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PolyU study reveals effectiveness of GBGI infrastructure in mitigating urban heat, proposing nine-stage framework for development of a sustainable city

Primarily due to the impact of urbanisation and global warming, urban heatwaves have become a challenging issue worldwide, with Hong Kong persistently experiencing record-breaking high-temperature days. Mitigating urban heat through green and blue infrastructures is essential for creating a sustainable environment. Prof. Hai GUO, Professor of the Department of Civil and Environmental Engineering at The Hong Kong Polytechnic University (PolyU) and global researchers have conducted a first-of-its-kind study on the effectiveness of green interventions in cooling urban heat across various regions that can assist policymakers in prioritising effective interventions to develop sustainable cities. The study findings have been published in the international interdisciplinary journal The Innovation. Globally, the most efficient air cooling was observed in botanical gardens, wetlands, green walls, street trees and vegetated balconies. In light of this, the research team conducted a global review of the effectiveness of green-blue-grey infrastructure (GBGI) in air cooling. GBGI refers to green infrastructures that encompass naturally vegetation-based elements like trees, grass and hedges; blue infrastructures are related to water-based features like pools, lakes and rivers; and grey infrastructures comprise engineered structures including green walls, green facades and roofs. The Study revealed regional and city-specific variations in the effectiveness of GBGI for mitigating urban heat. In Europe, Asia, North America and Australia, the overall cooling effect of GBGI is up to 18.9°C, 17.7°C, 12°C and 9.63°C respectively. In addition, the implementation of green and blue infrastructures has proven to be highly effective in lowering air temperatures globally. While green infrastructures can regulate urban heat through evaporation, transpiration, shading and thermal insulation, blue infrastructures absorb heat and cool the surrounding area through evaporation. In Asian cities, constructed grey infrastructures, especially roof gardens and pergolas, are found to be the most effective for urban cooling. Roof gardens in Singapore achieved the most significant temperature reduction of 17.7°C. Pergolas and green roofs in Japan and South Korea also had substantial impact, resulting in cooling temperatures by 16.2°C and 10.8°C, respectively. Linearly planted hedges and street trees contributed to lowering temperatures by up to 10.8°C. Authorities are advised to plant more street trees, not only for their impressive cooling efficiency but also for their substantial potential to create other positive environmental impacts. The Study also showed notable effects of various GBGI features in mitigating urban heat in Mainland China cities. The most effective means include botanical gardens, wetlands, green walls and attenuation ponds which exhibited temperature reductions of up to 10°C, 9.27°C, 8°C and 7°C respectively. Although the cooling effect ranges are generally similar in the north and south of China, there is variability within the same region. For example, in Beijing, botanical garden could result in up to 10°C temperature decrease while that in Shaanxi province only contributed to 2.7°C. In Hong Kong, parks, green roofs and golf courses were found to play substantial roles in cooling urban heat, resulting in temperature reductions of 4.9°C, 4.9°C and 4.2°C respectively. A “Shining City Project” was proposed by the Hong Kong government in last year’s Policy Address to enhance urban green space. This initiative includes the greening of riverbanks to turn them into flower viewing points and the extensive planting of trees in government venues and at roundabouts on major roads. Prof. Guo said, “With their distinctive location and natural environment, the types of GBGI in Hong Kong are unique. The city features a network of oceans, rivers, wetlands and reservoirs, with remarkable vegetation cover, encompassing approximately 70% of its land area of which country parks occupy around 40%, and possesses a precious natural asset in the Victoria Harbour. Meanwhile, the Government actively promotes GBGI in new development areas and the adoption of green building design in new government projects. These forward-looking initiatives highlight Hong Kong’s dedication to sustainable and resilient urban development.” Globally, the types of GBGI vary significantly across continents due to diverse regional contexts, climate conditions and urban planning priorities. The Study’s GBGI heat mitigation inventory can assist policymakers and urban planners in prioritising effective interventions to reduce the risk of urban overheating and promote community resilience. At this point, the research team has introduced a nine-stage framework to facilitate the implementation of GBGI that outlines stages of stakeholder engagement, feasibility studies, design, policy development, implementation, monitoring, evaluation, and eventual upscaling and replication. Prof. Guo emphasised, “This framework serves as a strategic roadmap, optimising GBGI implementation to maximise benefits. Policymakers should conduct thorough investigation and planning tailored to the specific context and needs of their cities. In Asia, the extensive development of GBGI is a response to challenges posed by rapid urbanisation and cultural preferences that prioritise green areas for community activities, together with environmental goals focused on biodiversity conservation, improved air quality and mitigation of the urban heat island effect. It is crucial for future GBGI implementation to adopt a holistic approach, optimising their multifunctional benefits to effectively address sustainability goals.”

Media Interview: Prof. Wu Bo shares on PolyU’s deep space research

Prof. WU Bo, Fiona Cheung Professor in Spatial Science, Associate Head (Research) of the Department of Land Surveying and Geo-Informatics, and Associate Director of Research Centre for Deep Space Explorations of PolyU shared the University’s deep space exploration research and Hong Kong’s atmosphere of scientific research in a recent interview.  Prof. WU has dedicated himself to photogrammetry, planetary mapping and planetary science research for many years. Regarding the Nation’s  lunar exploration missions, including Chang'e-3, Chang'e-4, Chang'e-5 and Chang'e-6, as well as the Mars exploration project, Prof. WU and his team made use of advanced topographic mapping technologies to evaluate and identify the best landing sites for spacecraft. In addition, PolyU launched the Space Resources Laboratory to properly store and analyse lunar soil, and to conduct biological and material science research. 《Nanfang Daily》Full Interview :  https://polyu.me/3QGEJf7 For more︰https://polyu.hk/qIxgV  

Visit by Delegation of Member of the Standing Committee of the Fujian Provincial People's Congress

A delegation led by Mr LI Jianhui, Member of the Standing Committee of the Fujian Provincial People's Congress and Mr Wang Mingyuan, Mayor of Jinjiang Municipal People’s Government, visited the Hong Kong Polytechnic University (PolyU) on 6 May to exchange views on strengthening cooperation in technology and innovation between Fujian and Hong Kong. The delegation was warmly welcomed by Dr LAM Tai-fai, Council Chairman of PolyU; Prof. Jin-Guang TENG, President of PolyU; Prof. Wing-tak WONG, Deputy President and Provost of PolyU; Prof. Christopher CHAO, Vice President (Research and Innovation) of PolyU, and other representatives from PolyU. Dr LAM stated that as a world-class research-oriented university, PolyU maintains its dedication to focusing on technological innovation and nurturing scientific research talent. He expressed his hope to strengthen collaboration with Quanzhou City, aiming to introduce more globally-renowned technological achievements to be implemented and transformed in the region. This initiative will significantly enhance industrial development and provide innovative drive for the economic and social development of Quanzhou City. Mr LI stated that the PolyU-Jinjiang Technology and Innovation Research Institute (Research Institute) is an important initiative in Fujian Province. The Government is committed to supporting and facilitating the transformation and implementation of the research outcomes. Since the establishment of the Research Institute, both parties have demonstrated strong commitment and exceptional efficiency. Moving forward, PolyU hopes to cooperate with Quanzhou City to jointly establish a comprehensive ecosystem involving with the government, industry, academia, and research institutions, aligning with the major strategic development of Quanzhou City, Fujian Province, and even the nation as a whole.  

PolyU researchers create 2D all-organic perovskites and demonstrate potential use in 2D electronics

Perovskites are among the most researched topics in materials science. Recently, a research team led by Prof. LOH Kian Ping, Chair Professor of Materials Physics and Chemistry and Global STEM Professor of the Department of Applied Physics of The Hong Kong Polytechnic University (PolyU), Dr Kathy LENG, Assistant Professor of the same department, together with Dr Hwa Seob CHOI, Postdoctoral Research Fellow and the first author of the research paper, has solved an age-old challenge to synthesise all-organic two-dimensional perovskites, extending the field into the exciting realm of 2D materials. This breakthrough opens up a new field of 2D all-organic perovskites, which holds promise for both fundamental science and potential applications. This research titled “Molecularly thin, two-dimensional all-organic perovskites” was recently published in the prestigious journal Science. Perovskites are named after their structural resemblance to the mineral calcium titanate perovskite, and are well known for their fascinating properties that can be applied in wide-ranging fields such as solar cells, lighting and catalysis. With a fundamental chemical formula of ABX3, perovskites possess the ability to be finely tuned by adjusting the A and B cations as well as the X anion, paving the way for the development of high-performance materials. While perovskite was first discovered as an inorganic compound, Prof. Loh’s team has focused their attention on the emerging class of all-organic perovskites. In this new family, A, B, and X constituents are organic molecules rather than individual atoms like metals or oxygen. The design principles for creating three-dimensional (3D) perovskites using organic components have only recently been established. Significantly, all-organic perovskites offer distinct advantages over their all-inorganic counterparts, as they are solution-processible and flexible, enabling cost-effective fabrication. Moreover, by manipulating the chemical composition of the crystal, valuable electromagnetic properties such as dielectric properties, which finds applications in electronics and capacitors, can be precisely engineered. Traditionally, researchers face challenges in the synthesis of all-organic 3D perovskites due to the restricted selection of organic molecules that can fit with the crystal structure. Recognising this limitation, Prof. Loh and his team proposed an innovative approach: synthesising all-organic perovskites in the form of 2D layers instead of 3D crystals. This strategy aimed to overcome the constraints imposed by bulky molecules and facilitate the incorporation of a broader range of organic ions. The anticipated outcome was the emergence of novel and extraordinary properties in these materials. Validating their prediction, the team developed a new general class of layered organic perovskites. Following the convention for naming perovskites, they called it the “Choi-Loh-v phase” (CL-v) after Dr Choi and Prof. Loh. These perovskites comprise molecularly thin layers held together by forces that hold graphite layers together, the so-called van der Waals forces – hence the “v” in CL-v. Compared with the previously studied hybrid 2D perovskites, the CL-v phase is stabilised by the addition of another B cation into the unit cell and has the general formula A2B2X4. Using solution-phase chemistry, the research team prepared a CL-v material known as CMD-N-P2, in which the A, B and X sites are occupied by CMD (a chlorinated cyclic organic molecule), ammonium and PF6− ions, respectively. The expected crystal structure was confirmed by high-resolution electron microscopy carried out at cryogenic temperature. These molecularly thin 2D organic perovskites are fundamentally different from traditional 3D minerals, they are single crystalline in two dimensions and can be exfoliated as hexagonal flakes just a few nanometres thick – 20,000 times thinner than a human hair. The solution-processibility of 2D organic perovskites presents exciting opportunities for their application in 2D electronics. The Poly U team conducted measurements on the dielectric constants of the CL-v phase, yielding values ranging from 4.8 to 5.5. These values surpass those of commonly used materials such as silicon dioxide and hexagonal boron nitride. This discovery establishes a promising avenue for incorporating CL-v phase as a dielectric layer in 2D electronic devices, as these devices often necessitate 2D dielectric layers with high dielectric constants, which are typically scarce. Team member Dr Leng successfully addressed the challenge of integrating 2D organic perovskites with 2D electronics. In their approach, the CL-v phase was employed as the top gate dielectric layer, while the channel material consisted of atomically thin Molybdenum Sulfide. By utilising the CL-v phase, the transistor achieved superior control over the current flow between the source and drain terminals, surpassing the capabilities of conventional silicon oxide dielectric layers. Prof. Loh’s research not only establishes an entirely new class of all-organic perovskites but also demonstrates how they can be solution-processed in conjunction with advanced fabrication technique to enhance the performance of 2D electronic devices. These developments open up new possibilities for the creation of more efficient and versatile electronic systems.

PolyU research advocates for privacy protection for Central Bank Digital Currency Development

Privacy protection is pivotal in the development of Central Bank Digital Currency (CBDC). Computing scientists at The Hong Kong Polytechnic University (PolyU) are conducting research to investigate the applications of privacy-enhancing technologies (PETs) to ensure the confidentially and integrity of CBDC transactions.  Prof. Allen Man Ho AU, Professor of the Department of Computing of PolyU, is undertaking research for a white paper by the CBDC Expert Group on privacy protection in CBDC development to enhance confidence among the public and industry. “It is crucial to have CBDC with PET included by design, and we should be transparent for the system design for public inspection,” said Prof. AU.  The research primarily investigates technologies such as pseudonyms, zero-knowledge proofs, ring signatures, and secure multiparty computation. Each of these technologies offers distinct advantages in safeguarding transactional privacy. For instance, zero-knowledge proofs enable transaction verification without disclosing any transactional or personal details, thereby maintaining transactional unlinkability and user anonymity.  Zero-knowledge proofs, also known zero-knowledge cryptography, allows a “prover” to convince a person of the validity of a computation without leaking any information; it is hence referred to as zero-knowledge cryptography. It is seen as a breakthrough technology impacting Web3, a decentralised online ecosystem based on blockchain, because it enables data privacy protection, efficiency improvement and scalability of transparent systems such as blockchain.  Prof. AU, said, “To enhance public and industry confidence in the privacy of CBDCs, we advocate for a comprehensive strategy. First, it is crucial to integrate advanced PETs such as zero-knowledge proofs and secure multiparty computation. These technologies enable transactions while safeguarding user identities and details.”  The research also delves into the challenges of integrating these technologies into CBDC systems, considering different architectural designs—whether public or permissioned blockchains—and whether they employ a UTXO (unspent transaction outputs) or an account-based data model. The analysis addresses critical factors such as scalability, risk, auditability, and, importantly, regulatory compliance. By publishing white papers and actively engaging in public dialogue, the promotion of transparency can help to demystify CBDC technologies and effectively address any concerns within the community. Prof. AU added, “Regular audits and compliance checks conducted by third parties will further validate the integrity of privacy protections.” CBDC is expected to undergo significant advancement in the next five years. More countries will launch pilot programmes to text various use cases, encompassing both retail to wholesale applications. This will include a combination of advanced economies and emerging markets, each delving into CBDCs customised to suit their specific economic and social needs.  In order to sustain its leading position in the CBDC field, Prof. AU said “Hong Kong should continue investing in research and development while promoting innovation through collaborations among the government, industry and academia. The focus is on pioneering new CBDC technologies and use cases that can serve as benchmarks globally.”  Recently, HKMA has commenced Project Ensemble, a new wholesale CBDC project to support the development of the tokenization market in Hong Kong. Since the establishment of the CBDC Expert Group,  PolyU researchers and Prof. AU along with other members have been closely collaborating with HKMA to examine various aspects of CBDCs and related digital currencies. 

Visit by China University of Petroleum

A delegation from the China University of Petroleum, Beijing, visited PolyU for an exchange meeting and laboratories visit on 30 April. Prof. DONG Cheng, Associate Vice President (Mainland Research Advancement) of PolyU, welcomed the delegation and provided an overview of PolyU's latest research developments. During the meeting, PolyU and the delegation  explored opportunities for joint research projects, co-authoring academic publications, and organizing international conferences. At the same time, both parties also shared possible teacher-student exchange activities, such as scholars’ interview, summer programmes and joint student mentoring. The delegation also toured Rock Mechanics Laboratory, Smart Geotechnology Laboratory and Space Resources Laboratory. During the field visits, the guests gained a deeper understanding of PolyU's construction and environmental excellence and scientific development.  

Media interview: PolyU research helps enhance children’s safety awareness in online world

A study led by Dr Jessica LI Chi-mei, Associate Professor of the Department of Applied Social Sciences of PolyU has found that the increase in the usage of electronic devices fuels the opportunity of online child sexual abuse.  Dr. Li and her research team have incorporated the principles of reality therapy to develop 16 sets of educational materials. These resources are designed to assist teachers and social workers in promoting children's awareness of online safety. Full interview:  https://polyu.me/4a1AO2Z https://polyu.me/3UAQfe0 https://polyu.me/4bwwaLV  

PolyU nurtures young researchers under the RGC Postdoctoral Fellowship Scheme

The Hong Kong Polytechnic University is dedicated to nurture young researchers, with seven awardees selected by the RGC Postdoctoral Fellowship Scheme (PDFS) in 2024/25.  The seven awardees will engage in projects covering a diversified fields including linguistics, electronic engineering, building and real estate, rehabilitation sciences, aviation engineering, applied biology and chemical technology and biomedical engineering. This demonstrates PolyU’s research excellence in multidisciplinary fields and the development of young scholars.  These PDFS awardees are subject to final confirmation of their selection. The RGC PDFS aims to encourage doctoral graduates in pursuing career in research and provide promising researchers with support at a pivotal time in their very early career, so as to ensure a supply of talent with scientific and research skills for research and development in Hong Kong. The PDFS provides support to 50 awardees for a period of 36 months in terms of full-time appointment as a postdoctoral fellow at a UGC-funded university in each round of the yearly exercise.  

PolyU collaborates with Shanghai Westwell Technology to establish joint innovation laboratory

The Shanghai Municipal People’s Government held the “Invest in Shanghai • Share the Future” promotion campaign in Hong Kong on 26 April. Witnessed by Mr GONG Zheng, Mayor of Shanghai and Mr John LEE Ka-chiu, Chief Executive of the Hong Kong Special Administrative Region, The Hong Kong Polytechnic University (PolyU) and Shanghai Westwell Technology Co. Ltd (Shanghai Westwell Technology) signed an agreement for research collaboration in artificial intelligence and autonomous vehicle technology. The two parties will together build a joint innovation laboratory to explore the frontiers and application practices in these fields. At the event, 18 enterprises and institutions from Hong Kong and Shanghai signed eight key cooperation agreements, involving cooperation in fields such as financial services, energy investment, and industry-academia-research collaboration, including the establishment of the PolyU and Shanghai Westwell Technology joint innovation laboratory. Leveraging the joint laboratory platform, the collaboration between the two parties will promote the sharing and integration of resources. It will also foster technological breakthroughs and industrial applications in areas of common focus such as advanced navigation and positioning systems, spatial perception technologies, new auxiliary technologies and unmanned driving control technologies. The partnership will also deepen research cooperation between industry and academia, fostering the cultivation of high-quality scientific research and engineering talents. Prof. Christopher CHAO, Vice President (Research and Innovation) of PolyU, said “Deep integration of industry, academia and research has become key to technological innovation and development. Therefore, the collaboration between PolyU and Shanghai Westwell Technology carries great significance. The two parties will fully leverage their respective advantages at the forefront of artificial intelligence and move forward in collaborative innovation, talent cultivation and other areas, providing new impetus for the development of artificial intelligence technologies.” Mr TAN Limin, Founder and Chairman of Shanghai Westwell Technology, said, “As a technology company deeply engaged in the application of artificial intelligence, Shanghai Westwell Technology is honoured to collaborate with The Hong Kong Polytechnic University. We look forward to climbing the peaks of sci-tech innovation together with PolyU and applying artificial intelligence technologies to enhance human well-being and build a better world.” Looking ahead, PolyU will join hands with Shanghai Westwell Technology to build an innovative alliance with deep integration of industry, academia and research. They will promote close cooperation and exchanges in artificial intelligence and autonomous driving to propel research breakthroughs and knowledge transfer, accelerating the development of new quality productive forces.

Visit by delegation from Hetao Development Authority

A delegation led by Ms LI Huilai, Deputy Director of Hetao Development Authority visited PolyU on 24 April and they toured  three laboratories:  State Key Laboratory of Chemical Biology and Drug Discovery, Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch), and Smart Cities Research Institute.  Prof. Jin-Guang TENG, President of PolyU; Prof. Kwok-yin WONG, Vice President (Education) of PolyU; Prof. CHOW Ming-cheung, Larry, Head of Department of Applied Biology and Chemical Technology; Ir Prof. Michael C.H. YAM, Head of Department of Building and Real Estate; and Prof. John W.Z. SHI, Director of Smart Cities Research Institute and Chair Professor held a meeting with the delegation. Their discussion mainly focused on the future development and collaboration opportunities in the promising Hetao Area. PolyU remains committed to fostering collaboration with industry counterparts and governmental entities to promote knowledge transfer, research excellence, and societal impact.