artigo 12b_a review of buildability performancein hong kong

8/18/2019 ARTIGO 12B_A Review of Buildability Performancein Hong Kong

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ABSTRACT

Whilst the Construction Industry Review Committee (CIRC) report highlights the room for improvingdesign buildability in Hong Kong, very few studies have been conducted to examine the issues in thelocal context. This paper, therefore, aims to expound the current state of buildability performance inHong Kong, and recommends strategies for needed improvements. Various indicators, includingconstruction cost, output statistics, and the degree of involvement of construction experts in designdevelopment, have been examined. The analysis has been supplemented and confirmed throughthe interview of practitioners whose views echoed the CIRC’s findings that little emphasis is placed onbuildability during design development. To reduce the waste of resources and the constraints due tocomparatively low productivity, measures to uplift the standards of design buildability are necessary.To this end, the increased use of prefabrication and the benchmarking of building designs using aBuildability Assessment Model (BAM) are proposed. The deliberations in the formulation of the BAMhave built the solid ground works for developing improvement measures to uplift the overall buildabilityof building designs in Hong Kong, in addition to fostering a sustainable built environment.

KEYWORDSDesignProductivityBuildability Assessment Model

A Review of Buildability Performance

in Hong Kong and Strategies for

ImprovementFWH Wong1, PTI Lam1, APC Chan1, and EHW Chan1

1Department of Building and Real Estate, The Hong Kong Polytechnic University

Email: [email protected]

Surveying and Built Environment Vol 17(2), 37-48 December 2006 ISSN 1816-9554


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INTRODUCTION

The construction industry in Hong Kong has longmade major contribution to its GDP, which,through the multiplier effect, has provided

extensive job opportunities for the local workforce(Chiang, et al, 2004). On one hand, the industryhas enjoyed a good reputation in the rapidconstruction of high-rise buildings and the use ofspecialised construction techniques (TDC, 2004).On the other hand, its image has been tarnishedby unsafe site practices and the lack of drive inenhancing long-term competitiveness. Theproblemat ic indus t ry s t ruc ture, whichencompasses exploitative multi - layeredsubcontracting and a fragmented productionprocess, has failed to catch up with surging socialexpectations (HKHA, 2000; CIRC, 2001).These have culminated in knotty problemsincluding, inter alia, higher construction costs overother developed countries (HKHA, 2000; WB,2000).

Against this background, the then-Chief Executiveof the Hong Kong Special Administrative Regionappointed the Construction Industry Review

Committee (CIRC) to examine the current stateof the construction industry and suggest actionsand strategies for improvement. The CIRC (2001)then put forward measures to enhanceconstruction efficiency and productivity, and wereaimed at realising the vision of an integratedconstruction industry that is capable of continuousstrides towards excellence in a market-drivenenvironment. In particular, the report highlightedthat litt le emphasis has been placed onbuildability, and pointed out that considerations

of buildability at the start of project designs wouldlead to the wider adoption of cost-saving andlabour-saving construction technologies, as wellas a minimisation of material waste.

In Hong Kong, where most construction sites arecongested with restrictive surroundings in busyurban areas, buildability becomes critical inensuring smooth project delivery. Constructionprogrammes are usually tight due to high land

costs. Construction difficulties and non-productivereworks result in delays and cost overruns. Inorder to uplift overall project performance,imminent improvement measures are needed,both at the project level and the industry level.

This paper therefore aims to enable anunderstanding of the current state of buildabilityperformance in Hong Kong, and recommendsstrategies to bring about the necessaryimprovements. The authors hope that the papercan arouse attention to be paid to this importantarea and hopefully pave the way for the buildup of a solid foundation for enhancing theproductivity performance of the constructionindustry, resulting in value for the money and amore sustainable built environment.

THE CONCEPT OF

“BUILDABILITY”

Despite the emergence of many interpretations

A Review of Buildability Performance in Hong Kong and Strategies for Improvement

of ‘buildability’ (Griffith, 1987; Ferguson,1989; McGeorge, et al, 1992; SAB, 1993;Low and Abeyegoonasekera, 2001; BCA,2005a), the definition that was developed by

the UK pioneer proponent of buildability, theConstruction Industry Research and InformationAssociation (CIRIA) (1983), is by far the mostsuccinct, and hence, frequently, publicised one.According to this definition, ‘buildability’represents ‘the extent to which the design of abuilding facilitates ease of construction, subject to the overall requirements for the completed building’ . As one of the technical designrequirements, ‘buildability’ can be translated intopractical terms as a factor that facilitates the

ease of construction through a visualisation ofbuilding designs and re-moulding them, ifnecessary, before construction starts. A similarconcept of ‘constructability’ evolved in Australiaand the US, and it deals with both design andmanagement functions. The significance ofaccessibility considerations at the early projectstages of Conceptual Planning and Design onthe construction process is also substantiated(CII Australia, 1996b).


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CURRENT STATE OF

BUILDABILITY PERFORMANCE

Buildability is such an abstract concept that itmakes direct measurements difficult. However,by understanding the current state of buildingperformance related to buildability, we can drawsome inferences from some indicators, as follows.

Construction productivity

As mentioned, buildability can be known as theextent to which a building design can facilitate theefficient use of construction resources and enhancethe ease and safety of construction on site whilst

the client’s requirements are met. Thus, construction

productivity, which is a measure of efficiency andeffectiveness of a contractor’s resources employedto produce a finished facility per unit of time (Chauand Walker, 1988; Oglesby, 1989), can beaffected by the buildability performance of designs.In fact, low productivity has been attributed to theinsufficient attention being paid to buildable design(CIDB, 1992).

It is noted that the Hong Kong construction industryhas experienced a slow growth of productivity(Walker and Chau, 1999). From 1994 to 1998,a declining trend of the total factor productivity ofthe industry was recorded (Walker and Chau,1999). One of the adverse effects of decliningproductivity was manifested in an increase in thebuilding costs of the industry, which was amongstthe highest in developed countries (HA, 2000). Ina report comparing the construction cost in HongKong to those in other countries (WB, 2000), the

labour cost input of a typical building project inHong Kong was found to be higher compared tothat of Singapore, whilst the measure of productivityin terms of output per site worker in the US is higherthan that in Hong Kong.

Involvement of construction experts indesign development

‘Conservative’ has been the adjective used for

years to describe the local constructionindustry, where the majority of constructionprojects have been adopting the traditionalprocurement system (Tam, 1992; Chan,1996; Rowlinson, 1997; Wong and Yau,

1999; Chan and Yung, 2000; Chan, et al,2001). Under the traditional method, theproperty owner employs a consultant on hisbehalf to design and supervise the worksaccording to the design. Contractors do nothave any involvement in developing the designon which they base their work. This practicehas been one of the major hurdles hinderingthe improvement of buildability (Griffith, 1989;O’Connor and Miller, 1994; Uhlik and Lores,1998; Ma, et al, 2001; and Wong, et al,2004). On the other hand, comparatively fewprojects adopt non-traditional procurementmethods, such as management contracting orconstruct ion management, to which acontractor can contribute its constructionexpertise (Tam, 1992; Chan, et al, 2001).The predominant usage of the traditionalprocurement system may be attributable to theculture and inertia under which the industryused to operate. For example, contractors are

sceptical of tendering for Design and Buildprojects because of their inherently higher risk and liability, as well as the fear of losingdesign cost if the contract is not awarded tothem (Lam, 2005).


Numerous studies have reported on theimprovement of buildability that can beachieved through the early involvement ofconstruction experts in the design developmentstage to iron out any foreseeable problems

during construction (Denman, 2001; Low,2001; Arditi, et al, 2002; Fox, et al, 2002;Lam, 2002; Ballal and Sher, 2003; Yang, etal, 2003; Ugwu, et al, 2004; Zin, et al,2004). The fact that the majority of projects inHong Kong still use the traditional procurementsystem means that contractors are seldomengaged during the design stage, resulting insluggish advancement in the pursuit of betterdesign buildability.


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Buildability problems as perceived by practitioners

In a series of interviews with seven seniorconstruction practitioners in Hong Kong, the

widespread problems of buildability were foundto stem from a number of sources (Wong, et al,2004). At the project level, these problems weredue to designers’ lack of knowledge andexperience in construction; designing withoutinput or the involvement of contractors; projectswith increasingly demanding coordinationrequirements (such as sophisticated buildingservices and building automation systems); anignorance of contractors’ proposed changes, alack of communication between the parties

involved, etc. Added to these, the additionaltime taken for a plan to be approved by thegovernment means that consultants would bereluctant to change their basic designs for betterbuildability at the contractors’ advice. They wouldreason that resolving buildability problems shouldbe part of a contractor ’s responsibilities.Contractors, on the other side of the fence, wouldevade this responsibility by saying that they coulddo very little if they are not given the right designs

to work on, especially when the incentive forsaving on time and costs is minimal after thecontract is awarded. The tight timeframe fordesigning and tendering has also resulted indesigners and tenderers not having enough timeto prepare careful designs and pricing,respectively. The highly fragmented roles andspecialisation of various consultants in a projectteam further complicate the responsibility foreffecting buildability improvements.

THE NEED FOR IMPROVING

BUILDABILITY

The above findings are consistent with those ofthe CIRC Report (2001), which spotlighted thelack of consideration on buildability performancein the Hong Kong construction industry. Giventhat a low level of technological competencyhas already restrained local contracting

companies from undertaking large andtechnologically savvy projects (Chiang, et al,2004), the poor buildability of design wouldfurther embroil them in spending additional timeand costs to work out solutions for construction

problems, such as clashes and fixing difficulties.Owing to such inefficient and wasteful processes,the competitiveness of the industry would behampered as a matter of course. As such,measures to uplift the standards of designbuildability in Hong Kong are imminentlyneeded.

Potential benefits of improved buildability aremulti-faceted. Numerous studies across the worldhave pointed to the tangible benefits of time,cost, quality, and safety, as well as intangiblebenefits brought about by improved buildability(Table 1). Apart from these potential gains,buildable designs can also bring aboutincreased productivity in Hong Kong (Chan,1999). To this end, as building designs havesignificant effects on downstream activities (CII,1986; CIDB, 1992; CIRC, 2001; Fox, et al,2002), design professionals should no longerindulge themselves in aesthetic excellence (Smith,

1999), but take a lead to enhancing buildability.For example, careful buildability considerationsof material usage and the construction processat the design stage (Poon, 1997, 2002; Poon,et al, 2004) would help ease the ill-famedpractice of generating considerable amounts ofconstruction and demolition waste (Cheung, etal, 1993; Poon, 1997; HA, 2000; CIRC,2001; EPD, 2004).

MEASURES FOR IMPROVINGBUILDABILITY

Past experience has brought to light the difficultiesencountered in the course of enhancingbuildability. These difficulties include the lack ofconstruction experience on the part of designers;late requests for construction input; a reluctanceto invest additional money and effort during theearly project stages; a lack of mutual respect



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amongst designers and constructors (O’Connorand Miller, 1994); ignorance of the buildabilityconcept (Uhlik and Lores, 1998); a lack ofqualified practitioners to carry out the necessaryimprovements (Ma, et al, 2001); and the

fragmented nature of the construction industry(Wong, et al, 2004). Despite these difficulties,the CIRC (2001) report stated the undesirabilityof introducing statutory controls as a measure toimprove buildability. As such, alternative measuresthat suit the local situation have to be found.

Use of prefabricated and standardisedcomponents

The use of prefabricated parts coupled withstandardised and modular components has beenincreasingly practiced in Hong Kong to enhancingbuildability (Chiang, et al, 2004). By shifting theproduction process from sites to factories,prefabrication reduces wet trades and the use ofunskilled labour on site, thus ensuring more efficientand economic use of contractors’ resources. Thedetailed planning and design of precastcomponents also discipline design professionalsto consider buildability at the early stages. As for

standardisation, it contributes to good buildabilityby reducing the number of mould changes bothon site and in factories, hence improvingproductivity (Griffith and Sidwell 1995; CIIAustralia, 1996a; BCA, 2005a; Low andAbeyegoonasekera 2001; Nima, et al, 1999;Egan, 1998). In view of these benefits, the HousingDepartment has taken the lead in introducingprefabrication and standardisation for its massconstruction of public housing (Wong and Yau,1999; Chiang, et al, 2004). In the private sector,

the government has recently provided incentivesto encourage the use of prefabricated componentsby exempting the wall thickness from plot-ratiocalculations (Buildings Department, 2001).

Assessment of designs for buildability

Whilst the industry continues to explore ways toenhance buildability, such as the use ofprefabricated, standardised, and modular

components, as well as the adoption ofalternative procurement methods (CIRC, 2001;Chiang, et al, 2004), a Buildability AssessmentModel (BAM) for quantifying the buildability ofdesigns is being developed (Wong, et al,

2003). The researchers of the BAM wereinspired by the Buildable Design AppraisalSystem (BDAS) in Singapore, which quantifiesthe buildability of designs based on threeprinciples: Standardisation, Simplicity, and theSingle Integrated Element (BCA, 2005a; Lam,2000). Following the successful experience ofBDAS in Singapore (Poh and Chen 1998; Low2001; Lam 2002), the BAM is designed foruse in Hong Kong as a scoring system takinginto account various factors that are specificallyapplicable to construction in Hong Kong. Forexample, construction sites are commonlyrestricted by surrounding buildings. In addition,considerations for mechanical and electricalsystems have been incorporated into the HongKong BAM system, which should render it morecomprehensive in coverage than its Singaporepredecessor. Figure 1 is a schematic of the BAM,as it is being conceived, in the developmentalprocess. An overall Buildability Score (BS) for a

building design will be calculated based on theconstruction systems and finishing systems used,as well as building features, building servicesaspects, and site specific factors. The requiredinformation for the assessment was extracted fromdesign documents, such as drawings andspecifications. In calculating the overall BS, aset of buildability indices for different componentsof a design was used for the assessment. Theseindices were developed from a number of surveyswith local practitioners.

The overall BS is the summation of componentscores for the five aspects in a building design.The buildability component scores for constructionsystems and finishing systems were calculatedbased on the multiplication of respectiveproportional volume or area coverage and therelated buildability indices. In addition, thedesign is assessed against checklists of designfeatures enhancing buildability, building services



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design features enhancing buildability, and site-specific factors reflecting design considerationswith an aim of adapting to site conditions. Abonus score is given for innovative ideas thathave not been covered by the Model.

The assessment is based only on designdocuments instead of on other process variablesor subjective judgements, though processconsiderations did form part of the initial surveyon the relative importance of a comprehensivelist of buildability attributes. The criteria forassessment were also self-explanatory andunambiguous for users. Therefore, the BAM isobject ive and manageable for designprofessionals who can self-check the buildabilitystatus of their designs. In the long run, the BAMcan be used to benchmark the buildabilityperformance of different building designs, whichcan eventually help design professionals developmore buildable designs when suitable incentivesor punitive measures are introduced. In thisconnection, it is worth pointing out that Singaporeinitially promoted their BDAS with an incentiveapproach, but in an attempt to bring forth thebuildability concept to critical mass, buildability

legislation was enacted to the effect of enforcingminimum Buildable Scores before building planapproval (Lam, 2002). This measure has bornefruit in the form of productivity gains in recent years (BCA, 2005b, 2005c).

CONCLUSION

There is a real and imminent need for the localconstruction industry to improve its overall

buildability performance. As the traditionalconstruction method and procurement approachstill dominate the industry, any abrupt changewould be resisted stubbornly. The BuildabilityAssessment Model (BAM), which is a quantifiedapproach for measuring the buildability ofdesigns, will bring about gradual improvementsthrough a self-perfecting process within the buildingdesign profession in Hong Kong. By using theBAM, building clients will also be able to assess

the buildability performance of their consultants’designs, thereby gaining a picture of the possibleeffects on construction time, cost and quality. Withincreasing awareness of the need to improvebuildability, overall project performance can be

enhanced, leading to an increase in productivity,the maximisation of resources usage, and theprovision of safe workplaces.

RECOMMENDATION FOR

FURTHER STUDIES

Upon its completion, the prototype BAM will bevalidated by using it to score completed projectswith known buildability performance. Building

projects from the public and private sectorscurrently being built or completed have beentargeted for an extensive case study. Before long,it is hoped that a data bank of buildability scoresfor different types of building projects in HongKong can be established for benchmarkingpurposes.

ACKNOWLEDGEMENT

The work described in this paper was fullysupported by a grant from the Research GrantsCouncil of the Hong Kong Special AdministrativeRegion, People’s Republic of China (RGC ProjectNo. PolyU5155/04E).


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“Buildability” refers to the extent to which a design facilitates the efficient use of construction resources and enhances

the ease and safety of construction on site, whilst meeting the client’s requirements. The captioned model will be

used to assess the buildability of a given building design by quantifying the following elements, each carrying their

respective buildability index:

(1) Construction systems adopted for constructing a building carcass

The buildability score for construction systems is calculated based on: (i) the proportional area or volume

coverage, and (ii) the buildability indices for various construction systems, such that:

Proportional volume using particular structural Buildability index for the particular

construction system structure construction system

Coefficient A x ∑ (Vs x BIs) (the structure)

+ Coefficient B x ∑ (A1 x BI1) (the slabs)

+ Coefficient C x ∑ (Ae x BIe) (the building envelopes)+ Coefficient D x ∑ (Ar x BIr) (the roof)

+ Coefficient E x ∑ (Ai x BIi) (the internal walls)

= Buildability score for construction systems

(2) Finishing systems adopted for different locations of a building

Similarly, the buildability score for finishing systems is calculated based on: (i) the proportional area

coverage, and (ii) the buildability indices for various finishing systems.

(3) Other buildability features

Design is assessed against a list of design features enhancing buildability. Examples include the use of

standardized and prefabricated elements, and designing components that are easy to assemble on site.

(4) Aspects of building service design

Design is assessed against a list of building service design features that enhance buildability. Examples

include adequate headroom for ducting and clear details of supports to equipment.

(5) Site-specific factors

Design is assessed against a list of site-specific factors reflecting design considerations in adapting to site

conditions. For example, designs allowing for the movement of a plant with an adequate turning radius and

working space that is adequate for safe construction.

Figure 1: Schematic of the Buildability Assessment Model

A buildability score will be calculated for each of the above five aspects.

The Total Buildability Score of a project is the sum of these buildability scores, together with a bonus

score for innovative ideas that have not been covered by the Model.


artigo 12b_a review of buildability performancein hong kong

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