Centre of Urban Sustainability

 

1. Data Platform of Urban Environmental Quality for Sustainable and Resilient Cities 

Climate change causes a wide range of environmental impacts which affects the living quality of humans. In urban areas, vast urbanization exacerbates such impacts and leads to increasing vulnerability. To adequately and accurately assess the impacts of climate change on cities, urban environmental quality is of utmost importance since it affects urban liveability and the well-being of urban inhabitants. A holistic assessment of urban environmental quality is therefore required to understand the impact of changing climate and urbanization on urban liveability.

 

This project aims to develop a data platform which incorporates urban morphological, meteorological, socio-economic and demographic data. Technical inputs will also be incorporated into the data platform for the assessment of urban environmental quality. The resultant platform can be applied at different spatial scales to suit the need of urban planning practices.

 

Principal Investigator(s):

Prof Edward NG, Dr Kevin Ka-Lun LAU

Project members:

Dr Yuan SHI, Mr Hongning LAN, Miss Yu Ting KWOK, Prof Chao REN

 

     Study1 DataPlatform 1

         The Study Scope

Study1 DataPlatform 2Study1 DataPlatform 3

Figure Caption: Field measurements of dynamic thermal comfort in Hong Kong and Genova, Italy 

 

             Study1 DataPlatform 4

Figure Caption: Numerical modelling of the thermal benefits of urban greenery in high-density settings

 

Selected Publications

Lau KKL, Shi Y, Ng EYY, 2019. Dynamic response of pedestrian thermal comfort under outdoor transient conditions. International Journal of Biometeorology, in press.

Lau KKL, Chung SC, Ren C, 2019. Outdoor thermal comfort in different urban settings of sub-tropical high-density cities: An approach of adopting local climate zone (LCZ) classification. Building and Environment 154: 227-238.

Tan Z, Chung SC, Roberts AC, Lau KKL, 2019. Design for climate resilience: influence of environmental conditions on thermal sensation in subtropical high-density cities. Architectural Science Review 62: 3-13.

Kwok YT, Schoetter R, Lau KKL, Hidalgo J, Ren C, Pigeon G, Masson V, 2019. How well does the Local Climate Zone scheme discern the thermal environment of Toulouse (France)? An analysis using numerical simulation data. International Journal of Climatology, in press.

Morakinyo TE, Lai A, Lau KKL, Ng E, 2019. Thermal benefits of vertical greening in a high-density city: Case study of Hong Kong. Urban Forestry & Urban Greening 37: 42-55.

Shi Y, Ren C, Lau KKL, Ng E, 2019. Investigating the influence of urban land use and landscape pattern on PM2. 5 spatial variation using mobile monitoring and WUDAPT. Landscape and Urban Planning 189: 15-26.

Lam CKC, Lau KKL, 2018. Effect of long-term acclimatization on summer thermal comfort in outdoor spaces: a comparative study between Melbourne and Hong Kong. International Journal of Biometeorology 62(7): 1311-1324

Morakinyo TE, Lau KKL, Ren C, Ng E, 2018. Performance of Hong Kong's common trees species for outdoor temperature regulation, thermal comfort and energy saving. Building and Environment 137: 157-170.

Lau KKL, Ng E, Ren C, Ho JCK, Wan L, Shi Y, Zheng Y, Gong F, Cheng V, Yuan C, Tan Z, Wong KS, 2017. Defining the environmental performance of neighbourhoods in high-density cities. Building Research & Information 46: 540-551.

Tan Z, Lau KKL, Ng E, 2017. Planning strategies for roadside tree planting and outdoor comfort enhancement in subtropical high-density urban areas. Building and Environment 120: 93-109.

Shi Y, Lau KKL, Ng E, 2017. Incorporating wind availability into land use regression modelling of air quality in mountainous high-density urban environment. Environmental Research 157: 17-29.

Morakinyo TE, Kong L, Lau KKL, Yuan C, Ng E, 2017. A study on the impact of shadow-cast and tree species on in-canyon and neighborhood's thermal comfort. Building and Environment 115: 1-17.

Kong L, Lau KKL, Yuan C, Chen Y, Xu Y, Ren C, Ng E, 2017. Regulation of outdoor thermal comfort by trees in Hong Kong. Sustainable Cities and Society 31: 12-25.

 

 


 

2. Healthy Cities – Impact of Built Environment on Urban Living 

Urbanization is one of the leading global trends of the 21st century, and has a significant impact on health and well-being, particularly in relation to noncommunicable diseases (NCDs).The factors influencing urban health include urban governance, population characteristics, the natural and built environment, social and economic development, services and health emergency management, and food security.

 

Cities are in prime position to support people living with NCDs, to co-create health with patients and communities, build health literacy and foster empowerment and, through adopting evidence-based interventions, build physical, socioeconomic and cultural environments that tackle NCD risk factors.

 

The objectives of this study are:

  • To obtain empirical understandings of how the built environment affects the health and well-being of residents, especially vulnerable groups of population;
  • To develop practical guidance and evaluation tools for healthy communities through neighbourhood and building design.

 

Project Coordinator:

Dr Kevin Ka-Lun LAU

Collaborators:

Prof Hendrik TIEBEN, Dr Faye CHAN, Mr Jiesheng LIN, Miss Cheryl YUNG, Miss Patricia CHAN

 

 

Selected Publications

Yu R, Cheung O, Leung J, Tong C, Lau K, Cheung J, Woo J, 2019. Is neighbourhood social cohesion associated with subjective well-being for older Chinese people? The neighbourhood social cohesion study. BMJ Open 9: e023332.

Yu R, Wang D, Leung J, Lau K, Kwok T, Woo J, 2018. Is Neighborhood Green Space Associated with Less Frailty? Evidence from the Mr. and Ms. Os (Hong Kong) Study. Journal of the American Medical Directors Association, in press.

Wang D, Lau KKL, Yu RHY, Wong SYS, Kwok TTY, Woo J, 2017. Neighboring green space and mortality of the Chinese elderly in Hong Kong: A retrospective cohort study. BMJ Open 7: e015794.

Yu R, Cheung O, Lau K, Woo J, 2017. Associations between perceived neighborhood walkability and walking time, wellbeing, and loneliness in community-dwelling older Chinese people in Hong Kong. International Journal of Environmental Research and Public Health 14(10), 1199.

Ho HC, Lau KKL, Yu R, Wang D, Woo J, Kwok TCY, Ng E, 2017. Spatial variability of geriatric depression risk in a high-density city: A data-driven socio-environmental vulnerability mapping approach. International Journal of Environmental Research and Public Health 14(9), 994.

Wang D, Lau KKL, Yu RHY, Wong SYS, Kwok TCY, Woo J, 2016. Neighbouring green space and all-cause mortality in elderly people in Hong Kong: a retrospective cohort study. The Lancet 388: S82.

 


 

3. Increasing the Resilience to the Health Impacts of Extreme Weather on Elderly People under Future Climate Change

 

Funded by Research Impact Fund, Research Grant Council, Hong Kong (Amount: HKD 9,836,000)

 

Extreme hot weather is expected to be more frequent and intense in Hong Kong under future climate change. The impacts will be exacerbated due to the presence of urban heat island (UHI) phenomenon in our high-density city. In particular, elderly people are more vulnerable to the impacts of extreme hot weather because of their decline in physiological functions and their behaviour and response. As such, plans for “mitigation” and “adaptation” actions are urgently needed.

 

Numerous studies have proved that excess mortality and morbidity are associated with extreme hot weather. It is important for different sectors of the society to take necessary actions. However, there are three issues to be addressed for successful responses, including lack of data at different spatial and temporal scales for understanding the extreme hot weather, lack of evidence-based mitigation and adaptation response plans.

 

The study team consists of twelve researchers from four local universities, with expertise ranging from global and regional climate modelling, urban-scale microclimatic studies, neighbourhood and building designs, public health, geriatric and gerontology, psychology.

 

The objectives of the present study are:

  • To downscale global climate data to urban scale for weather information services and health impact assessment;
  • To develop a mitigation action plan with better urban planning and building design under extreme weather
  • To develop an adaptation action plan for supporting services to increase the resilience of elderly people to extreme weather.

 

Project Coordinator:

Prof Edward NG

Co-Principal Investigators: 

Prof Gabriel LAU, Prof William GOGGINS, Prof Jean Woo, Prof Helene FUNG, Dr Kevin Ka-Lun LAU (CUHK); Prof Patsy CHAU, Prof Yuguo LI, Prof Chao REN (HKU); Prof Tin-tai CHOW, Prof Square FONG (CityU); Prof Jimmy FUNG (HKUST)

 

    Study3 Resilience 1

Study Framework

 

Selected Publications

Shi Y, Ren C, Cai M, Lau KKL, Lee TC, Wong WK, 2019. Assessing spatial variability of extreme hot weather conditions in Hong Kong: A land use regression approach. Environmental Research 171: 403-415.

Wang D, Lau KKL, Ren C, Goggins WB, Shi Y, Ho HC, Lee TC, Woo J, Ng E, 2019. The impact of extremely hot weather events on all-cause mortality in a highly urbanized and densely populated subtropical city: A 10-year time-series study (2006–2015). Science of the Total Environment 690: 923-931.

Morakinyo TE, Ren C, Shi Y, Lau KKL, Tong HW, Choy CW, Ng E, 2019. Estimates of the impact of extreme heat events on cooling energy demand in Hong Kong. Renewable Energy 142: 73-84.

Ho HC, Lau KKL, Ren C, Ng E, 2017. Characterizing prolonged heat effects on mortality in a sub-tropical high-density city, Hong Kong. International Journal of Biometeorology 61(11): 1935-1944

 


 

4. Study of Design Considerations for Government Infrastructures in Hong Kong under Extreme Temperatures

Funded by Architectural Services Department, Hong Kong Government (Amount: HKD 1,950,000)

 

According to Hong Kong Observatory’s climate projection, the warming trend will continue for the rest of the 21st century.  Even under the medium-low and medium-high greenhouse gas concentration scenarios, the number of very hot days will increase significantly, and the number of cold days will continue to drop.  It is therefore necessary for Hong Kong to strengthen resilience to the increasingly warm weather with increasing heat extremes and reduce the impacts on the population and physical structures.

 

The objectives of the study are to carry out research to study the effects of extreme temperatures and their potential impacts on major Government infrastructures in Hong Kong; and to advise on the possible measures / action plans for consideration by the Government to alleviate the impacts in respect of Government infrastructures design under extreme temperatures. The team approached the study using a scoping approach based on existing literature and data.  No study-specific experimentation, calculation or simulation had been conducted in this study.  The study team has hoped to provide a generic and scoping understanding of the Study using a three-stage approach: (a) review, (b) impact understanding, and (c) initial recommendation and further work required

 

This 8-month study includes the impact of extreme weather on EIGHT focus areas: (1) Energy use, comfort and building design; (2) Urban built environment; (3) Building materials; (4) Highway structures and the associated elements; (5) Road pavements; (6) Coastal structures and facilities; (7) Waterworks structures and facilities; and (8) Stormwater drainage, sewerage and associated facilities.

 Study4 GovernmentInfrastructures 1

Figure Cation: Impacts of Extreme Temperatures on Infrastructure

 


 

5. Designing better urban green spaces for active ageing in high-density cities

Funded by General Research Fund, Research Grant Council, Hong Kong (Amount: HKD 621,992)

 

Green and open space in urban area has gained attention in recent years, especially for its capacity to improve the well-being of ageing population in high-density cities. Including Hong Kong, Asian cities is expecting a rapid growing elderly population, and promoting healthy ageing will become a major challenge. The aim of this study is to understand elderly’s perception, usage of urban green space, and develop design practices and evidence-based design guidelines for urban planners and designers based on the findings. We investigate the elderly’s perception, usage of urban green space in their neighbourhood as well as their health by questionnaire survey and conduct statistical analysis to determine their interrelationship.

 

Site audit and questionnaire survey has been conducted in urban green space across districts in Hong Kong. Results show that elderly’s usage pattern varied across types of urban green space, which are different in size, landscape design and facilities offered. Certain perceived qualities of urban green space have also been identified to be linked with elderly’s usage intensity, which could help in promoting the use of these spaces. The next step is to put these findings into application. Urban planners and designers will be engaged for seminars and workshops, the collaboration will work in an effort to contribute to the existing design guidelines and industry practices.

 

Study5 GreenSpaces 1

 

 Figure Cation: Typical Urban Green Spaces commonoly used by elderly people in Hong Kong. 


 

6. The impacts of future urban development on the urban climate of Hong Kong: A numerical modelling approach

 Funded by PROCORE-RGC Research Grant, Research Grant Council, Hong Kong

 

Numerical models are powerful tools that enable the quantification of climate conditions over cities for future or hypothetical scenarios. Such information is crucial for environmental risk assessments, heat-health impact studies, strategical urban planning, and climate change mitigation. The objective of this study is two-fold: to improve the performance of fine-scale urban climate simulations for high-rise high-density cities using Hong Kong as a case study, and to examine the effects of different urban development scenarios on the city’s urban climate and provide practical recommendations for urban planning. 

 

Mesoscale atmospheric models are suited for simulating the meteorological conditions over the scales of cities to countries. Urban canopy models of different complexities are often coupled to represent the unique surface characteristics and geometrical features of urban areas, depending on the purpose of study, precision of surface input data, model compatibility, and available computational resources. In this study, a new multi-layer coupling approach between the mesoscale model MesoNH and urban canopy model TEB is developed. This allows the direct interaction between tall buildings and the atmosphere, notably the drag effects on air flow and thermal effects due to heat release at high levels. Furthermore, a detailed urban surface database, constructed based on real building data, land use maps, and the field mapping of representative building types, is employed to achieve the best-possible model performance. An initial evaluation of this enhanced model using measured data from the Hong Kong Observatory shows significant improvements in all important meteorological variables, such as air temperature and wind speed.

                   Study6 UrbanClimateHK 1

                            Figure Caption: Examples of urban canopy models with different levels of complexity.

                   Study6 UrbanClimateHK 2

 Figure Caption: Tall buildings in Hong Kong which interact with multiple levels of an atmospheric model (Source: SCMP).

 


 

7. 3D Building extraction Using Satellite Images

Figure 1(a) satellite derived

 We investigated the usage of high-resolution satellite data to conduct urban climate studies. The main objectives of this research is to: 1) Develop cutting-edge satellite technology and generate freely available high-quality urban morphology information from high-resolution satellite data; 2) Provide urban climatic maps for developing countries without actual urban

morphology information; 3) Using high-resolution satellite images to assess urban wind ventilation and urban thermal environment; 4) Provide data-based early warning of high-risk urban areas with adverse urban climate issues.

 

 The completed works include as the following:

 1. Urban morphology extraction (Figure 1)


A new satellite technology has been developed to extract 3D urban morphology by using World-view-2 stereo satellite images and Terra-SAR images. The benefit of the proposed approach is that the advantages of both stereo and SAR images are well combined, as SAR images are good at predicting the heights of tall buildings while stereo images can provide the complementary height information of buildings for which SAR is missing. Experimental results showed that the overall prediction accuracy is about 80-90%. (Details are provided in the references [1-2])

 

2. Validation of satellite-derived morphological parameters for urban climate studies (Figures 2)

 

  • A set of urban morphological parameters were calculated based on satellite-derived building morphology. Five most widely used urban morphological parameters—building coverage ratio (BCR), building volume density (BVD), frontal area index (FAI), sky view factor (SVF), and roughness length (RL) —were validated with high prediction accuracy.

  • Impacts of satellite-derived morphological parameters on urban air temperature and urban ventilation at pedestrian level were investigated, and empirical relationships between satellite-derived morphological parameters and urban climate (e.g., urban air temperature difference and wind dynamics) were built.
    In this study, the physically based simulation model parallelized large-eddy-simulation (LES), was used to test the impact of satellite-derived morphological parameters on pedestrian-level wind ventilation, while the WOLWEIG-model, developed by Göteborg Urban Climate Group, was used to test their impact on the mean radiant temperature.

3. Quantitative urban climate mapping using satellite data (Figure 3)

Based on the empirical relationships between satellite-derived morphological parameters and urban climatic environments, an urban climate map can be generated from the satellite-derived morphological parameters.

      (a) Figure 1(a) satellite derived    (b) Figure 1(b) 3D actual

Figure 1. The retrieved 3D building information from satellite data using our proposed approach. (a) Satellite-derived 3D model. (b) Actual 3D model for comparison.

 (a) Figure 2(a) vr satellite  (b) Figure 2(b) vr actual

Figure 2. Urban ventilation simulations at pedestrian level using (a) Satellite-derived model. (b) Actual 3D model.


 

(a) Figure 3(a) Ucmap actual  (b) Figure 3(b) Ucmap satellite


Figure 3. Urban climatic maps generated from (a) Actual GIS data. (b) Satellite data

 

References:
1. Xu, Y., Ma, P., Lin, H., & Ng, E., 2015. Fusion of World-view2 stereo and TerraSAR-X images for 3D building extraction in high-density urban areas. 9th International Conference on Urban Climate (ICUC 9), France, July 20-24, 2015.
2. Xu, Y., Ma, P., Ng, E., & Lin, H. 2015. Fusion of WorldView-2 Stereo and Multi-temporal TerraSAR-X Images for Building Height Extraction in Urban Areas. IEEE Geoscience and Remote Sensing Letters, 12(8), 1795-1799.