Design Considerations for Environmental Sustainability in High Density Development a Case Study of Hong Kong

8/3/2019 Design Considerations for Environmental Sustainability in High Density Development a Case Study of Hong Kong

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Design considerations for environmental sustainability

in high density development: a case study of Hong Kong

Edwin H. W. Chan Grace K. L. Lee

Received: 23 April 2007 / Accepted: 8 August 2007 / Published online: 29 August 2007 Springer Science+Business Media B.V. 2007

Abstract This study has indicated that there is close relationship between development

density and environmental quality; therefore, it is necessary to decide the form of devel-

opment carefully beforehand. The form of development is shaped either by new

development or urban renewal which is a major tactic nowadays adopted by the Hong Kong

Government to improve the living condition of the citizens and the quality of the built

environment. This study is limited to urban renewal and aims to find out the major urban

design considerations for sustaining the environment. Through a questionnaire survey car-ried out in Hong Kong, the opinions of architects, planners, property development managers,

and local citizens were sought and evaluated, and critical design factors for enhancing

environmental sustainability of urban renewal projects are highlighted. The results derived

from factor analysis indicated that certain design considerations should be incorporated for

sustaining the urban environment. Land Use Planning, Quality of Life, Conservation

& Preservation, Integrated Design, Provision of Welfare Facilities, and Conserva-

tion of Existing Properties were believed to be the significant underlying factors for

achieving environmental sustainability of local urban renewal projects.

Keywords Critical Factors Environmental sustainability Factor analysis High density development Hong Kong Urban renewal

1 Introduction

Hong Kong is a city well known for its high development density. Throughout the years,

many (re)development projects are conducted and numbers of environmental problems

Readers should send their comments on this paper to: [email protected] within 3 months of publication

of this issue.

E. H. W. Chan G. K. L. Lee (&)Department of Building and Real Estate, The Hong Kong Polytechnic University, Hung Hom,

Kowloon, Hong Kong

e-mail: [email protected]

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Environ Dev Sustain (2009) 11:359374

DOI 10.1007/s10668-007-9117-0


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have been generated. In the first part of this paper, the negative impacts of high-density

development on the built environment are revealed. Nowadays, urban decay problem in

Hong Kong is serious and urban renewal projects to improve the urban environment are

urgently required. However, many renewal projects conducted in the past failed to solve

urban decay; in contrast, they had worsened the condition of the built environment. In viewof it, this study attempts to incorporate sustainability concept in the urban renewal

proposals and find out a list of urban design considerations that can contribute to envi-

ronmental sustainability.

In this paper, critical environmentally sustainable factors are also discussed to provide

valuable information for the professionals to make decisions among different design

options when preparing the urban design proposals.

2 Relationship between high density development and environmental quality

As all know, land is a scarce resource in Hong Kong and high-density urban form of

development is adopted here to cope with different economy and population needs. Such

kind of spatial development usually generates negative impacts on the urban environment

that should be tackled without delay. For examples:

2.1 Traffic congestion

High density development leads to a heavy concentration of people living and/working in

certain urban areas. Many people have to commute between home and work frequently,which overloads the transport system. When the carrying capacity of the transportation

network is beyond its limit, traffic congestion results. The additional traffic not only creates

air and noise pollutions but also increases traffic and time costs, lowers fuel efficiency due

to long waiting time, and causes health hazards to pedestrians. Except the railway trans-

portation systems, nobody can predict the traffic time accurately especially when they run

into congested zones like Mongkok and Causeway Bay during rush hour. Even though

there are 2 cross harbour tunnels, severe traffic congestion still exists and the congestion

even extends to the inner streets of Wanchai, Causeway Bay, Yau Ma Tei and Hunghom

that causes further traffic delay. This also explains why many Hong Kong citizens have to

take over 2 h commuting from home to work and vice versa everyday.

2.2 Pollution problems

As mentioned before, high density development overloads the transportation system, and air

and noise pollutions are direct results of heavy transportation load. Most urban areas and

roadsides experience higher levels of air pollution caused by vehicle emissions. The air

pollutant index always stands at high level/extremely high level in Hong Kong. As Hong

Kong has limited spaces, buildings, roads and/railways are situated closely together within a

development and the citizens have to face another problemtraffic noise. Residents living

next to busy roads or railways are exposed to noise levels over 75 decibels throughout the

day, and they are under a lot of stress and their psychological health is also adversely

affected. Apart from air and noise pollution, Hong Kong also suffers light pollution that

is induced from residential lights, streets and advertisement signs in the street. Urban

areas with intensive commercial and residential development are heavily light-polluted.

360 E. H. W. Chan, G. K. L. Lee

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2.3 Heat island effect

Heat island effect is a common phenomenon in urban areas, and it adversely affects the

citizens health and the natural environment. It is because heat islands can amplify hot

weather events, which cause heat stroke, organ damage and even death. In addition, heatislands increase energy demand for summertime cooling, raising emissions of harmful

pollutants from power plant and energy expenditures. Heat island seems to be getting

worse especially in high density cities like Hong Kong. Urban areas can easily be heated

up in several ways. For instance, emissions from the combustion of carbon-based fossil

fuels for the generation of energy during the whole construction process, from building

materials extraction, product manufacture, product transportation to building construction,

operations and maintenance, and building disposal create local greenhouse effect that

increase the heat island. Concrete, the most commonly used building material in urban

areas, generates heat during hydration process and has high heat capacity, causing the

urban area to reach higher temperature. The tall buildings in urban areas provide multiple

surfaces for the reflection and absorption of sunlight, increasing the efficiency with which

urban areas are heated. As high density cities are often densely populated, heat generation

by human activities e.g. cooking, and operation of automobiles and air conditioning units

also contributes to the heat island.

2.4 Distortion of micro-climate

Form of development can significantly changes the micro-climate of the urban areas in

terms of temperature, relative humidity, ventilation flow, air quality, and lighting level,which greatly influence the human comfort of the occupants. The recent high rise and high

density residential developments form barriers to wind flow that inhibit natural cooling by

convection, worsen heat island effect, and cause contamination of pollutants like dust and

car exhaust between buildings and wind-tunnel effects on streets and in public spaces. In

addition, many early developed urban areas do not have provisions of green spaces which

inhibit natural cooling by evapotranspiration. The public places at lower and ground level

turn dark earlier than before because dense development of buildings has reduced the

penetration of natural lighting into the roads, streets, pedestrian walkway and other

common areas. Therefore, it is not surprising that the urban areas are usually hotter,

muggier, and dimmer than the rural areas, and many people are not willing to live and

work in urban areas when taking into account of the quality of micro-climate.

Undoubtedly, there is close relationship between development density and environ-

mental quality. In order to minimize the negative impacts of high density development on

the built environment, it is necessary to have comprehensive planning before the devel-

opment takes place. The approach of comprehensive planning applies to new development

as well as urban renewal. Nowadays, Hong Kong suffers severe problem of urban decay

(Chan and Lee 2006) and the Hong Kong Government attempts to carry out urban renewal

to improve the living conditions of the citizens and the quality of the urban environment.

Although the Government has implemented different urban renewal programmesthroughout the years to achieve these goals, not all of them succeeded because many of

them were uncoordinated, sporadic and profit-based. Those practices not only worsened

existing built environment but also adversely affected the way of life of the citizens. As

mentioned by Chan (2002), urban problems especially environment related challenges still

existed even though the urban renewal projects were conducted. In order to ensure that

Design considerations for environmental sustainability 361

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urban renewal projects can effectively improve the built environment, researchers and the

Government highly recommend integrating sustainability concepts into urban renewal

process.

3 Sustainable (re)development in Hong Kong

Sustainability is a buzzword in urban development in past decade. The concept of

sustainable development was defined by World Commission on Environment and Devel-

opment (WCED) as a development that meets the needs of the present generation without

compromising the ability of future generations to meet their own needs in 1987 (WCED

1987). Although many discussions about the definition and components of sustainability

have been held in the world, it is generally agreed that economy, environment and social

equity are three foremost values in sustainability concept.

Like other foreign countries, Hong Kong government shows interest of merging sus-

tainability concept into urban development policies through urban design skills. To define

the physical form of an urban area fulfilling the sustainable development objectives,

Planning Department has issued urban design guidelines, which underpin the future urban

development directions of Hong Kong. They emphasize the importance of urban design

and address issues like development height profile, waterfront development, cityscape,

pedestrian environment and pollution mitigation (Planning Department 2002). Apart from

urban development, the same idea has also been introduced to local urban renewal prac-

tices (URA 2003). That explains why the Government has recently stated in the Urban

Renewal Strategy that sustainable development is one of the major objectives of localurban renewal (Housing Planning and Lands Bureau 2001). However, the Hong Kong

Government and the private developers, two major parties conducting urban redevelop-

ment projects in the territory, mainly attempt to achieve various socio-economic objectives

through urban renewal. To ensure that environmental aspects are not overlooked when

planning urban redevelopment projects in future, critical design considerations for

sustaining the physical environment should be highlighted.

4 Urban design considerations for sustaining built environment

According to Department of the Environment, Transport and the Regions (DETR)

(2000), urban design is a key to create sustainable development. This idea is supported

by Maroochy Shire Council (2005) that [g]ood urban design can contribute to urban

sustainability by improving or enabling social equity, economic vitality and environ-

mental responsibility. In order to ensure that sustainable development can be achieved

through urban design, numbers of design considerations have to be taken into account

when preparing urban renewal proposals. After the literature review, it can be observed

that Montgomery (1998), Rowley (1998), Corbett and Corbett (2000), DETR (2000),

Lee (2003) and local departments like Planning Department (2002) and Council forSustainable Development (2004) have provided some clues for achieving good urban

design. However, there are no consistent and definite rules in producing good urban

design. Various scholars and urban planners have their own considerations when

designing urban areas (Lee 2003). In this study, 30 urban design considerations were

shortlisted under 2 criteria:


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(i) The considerations are widely recognized in the abovementioned literature that can

significantly contribute to the sustainability of urban redevelopment projects; and

(ii) The considerations can turn the following urban design principles identified by Lee

and Chan (2007) into practical design guidelines. The urban design principles are:

Compact design and intensive development Proper mix and balance of land uses

Establishment of inter and intra-regional linkage

Respect for positive identity

Plan for comfort and quality living

Maximization of community participation

The urban design considerations selected for further analysis are shown in Table 1.

5 Research methodology

The research framework of this study is based on a literature review, questionnaire survey,

descriptive analysis and exploratory factor analysis. This study begins with a compre-

hensive literature review which helps to develop a framework for this study and prepare for

the questionnaire survey. A total of 30 urban design considerations applicable to local

context were verified through a pilot study. Industry practitioners having prominent role in

urban redevelopment, including architects, planners and senior management representa-

tives of property development companies (known as property development managers) in

Hong Kong were the target respondents for the survey. With the help of the professionalinstitutes e.g., Hong Kong Institute of Architects (HKIA), Hong Kong Institute of Planners

(HKIP), and Real Estate Developers Association of Hong Kong (REDA), questionnaires

were sent to 300 members randomly selected from each institute through email. Electronic

survey was chosen in this study because it eliminates costs of printing, paper usage or

postage, reduces the turnaround time for the questionnaires, and provides instant com-

munication between the researcher and the target respondents.

In addition, a total of 900 local citizens met on street in four selected districts namely

Yau Tsim Mong, Sham Shui Po, Wan Chai, and Central & Western districts were invited to

join the questionnaire survey. However, only the citizens who showed interest in this

survey and fulfilled the following criteria were sampled for this research:

(i) The resident has lived in the district for more than 10 years;

(ii) The resident has been affected by local urban renewal project(s); and

(iii) The resident has some knowledge about the concept of sustainability.

The respondents were given self-administered questionnaires and they were asked to rate

the extent to which individual urban design consideration affected three sustainable values

i.e., economy, environment and social equity of urban renewal projects according to a

5-point Likert scale (1 = least important while 5 = most important). A total of 1,800

questionnaires were sent and 247 valid responses were received for analysis. The overall

response rate was 13.7%. A summary showing the response rate of this questionnaire

survey is depicted in Table 2.

Data collected from the questionnaire survey was converted into code before being

entered into a database created in Statistical Package for Social Science (SPSS) for

Windows version 12, which was employed for descriptive and factor analyses. Since this


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study aims to identify the major urban design considerations for sustaining the built

environment, only relevant results are revealed here.

6 Findings and discussions

6.1 Result of descriptive analysis

From Fig. 1, it can be noticed that the respondents gave at least 2.6 to individual urban

design consideration and they ranked D18Provisions to control pollution; D19Green

features (design related); D20Green features (construction related) and D14Provision

Table 1 Urban design considerations shortlisted from the literature

Urban design considerations

D 1. Mixed development i.e., various uses within the same building or an area

D 2. Adaptability of development to the changing needsD 3 Efficient use of land & space

D 4 Establishment of different business activities e.g., retail shops, banks

D 5. Proximity to business activities

D 6. Availability of local employment

D 7. Access to work

D 8. Convenience, efficiency & safety for drivers

D 9. Convenience, efficiency & safety for pedestrian & public transport users

D 10. Provision of accommodation for different income groups

D 11. Provision of public facilities e.g., school, health care services, sports facilitiesD 12. Access to public facilities

D 13. Provisions for basic needs of disabled, elderly or children with proper access

D 14. Provision of open spaces e.g., parks, seating areas & promenade

D 15. Design of open spaces in terms of appearance, location, size & use of materials

D 16. Access to open spaces

D 17. Management of buildings, facilities & spaces

D 18. Provisions to control pollution e.g., air & noise

D 19. Green features (design related) e.g., optimization of natural lighting & ventilation, provision

of sun shades, balcony

D 20. Green features (construction related) e.g., Installation of energy efficient/water saving devices,

use of recyclable/durable construction materials

D 21. Preservation of historical structures & features

D 22. Rehabilitation of repairable building structures

D 23. Building design in terms of appearance, density, height & mass

D 24. Compatibility with neighborhood

D 25. Layout of building and streets

D 26. Promotion of local distinctiveness

D 27. Preserving & facilitating social network

D 28. Community involvement in public decision making

D 29. Sense of belongings on community

D 30. Security against crimes


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of open spaces as the most significant considerations (with an average score of more than4.0) for sustaining the built environment.

Provision of anti-pollution measures is perceived as an essential design consideration as

it not only offsets negative environmental impacts imposed by the developments but also

safeguards the physical and mental health of the citizens living or working within the

developments.

Table 2 Response rate of this study

Target respondents Sample size No. of valid reponses (%)

Practitioners Architect 300 41 (13.7)

Planner 300 41 (13.7)Property development managers 300 38 (12.7)

Sub-total 900 120 (13.3)

Citizens Sham Shui Po 225 34 (15.1)

Yau Tsim Mong 225 30 (13.3)

Wan Chai 225 31 (13.8)

Central & Western 225 32 (14.2)

Sub-total 900 127 (14.1)

Total (%) 1800 247 (23.3)

1 2 3 4 5

D1

D3

D5

D7

D9

D11

D13

D15

D17

D19

D21

D23

D25

D27

D29

UrbanDesignConsider

ations

5-point Likert scale

(1 = least important,5 = most important)

Fig. 1 Importance of individual urban design consideration


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In recent years, green building design and installation are highly recommended by the

Government and building practitioners because of their merits. For instance, selection of

durable construction materials, and recycling of materials can reduce total amount of

wastes generated in the long run and lower the workload of local landfill sites. Proper

building orientation and facade design can maximize the ingress of sunlight and facilitatenatural airflow. Provision of external shading devices such as fins and balconies, etc. can

regulate heat entering and leaving the buildings without inducing a great need for artificial

lighting, and additional cooling and heating provisions. In addition, installations of envi-

ronmentally friendly fittings such as energy efficient and water conservation devices can

prevent unnecessary wastage of scare resources of power and water during operation of the

buildings. In the view of this, it is not surprising that these considerations have higher

priority over the others.

Provision of open spaces with natural landscape is considered as another important

design consideration to sustain the environment. Open spaces provide buffer zones and

breathing spaces in crowded areas with high development density while green spaces such

as parks ameliorate local climate (Oktay 2004). Trees and plants moderate wind speed and

regulate wind direction to control the airflow patterns between and within the buildings.

They also provide shading over the land surfaces to control indoor and outdoor temper-

atures. Furthermore, vegetation keeps the air fresh by removing suspended particulates in

the ambient air, and regulating the level of greenhouse gas i.e., carbon dioxide and the

oxygen level in the atmosphere.

6.2 Result of exploratory factor analysis (EFA)

EFA was adopted here to identify the underlying factors affecting environmental sus-

tainability of local urban renewal projects. By adopting this technique in this study, 30

items highlighted in the study were reduced into small number of latent factors that could

make the renewed communities become more environmentally sustainable in terms of

urban design considerations. So as to obtain reliable results from this analysis, five major

steps including (i) identification of the variables; (ii) computation of a correlation matrix

for the variables; (iii) extraction of the unrotated factors to see whether the chosen model

fits the data; (iv) rotation of the factors to make them more interpretable; and (v) inter-

pretation and labeling of the rotated factors were followed (Comrey and Lee 1992).To determine how many factors were required to represent 30 urban design consider-

ations, the total percentage of variance explained by each factor was examined. In this

study, principal axis factoring (PAF) with promax (nonorthogonal) rotation was conducted

to generate factor loadings for the factors extracted from a sample of 247 responses. PAF is

regarded as common factor analysis assuming that the variance in a given variable can be

explained by a small number of underlying common factors and by variance that is unique

to the variable. The factors in PAF are not defined as linear combinations of the observed

variables as they are generated from common variance instead of total variance (Pett et al.

2003).A total of six factors were extracted that accounted for about 59.2% of the variance in

responses, and the first two factors had accounted for 30.1% and 10.0%, respectively. Six

factors were extracted because first six factors had eigenvalues (refer to the Appendix for

the details) greater then 1.0 and the sixth factor only accounted for less than 5% of the

explained variance. Such finding was also confirmed by a scree plot in Fig. 2. The graph


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has plotted the extracted factors against their eigenvalues in descending order of magnitude

to identify distinct breaks in the slope of the plot.

The details of the extracted factors, their factor loading, percentage of variance

explained and the cumulative percentage of the variance are shown in Table 3.

6.2.1 Factor 1: land use planning

This factor has six items related to zoning and land-use distribution. It includes availability

and accessibility of employment and business establishments, provision of accommodationand mixed development. Land is a natural resource which is indispensable to the ecology

as it supplies food, and supports construction of working places, shelters and other

infrastructure. When a development exceeds the carrying capacity of a land, the ecology is

harmed and environmental sustainability cannot be achieved (Tang and Lam 2000).

6.2.2 Factor 2: quality of life

This factor consists of five variables in which all of them intend to create a living envi-

ronment that increase the feeling of psychological well-being of the public through urban

design. It aims to enhance sense of belongings of the citizens, preserve community ties,

reduce crime, promote local distinctiveness, and facilitate public participation in policy-

making. When the psychological needs of the citizens are gratified within their commu-

nities, they feel happy and their senses of civic pride enhance. Based on an assumption that

people concern what they like, the citizens will pay more attention to their environment

and protect urban ecology.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1920 21 22 23 24 25 26 27 28 29 30

Factor Number

0

2

4

6

8

10

Eigenvalue

Fig. 2 Scree plot of 30 urban design considerations


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Table3

Factorstructureonenvironmentallysustainableurbandesignconsiderations

Urbandesignconsiderations

Factorloadings

(indescendingorder)

%

ofvariance

explained

Cumulative%

ofvariance

Factor1:landusepl

anning

D7.

Accesstow

ork

0.7

36

D6.

Availability

oflocalemployment

0.7

14

D5.

Proximityto

businessactivities

0.7

13

D4.

Establishmentofdifferentbusinessactivitiese.g.,retailshops,banks

0.6

71

D10.

Provisionof

accommodationfordifferentincomegroups

0.5

84

D1.

Mixeddevelopmenti.e.,varioususeswithint

hesamebuildingoranarea

0.5

05

30.1

40

30.1

40

Factor2:qualitylivingcondition

D29.

Senseofbelongingsoncommunity

0.8

21

D27.

Preserving&

facilitatingsocialnetwork

0.8

16

D30.

Securityaga

instcrimes

0.6

30

D26.

Promotiono

flocaldistinctiveness

0.6

24

D28.

Community

involvementinpublicdecisionm

aking

0.5

46

9.9

79

40.1

19

Factor3:conservatio

n&

preservation

D19.

Greenfeatures(designrelated)e.g.,optimizat

ionofnaturallighting&

ventilati

onprovisionofsun

shades,ba

lcony

0.8

24

D18.

Provisionstocontrolpollutione.g.,air&

noise

0.7

89

D20.

Greenfeatures(constructionrelated)e.g.,

inst

allationofenergyefficient/watersavingdevices,use

ofrecycla

ble/durableconstructionmaterials

0.7

64

D2.

Adaptability

ofdevelopmenttothechangingneeds

0.5

32

D17.

Managementofbuildings,facilities&

spaces

0.4

65

6.0

55

46.1

75

Factor4:integrateddesign

D23.

Buildingdesignintermsofappearance,

density,

height&

mass

0.7

47

D25.

Layoutofbuildingandstreets

0.6

33

D9.

Convenience,efficiency&

safetyforpedestrian&

publictransportusers

0.6

31


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Table3

continued

Urbandesignconsiderations

Factorloadings

(indescendingorder)

%

ofvariance

explained

Cumulative%

ofvariance

D24.

Compatibilitywithneighborhood

0.5

53

D15.

Designofopenspacesintermsofappearance

,location,size&

useofmaterials

0.5

51

D3.

Efficientuse

ofland&

space

0.4

73

D8.

Convenience,efficiency&

safetyfordrivers

0.4

38

4.6

15

50.7

89

Factor5:provisiono

fwelfarefacilities

D14.

Provisionof

openspacese.g.,parks,seatinga

reas&

promenade

0.8

72

D12.

Accesstopublicfacilities

0.6

77

D13.

Provisionsforbasicneedsofdisabled,elderly

orchildrenwithproperaccess

0.5

48

D16.

Accesstoopenspaces

0.4

73

D11.

Provisionof

publicfacilitiese.g.,school,healthcareservices,sportsfacilities

0.4

64

4.2

60

55.0

49

Factor6:conservatio

nofexistingproperties

D22.

Rehabilitatio

nofrepairablebuildingstructures

0.7

08

D21

Preservation

ofhistoricalstructures&

features

0.6

16

4.1

78

59.2

28


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6.2.3 Factor 3: conservation & preservation

This factor contains five items which concern preservation of scarce resources and quality

of the built environment, including environmentally friendly design and installations,

pollution control provisions, adaptable development and effective management.Undoubtedly, proper building deposition and design, provision of pollution control mea-

sures, installations of environmentally friendly devices, and effective management

safeguard the environment as they optimize the use of natural resources available in a

community, improve environmental quality of the city, and minimize wastage of scarce

resources. Adaptability of development to the changing needs is also contained in this

factor because highly adaptable building and urban forms can cater for changing political

environment, economic condition, technology level, and demands of the citizens without

leading to premature replacement and unnecessary consumption of resources.

6.2.4 Factor 4: integrated design

This factor includes seven variables pertaining to the design and integration of public and

private spaces in a physical environment. Layout of building and streets, building and open

space design, transportation modes, compatibility with neighborhood, and efficient use of

land & space are included in this category. Buildings and streets should be of appropriate

form, mix and position in order to ensure that the uses are compatible with the surrounding

areas, disruption to the urban spaces and natural landscapes is minimized, and negative

impacts on local climate are avoided. Convenient pedestrian and public transport routes,and efficient motor access are beneficial to the environment by reducing energy con-

sumption and emission of pollutants (CABE and DETR 2001). Well-located and proper

designed open spaces with greenery can mitigate harshness of the environment and

enhance aesthetic value of an urban area simultaneously (Ong and Zhang 2004).

6.2.5 Factor 5: provision of welfare facilities

This factor is composed of five variables which include availability of accessible open

spaces, public facilities and provisions for the vulnerable groups e.g., disabled, elderly orchildren. Open spaces and the premises accommodating public facilities commonly have

lower density than the residential and commercial developments. They provide buffer

zones in congested urban environment which improve air flow between and within

buildings, and minimize urban heat island effect (Lim and Leung 2000). Access to opens

spaces and public facilities for various parties are also included in this factor because the

citizens have more incentives to travel on foot when accessibility of social facilities

increases. In this way, total vehicular movement reduces, and pollutants emitted by

vehicles, traffic noise also diminish substantially.

6.2.6 Factor 6: conservation of existing properties

This factor involves two items showing the importance of building rehabilitation and

heritage preservation in improving environmental sustainability of urban renewal projects.

When the derelict properties are refurbished and the heritage is retained, generation of


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demolition and construction wastes can be minimized (Jones and Clements-Croome 2004).

In addition, repairing and preserving existing structures consume fewer building materials

and natural resources than new construction (Pearce et al. 1996). Therefore, more resources

can be saved and used elsewhere.

To evaluate the internal consistency of each factor, a set of Cronbachs alpha, denotedas a (refer to the Appendix for the details), for the group of items that loads on a single

factor was generated. All extracted factors had a of at least 0.7, which implied that the

reliability for these factors was quite high. The a for each factor is provided in Table 4.

7 Recommendations

In response to the findings of the questionnaire survey and the data analyses, numbers of

recommendations for improving the environmental sustainability can be made. Before

defining the scope of the urban renewal programme, it is suggested conducting a survey toidentify total numbers of buildings that can be rehabilitated with reasonable efforts and

affordable expenses, and those that should be preserved to retain original positive identity

of the renewed area. Once the relevant information has been gathered, the next step will be

preliminary design of the renewal proposal.

In order to establish a vibrant living, business and leisure environment, and to secure an

efficient and effective uses of scarce land resources, it is recommended having a proper

mix of uses including office, residence, retail, welfare service, entertainment, etc. per-

forming in mutually supportive manner. But bearing in mind that quality of the built

environment should not be sacrificed for efficient land use and high density development.

Hence, it is proposed to conduct natural lighting and ventilation assessments beforefinalizing the renewal schemes. Natural lighting assessment is valuable to assess whether

ingress of natural sunlight is maximized by passive solar design and efficient energy

consumption for artificial lighting and cooling is achieved while ventilation assessment is

crucial to determine the effects of the redevelopment proposals on external air movement

for achieving a good micro climate and an acceptable macro wind environment, and to

promote better layout of building blocks. In addition, traffic impact assessment should be

carried out for large scale renewal projects to assess additional traffic generated by the

renewal project, and work out workable measures to minimize its loading on existing

transportation systems. So as to encourage the construction industry to contribute towardsenvironmental sustainability, the Government can consider providing various forms of

incentives e.g., tax reduction, bonus development potential, direct subsidy, etc. when the

developments have incorporated designs/installations reducing future consumption of

natural resources and/emission of pollutants.

Table 4 Reliability of the extracted factors for environmental sustainability

Factor No. of item a

Factor 1: land use planning 6 0.819

Factor 2: quality living condition 5 0.810

Factor 3: conservation & preservation 5 0.776

Factor 4: integrated design 7 0.767

Factor 5: provision of welfare facilities 5 0.798

Factor 6: conservation of existing properties 2 0.712


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Furthermore, to increase the acceptability of the urban renewal programme, adequate

time for reviewing the preliminary proposal design by the local citizens, practitioners and

other concerned parties, and necessary amendment and refinement have to be allowed.

8 Conclusion

This study has highlighted the importance of different urban design considerations in

achieving environmental sustainability of an urban renewal project. Six critical factors

were extracted by exploratory factor analysis on 30 variables produced through a com-

bination of literature review and pilot study. These factors that formed a basis for

evaluation of the environmental sustainability of urban renewal projects include Land

Use Planning, Quality of Life, Conservation & Preservation, Integrated Design,

Provision of Welfare Facilities, and Conservation of Existing Properties.It is believed that such evaluation of critical factors based on the perceptions of different

stakeholders who design, build and use the urban fabric can strengthen the understanding

of local developers, urban designers and government officials on the interrelationships

between spatial and physical characteristics of an area and its environmental qualities

which are very helpful in planning local urban renewal strategies in future.

Of course, to ensure that best practices of urban renewal projects can be established and

effective strategies can be prepared for improving project performance in future, further

studies should be launched to identify the critical factors for enhancing other sustainable

values i.e., economy and social equity, and to verify the applicability and reliability of the

factors.

Acknowledgements This study is supported by research grant provided by the Hong Kong Polytechnic

University

Appendix

Regarding the comments from the reviewer, more information about the terms eigen-

values, eigenvectors and Cronbachs alpha is given in this appendix.

Eigenvalues

An eigenvalue (k) in PAF represents the amount of common variance among the variables

i.e., urban design considerations in this study that are explained by the particular common

factor (Pett et al. 2003). Generally speaking, eigenvalues can be negative and positive but

in factor analysis, all eigenvalues have to be greater than 0 as they represent the amount of

explained variance in the variables associated with a given common factor (Pett et al.

2003). The eigenvalue associated with a given common factor is equal to the sum of the

squared factor loadings for each variable on that factor that is presented in the following

equation:

kn =X

jfn

2


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where

kn

= Eigenvalue of factor n

fn

= Factor loading on factor n

j = 30 urban design considerations

n = 6 factors to be extracted from PAF

Eigenvectors

In order to obtain reliable results from the exploratory factor analysis, computation of a

correlation matrix for the variables i.e., 30 urban design considerations is an important step

to be carried out. An eigenvector of a correlation matrix is a column of weights and each of

these weights is associated with a variable in the matrix (Pett et al. 2003). In this study, a

30 30 correlation matrix is formed and therefore, a total of 30 eigenvectors is generated.

Cronbachs alpha

Cronbachs alpha (a) is the most widely used measure of reliability (Aron and Aron 2002).

Reliability is concerned with the degree to which the results can be replicated and reli-

ability analysis is useful to measure the degree of stability or consistency of measurement

scales and the variables that make them up. According to Aron and Aron ( 2002), a in value

from 0 to 1 was used to measure the internal consistency of the data collected. The higher

the value (i.e. a closer to 1) is, the more is the reliability of the data. They also specified

that it should have a a of at least 0.7 and it was preferable to have a a closer to 0.9 (Aron

and Aron 2002). In this study, reliability analyses were performed to evaluate the internal

consistencies of the extracted factors.

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Design Considerations for Environmental Sustainability in High Density Development a Case Study of Hong Kong