urban climatic map and standards for wind environment

Planning Department: Urban Climatic Map and Standards for Wind Environment – Feasibility Study INCEPTION REPORT

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Urban Climatic Map and Standards for

Wind Environment - Feasibility Study

Inception Report:

October 2006

C U H K


Department of Architecture, CUHK Page 1 of 44

CONTENTS 1 BACKGROUND OF THE STUDY 2 2 UNDERSTANDING THE OBJECTIVES OF THE STUDY 3 2.1 Understanding the Objectives 3 2.2 Identification of Key Issues 4 2.3 Appreciation of Project Constraints and Special Requirements 5 3 METHODOLOGY AND WORK PROGRAMME 5 3.1 Detail Task Analysis 5 3.1.1 Task 1A and 1B UC Map and PF Map 6 3.1.2 Task 2 Benchmarking Studies 18 3.1.3 Task 3 Wind Performance Criteria and Standard 24 3.1.4 Task 4 Refinement of AVA 26 3.2 Technical Inputs 29 3.2.1 Site Wind Availability 30 3.2.2 Field Measurement and Validation 32 3.2.3 User’s Wind Comfort Level Survey 33 3.3 Stakeholders’ Engagement 36 3.4 Study Programme 39 4 STAFFING 40 4.1 Organization Chart 40 4.2 Name List of Key Consultancy Staff 41 4.3 Contacts of Investigators 42 APPENDICE Appendix 1 Full Names of the Abbreviations 43 Appendix 2 Summary of Tasks 44



1 BACKGROUND OF THE STUDY

This report shows the background, objectives, methodology, contents and staffing of the study. This gives readers an understanding to the study. After the outbreak of the Severe Acute Respiratory Syndrome (SARS) in 2003, the Chief Executive tasked the Chief Secretary for Administration to set up Team Clean in early May 2003 to

develop and take forward proposals for improving environmental hygiene in Hong Kong. The final report of Team Clean, “Measures to Improve Environmental Hygiene in Hong Kong”, was released on 9 August 2003. The report pointed out that the Government was examining the practicality of stipulating air ventilation assessment as one of the considerations for all major development or redevelopment proposals and in future planning to promote better layout of building blocks in the city.

Furthermore, in the “First Sustainable Development Strategy for Hong Kong” promulgated by the Office of the Chief Secretary for administration in May 2005, a strategic objective to promote sustainable urban planning and design practices has been set out amongst other objectives with special regard to issues such as buildings affecting view corridor or restricting air flow. The above specific initiatives directly set out the background of this Study. In order to improve the urban environment of Hong Kong, the need for establishment of

an urban climatic map and standards for wind environment for Hong Kong was one of the recommendations of the “Feasibility Study for Establishment of Air Ventilation Assessment System” (AVAS Study) completed in 2005. Findings of the AVAS Study and the recommendation of carrying out this Study (i.e. “Urban Climatic Map and Standards for Wind Environment - Feasibility Study”) were endorsed by CPLD at its meeting on 7 June 2005.



2 UNDERSTANDING THE OBJECTIVES OF THE STUDY 2.1 Understanding the Objectives The project, commissioned to researchers at CUHK, was completed in July 2005. The “Feasibility study for Establishment of Air Ventilation Assessment System” recommended a staged approach to launch the Air Ventilation Assessment System (AVAS), as follows: Year 1 Year 2 Year 3 Year 4

Stage A–Performance-based Evaluation (comparative) Establishment of a methodology for AVA to enable objective comparison between different design options, and formulation of qualitative urban design guidelines.

Stage B–Urban Climatic Map Identification of climatically problematic/ sensitive areas

that require particular attention or in need of planning and design interventions.

Stage C–Performance-based Evaluation (with criteria) Establishment of a set of objective assessment standards and criteria for AVA.

Stage D–Quantitative Guidelines Formulation of quantitative design guidelines.

Remarks: Stage A had been completed and Stage D will not proceeded in this study.

Stage A defined a performance based AVA methodology that designs could be compared objectively, and better designs could be identified and selected. This allowed the government a head start towards a better guided air ventilated high-density city. A Technical Guide for AVA for Developments in Hong Kong was published in PlanD’s web site (http://www.pland.gov.hk/) for public reference. Stage B – Urban Climatic Map was proposed to further the understanding by developing a planning map that will provide an overview and strategically take climatic and air ventilation considerations into account. This will allow pro-active planning decisions and policies to be made at the city scale. Stage C – Benchmarking and Standard will allow the methodology in Stage A to be further substantiated. Stage A only allowed designs to be compared. No standard was stated, but eventually this would be needed. Before any standard being stated, three conditions must be

1-2 Years

2-3 Years

2-4 Years

Completed



investigated: (I) what is available [climatic data and wind availability]? (II) what can reasonably result [practice and benchmarks]? And (III) what is expected [user survey]? Stage C can provide information so that such a standard may be stated. Stage A has been implemented by Government through promulgation of the HPLB & ETWB Joint Technical Circular No. 1/06 in July 2006 and revised urban design guidelines to incorporate air ventilation considerations in Chapter 11 of the Hong Kong Planning Standards and Guidelines (HKPSG) in August 2006. Government would take the lead to apply AVA to all major Government projects and relevant planning studies. The revised HKPSG provides advisory guidelines as reference to project proponents to improve air ventilation in the planning stage of projects. However, CPLD in June 2005 decided not to proceed with Stage D. This study covers Stages B and C. 2.2 Identification of Key Issues One of the key issues is that this assignment is about planning study. Unlike pure scientific studies the outcomes of the study are expected to be useful, relevant and applicable to real life problems and conditions. For example, the science of wind studies is complicated. Many researchers opine that mechanical wind as well as thermal wind should be accounted for when wind environment is considered. The concern is noble but the scientific understanding is still, by and large, a matter of research investigations. The effects of thermal wind are localized. Its understanding may not be too important when considering large scale planning. Thermal wind is largely due to solar radiation, building orientation and facade materials which may not be the key concerns during planning. Instead of approaching the problem from science alone, it may be important approaching the problem from a planning point of view. What are the parameters the planners could apply to optimize the urban environment? Density, block spacing and layout, building height, and so on are some examples. All these parameters reveal that they have a high impact on the mechanical wind if they are not designed properly. Therefore, it is useful to get the more important thing first, and consider other minor concerns after further refining the methodology. Overloading a practical methodology too early with too precise scientific concern may not be conducive to the professional practice and real life working. In short, science is here to serve practice, not the other way around. As emphasized here as a key concern, the setting of the standard is not purely scientific. It is based on the values of the public, stakeholders and the government, like their economic situations and so on. Standard, especially environmental standard setting can firstly be guided with a scientific understanding, but its eventual quantity in most cases will be a



matter of “judgment”. As such, there is a need to conduct some well-organized discussions and consultations. Hence, the consultant’s proposal includes a small team which is composed of different well- respected professionals to champion the tasks. 2.3 Appreciation of Project Constraints and Special Requirements Considering everything which needs to be done in this study, time available is very short. The constraint is practice based, but it is useful to be able to come up with a “reasonable” Urban Climatic Map and standards as well as a “more refined” AVA methodology. Some compromises are needed. The approach is to have long term measurements from the established reliable sources (e.g. from HKO), and then supplement it with spot measurements. The data should be examined carefully. By using multiple ground level measurement points, top of urban canopy layer measurement, and observatory measurement, Professor Katzschner has developed a methodology which can predict wind behaviour on the ground. The method basically takes measurement snapshots of the ground conditions under known regional conditions in order to provide additional data to refine a general understanding of the wind patterns on ground. To account better the thermal effects, measurements are typically carried out in the morning, at noon, and in the afternoon. Moreover, due to the time constraint, there is a need to conduct the major tasks in parallel. Good management in this study is a must. However, since there are still many things unknown, it may be difficult to synchronize the tasks at times. Apart from the above, user survey and field measurements depend on the weather conditions. In a study for BD earlier, the study team had to wait 3 months before a more ideal weather conditions appeared. Sometimes, it is necessary to adopt this “get ready but wait” mentality. This is a reason why user survey and field measurements are usually staged into two summer sessions, two winter sessions, and so on, instead of one. 3 METHODOLOGY AND WORK PROGRAMME 3.1 Detail Task Analysis The following key tasks are required for this study. See also Appendix 2 of this report.

Task 1A- Urban Climatic Map Task 1B- Planning Function Map Task 2- Benchmarking Studies



Task 3- Establishment of Wind Performance Criteria Task 4- Refinement of the AVAS

3.1.1 Task 1A and 1B Urban Climatic Map (UC Map) and Planning Function Map

(PF Map) As outlined in the study brief, the schema of investigations which is necessary to complete the urban climatic mapping and benchmarking may be understood in the diagram below. Apart from strategically understanding the tasks, synergy among different tasks is needed. There should be no weak link, and then the objectives of each task can be better articulated.

Urban Climatic Mapping

Benchmarking

3.1.1.1 Examples of Mapping and Similar Scientific Efforts The concept of urban climatic mapping must not be confused with scientific efforts which provide mapping of the earth surface (urban or rural) based merely on the surface temperature or heat island energy budget. The concept of urban heat island is not new.

Wind tunnel modelling

Urban Climatic Map

Planning information

(PlanD): land use,

building height,

greenery, etc.

Criteria and Code of Practice for design and

planning in Hong Kong for better wind

environment

User expectation survey and site

measurement

Other considerations

Planning policy and

framework

Site evaluation + selection

Validation (field study)

Benchmarking of

existing urban

conditions

Planning Function Map (Planning

evaluation and advisory map)

Site wind availability and potential

Meteorological data

(HKO)



Researcher Oke (1987) in the US first defined it based on the heat island energy budget. Many research groups around the world are working on it. For example, in the US, The US Environmental Protection Agency (EPA) has teamed up with Lawrence Berkeley National Laboratory (LBNL) and US National Aeronautics Space Administration (NASA) to study a whole range of cities in the US. So far the study has been one of monitoring, detecting, modelling understandings. Action plans like “greening” and “whiting” have been proposed. These are the classical measurements to deal with urban heat island, and the dynamic (like wind) parameters are seldom factored in most cases.

(Left) A representation of Urban Heat Island. (Right) Thermal imaging of Washington DC. Cooler

temperature in RED. Cities with higher surface temperature in GREEN and indicating Heat Island.

Heat Island will result when there is a surplus amount of energy on the earth surface. This always happens in cities. High heat island effect will result when the short wave sun energy turns into long wave heat energy, which is absorbed and then stored in the materials of the cities and re-radiated back to increase the ambient (air) temperature. Heat island is caused finally. Typically, there are some ways to solve the problems caused by heat island effect. For examples, using high reflectance materials like painting the buildings white, greening and vegetation to balance the energy budget through the evaporation and photosynthesis processes, improving the ambient wind and ventilation to bring cooler surrounding air especially when the cities are long and narrow and some cooler sources are near them, say water bodies or forest.

Dr. Wong from Singapore (a collaborator of the study) has conducted the extensive studies of the heat island effects in Singapore. His team in National

University of Singapore also used the concept of Sky View Factor to predict heat island effect. His know-how will be factored into the Urban Climatic

Mapping development.



The scientific working of urban heat island effect and the process of the surface temperature to air temperature is a sub-set of the urban climatic mapping process. Urban climatic mapping and planning function mapping are the sophisticated, scientific and practical processes. Beyond the simple understanding of heat balance and energy budget, the dynamic process of the climatic conditions (e.g. wind) is also emphasised. It is useful to the important decision making of the planning process. 3.1.1.2 Urban Climatic Map (UC Map) In order to help planners understand and evaluate the effects of ventilation and thermal comfort, an urban climatic map can be considered a tool of translating the climatic knowledge to the planning process. Urban climatic map has to cover the whole city area and give help to the planning decisions. The map helps to fix the investigation depth in order to avoid unneeded experiments. It also helps to draw attention to the crucial places, and fundamentally describes the atmosphere near the ground within the Urban Canopy Layer (i.e. surface to mean roof level). Two different aspects are mainly investigated: (a) the dynamic analysis for breezeways, air paths and thermal induced circulations, and (b) the thermal analysis in respect of heat island and thermal comfort. Urban climatic maps are of increased interest throughout Europe, and so on, in recent years. In many countries, environmental plan is included in master plans and there is a need for reliable framework, which can make decisions clearer. Furthermore, there is a “mega city programme” with the efforts of many countries to solve the problems of the large cities. Urban climate can provide the background knowledge for air flow and thermal conditions. The following cities have already conducted UC Map studies: in Europe: Athens, Berlin, Frankfurt, Kassel, Milano, Stuttgart, and Zürich.

An Urban Climatic Map of Kassel, Germany

An Urban Climatic Map of Salvador, Brazil

By Professor Katzschner



Outside Europe, many cities have conducted pre studies like Buenos Aires (Argentina), Sao Paulo, Salvador (Brazil), Tokyo and Vancouver (Canada). Once the UC Map is developed, the information will be used by the planners to resolve the climatic classification into planning functions (i.e. Planning Function Map [PF Map]). This map can be used as the guidance in planning and strategic urban developments. The cities marked with # are likely candidates of the desktop study. They are the cities that UC Maps have been produced. No city is like Hong Kong; hence no desktop study could directly inform the Hong Kong’s study. Therefore, the desktop study aims mostly and more importantly at an understanding of the methodology and experiences in producing the UC Map.

From Urban Climatic Map to Planning

Function Map.

Germany as an example: According to the German law, air and climate have to be one of the considerations in planning. The law requires that the existing conditions cannot be worsened. This means the German government or communities ought to have a suitable information background to evaluate the plans. This can be done through an Urban Climatic Map. The responsible parties which involves in the planning ought to respect these climatic studies and implement them into their master or city planning. For examples:

(a) Stuttgart in Europe developed a guideline for urban climate www.staedtebauliche-klimafibel.de. In a huge project “Stuttgart 21”, intensive research about wind simulations was carried out before any plans were decided in the parliament.

(b) Government of the State Hessen in Germany, Klimabewertungskarte Hessisches Ministerium für Wirtschaft Verkehr und Landesentwicklung, Wiesbaden.

(c) National guideline for human-biometeorological evaluations in the urban context by: Verein Deutscher Ingenieure, Düssendorf, Germany.

From those products, urban climate is seen as the background knowledge for future planning on all levels. Climate has to be implemented into the law-planning-systems.



3.1.1.3 Background of UC Map In 1980, the Working Group of Environmental Meteorologists within the German Society of Meteorology developed the idea of urban climate assessment. In various discussions, a guideline would be followed if someone can give meteorological answers to the urban planning questions. In a workshop, an idea was born to present urban climate resulting in a spatial resolution, which was an urban climatic map. The first book specially issued for urban climate was published in 1984 Schmalz, das Stadtklima, Müller Verlag Karlsruhe, together with the WMO TN review of urban climatology Geneva 1985. Stuttgart in Europe first employed meteorologists to implement this idea into administration under the support of the minister of economics. Result was a guideline städtebauliche Klimafibel. The relevant investigations were intensified at different German and Swiss Universities. Namely at the University München the “Stadtklima Bayern” from 1980 was developed. Münchener Universitätsschriften, Wissenschaftliche Mitteilungen Bd. 53(1986) and Bd. 58(1987). Followed up by the urban climatic maps of the “Ruhrgebiet” (1987) Klima und Lufthygiene als Planungsfaktoren, Kommunalverband Ruhrgebiet, Essen (1987). The research focus of the University of Kassel under Professor Katzschner was given to urban climate and urban planning. The ideas pushed in 1985 were not only about an urban climatic map, but also about a planning oriented evaluation map. More important thing is the continuing use of such projects and investigations. The Ruhrgebiet in the centre of Germany updates its urban climatic maps every 6 years to include new developments and more accurate data. In Kassel and Freiburg, the urban climatic map is used as a background for master plans, human-comfort conditions and open-space planning. Normally these maps are the instrument of the urban planning department and are brought into practice during every decision making process of the new building sites, traffic and industrial developments. 3.1.1.4 Expertise and Experience Zürich in Switzerland found a consulting company, Ernst Basler + Partner AG, to look for people who were professional and capable of carrying out the survey of urban climate. The researchers interviewed experts from Stuttgart, Berlin, Basel, München and Kassel. Finally they found that the Kassel’s team leaded by Professor Katzschner has the widest experiences in the linkages of planning processes and urban climate. Also, the methodology they applied to was the most effective. The Ernet Basler + Partner AG’s study concluded that the Kassel team led by Professor Katzschner was the most comprehensive and



competent team which could provide research services related to urban climatic map and planning function map. 3.1.1.5 Scientific Fundamentals and Methodology The principal of the methodology is an evaluation of the urban climate conditions. This is based on the land use from atlas and topographical data. The meteorological input parameters can be obtained from the stations nearby or meteorological recorded data.

Spatial development plan, urban climate and evaluation for the city of Kassel

Through the Geographical Information System (GIS Arc. Info), geographical and land use data can be classified and transformed to urban climatic functions like thermal aspects (i.e. heat and cooling rates), wind classification with ventilation paths and topographically influenced downhill movements. The building fabric is classified through roughness length1 and thermal radiation processes. The following factors are used:

(a) land use classifications for thermal and radiation with categories of city structures, industrial areas, gardens and parks, forests, green land and agricultural areas. Water is only used from lakes when train tracks get special classifications as they have a large daily variation in the surface temperature and therefore radiation differences;

(b) topographical and geographical data which influence the local circulation pattern, and

(c) ventilation through an analysis of the roughness length. Evaluation is carried out through a GIS based calculation method, which calculates weighting factors for every grid with a result for thermal and dynamic maps (Heat island = heat capacity, radiation income, reflection and adsorption, vegetation; Ventilation = 1 The roughness length characterizes the size and spacing of the roughness over which the wind is flowing (i.e. it is a measure of the aerodynamic roughness of a surface. To get more detailed, it is representative of the size of a characteristic vortex that forms as a result of friction between the wind flow and the ground surface (roughness) and, by definition; it is the height above ground at which the mean wind velocity is zero.



roughness length (z0), H/W ratio, effective height). This then is combined to the planning function map with an evaluation to the urban climatic map for planning use. Due to adopting the above methodology, the urban climatic map has two levels: 1) being used to deal with the thermal aspect 2) being used to deal with the dynamical aspect. Therefore, it is possible to have classification in the final map, which can differentiate the areas with the existence of heat island effects from the well or weak ventilated areas in order to get more improvements. The same method is used at different scales with various grids in order to get answers to different planning levels. • Procedures The working procedures are based on GIS (geographical information system) programme (ARC.MAP). Planning data, surface conditions and meteorological data are combined and calculated under the urban climate classification system. For example:

(a) building structures and heat exchange, heat island; (b) land use classifications and surface temperatures with effect on thermal

circulations; (c) roughness (zo) through city structures (heights, H/W ratio classification of

densities); (d) topographical situation (wind channelling effects and downstream wind), and (e) data evaluation from existing measurements of the meteorological observatory.



Working procedures:

Data evaluation (meteorological, land use, topographical, city fabric, green), defining and producing of the different levels (at this stage Hong Kong data are

needed) ↓

Calculation of the different levels for urban climate in GIS ↓

Analysis of the climate functions (Urban Climatic Map) ↓

Discussion with planners and Planning Department ↓

Planning Function Map (Finalised)

1. The planning function map could be developed based on the climatic map. The

criteria mentioned above would be transformed to an understanding of the climatic effect in the neighborhood, the urban space and the city.

2. All effects will be transferred into areas calculated by GIS software. 3. The development of the planning function map comes through different calculations

matrix, which connects all influential parameters. Steps to be taken:

1. Land use data and heat balance calculation. 2. Land use data and roughness, ventilation criteria. 3. Topographical classification and ventilation. 4. Meteorological data statistics.

A matrix will be developed with the input parameter of land use, building density and building height, topographical situation and the existing meteorological data. It is formed with weighting factors. Results are the classification of heat island, roughness, ventilation and air mass exchange. From here, the urban climate evaluation is carried out to study the importance of every singe climatic effect. The final urban climatic map is the annual distribution of these evaluations as a result of GIS calculation. Positive climate potentials are: Parameters

• ventilation paths v, T, zo • downhill movement L, T, H



• air masses exchange v, L,V, zo • bioclimatic effects from vegetation L • areal neighbourhood effects L, H, G

Negative climate effects: • heat island L, v, D • reduced ventilation L, v, H, zo • no air path effect L, v, V, zo

Remarks: v = wind speed; T = topography, absolute height; H = slope; L = land use,

D = density; zo= roughness; G = generalisation of areas; V = ventilation zone • Initial data needed for calculation The following data are needed for calculation. Planning Department Digital data (shape files) with:

(a) classification of land use (b) topographical map, digital data (shp) of NN in 20 m and 100x100m resolution (c) green maps if not included in land use data (d) map of building heights (e) map of podium buildings, AND if possible also: (f) city fabric classification (density factors) (g) classification of height/width relation

Meteorological Observatory Analysis of existing weather stations:

(a) monthly mean values of wind speed and direction; 3 (or more) years average (b) monthly mean values of air temperature and humidity; 3 (or more) years average (c) description of weather stations: NN, sensor heights, location (d) mean daily variation of wind speed, direction and air temperature at each station

The data have to be worked out under a homogenous system. In order to incorporate the stations, the stations have to be classified into heights, surroundings and so on. An extra input level “meteorological data” should be created.



• Computation and Analysis of climate functions

Layer Criteria A dynamic potential in the inner city B heat island C deficit areas in the sense of bioclimatic conditions and air flow 1 air paths 2 air paths and air mass exchange during strong wind situations 3 cold and fresh air production 4 various balance potentials 5 green area micro climates 6 potential balance effect Result urban climatic map planning function map

Factors for computing: land use, effective building height, density and vegetation percentage will result in heat island. Land use, roughness length, and wind distribution frequency will result in the dynamic result. A matrix is defined and changed from step to step. The methodology based on calculations of different steps can be described in the Kassel case. In Kassel 9, steps were used to judge and calculate the criteria of the negative factors: heat island, highly reduced ventilation and blocking obstacles. In another part, the mapping included the positive influential factors for urban climate. The computation was a series of different matrices, which were made according to the classification of meteorological characteristics of the buildings and land use in parallel with topographical information. For example, fresh air production was dependent on land use heat balance multiplied by a slope classification. Ventilation had reduction effects on heat island. Criterion dynamics (A) here the potential ventilation areas are calculated. Even if these areas are not always in function dynamically, they are still working during the strong wind situations. The levels B and C are two criteria for heat island situation. One can see the maximum of heat island caused by densely packed buildings and streets which have a high radiation income and high long wave radiation. Those areas from criterion C have added to those air flow problems, through wind stagnation zones. All criteria with numbers are considered as positive for urban climate. The weighting factors are implemented again into the calculation matrices. Criterion 1 calculates the air paths as ventilation areas out of the roughness length, which again is derived from building density, height and structure oriented to the main wind direction. This is followed by the air mass exchange rate



(criterion 2), which includes strong winds passing these areas. One influencing factor here is the wind direction distribution. Cold and fresh air production is coming from empirical measurements (criterion 3) to get volume figures per ha and hour and links this with slopes to get the wind speed. Criterion 4 describes the positive factors in microclimate with mean density, low roughness length. If the importance for urban climate is small, microclimate from the vegetation areas will be effective (criterion 5). This calculation comes from the land use data combined with low effective heights, or vegetation which can be penetrated. Neighborhoods with positive air mass exchange effects to their surrounding, even in a smaller scale are mapped in criterion 6, especially if they are situated next to areas from criteria A to C. • Urban Climatic Map (UC Map) into Planning Function Map (PF Map) Once the UC Map is generated, the information can be developed into planning functions. Scientists have to interface with planners to intelligently interpret the climatic variables into planning classifications, zones and decisions. No less than 8 climatic sensitivity zones can typically be classified, more when needed. For example, when the map (above) is used, the pixel which contains information of the climatic characteristics of the area of interest will be noted. Say area X may have problem because of little air ventilation, or say area Y may have a problem because of high thermal capacity. The information can be grouped into zones. Typically, zones with various degree of climatic sensitivity can be classified. Then, they will form the basis of different planning decisions.

zone 1

zone 2

zone 3

zone 4

zone 5

zone 6

zone 7

zone 8

climatic importance

climatic vulnerability/sensibility

operation I operation II result

criterion Icriterion IIcriterion IIIcriterion IVcriterion Vcriterion VI

classifi-cation(five classes)

criterion Acriterion Bcriterion CPA

RT

2PA

RT

1

criteria (each graduated and weighted)

urban climate evaluationmap

eightzones

combination by

addition

combination by

addition

classifi-cation(four classes)

Refer to table

on page 14



When using the PF Map, climatically sensitive areas can be classified into zones, and building sites or developments within highly sensitive zones will have to be evaluated carefully. For example, as the diagram shown in the previous page, various development sites are indicated as “red”. Site areas hatched “blue” are in the air stream of the city, they must therefore demonstrate the design which does not intrude into the air stream. With the existing land use and building bulk characteristics, the Urban Climatic Map can identify the “base scenario” for Hong Kong. Adding the planned land use and building bulk information, the Urban Climatic Map can project the possible climatic scenario for the “ultimate state” as planned (or “planned scenario”). Comparing the “base scenario” with the “planned scenario”, the current problem areas can be classified and the deteriorating problems areas can also be identified. The different climatic sensitivity zones may be translated into a hierarchy of area based strategic development guidelines. The most critical problem areas should be the “priority areas” for manning review and identification of manning actions to improve the situation. Certainly the review should take all major economic, social and political considerations into account. It is more effective to rectify the situation through proactive planning for an area rather than control at site level. When benchmarking has been completed and standards have been established, it will be more appropriate to refine the Planning Function Map and categorize different requirements for addressing the air ventilation problem in different categories. • Updating Once the computational equations of the individual layers and the classification of information are incorporated into the Urban Climatic Map and Planning Function Map, they require little scientific changes. Updating is achieved mainly through new information input to the layers. For example, the city buildings may change, buildings may get higher, new areas may be developed, and so on. These geometric changes could be input into “building height” layer or other aspects of the map. A quick automatic re-computation will generate a new map then. Updating can generally be adopted every 4-6 years. This depends on the pace of the geometric changes and the climatic sensitivity to the Urban Climatic Map. A more precise estimation of the update frequency of the geometric data of the Urban Climatic Map can be decided at the end of the study after the map has been made and its characteristics have



been better known. The rapid pace of property development in Hong Kong might justify a shorter updating; a review system could be further considered when the UC Map and the PF Map are produced, and their characteristics are better understood. Geometric changes are relatively straightforward. Officers from the Planning Department who are familiar with the operation of GIS could handle. New climatic data can also be input, typically once every 10 years would suffice. There is a need of experts who have knowledge of the wind environment and the climatic conditions. In summary, general geometrical updating can be carried out by Planning Department every 4-6 years (as discussed above, if it is necessary, updating could be carried out more frequently). Major scientific and climatic updating should be carried out at least once every 10 years. Geometric updating can be accomplished by an officer in a month or two if all geometric data are available and in the right format. Climatic updating could be time- demanding. It might require a team of scientists around 3 to 6 months to complete. 3.1.2 Task 2 Benchmarking Studies

In Japan, research studies have indicated that a Velocity Ratio of 0.2 to 0.4 is achievable in wider streets, and a VR of 0.1 to 0.2 can be expected in narrower streets. But building

height to street width ratio in Japan is much lower. What are the ranges of VR that Hong Kong’s streets and spaces could expect?

The figure on the left shows the calculation of Velocity Ratio. The higher the value of VRw, the lesser the impact of buildings on wind

availability.

It is important to understand the existing pedestrian wind environment of Hong Kong from the quantitative point of view. The relevant information will establish the current situations. For example, it is possible to determine the range of velocity ratios that a high density urban environment like Hong Kong can provide. It is also possible to pin-point the problem areas quantitatively, so as to seek some ways to avoid them in the future. Furthermore, it is



possible to identify some favorable sites and conditions, so that their design features can be learnt. In short, the exercise can provide the much needed quantitative data to further advance the methodology. An initial qualitative wind environment assessment can be conducted to finalise the test details of each site, including the surrounding areas, the assessment areas as well as the locations of the 80 test points. The test procedures will follow the methodology established in Stage A of AVA. Wind tunnel will be used for testing. Among other quantities, velocity ratios and two spatial averages VR of the test sites will be reported. Two of the sites will be selected for limited spot measurement. This will provide some data for validation then. The details about selection of the study sites will not be mentioned here, but in Working Paper No.2. 3.1.2.1 Wind Availability Due to Hong Kong’s complicated topographical conditions, wind availability of the particular site under study must be firstly estimated. This can be done using large scale topographical model (typically 1:2000) in wind tunnel (an example as below). Professor Kenny Kwok of CLP Wind & Wave Facilities possesses a large cross section wind tunnel which is the only one of this type in Hong Kong; this wind tunnel is capable of conducting topographical studies using large models. Unlike typical topographical studies for structure which allow the use of smaller section wind tunnels, AVA requires wind direction characteristics be accounted and thus requiring the use of large cross section wind tunnel. Using long term HKO Waglan Island wind data as the basis, the site wind data at V infinity height can be estimated. The direction, probability of occurrence and wind profile can also be worked out. With the site wind data, further studies of buildings on site using model scale 1:400 can be conducted.



The test site and the approaching wind set up in a wind tunnel; note the roughness in front of the

model to reproduce the boundary wind conditions.

1:400 scale model study in the high-speed test section of HKUST wind tunnel. Note also the

roughness in front.

When the site wind availability and characteristics are known, the wind tunnel can be set up properly for the scale of the model to represent the wind profiles of the site when wind comes from different directions. This is important because wind characteristics are easily misrepresented.



3.1.2.2 Model Making and Testing Models of the test sites and their surroundings are built. The model (an example on the right) includes the test site (shown in blue in the model on the right), and the assessment area is typically H from the test site boundary (H being the tallest building on the test site). Outside the assessment area is the surrounding areas. The eventual model typically will be 5H, or larger, in diameter. A large cross section wind tunnel (of at least 2.5m x 2m) is required to study the tall and large developments in Hong Kong. Using hot wire anemometer, test points can be measured at a time. It is better for inserting some thermisters into the ground level of the model because wind velocity of many test points can be simultaneously captured. Velocity ratios of 80 test points per site can be tested. Wind from 16 directions will be factored by rotating the model inside the tunnel. Model making and testing are time consuming but technically straightforward. The following guidelines and standards should be followed:

(a) Manuals and Reports on Engineering Practice No. 67: Wind Tunnel Studies of Buildings and Structures, Virginia 1999 issued by American Society of Civil Engineers, and

(b) Wind Engineering Studies of Buildings, Quality Assurance Manual on

Environment Wind Studies AWES-QAM-1-2001 issued by Australasian Wind Engineering Society.



The model and positions of the test points (HKUST)

The model and positions of the test points with thermisters

The results of the tests would be reported as velocity ratios. The site and local VR, conditions of the stagnant zones and wind amplification will also be reported. 3.1.2.3 Benchmarking As long as the velocity ratios of all test sites have been obtained, the task of benchmarking will start. Benchmarking only answers a few questions:

(a) What are the ranges and characteristics of wind velocity ratio that one typically expects in Hong Kong?

(b) What is the “most desirable” performance standard of outdoor comfort?



(c) Can such standard be “reasonably” expected based on current climatic and practical constraints?

(d) If not (and will likely be the case of Hong Kong), what standard should be stated to yield an “acceptable” or “aspired” condition?

Professor Ng had experiences of standard making in the UK (British Standard) and in Singapore (PSB) prior to coming back to Hong Kong. Recently he has helped Building Department remake their Daylight Standard for Building Regulations. The standard process typically involves two key stages. The first stage is mostly scientifically focused. Wind science, velocity ratios and thermal comfort can be objectively stated. The second stage is mostly socially and politically focused as most environmental conditions are psycho-somatic in nature. That is to say, there is no clear boundary between black and white. Instead, if the environmental performance improves, more people will be satisfied, vice versa. Referring to the results of the typical survey graph above (i.e. performance vs. satisfaction), the blue crosses indicate the responses of a sample group under a specific condition. The red crosses indicate the responses of another sample group under different conditions. The first question is what percentage the standard needs to satisfy? And under which condition(s) the standard must be based? The answer of these questions is a “judgment” in which the performance level should be stated. The judgment can only be based on the “reasonable” and “consensual” logic. Now, let’s consider an easier scenario that only one condition is detected. Performance level A (right) will satisfy anything from percentage “2” to percentage “4”. So should the mean, median or anything else be stated? Although it is a statistical problem, there is the difference if one can say 80% or 90% of satisfaction. Again, some judgments are involved there. Based on some Japanese experiments, VR range from 0.1 to 0.3 may be expected in Hong Kong subject to the findings of this study. If the median V infinity wind speed of the site is 3m/s, then wind speed of 1.5m/s can satisfy the thermal comfort of 80% of inhabitants



during the hot summer months, and VR 0.5 will be needed. It is difficult, but not impossible, to achieve. A smaller, but still reasonable standard may need to be quoted. The smaller number may not be life and death, but may be ‘acceptable’. However, of course, if the performance is very bad (e.g. VR 0.05), there will be a cause of alarm. In this study, no foreign cities’ data will be used in benchmarking. Instead, wind tunnel tests and local user surveys will be conducted. However, methodology from overseas could be referenced. 3.1.2.4 Computational Fluid Dynamics Simulations (CFD) CFD tests should be done in the study. Up to four benchmarked areas will be selected for CFD simulation and cross check with the wind tunnel data. The comparative study will be “blinded”. This means CFD specialists and wind tunnel specialists will firstly conduct their tests independently. The results from the tests will be collated later. However, CFD may be conducted for few times in the same site. The methodology follows many similar studies like the URBVENT (European Urban Ventilation) project. CFD was originally developed for indoor air flow studies. Recently some researchers and consultants are using it for outdoor studies. There are some known problems. For example, the vortex shedding effect is one of them. That means some simpler k-e models that many CFD users commonly use cannot cater for the outdoor studies. Although Large Eddy Simulation exists, it is impractical because of its heavy computational demands. The Ove Arup’s team in Hong Kong, Professor Mochida’s team in Japan and Professor Jones’ team in the UK will try some tests to see if the devices can be used, and what limits will exist. The aim of the comparative study is to establish a preliminarily understanding to see whether CFD can be used for AVA. This will provide the insights to Task 4 when the methodology of AVA is reviewed.

*Should CFD be proven viable, then a guideline is needed. It may be based on the Architect Institute of Japan CFD Guideline. Some extensions would be needed for Hong Kong. (Optional item)

3.1.3 Task 3 Wind Performance Criteria and Standard Stage A of Air Ventilation Assessment (AVA) preliminarily suggests that:



Outdoor thermal comfort could be achieved when the following factors are balanced: air temperature, wind speed, humidity, activity, clothing and solar radiation. Based on preliminary researches, for example, when a pedestrian is under shade, a steady mean wind speed at pedestrian level of around 1.5 m/s will be beneficial. And a good probability (50% median) of achieving this 1.5 m/s mean wind speed is desirable, but may not be achievable in Hong Kong.

Further researches and detail investigations are necessary to establish a more robust understanding of criterion and standard that can be stated. Typically, a criterion or standard can be stated when the following conditions are considered and met: PEOPLE The physiological and psychological needs of people taken into account

their health (WHO 1948 definition) and comfort when carrying out their activities in an outdoor environment.

PLACE The availability of wind which is naturally available to a location. POLICY A balance view of the general conditions, practice, value and aspiration as

well as a note of the existing conditions. Key considerations of establishing a criterion or standard are “Desirable”, “Achievable”, and “Practical”. This understanding of methodology is universal and may be applied to any standard making process. A criterion or standard may be established if it can allow a desirable state to be reached. For example, setting a maximum air flow threshold or setting a noise control mechanism. The desirable state must possess the known benefits which can be objectively or statistically quantified. For example, having a brighter reading space will improve work performance or people will be more comfortable if the air temperature can be maintained at around 23 degrees. Typically, in the environmental studies, user survey in tandem with on-site measurement techniques is used to allow correlation. A desirable state must be reasonable. There is no point of trying to be idealistic. A criterion or standard must be “achievable”. For example, trying to apply the daylight standard in UK to Hong Kong is desirable, but it is also un-achievable. When Buildings Department tried to establish the performance based lighting and ventilation building regulations in 2000, the first task was to evaluate what could reasonably be achieved in the existing environment. This formed the basis of further discussion. Therefore, the results of benchmarking of the existing conditions are important. After coupling with a wide public consultation, a way forward may be charted.



Lastly, a criterion or standard should be practical. The procedures which can be objectively followed and assessed when a stated criterion or standard has or has not been achieved are definitively important. Moreover, a criterion or standard should be applicable and usable. There must be some simple-to-use equipment or testing methods that one can evaluate an achievement, or a set of simple software exists to allow calculations and predictions to be made. A good standard for PEOPLE means the standard is satisfactory and aspiring. It is relevant to PLACE and different environmental conditions as well as fit in with POLICY of the location. A synergetic condition of the findings of the studies includes:

Report – User’s Wind Comfort Level Survey (PEOPLE) Report – Site wind availability and characteristics (PLACE) Task 1A – Urban Climatic Mapping (PLACE) Task 1B – Planning Function Mapping (POLICY) Task 2 – Benchmarking of existing conditions (POLICY), and

A “judgment” to be agreed by the stakeholders, policy makers and the general public

It may be possible to input the standard of particular wind performance standard as part of the Planning Function Map. This will make the criterion and standard as a kind of reference. 3.1.4 Task 4 Refinement of AVA AVA is unprecedented. Many countries like Australia have the codes to deal with gusts and strong wind. Some countries like Japan have requirements to deal with urban heat island effects. Although these experiences are worth learning, these countries do not have such a congested urban environment like Hong Kong. On Stage A of the study, many international experts opined that Hong Kong was a unique place and therefore its assessment methodology should be unique too. The diagram below summarizes the methodology of Stage A of the study. This gives the industry a reasonable starting point. Like all new adventures, continued developments and refinements learnt from the experiences are important.



When the above mentioned methodology was proposed in the previous study, a number of limitations were stated:

(a) Lack of quantitative data of the existing conditions that can pin down the exact performance, problem and issue to a greater extent

(b) Lack of a holistic understanding to aid design and planning strategically (c) Lack of generic data of wind of the urban conditions at pedestrian level (d) Needs to refine the performance criteria for the local inhabitants under diverse

conditions when taking the socio-habitual culture of Hong Kong into account (e) Lack of research data to develop the quantitative guidelines in detail

Further studies explained earlier in this report will more or less address them and provide the raw scientific data of Hong Kong for guiding further actions. With further studies, many questions may be answered in a better way on the one hand, and AVA may be correspondingly improved and consolidated on the other. The questions below are the examples:

(a) Is the use of a yearly representation of wind velocity ratio a good enough indicator? Should it be further elaborated and take the seasonal effects into account? Should different ratios be stated in different locations? Can the

Resolve the meteorological wind availability data (16 directions, strength and frequency) to site wind data using simulation or topographical models in wind tunnel.

Based on Site Spatial Average VR (SVRw) and Local Spatial Average VR (LVRw), evaluate the wind impact of the design. Also note stagnant zones (low VRw) and wind amplification (high VRw).

Based on a wind boundary layer profile appropriate to the urban condition under study, conduct tests (either by simulation, or more accurately for complex scenes, using wind tunnel) to obtain results to be reported based on: Wind Velocity Ratio (VRw).

Design, planning and development proposals need to be studied.

Selected sites and affected areas surrounding the proposal are identified.

Modify design and re-test if necessary in order to optimize the proposal for attaining higher wind velocity ratio (VRw).

Further Assessment if needed for exposed sites: (a) Actual wind speed and occurrence (b) Wind gust evaluation



formulation of the ratio be simplified without losing its accuracy? Once an understanding of the user preference is made known, can the understanding of the ratio be refined? Apart from the indicator, can a simple criterion be stated?

(b) Can a better meso-scale understanding of Hong Kong’s wind environment be developed? And how can it be interpreted for the urban canopy layer wind studies? Can a better procedure be developed to ensure that the wind availability data of every site in Hong Kong can be available?

(c) Once the Urban Climatic Map and Planning Function map of Hong Kong have been developed, can the assessment methodology be fine tuned to suit different sites? For example, can different requirements for AVA be stated to deal with the sensitive or non-sensitive sites?

(d) Once benchmarking of the existing conditions has been done, and a judgment on the desirable threshold can be stated, should there be some differences in application? Can the benchmarking results improve our understanding of the qualitative guidelines? Can the benchmarking results refine our methodology like computing the spatial average wind velocity ratios?

(e) Stage A of AVA has sought ways to maximize urban wind availability as a priority. However, as AVA is developed, how should wind gust be factored in the system?

(f) For better application, a Code of Practice of AVA may be needed. This study should provide better guidance. Experiences learnt during the early implementation of Stage A should provide some feedbacks.

Many of these questions will be considered when Stage A of the study is reviewed and refined. Apart from the scientific and field considerations, the issues of implementation need to be further examined. At the moment, the following considerations determine if the development is subject to the assessment:

(a) Planning studies for new development areas (b) Comprehensive land use restructuring schemes, including schemes that involve

agglomeration of sites together with closure and building over of existing streets (c) Area-wide plot ratio and height control reviews (d) Developments on sites of over 2 hectares and with an overall plot ratio of 5 or

above (e) Development proposals with total GFA exceeding 100,000 sq.m. (f) Developments with podium coverage extending over 1 ha. (g) Developments above public transport terminus



(h) Buildings with height exceeding 15m within a public open space or breezeway designated on layout plans / outline zoning plans or proposed by planning studies

(i) Developments on waterfront sites with lot frontage exceeding 100m in length (j) Elevated structures of at least 3.5m wide which abut or partially cover a

pedestrian corridor along the entire length of a street block that has/ allow development at plat ratio 5 or above on both sides, or which covers 30% of a public open space

Can the list above be refined? Should various conditions merit different levels of the assessment? Should the assessment methodology be different for different conditions? Is it possible to develop any guidelines to make the tasks easier? More similar questions are existing but cannot be listed one by one. Many of these questions can be investigated and answered. In order to make the process operate rather smoothly, a constant and close dialogue with the government and industry stakeholders should be maintained. The review process will be partially inspired by the new scientific data obtained. Equally important, the industry will give advice during the review process. The team formed by multi-disciplines will give immense assistance. Once the Urban Climatic Map has been completed, the scope of application of the initial AVA can be refined by introducing the area-specific requirements. The developments within the identified problematic and sensitive areas shown in the Planning Function Map will be required to address the air ventilation problem. The need of conducting the study of AVA will depend on the level of climatic sensitivity of certain areas. If the criteria for optimal wind performance with a solid scientific foundation are established, some more proactive means of implementation can be considered, such as including the requirements of AVA in the planning submission process under the Town Planning Ordinance or land administration system. Besides, climatological, political, economic and social dimensions will be taken into account when other appropriate means of implementation are being recommended. 3.2 Technical Inputs Apart from the main tasks, a number of technical inputs are needed for this study:

1 Site Wind Availability 2 Field Measurement and Validation 3 User’s Wind Comfort Level Survey



3.2.1 Site Wind Availability

Large Scale Test Section

Heat Exchanger

High Speed Test Section

Flow Direction

Flow Direction

FanHoneycomband Screens

61.5 m

16.5

m

3 m x 2 mCross Section

5 m x 4 mCross Section

Purg

e D

oors

Wind tunnel test sections of the CLP Power Wind/Wave Tunnel Facility (WWTF)

It is proposed that the data obtained from the wind tunnel experiment should be collected for this study. Together with the data from HKO, the data from the wind tunnel experiment will provide some useful data for Task 1A and 2. Hong Kong’s hilly topological conditions create a complex wind field. Although computational models like MM5 may provide approximation of the site wind availability data, there is a need to investigate it further with wind tunnel testing. Using an appropriate topographical model, the wind boundary profile and turbulence intensity profile of the site can be recorded. This information indicates the wind availability of the site. It can be used in Task 1A and 2.

Typically a topographical model with scale 1:2000 will be built. The particular location is tested. The results will then be referenced

back to the HKO Waglan Island wind data. For example, the model as shown on the left will provide the required data for West Hong Kong Island, Tseung Kwan O, Junk

Bay and so on.



For example, in Task 2, the wind tunnel should be set up correctly (left) to account for reduced wind speed near the ground. In

this case, the correct wind profile and turbulence intensity characteristics should be created at lower level, and extra roughness and blockage should be installed

inside the wind tunnel.

An example of the wind profile and turbulence intensity profile of a site in Hong Kong from 0 to 700m can be captured when wind approaches the direction of 270 degrees (below). The reference approaching wind profile (Waglan Island) is represented by the solid line. The square dots are the measured data. In this case, at lower level, say from 0 to 200m, there is a significant reduction of wind speed with higher turbulence. This indicates that the wind is approaching over a rough city fabric with many tall structures.

0

100

200

300

400

500

600

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

normalized wind characteristics

prot

otyp

e he

ight

(m)

target turbulence intensity profile target mean wind speed profile

simulated turbulence intensity profile simulated mean wind profile

Simulated mean wind speed and turbulence intensity profiles



0.01

0.1

1

0.01 0.1 1 10 100

frequency/mean wind speed (n/U)

norm

aliz

ed w

ind

spec

trum

Harris-von Karman Spectrum, xLu = 550 m, scale 1:2000measured spectrum at wind tunnel centreline, height = 200 m

Longitudinal turbulence spectrum

1:2000 scale topography model of Hong Kong and Kowloon Peninsula (HKUST wind tunnel)

3.2.2 Field Measurement and Validation The study cannot allow long term measurement to be made because HKO provides a lot of useful and long term data for the study. This explains why the cooperation with the colleagues from HKO is so important. Some limited field measurements and site data at the urban canopy layer can be conducted. They will provide the validation data for Task 1A and 2. Spot daily measurement which uses the ground level field work with the roof top



station will be sufficient. The methodology should follow Oke’s guidelines published by World Meteorological Organization (WMO). Repeated periods of the short term measurements throughout the year will provide sufficient data. Fixed anemometer can be mounted on the site to provide the ground level wind conditions. A reference anemometer nearby will provide the wind conditions at the roof top (urban canopy layer). The data from HKO can be the references for calibration. The data, together with results obtained from 3.2.1, will provide the information of the site wind boundary layer conditions. Furthermore, spot measurements with mobile hot wire anemometer (up to 10 at any one time) should be used to capture velocity ratio of multiple test points at pedestrian level. Surveyors (up to 10) can be sent out to capture VR of the site simultaneously. Typically, apart from the wind data and air temperature, humidity and solar radiation data will also be captured at the same time. Equipment available at CUHK can be arranged for this study. In addition to the ground level wind velocity ratio measurements, there may be a need to get some data which are about the vertical canopy layer wind environment. The information obtained is necessary for calibration of the Urban Climatic Mapping (Task 1A). Apart from the roof top station and ground mobile units, the data of wind velocity, globe temperature# and air temperature might be required vertically in the urban canyon for Task 1A. Typically, 3 to 4 points vertically along the façade of the building of the canyon will be sufficient. For example, if the building is 50m tall, then the measurements at 10m and 30m are needed.

# globe temperature takes into account the air temperature and the increase of temperature due to solar radiation. It is typically measured with a thermometer inside a matt black ball.

3.2.3 User’s Wind Comfort Level Survey In order to establish the eventual benchmark and standard for Hong Kong, human dimension must be further understood. Under the habitat of the high density and sub-tropical urban living environment like Hong Kong, what is the desirable outdoor environment for the inhabitants? What can the inhabitants tolerate? What can they reasonably expect? And what are their aspirations? Stage A of AVA suggested comfort exists when the wind environment is at lower range. It opined that a mean wind speed of 1.5 m/s 50% of the time can provide a desirable comfort environment during the summer months of Hong Kong when the pedestrians are walking under shade. This understanding is an approximation, and is based on the researches conducted in the similar tropical environments elsewhere with theoretical calculations. It is



necessary to confirm the information obtained by observation with some local data. In addition, it is desirable to evaluate the feelings of outdoor wind environment among the Hong Kong pedestrians, and see whether they enjoy it or not. Therefore, field user survey is important. Making use of the benchmarked sites of Task 2, user survey can be conducted. A mobile monitoring station (see figure below left), which can provide the data of the ground weather conditions, should be positioned near the survey site. A roof top station will provide the reference data.

User satisfaction rates and comfort indices (see figure below right) can be statistically analyzed in correlation with the ground weather data.



Key Methodology Thermal comfort study methodology of this study will follow established international protocols. A key literature example is ASHRAE RP-884 by Richard de Dear. The protocols have been regarded by the international scientific community as being reasonable and effective, and are robust enough to give the required information to calibrate established thermal physiological models for a particular locality due to differences in environmental parameters. Outdoor urban activities on the streets, at plazas, playgrounds, urban parks and so on, may be greatly affected by the outdoor climatic conditions. For example, thermal discomfort will be assessed when people stay outdoors and expose to the sun in the hot summer time. This may discourage them from utilizing the open areas like urban park. The level of thermal comfort depends on the particular combination of air temperature, surface temperature of the surrounding areas, wind speed, impinging solar radiation level and humidity level. The availability of the shaded outdoor areas may result in greater utilization of the open space by the public. In a similar way, in a cold season, a combination of wind speed and air temperature, but without any sunshine, may discourage people from staying outdoors. However, areas where sunshine can be obtained may protect people from strong wind, and encourage them to stay at such outdoor areas. The objective is to find out the "comfort temperature" among a specific group of people in the given location and season. This means what outdoor temperature will make the general public feel comfortable. The complementary research findings show the statistical distribution of the thermal sensations. The scale ranges from "cold”,"neutral" to "hot". To obtain the data which can be the representation of a society, the sample size should be as large as possible, and each interviewee should be interviewed only once. A total sample size of 1000 will be obtained from the survey. Questionnaire will be used in the survey. The format and content of the questionnaire will be with reference to the questionnaire used in the RUROS Project (‘Rediscovering the Urban Realm and Open Spaces’ Project funded by European Union) and questionnaire appended in ASHRAE Standard 55-2004. Opinions of the experts like Prof. Baruch Givoni and Dr. Wong Nyuk Hien will also be adopted. The arrangement of the survey is like this: total 10 students (5 teams) will conduct the field measurements and surveys in the selected areas. The students will randomly approach subjects and an initial verbal permission from the subject will be obtained. Microclimatic



environmental variables (air temperature, globe temperature, wind speed, solar radiation, and relative humidity) in the immediate surrounding of the subject will be measured using some portable devices. The clothing index and activity level of the subject will be estimated. Then the subject will be asked to respond to his/her comfort conditions which include 1) 7-point scale of thermal and wind sensation; 2) 3-point scale of solar and humidity sensation; 3) 5-point scale of sweating level; and 4) the overall comfort vote. The survey will typically last 5 minutes. The user survey data will be correlated to the field measurement data and by doing so, the criteria of thermal and wind comfort for Hong Kong people can be examined. A separate user’s wind comfort level survey report would be prepared and a summary would be incorporated in Working Paper No.3. 3.3 Stakeholders’ Engagement This study will consult relevant professional institutes, industries, organizations and stakeholders. The consultation can make the study more comprehensive, international and professional. As discussed elsewhere and emphasized here as a key concern, the setting of standards is not purely scientific. It is based on prevalent values of the public, stakeholders and the Government; and circumstances, economics and so on. Standards especially environmental standard setting could firstly be guided with a scientific understanding but its eventual quantity will be in most case a matter of collective “judgment”. As such, there is a need to conduct well organized discussions and consultations. In this connection, the Consultant Team includes Professor Bernard Lim and K S Wong, who are actively involved in both local practice and research, will serve to support the linkage with the industry, thereby ensuring proper consultation and flow of information. The linkage is critical for making the Study eventually be useful and acceptable to the industry as well as general public. The important spirit of the Study is not science, but practice. The understanding and acceptance of the stakeholders to the eventual findings and recommendations are crucial. To facilitate such understanding and subsequently acceptance, the communication has to be effective. While a study of this technical nature will inevitably involve use of terms not familiar to the practitioners, especially architects, town planners and project managers, as



well as the public and NGOs, the challenge for the Consultants is to try their best endeavors in resolving the terms to “layman and design” language with respect to town planning, urban design and architecture. This will greatly smooth the process of endorsement as well as the eventual implementation. According to the Brief, the Study shall have public engagement activities in two (2) stages as below: • Stage 1 Stakeholder Engagement Activities

On the basis of the work done for Tasks 1A and 1B, the Stage 1 stakeholder engagement workshop and/or other separate consultation briefings and presentations will be organized to consult professional institutes, stakeholders and other relevant consultees such as those listed in Section 13.3 on the initial Study Findings. The scope shall include the draft Urban Climate Map. Draft Planning Function Map, initial findings on the users’ wind comfort level survey and benchmarking studies.

• Stage 2 Stakeholder Engagement Activities On the basis of the work done for Tasks 2 to 4, the Stage 2 stakeholder engagement workshop and/or other separate consultation briefings and presentations will be organized to consult professional institutes, stakeholders and other relevant consultees such as those listed in Section 13.3 on the initial Study Findings. The consultation should address the summary of the draft Study findings and recommendations on refinements of the Air Ventilation Assessment System, including recommendations of wind performance criteria, before conclusion of the Study and submission of the draft final report and draft executive summary.

The following represents the key organizations to be included in the consultation process as appropriate: • Advisory Council on the Environment, • Committee on Planning and Land Development, • Council for Sustainable Development, • HK-BEAM Society, • LegCo Panels, • Planning Sub-Committee of Land and Building Advisory Committee, • Policy Committee,



• Professional Green Building Council, • Real Estate Developers Association of Hong Kong, • Town Planning Board, • academic institutions, • green groups, and • professional institutes in relation to built environment, health and urban climate, etc. After each stage of stakeholder engagement activities, the Consultants will prepare and distribute a report covering the gist of the comments and discussion as well as the Consultants’ responses.



3.4 Study Programme The study programme (table below) will follow largely that defined in the study brief.

Study Programme Table



4 STAFFING 4.1 Organization Chart (key professionals)

Study Steering Group

Industry Stakeholders, Groups, NGOs and so on.

Team 1 Meteorological and Urban Climatic Professor Lutz Katzschner Mr. Jochen Mulder Professor Edward Ng Dr. Stephen Belcher Professor Alexis Lau Professor Jimmy Fung

Professor Bernard Lim Mr. K S Wong

Project Core Investigators Professor Edward Ng (Coordinator) Professor Lutz Katzschner Mr. Derek Sun Professor Kenny Kwok Dr. Raymond Yau

Team 2 Wind Engineering Professor Kenny Kwok Dr. P A Hitchcock Professor Edward Ng Dr. Raymond Yau Dr. Vincent Cheng Professor Ryuichiro Yoshie Professor Akashi Mochida

Project Advisors Professor Shuzo Murakami Professor Mat Santamouris Professor Phil Jones Professor See Chun Kot Professor Tze Wai Wong

Team 3 Thermal Comfort & Heat Island Professor Edward Ng Professor Baruch Givoni Professor Lutz Katzschner Dr. Nyuk Hien Wong Dr. Raymond Yau Professor Akashi Mochida

Team 4 Town Planning and Design Mr. Derek Sun Mr. Geoffrey K Y Chan Professor Lutz Katzschner Professor Edward Ng Professor Bernard Lim Mr. K S Wong Dr. Raymond Yau

Assistant Director/ Special Duties Planning Department



Professor Ng is the key coordinator of the study. He is directly answerable and responsible to the Client, as well as ensuring effectiveness and efficiency of the organization. Around him is the immediate core investigator team, they are basically the leaders of the sub-teams. This core group ensures that information and results can be shared and synergized. Strategic decisions were made. Each sub-team was responsible for a key task of the study. Tasks will be done in parallel. Along side the working teams are the project advisors, will form the internal auditing body, as well as making input based on their diverse and international background. Professor Bernard Lim and Mr. K S Wong also serve as the linkage between the industry and the study team ensuring proper consultation and flow of information. This linkage guarantees that the study will eventually be useful and acceptable to the industry and the general public. 4.2 Name List of Key Consultancy Staff

Project Coordinator and Investigator Professor Edward Ng (The Chinese University of Hong Kong) Co-Principal Investigators Mr. Derek Sun (EDAW City Planning Ltd.) Prof. Lutz Katzschner (University of Kassel) Prof. Kenny Kwok (The Hong Kong University of Science and Technology) Dr. Raymond Yau (Ove Arup & Partners HK Ltd.) Professional Support Prof. Akashi Mochida (Tohoku University) Prof. Alexis Lau (The Hong Kong University of Science and Technology) Prof. Baruch Givoni (UCLA) Prof. Bernard Lim (The Chinese University of Hong Kong) Mr. Geoffrey K Y Chan (EDAW City Planning Ltd.) Prof. Jimmy Fung (The Hong Kong University of Science and Technology) Mr. Jochen Mulder (University of Kassel) Mr. Kam Sing Wong (The Chinese University of Hong Kong) Dr. P A Hitchcock (The Hong Kong University of Science and Technology) Prof. Ryuichiro Yoshie (Tokyo Polytechnic University) Dr. Nyuk Hien Wong (National University of Singapore) Dr. Vincent Cheng (Ove Arup & Partners HK Ltd.) Advisors Prof. Mat Santamouris (University of Athens) Prof. Phil Jones (Cardiff University) Prof. See Chun Kot (The Hong Kong University of Science and Technology) Prof. Shuzo Murakami (Keio University) Prof. Stephen Belcher (Ove Arup & Partners HK Ltd.) Prof. Tze Wai Wong (The Chinese University of Hong Kong)



4.3 Contacts of Investigators

Prof. Edward Ng (Principal Investigator and Project Coordinator) Professor, Department of Architecture, The Chinese University of Hong Kong Shatin, NT, Hong Kong Tel: 852-2609 6515 Fax: 852-2603 5267 E-mail:[email protected] www.edwardng.com

Mr. Derek Sun (Co-Principal Investigator) Director, EDAW City Planning Ltd. Suite 2808, 20F Two Chinachem Exchange Square, 338 King’s Raod, North Point, HK Tel: 852-2890 9228 Fax: 852-2890 8072 E-mail: [email protected] http://www.cityplan.com.hk

Prof. Kenny C S Kwok (Co-Principal Investigator) Professor of Civil Engineering Director, CLP Power Wind/Wave Tunnel Facility Hong Kong University of Science and Technology Clear Water Bay, Kowloon, Hong Kong Tel: 852- 2358 7151 Fax: 852-2358 1534 Email: [email protected]

Dr. Raymond Yau (Co-Principal Investigator) Director, Ove Arup HK Ltd. Level 5, Festival Walk, Kowloon Tong, Kowloon, Hong Kong Tel: 852-2528 3031 Fax: 852-2865 6493 Email: [email protected]

Prof. Lutz Katzschner (Co-Principal Investigator) Department of Architecture and Planning, University of Kassel Henschelstr. 2, D-34127 Kassel, Germany Tel: 49-561 804 2796 49-561 804 2387 Fax: 49-561 804 3451 E-mail: [email protected]



APPENDICE Appendix 1 Full Names of the Abbreviations

Abbreviation Page Number

Full Name

AVAS P.2 Air Ventilation Assessment System CPLD P.2 The Committee on Planning and Land Development CUHK P.3 The Chinese University of Hong Kong PlanD P.3 Planning Department HKPSG P.4 The Hong Kong Planning Standards and Guidelines BD P.5 Buildings Department HKO P.5 Hong Kong Observatory PF Map P.5 Planning Function Map UC Map P.5 Urban Climatic Map EPA P.6 The US Environmental Protection Agency LBNL P.6 Lawrence Berkeley National Laboratory NASA P.6 US National Aeronautics Space Administration WMO TN P.10 World Meteorological Organization Tanzania GIS P.11 The Geographical Information System H/W ratio P.12 Height/ Width ratio VR P.18 Velocity Ratio VRw P.18 Wind Velocity Ratio HKUST P.21 The Hong Kong University of Science and Technology PSB P.22 Productivity and Standards Board CFD P.23 Computational Fluid Dynamics URBVENT P.23 European Urban Ventilation WHO P.24 World Health Organization LVRw P.26 Local Spatial Average Velocity Ratio SVRw P.26 Site Spatial Average Velocity Ratio GFA P.28 Gross Floor Area MM5 P.29 (PSU/NCAR) Mesoscale Model WWTF P.29 Wind/Wave Tunnel Facility ASHRAE P.35 The American Society of Heating, Refrigerating and

Air-Conditioning Engineers RUROS Project P.35 Rediscovering the Urban Realm and Open Spaces Project



Appendix 2 Summary of Tasks of the Study

Task Scopes Duration (concurrent)

Task 1A- Urban Climatic Map

Review of international examples and the preparation of an Urban Climatic Map for Hong Kong which involves data on the meteorology, topography, building heights, densities, greening distribution and land use to identify areas which are most in need of attention and improvements from the wind perspective.

30 months

Task 1B- Planning Function Map

The Urban Climatic Map shall be resolved to a Planning Function Map to guide strategic and district planning.

33 months

Task 2- Benchmarking Studies

Aim to establish the existing wind performance conditions of Hong Kong through carrying out AVA for selected benchmark areas, and with limited field measurements for validation purpose.

30 months

Task 3- Establishment of Wind Performance Criteria

The criteria establishment is based on findings of the Urban Climatic Map, benchmarking studies and users’ wind comfort level survey. These criteria may be used for AVAS and improving the design of (re)development and planning proposals.

33 months

Task 4- Refinement of the AVAS

Review of the initial AVAS based on known project experience in implementing the initial AVAS and the findings of the Study.

33 months

urban climatic map and standards for wind environment

Documents