TopModule Title: Integrated Urban Wind Environment Design
Following the latest released Intergovernmental Panel on Climate Change (IPCC) AR5 report, buildings and cities are urged to consume less energy and resources, provide comfort and quality living environment, and be sustainable and responsible for our future generations.
This module focuses on architectural and urban design principles to improve the urban wind environment. Urban wind environment is essential to address lots of urban environmental issues, such as urban heat island (UHI) and air quality. This module aims to provide students with theoretical knowledge and hands-on skills on performance and evidence-based planning and design strategies.
This module introduces the multi-scales principles of urban wind environment design, so as to provide comfort and quality living environment and minimize the need for natural resources. After reviewing the effects of wind environment on urban heat island, anthropogenic heat dispersion, thermal comfort, and air quality, students know why we need to do the wind analysis in the urban planning and design practice.
Simulation knowledges and tools are introduced for planning and design practices from the urban scale to building scale. The simulation part in this module enables and encourages students to apply the wind principles into the real design problems, i.e. the identification of important wind criteria, spatial scales, and issues in the particular design process, and the expressions of the simulation results to compare the design options.
Learning outcomes are measurable, by report writing, design project, and simulation practice, respectively.
- Latest sciences and knowledge related to wind environment from the regional scale to the building scale.
- Integrated multi-scales simulation technologies and practical tools to be applied in the urban planning and architecture design:
- Basic knowledges of atmospheric wind envionrment analysis tools, such as Weather Research and Forecasting (WRF) (Regional scale);
- Principles and practices of urban permeability analysis and related GIS-based tools to be appliyed in the urban planning to identify the urban air paths (Urban scale);
- Principles and practices of computational Fluid Dynamics (CFD) simulation to be applied in the urban and building design to optimise design options (Neighborhood and building scale);
- Multi scale wind environment analysis and implementation.
Week 1. Introduction: Impact of high density urban planning and climate change on urban wind environment
Background informatation about urban development and climate change will be provided to illustrate why it is necessary to ingetrate urban wind information into the urban planning and design.
Week 4. Neighborhood scale wind environment
Physical mechanism of how urban buildings and street grids affecting urban air flow at the neighbourhood scale will be introduced.
Based on the understandings from Lectures 3 and 4, a neighborhood scale morphological modelling method will be introduced as a user-friendly modelling tool to urban designers and architects.
- IPCC Fifth assessment report (AR5), 2016.
Week 2. Reginoal and urban scale wind environment
The concept of spatial scale will be introduced, which is critical to the climate modelling and analysis. The regional scale wind information and the corresponding modelling method, such as MM5 and WRF, will be introduced first in this lecture. Regarding the urban scale wind environment, the impact of urban air flow on thermal comfort and air quality will be clarified. Physical mechanism of how urban buildings, as roughness elements, affecting air flow at urban areas will be introduced. Modelling methods, such as CFD and wind tunnel, and corresponding urban planning implementation at this scale will also be introduced.
- Li, X-X, Koh, T.Y., Panda, J., Norford, L.K., 2016. Impact of urbanization patterns on the local climate of a tropical city Singapore: an ensemble study. Journal of Geophysical Research - Atmospheres, 121(9): 4386–4403.
- Li, X-X, Koh, T.Y., Entekhabi, D., Roth, M., Panda, J., Norford, L.K., 2013. A multi-resolution ensemble study of a tropical urban environment and its interactions with the background regional atmosphere. Journal of Geophysical Research - Atmospheres, 118: 9804–9818.
- Grimmond, Oke, 1999, Aerodynamic properties of urban areas derived from analysis of surface form, Journal of Applied Meteorology 38 pp. 1262- 1292.
- Givoni, B. 1998, Climate Consideration in Building and Urban Design, John Wiley & Sons
Week 3. Morpholgoical modelling and implementation
Based on the understandings frome Lecture 3, an urban scale morphological modelling method will be introduced as a user-friendly modelling tool to students to identify the urban areas with natural ventilation issues and develop the mitigation strategies.
The existing urban planning guidelines for urban wind environment will be introduced.
- Ng, E., Yuan, C., Chen, L., Ren, C., Fung, J.C.H., 2011, Improving the wind environment in high-density cities by understanding urban morphology and surface roughness: A study in Hong Kong, Landscape and Urban Planning. 101 (1), pp. 59-74.
- Yuan, C., Ren, C., and Ng, E., 2014, GIS-based surface roughness evaluation in the urban planning system to improve the wind environment -- A study in Wuhan, China, Urban Climate. 10, pp. 585–593.
- Yuan, C., Ng, E., Norford, L.K., Britter, R., Ng, E., 2016, A Modelling-Mapping Approach for Fine-Scale Assessment of Pedestrian-level Wind in High-Density Cities, Building and Environment. 97, pp. 152-165.
Assignment/Project I (4 weeks): urban wind environment analysis, and implementation)
Based on the understandings from Lectures 1 – 4, students will be required to conduct an analysis for the district-level (5 x 5 km) wind environment, identify natural ventilation issues, and establish corresponding planning strategies.
Week 5. CFD Simulation
CFD simulation will be introduced in this lecture for neighorhood-scale wind modelling. Basic principles of CFD simulation settings and corresponding physical understandings will be introduced to enable students to run an appropriate simulation.
Week 6. Building Scale wind environment
The effects of building typologies on surrounding air flow at the building scale will be introduced. A systematic method of air ventilation assessment (AVA), including how to run the simulation, identify wind issues, and develop mitigation strategies, will be introduced, so that students will be capable to evaluate and optimize their design projects.
- Tominaga, Y., Mochida, A., Yoshie, R., Kataoka, H., Nozu, T., Yoshikawa, M., Shirasawa, T., AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings. Journal of Wind Engineering and Industrial Aerodynamics, Volume 96, Issues 10-11, October-November 2008, 1749-1761.
- Givoni, B. 1998, Climate Consideration in Building and Urban Design, John Wiley & Sons.
- Yuan, C., Ng, E., 2012, Building porosity for better urban ventilation in high-density cities - A computational parametric study, Building and Environment. 50, pp.176-189.
Week 7. Anthropogenic heat dispersion
This lecture will extend the understandings of urban air flow to anthropogenic heat dispersion, which significantly depends on urban aerodynamic properties. The corresponding planning and design strategies will be introducfed to mitigate Urban Heat Island at urban areas.
Week 8. Air pollutant dispersion
This lecture will extend the understandings of urban air flow to air pollutant dispersion, which significantly depends on urban aerodynamic properties. The corresponding planning and design strategies will be introducfed for better air quliaty at urban areas.
- Yuan, C., Ng, E., Norford, L.K., 2014, Improving air quality in high-density cities by understanding the relationship between air pollutant dispersion and urban morphologies, Building and Environment. 71, pp. 245-258
Assignment/Project II (4 weeks): Air ventilation assessment on design studio project
Based on the understandings from Lecture 5 - 8, students will be required to conduct an AVA for their research projects in the design studio. Alternatively, student may select to conduct an independent study report approved by principle lecturer.
Week 9. Urban tree and natural ventilation performance
The concept of drag force of urban trees on air flow and the modelling methods, such as CFD simulation and wind tunnel experiment, will be introduced to students.
A semi-emprical model will be introduced to students, so that students will be capable to estimate the impact of urban trees on natural ventilation to make the evidence-based decision in the landscape design, such as green coverage ratio and tree species.
Week 10. Conclusion- Multi scale urban wind environment modelling and implementation.
As the conclusion, the physical understandings, modelling methods, and the implementation from urban scale, neighbourhood scale, to building scale will be summarized for more systematic understandings. Students are expected to be capable to do the comprehensive multi-scales wind analysis, and apply analysis results into planning and design.