses the pressing need to assess operational and energy-related factors influencing high-speed rail (HSR) decarbonization in fossil-dependent economies.Methods: A dynamic scenario-based mathematical modeling approach was applied, examining four operational parameters: train energy efficiency (0.03–0.07 kWh/pkm), grid emission factor (0.65–0.10 kgCO₂/kWh), renewable energy (RE) adoption (0–100%), and occupancy rates (25–100%). Real-world operational losses were incorporated through a 15% system efficiency adjustment. Multiple scenarios were simulated to capture nonlinear interactions between energy sourcing and passenger dynamics.Results: Three key findings emerged. First, in worst-case conditions (low occupancy and a fossil-heavy grid), the HHR system could result in a net increase of 187 kT of CO₂ annually compared to buses. Conversely, in best-case conditions (high occupancy and 100% renewable energy), it could achieve savings of 285 kT of CO₂ per year, which equates to a saving of 11.93 kg per passenger for the entire journey of 450 km. Second, occupancy rates exert an outsized influence on carbon performance. In multiple scenarios, ridership optimization yields greater emissions reductions than RE integration alone, particularly when grid decarbonization is partial. Third, the study identifies scenario-specific climate-positive thresholds: net CO₂ savings are achieved when occupancy exceeds 70–75% under the current grid mix, or 45–50% when RE adoption reaches 50%Discussion: These thresholds highlight the nonlinear interplay between energy sourcing and ridership dynamics, offering critical insights for Vision 2030 transport planning. By integrating operational variability and passenger behavior, the methodology provides a practical toolkit for aligning clean energy investments with ridership incentives and forecasting emissions under real-world conditions. Contributing to UN-SDGs 9, 11, and 13, the study establishes a foundational reference for future research on decarbonization thresholds in HSR systems, particularly in Middle Eastern and arid-region contexts.