Journal of Cleaner Production 245 (2020) 118861

Contents lists available at ScienceDirect

Journal of Cleaner Production

journal homepage: www.elsevier.com/locate/jclepro

Comparative analysis of modular construction practices in mainland

China, Hong Kong and Singapore
Zhao Xu a, *, Tarek Zayed b, Yumin Niu a
a
Department of Civil Engineering, Southeast University, Nanjing, China
b
Building and Real Estate Dept, Faculty of Construction and Environment, Hong Kong Polytechnic University, Hong Kong, China

a r t i c l e i n f o a b s t r a c t

Article history: Modular construction is considered as the future of the construction industry. While the sector is
Received 11 May 2019 growing rapidly in some areas, there are still barriers to overcome. For more than two decades, several
Received in revised form regions and countries, such as mainland China, Hong Kong, and Singapore, were using prefabricated/
14 September 2019
precast components to construct high-rise buildings in both private and public sectors. Such practices
Accepted 11 October 2019
Available online 22 October 2019
suffered from several limitations, which warrant the need for modular construction. Modular con-
struction method needs to evolve so as to meet different regional requirements and restrictions, namely
Handling editor: Giorgio Besagni regulations, economy, market and building types. But the regional requirements and constraints on
adopting modular construction remain unexplored. These differences are not widely appreciated. Hence,
Keywords: this research aims to perform comparative analysis of modular construction practices in terms of policies,
Comparative analysis specifications, and real projects in Hong Kong, Singapore, and mainland China. The results of the
Modular construction comparative analysis indicate that Singapore has developed a relatively effective policy system to help
Case studies the construction industry embrace modular construction, while the three regions have not issued
Policies
authoritative specifications. In general, modular construction still needs more support from the gov-
Specifications
ernment, especially in terms of technical guidance and innovation. Cases studies show that the sus-
tainability performance of modular construction is not balanced in terms of the economic, social and
environmental dimensions. The lessons and challenges of modular construction drawn from the cases
are also summarized. The construction industry should work closely with the government to achieve
sustainable construction of modular building. The developed research on modular construction will
increase the understanding of common practices in close countries where the industry in each can
benefit from such practices to advance the domain.
© 2019 Elsevier Ltd. All rights reserved.

1. Introduction assembly management due to limited site conditions, poor

communication among project stakeholders, and technical issues.
For more than two decades, several countries and regions, such These technical issues include water seepage from widows and
as Hong Kong, Singapore, and mainland China, were using pre- bathrooms, improper connection and fittings between pre-
fabricated/precast components to construct high rise buildings in fabricated/precast components, inaccuracy of manufactured
both private and public sectors (Jaillon and Poon, 2009; Xu et al., component sizes, and incompatibility of design and the actual
2015). The prefabricated/precast components improve the quality manufactured components (Li et al., 2016a&b; Tam et al., 2015;
and reduce waste and construction duration when compared to Abdul Rahim and Qureshi, 2019).
traditional construction techniques (Jaillon and Poon, 2009 Therefore, due to the above-mentioned limitations of the pre-
&2014;Li et al., 2014Abdul Rahim and Qureshi, 2019; Lu et al., 2018). fabricated/precast components, the government and industry of
However, prefabricated/precast components face ineffective Hong Kong and Singapore are lenient towards complete building
modules or elements, which are called MiC in Hong Kong or Pre-
fabricated Prefinished Volumetric Construction (PPVC) in
Singapore. Modular construction can reduce the construction time
* Corresponding author. and labor-intensive activities, minimize disruption to the adjacent
E-mail addresses: xuzhao@seu.edu.cn (Z. Xu), tarek.zayed@polyu.edu.hk
(T. Zayed), 220181176@seu.edu.cn (Y. Niu).
services, improve the quality and increase the productivity as well

https://doi.org/10.1016/j.jclepro.2019.118861
0959-6526/© 2019 Elsevier Ltd. All rights reserved.
2 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861

as sustainability. Modular construction is gradually adopted as one the first theme, “Performance of evaluation”, mainly focuses on the
of the significant means to embrace productivity. At least 15 pro- time, economic, social and environmental performance.
jects adopted PPVC in Singapore (Ho et al., 2019). Three large-scale Although the degree of time reduction varies depending on the
projects of modular construction have been completed and two type, size, and complexity of the project, the time-reduction ben-
projects are under construction in mainland China. In Hong Kong, efits of the modular construction have been amply demonstrated in
no modular building has not yet completed, but two public projects multiple cases. For example, Ho et al. (2019) and Rahman and Sobuz
have decided to pilot the MiC technology in response to the Policy (2018) argued that PPVC projects are anticipated to reduce con-
Agenda. struction duration by 2e6 months. Hammad et al. (2019) indicated
Although some projects have already constructed by modular that modular construction can cut down the construction duration
construction technology, modular construction is still not the by about 40% compared with conventional construction.
mainstream. On one hand, the popularity of modular construction The economic factor remains a major concern for the practi-
is related to the performance in real projects, and on the other tioners of construction industry (Hong et al., 2018). Lopez and
hand, it depends on the government’s implementation. The prac- Froese (2016) showed modular construction method is more cost-
tices of government provide greatest impetus for the adoption of effective than panel prefabrication. However, Ho et al. (2019)
modular construction. However, little literature attempted to argued that the modular construction might increase the cost by
explore practices covering both the government and the con- the ranges of 10%e20% and 15%e25% for concrete and steel PPVC,
struction industry. As a result, this research aims to perform respectively. Ho et al. (2019) also reported that the saving in costs
comparative and content analyses of modular construction in terms due to reduction in construction time might be counterbalanced by
of practices, policies, developments, specifications, and real case the cost of large variation in modules sizes, transportation, special
study projects in Hong Kong, Singapore, and mainland China. The crane that carry 25e30 tons, factory and holding yards, site su-
government practices focus on policies and specifications. Mean- pervision and quality control to assure compliance with industry
while, case studies analyze sustainability performance, technology codes.
system, and challenges. Besides, this paper conducts a comparative Social performance evaluation of buildings, especially modular
study among Singapore, Hong Kong and mainland China to explore buildings, are still lacking. Liu and Qian (2019) indicated that the
regional requirements and challenges. Hence, this research can social sustainability of modular building is superior to that of semi-
contribute to improve the understating of practices in each country prefabrication building. The modular construction has obvious
and advance the learning process. Meanwhile, the lessons deprived advantages on the worker’s health and safety, but the advantages
from the practices of three regions can provide insightful recom- are not significant in most indicators.
mendation to close countries on the implementation of modular Environment is one of the most important dimensions in the
construction. assessment of sustainable construction. Tavares et al. (2019)
investigated the energy consumption and greenhouse gas emis-
2. Literature review sions of a modular home by a “cradle-to-site” analysis, as well
emphasized the transport-related impacts that may jeopardize the
Modular construction comprises prefabricated room-sized potential benefits for overseas locations. Quale et al. (2012) figured
volumetric units that are normally fully fitted out in manufacture out that the impacts of modular construction were lower on
and are installed on site as load-bearing ‘building blocks’ (Lawson average than that of conventional construction, but the gaps were
et al., 2012). The modules can broadly be classified into rein- varied within each. Compared with conventional housing, modular
forced concrete, steel and wooden modules. The typical reinforced home reduced energy consumption by 4.6% and greenhouse gas
concrete and steel modules are shown in Fig. 1(a) and (b). emissions by 3% over a 50-year life cycle that excludes replacement
Recently the modular construction has aroused wide attention and the end-of-life phases (Kim, 2008).
from various countries. This widespread interest could be catego- Sustainability construction performance is indispensable for
rized into four topics, namely, (1) Performance evaluation, (2) achieving sustainable development (Shen et al., 2007). The Triple
Technology system, (3) Challenges and recommendations, and (4) Bottom Line (TBL) model, including social, environmental and eco-
Practices of government and construction industry. nomic dimensions, is widely accepted to assess the sustainability
performance (Berardi, 2013). Kamali and Hewage (2016) revealed
2.1. Performance evaluation that the researches concerning the life cycle performance of
modular construction mainly focused on the environmental per-
The lack of understanding of the benefits of off-site construction formance of modular construction. There were gaps in the literature
contributes to the low market share. Therefore, some studies made covering all the dimensions of sustainable construction (i.e., eco-
efforts on quantitatively evaluating the performance of modular nomic, environmental, and social) in modular construction envi-
buildings and comparing it with traditional buildings. Literature on ronment. The absence of a generalized framework made it difficult
to decide the appropriate construction method among different
methods (Kamali and Hewage, 2017). Hence, researches on the triple
bottom line of sustainability performance of modular construction
have become an increasing trend. For example, Kamali and Hewage
(2017) established the sustainability evaluation indicators which is
composed of economic indicators, social indicators and environ-
mental indicators. Hammad et al. (2019) proposed a building in-
formation modelling-based decision support tool to compare
modular and conventional construction through quantifying certain
economic, social and environmental factors.

2.2. Technology system

Figure 1. (a) concrete module, (b) steel module (image via the BCA, 2019a) Researchers have made extensive efforts in connection system
 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861 3

(Chen et al., 2017; Sanches et al., 2018), lateral force-resisting sys- China. Meanwhile related practice had been carried out since 2014
tem (Hong et al., 2011) and seismic design (Annan et al., 2009; (Ren and Chen, 2018; Wang et al., 2014). The first project of modular
Gunawardena et al., 2016; Fathieh and Mercan, 2016), to develop buildings is composed of ten 18-storey public rental buildings in
a more reliable high-rise modular system. There is pressure to Zhenjiang, Jiangsu, whose gross floor area up to 134,500 m2.
apply exclusively modular structures to high-rise buildings due to Nevertheless, as the modular construction is in the exploration
poor wind-resisting system. Therefore, hybrid structures are com- stage in mainland China, the government has not proposed a spe-
mon in high-rise modular buildings, such as, a platform or skeletal cific term to describe the modular construction.
structure, or a concrete core (Lawson et al., 2012; Lacey et al., 2018).
However, a new system presented by Gunawardena et al. (2016) 2.4.2. MiC in Hong Kong
was strategically placed stiff modules to replace the conventional In the mid-1980s, prefabrication along with standard modular
core. Besides, installation and manufacturing tolerance is an urgent designs were introduced into the public sector (Mak, 1998; Zhang
problem in the design of modular buildings (Lawson and Richards, et al., 2018). Recently, the HKSAR Government has been promot-
2010). ing MiC actively. As stated in the Policy Agenda, the HKSAR Gov-
ernment is determined to promote and lead the adoption of MiC.
2.3. Challenges and recommendations The Government injected $1 billion to set up Construction Inno-
vation and Technology Fund (CITF) to encourage innovation in the
Despite the inherent superiority of modular construction, the construction industry. The adoption of modular construction in
implementation of modular construction faces many challenges, within the scope of the funding (Tam, 2018). Meanwhile, the
from planning and design to transportation, and assembly. Ho et al. Housing Authority is planning to adopt a modular construction
(2019) and Abdul Rahim and Qureshi (2019) explored the defects in approach in an elderly home project (Financial Secretary, 2019).
using modular construction technology, which can generally be The MiC Display Centre firstly using MiC in Hong Kong dem-
categorized into the following seven perspectives, (1) lack of onstrates that modules’ performances can comply with the rele-
experience in how to design and install, (2) extensive coordination vant standards and regulations. Besides, two pilot projects are
and organization from design to construction (e.g. complex pro- already in statutory process in response to the Policy Agenda
curement and contracting issues), (3) additional transportation and (Financial Secretary, 2019).
logistics considerations, (4) higher construction costs, (5) complex
inspection and code compliance, (6) massive design work and 2.4.3. PPVC in Singapore
minimal changes, and (7) lack of understanding of modular con- At the outset, the construction industry in Singapore started
struction’s benefits among developers. Besides, few other man- using the prefabricated components since the 1980s (Ting and Jin,
agement issues are arising from the usage of modules, such as 2019). After long time using prefabricated components, the
progress payment framework, new procurement and business Singapore government represented by the Building and Construc-
model, coordination among stakeholders, oversize heavy truck tion Authority (BCA) decided to promote full fabrication module
transportation, and intellectual property of PPVC modules (Rahman technology, which is called Prefabricated Prefinished Volumetric
and Sobuz, 2018; Ho et al., 2019). Construction (PPVC). The PPVC is the synonym terminology of
In addition to the challenges mentioned above, each region faces modular construction that is used in other places, such as North
respective challenges due to different environments when adopt- America.
ing modular construction. Since November 2014, using PPVC method is one of the land
In Hong Kong, the harsh weather conditions and environment sales conditions in some selected land parcels (BCA, 2019b). The
make design and construction more complicated. The module first PPVC project was constructed at the Nanyang Technological
connections should be able to carry the strong wind loads due to University (NTU). This project assembled 1200 steel PPVC modules
Typhoons and heavy rains. Singapore is a country with limited land with a rate of 6e8 modules per day (Chain, 2018; Hwang et al.,
resource and industrial capacity, so most modules are produced 2018; Ho et al., 2019). Private sector is also participating in the
overseas and then imported into Singapore, which significantly development and usage of PPVC. One example is the Changi
increases the transportation cost (Hong et al., 2018a). Moreover, Crowne Plaza Hotel extension project, which shortened the con-
Singapore strictly controls the movement of heavyweight vehicles struction duration by 17% and labor by 40%; however, the cost was
(Land Transport Authority, 2016). increased by 10e15% (Ho et al., 2019).
Generally, in Singapore, an increasing number of apartments,
2.4. Practices of government and construction industry hotels, residential buildings, office buildings and industrial build-
ings are adopting PPVC method to build under the enthusiasm of
In Singapore and Hong Kong, due to the local authority realizes local governments. In contrast, the development of modular con-
the potential of modular construction, the practices mainly come struction in Hong Kong and mainland China lag behind Singapore
from the public sector, while the implementation of modular con- in terms of both the number of project and the range of
struction in the private sector lags behind. Whereas, the corpora- applications.
tions of mainland China are more motivated to promote modular Most of the literature focused on performance evaluation,
construction. Consequently, existing modular construction prac- technology system, and identifying barriers and developing stra-
tices of mainland China were found to be mainly confined to the tegies. Less literature studied the practices of government and
private sector. construction industry, especially policies and specifications which
play an indispensable role in encouraging the construction industry
2.4.1. Modular construction in mainland China to use innovative technologies. For example, prefabricated tech-
In mainland China, Hua and Wang (2017) indicated that the nologies were not popular in the private sector until the HKSAR
application of modular building is gradually moving to multi-storey Government encouraged the adoption of prefabricated materials by
and high-rise buildings. Since 2007, enterprises began to introduce introducing gross floor area recessions (Tam et al., 2015). Therefore,
advanced modular construction techniques actively. Furthermore, it is imperative to examine the modular construction practices.
the enterprises and scholars are working together to make the Nevertheless, these studies related to performance, technology
technological systems to fulfill statutory requirement of mainland system and challenges of modular construction provide a good
4 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861

reference to conduct case studies. Specifically, to make the case

studies valuable, it should cover performance, technology system,
challenges and lessons. According to the perspective of Kamali and
Hewage (2016&2017), the dimensions of sustainable construction
(i.e. economic, environmental, and social) must be considered
during performance evaluation in order to fully reflect the perfor-
mance of modular buildings. Besides, the results of the case studies
can be compared with existing research and then further improve
people’s understanding of modular construction.

3. Research methodology

Based on the above comprehensive literature review, it was

further found that the practices of modular construction was kept
unexplored particularly in Hong Kong and mainland China. This
research intends to explore modular construction practices
including policies, specifications and case study projects. This will
enhance the understanding of modular construction practices and
policies and assist in drawing lessons from the international prac-
tices. The qualitative Content Analysis method, which is used in an
inductive way to provide knowledge and new insights, is suitable to
analyze policies and specifications. However, the research will only
be limited to describe how policies and/or standards are developed
and implemented within a selected nation. Thus, in order to pro-
vide an informative study, the comparative analysis especially the
gap analysis is employed to explore the practices among mainland
China, Hong Kong, and Singapore. Comparative analysis is a com-
mon method used to holistically analyze the differences and simi-
larities in policies (Ronchi et al., 2019; Rodrigues et al., 2017) and
standards (Zhang et al., 2017) between different countries or re- Fig. 2. Overall research methodology.
gions. It is possible to improve the understanding of reality while
maintaining the nature of practices (Seny Kan et al., 2016). It should
be mentioned that the ultimate goal is not to identify an ideal 3.1. Data collection
system through the comparison, but to establish a broad frame-
work that distinguishes the key policies and specifications con- In order to discover how the government promotes the con-
cerning modular construction. It can also be used to clarify the struction industry adopt modular construction and further explore
similarity and differences between regional practices, which are their similarity and differences among three regions, a data
valuable references for further research. collection on policies and specifications related to modular con-
The utilized steps of content analysis include identification, struction is developed.
description of content, and discussion (Elo and Kyngas, 2008). The
overall research methodology is presented in Fig. 2 as follows: 3.2. Policies

(1) In the data collection phase, policies and specifications It is noted that no policy confines the modular construction is
related to modular construction were identified, deprived released in mainland China. However, there are many policies on
and coded. Relevant policies and specifications comprised generic off-site construction, which are also applicable to modular
the bases of qualitative content analysis and comparative construction to a certain extent. To facilitate the analysis, Nanjing,
study. where a demonstration modular building project is located, is
(2) After identifying a total of 12 key policies, the policies were chosen as the sample. The policies concerning modular construc-
classified into goal, control and regulation, economic in- tion to be further distilled are coded and listed in Table 1.
centives, and supporting activities in order to describe the
content. Comparative analysis is integrated into qualitative 3.3. Specifications
content analysis to further identify the gap, overlap or
inconsistency between the three regions. The specifications for modular construction are summarized in
(3) Similarly, six specifications, which were highly related to Table 2. Although these three specifications have known issues of
modular construction, were analyzed and compared ac- inconsistent hierarchy and classification. On the basis of frank
cording to the construction process of modular buildings. recognition of these limitations, the comparisons remain valuable
(4) The comparative analysis of real projects were conducted in for understanding the modular construction.
the case studies, providing valuable experience to the con-
struction industry. To be more specific and focused, this 4. Analysis of government practices
study only focused on high-rise building projects.
(5) According to the results of comparative analysis, the dis- 4.1. Policies
cussion explored the sustainability performance of modular
buildings, the common and regional challenges, the effec- The policies of modular construction implementation are cate-
tiveness of policy system and the guidance of specifications. gorized into goal, control and regulation. After identifying the
 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861 5

Table 1
Summary of policies concerning modular construction.

Item Source

Mainland 1. Opinions on Further Promoting the Development of Assembled Buildings Document

China 2. Implementation Opinions on Accelerating the Modernization of the Construction Industry and Promoting the Upgrade of the Construction Document
Industry
Hong Kong 1. 2018 Policy Address and Policy Agenda Document
2. 2017 Policy Address and Policy Agenda Document
3. Construction Innovation and Technology Fund (CITF) Website
Singapore 1. Building Control (Buildability and Productivity) Regulations 2011 Document
2. 1st Construction Productivity Roadmap Document
3. 2nd Construction Productivity Roadmap Document
4. Integrated Construction and Prefabrication Hub (ICPH) Website
5. Prefabricated Prefinished Volumetric Construction (PPVC) Website
6. Construction Productivity and Capability Fund Website
7. Building Innovation Panel (BIP) Website

Table 2
Summary of specifications concerning modular construction.

Item Hierarchy

Mainland 1. Specification for design of prefabricated monolithic modular building (Exposure Draft) (abbreviated as Specification for design) Association’s
China 2. Specification for construction and acceptance of prefabricated monolithic modular building (Exposure Draft) (abbreviated as standards
Specification for construction and acceptance)
3. Specification for isolation technology of prefabricated monolithic modular building (Exposure Draft) (abbreviated as Specification for
isolation technology)
Hong Kong 1. PNAP ADV-36 Appendix A: Design Requirements for Modular Integrated Construction (Building Department, 2017) Regulations
2. PNAP ADV-36 Appendix B: Quality Control and Supervision of MiC (Building Department, 2017)
Singapore 1. Design for Manufacturing and Assembly-Prefabricated Prefinished Volumetric Construction (Guidebook) Technical
specifications

related policies, economic incentives and support activities are products would account for more than 50% by 2020.
described in detail. Under each category, comparative analysis is
conducted to identify gaps, overlaps or inconformity among the
4.1.2. Control and regulation
three regions. The framework of this section is presented in Fig. 3 in
The control and regulation instrument regarded as the tradi-
which the economic incentives discuss the subsidy, tax breaks, and
tional but the most efficient policy, which can regulate the behavior
award regulations. However, land supply and approval regulations
of practitioners and the construction industry (Spence and
as well as logistic support and coordination with the government
Mulligan, 1995; Huang et al., 2015; Chang et al., 2016). The func-
are discussed for the categories of control/regulations and sup-
tion of this type of policy is to promote the adoption of modular
porting activities, respectively.
construction and to ensure that the performance of modular
building meets mandatory requirements. At present, the control
4.1.1. Goal instruments are mainly land supply and approval.
There are two policies, which are identified as goal, providing
overall guidance to construction industry. Other policies, namely (i) Land supply
control and regulation, economic incentives and supporting activ-
ities, are formulated to achieve goals. The government aimed to The Nanjing government divided the whole city into the cate-
increase productivity in the construction industry by an average of gorized areas: propulsion, active promotion and encouraged pro-
2e3 percent per annum between 2010 and 2020 (BCA, 2010). From motion. Hence, stipulated the prefabrication ratio not less than 50%
2014 to 2018, the goal has been achieved for five consecutive years and 40% in a residential and public building, respectively if the
(BCA, 2019d). However, the Nanjing government formulated the project is located in the propulsion area and single building area
development goal of assembled buildings, namely the pre- more than 5000 m2. Similarly, in Singapore, the Building Control
fabricated buildings would account for more than 30% of new (Buildability and Productivity) Regulations 2011 stipulated that the
buildings, and the residential buildings delivered with finished area of using PPVC shall account for more than 65% of the gross

Fig. 3. The analysis framework of policies.

6 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861

floor area when the building is used for residential purposes. (BCA, To complement incentive system, the “Opinions” also provided a
2011). Because land is so scarce in Singapore, this mandatory series of award measures. For example, if prefabrication ratio is
measure is a strong incentive for the construction sector to adopt more than 50% and the buildings are decorated when delivering,
modular construction method. the Pre-sale Permit certificate can be issued in advance, which is a
great incentive for developers to use off-site construction method.
(ii) Approval In addition, if developers take the initiative to adopt the off-site
construction technology, meanwhile the prefabrication ratio is up
It should be mentioned that the administrative procedures of to 40%, the government will provide incentives in the form of a
modular buildings still refer to administrative procedures of pre- gross floor area recessions.
fabricated components in mainland China. For example, the gov-
ernment cannot issue construction permits until the design 4.1.4. Supporting activities
documents project meet mandatory standards. The main body and The policies mentioned above are a strong impetus for the
the decoration need to be checked and accepted separately. How- construction industry to adopt modular architecture, but some
ever, partial decoration has been carried out in the factory, which obstacles remain unresolved, such as immature technology, low
brings some obstacles to the acceptance of modular building. awareness of benefits of modular construction, and complex
In addition to project approval, in Hong Kong, the supervision is administrative approval. Hence, the government carried out a
not limited to project assembly, but also includes module suppliers. number of supporting activities to address these barriers.
MiC systems must be approved in principle under the pre-
acceptance mechanism before they are manufactured and used. (i) Logistics support
The pre-acceptance mechanism aims to ensure that the materials
and designs should comply with Buildings Ordinance (BO). In To build native off-site manufacturing capacity, the Singaporean
addition, it can share the information on MiC with users and in- BCA formulated a masterplan for the development of Integrated
crease the public’s access to information. In Singapore, the accep- Construction and Prefabrication Hubs (ICPHs), which are multi-
tance framework was established by BCA to ensure that reliability storey advanced factories for manufacturing prefabricated ele-
and durability of proposed PPVC systems can meet the minimum ments (BCA, 2015). BCA has awarded five tenders of ICPH, site area
standards. up to 119,680.5 m2 before 31 August 2018.

(ii) Government coordination

4.1.3. Economic incentives
Apart from control and regulation, economic incentives can also In Singapore, after the BCA realized the difficulties encountered
change the behavior to achieve specific objectives; therefore, it is by the company in the process of obtaining approval, three com-
widely used by the government to encourage the construction in- mittees were established to assist enterprises to develop research,
dustry to adopt modular construction technology. Three kinds of obtain regulatory licenses, and resolve regulatory conflicts since
economic incentives are provided to help the construction sector 2019. These committees included: (1) Research & Innovation
offset the cost premium of adopting modular construction, i.e. Committee, (2) Technology Assessment Committee and (3) Inter-
subsidy, tax break, and award. Agency Coordinating Committee, In particular, the Technology
Assessment Committee will facilitate early resolution of
(i) Subsidy outstanding issues between the applicant that require multi-
agency regulatory assistance and respective authorities and
The HKSAR Government is committed to lead the adoption of agencies if the innovation can lead to at least 20% improvement in
MiC, which is supported by a $1 billion Construction Innovation and productivity or sustainability or the innovations are potential to
Technology Fund (CITF). Contractors and consultants can apply to significantly improve the built environment (BCA, 2019c).
CITF for subsidy when hiring professional consultants, purchasing The policies mentioned above are divided into sub-categories
or renting construction-related equipment, or even purchasing MiC and list in Fig. 4. It clearly presents the existence of some gaps
modules if the project adopting innovative technology (Financial which could be considered in future policy initiatives. Besides,
Secretary, 2019). through horizontal and vertical comparison.
In Singapore, small and medium-sized firms can use Construc-
tion Productivity and Capability Fund (CPCF) to purchase equip- 4.2. Specifications
ment. To further promote the implementation of innovative and
productive technologies in the public sector, a S$150 million Public The main specifications concerning modular construction in
Sector Construction Productivity Fund (PSCPF) was introduced three regions have been identified. This section will elaborate on a
since 2017. In mainland China, from 2016 to 2020, 10 million yuan comparative study from definition, design, manufacture, on-site
was arranged from the city’s urban construction funds for the construction and supervision.
modernization of the construction industry each year.
4.2.1. The definition of modular construction
(ii) Tax break The definition of modular construction, namely “a construction
method whereby free-standing volumetric modules (with finishes,
In Singapore, BCA (2015b) is extending the Land Intensification fixtures, fittings, etc.) are manufactured off-site and then trans-
Allowance (LIA) scheme to provide tax break on capital expendi- ported for constructing buildings” (Building Department, 2017), is
ture, which is required for the construction of ICPHs. In mainland almost the same in Hong Kong and Singapore. In Singapore, it is
China, the research and development expenses incurred in the further emphasized that modules are manufactured in an approved
development of new technologies can be deducted before the en- manufacturing facility using an approved manufacturing method.
terprise pay the income tax. However, the definition of module is “single room or a 3D unit with
certain functions prefabricated in a factory” in the “Specification for
(iii) Award design”. It does not highlight that the module units are integrated
 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861 7

Fig. 4. Policies comparison among mainland China, Hong Kong, Singapore.

(1) All policies mentioned above aim to directly increase the supply of modular buildings in the market, or to provide a lenient environment for the development of
modular buildings, which then indirectly increase the supply. However, the policy to stimulate the demand for MiC is ignored.
(2) The HKSAR Government has not formulated a distinct plan to implement MiC. In addition, the lack of mandatory policy and incentive measures lead to low MiC
adoption in the private sector.
(3) In general, Singapore had issued considerable policies and even set up new organizations to bolster its plan. Mandatory land supply, economic incentives and sup-
porting activities are implemented jointly, which is instrumental to form a virtuous circle and speeds up the application of PPVC method.
(4) The mainland China has issued a series of policies on off-site construction methods without being specific to modular construction. In this context, it is inevitable that
certain current policies do not apply to modular construction and even exert negative influence on implementing this method. If mainland China is to vigorously
promote modular construction, it is essential to recognize the differences between modular construction and prefabricated component construction, and then revise
items that is not applicable for modular construction.
(5) It is worthwhile to refer the pre-acceptance mechanism which had been set up in Hong Kong and Singapore in the context of lacking authoritative technical standards
or regulations.

with structure system, envelope system, MEP system and interior been issued in mainland China and Hong Kong.
decoration system.
4.2.4. On-site construction
4.2.2. Design of modules The “Specification for construction and acceptance” focuses on
Specifications on design of module have been issued in all three the specific operations, such as the requirements of materials,
regions. As shown in Fig. 5, there are great similarities in design transportation, hoisting and assembling. While, the “Guidebook”
considerations among three regions, they all emphasize modules focuses on the critical points of project management on construc-
connection, consideration of construction, structural design of tion site, the main concerns are as follows: (1) access and traffic
modules and fire safety. Moreover, three specifications can com- management, (2) Just-In-Time operation, (3) types of cranes, (4)
plement each other. For example, the “Specification for design” safety. The weight of the module can reach 30 tons or more, the
provided two requirements for modularization, however it did not type of cranes is closely related to the time, cost and safety.
stipulate when to operate it. In the “Guidebook”, it emphasized the Therefore, construction management personnel need to pay
modularization must be conducted simultaneously with the unit attention to the tower crane. The Just-In-Time operation is also
layout design. popular in Hong Kong as the construction sites generally are not
Different specifications also or proposed their own design con- available to unload and storage massive modules.
siderations as different natural environment. For instance, seismic
design was not highlighted in the “Guidebook” and PNAP ADV-36. 4.2.5. Supervision of modular construction
On the contrary, the “Specification for isolation” is specially In Hong Kong, Quality Assurance Scheme and Quality and
compiled to provide provisions for seismic design of modular Qualified Supervision had been carried out to guarantee that the
buildings because the Code of Seismic Design is stringent. In quality of module can satisfy the requirement of ordinances. Under
mainland China, most cities and regions are located in the areas the Quality Assurance Scheme, prefabricated factories are required
where earthquakes are a common occurrence, thus module con- to possess quality assurance certificates. Quality and Qualified Su-
nections should be able to resist the force of the earthquake. pervision made three main requirements, including the content,
frequency and supervisor.
4.2.3. Manufacturing the modules In Singapore, the inspection and quality check are divided four
The production process of reinforced concrete PPVC and steel aspects, namely (1) quality checks; (2) structural works inspection,
PPVC was introduced in the “Guidebook” respectively. Each step is (3) MEP works inspection and (4) architectural works inspection.
equipped with a corresponding picture, allowing practitioners to There is massive inspection work during the architectural works,
understand the module production process intuitively. Except the among which water tightness inspection is a critical point.
“Guidebook”, no excellent specification for module production has In mainland China, the supervision is mainly carried out in the
8 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861

Fig. 5. Comparison of design considerations in three specifications.

hoisting and assembling process. It is found that the “Specification and the frequency of inspections clearly as those of Hong
for construction and acceptance” is still based on certain preceding Kong.
standards and codes, and some previous items are emphasized or (3) Hierarchy: most of the supervision requirements in the PNAP
adjusted to fit the modular construction. ADV-36 and “Specifications for construction and acceptance”
The comparison of the supervision of module construction are mandatory, while the supervision in the “Guidebook” are
among three regions is shown in Table 3, and the differences are list almost optional.
as follows: (4) Inspector/supervisor: The “Specification for construction and
acceptance” mainly provides reference for the contractors.
(1) Phrase: the inspection and supervision in the “Guidebook” While the “Guidebook” provides workers in prefabricated
and PNAP ADV-36 are merely limited to the production factories with how to inspect modules. PNAP ADV-36 Ap-
phrase, while the supervision in the Specification has an pendix B proposes supervision requirements for AP, RSE and
orientation towards on-site supervision. the Registered Contractor (RC) (Building Department, 2017).
(2) Content: both “Guidebook” and “Specification for construc-
tion and acceptance” do not state the inspectors’ appointees

Table 3
: Comparison of the supervision of module construction.

Mainland China Hong Kong Singapore

Phase Manufacture and on-site construction Manufacture Manufacture

Supervision content (i) Production Testing; (i) Quality Assurance Scheme; (i) Quality Checks;
(ii) Entry Detection; (ii) Quality and Qualified Supervision. (ii) Structural Works Inspection;
(iii) Connection Detection; (iii) MEP Works Inspection;
(iv) Structure Detection. (iv) Architectural Works Inspection.
Hierarchy Mandatory Mandatory Optional
Inspector/Supervisor Contractors AP, RSE and the Registered Contractor (RC) Workers in prefabricated factories
 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861 9

5. Analysis of case studies technology to the high-rise residential building in mainland China.
The walls of the modules were the steel frame filled with light-
The selected case studies include the fire services accommo- weight concrete. Only trusses were set at the top of the module to
dation, student residences, and residential building. The general facilitate the placement of pipelines and equipment. The schematic
information about 4 cases is presented in Table 4. Based on the diagram of module system is given in Fig. 6(a). Each apartment was
results of the literature review, the case studies will provide a composed of five kinds of modular units, as shown in Fig. 6(b). The
comparative analysis focusing on the sustainable construction, size of module was: from 2.78m up to 5.51m width (3.79m on
including economic, environmental and social dimensions. In average), from 2.34 m up to 9.36m length (5.36m on average), 2.9 m
addition, the technology system and challenges will be analyzed height. The living room (36.18m2) was the largest module.
and compared. Thus, some valuable lessons will be learned and Currently, in mainland China, due to lack of experiences in
summarized in this section. modular construction, the modular construction project is regu-
lated strictly by the local government departments, which brought
some difficulty to the approval of this project. Therefore, a lot of
5.1. The on-going modular construction projects
time and efforts are devoted to the design phase to ensure the
feasibility of the drawing. The owner, architects, module suppliers
jointly participated in the drawing deepening process, which con-
Case 1. : The Disciplined Services Quarters for the Fire Services tributes to the successful delivery of the project. The participants
Departmental at Pak Shing Kok, Tseung Kwan O, is the first pilot focused on the following critical points in the design phase:
project using MiC in Hong Kong. This project turns a new page in
the construction industry of Hong Kong. (1) Story height
Case 2. : The Student Residence at Wong Chuk Hang Site for the
At first the floor to ceiling height less than 2700 mm. Due to
University of Hong Kong, has been selected by the Development
story height has a significant impact on the living comfort, project
Bureau as a pilot MiC project. Funding for this project has been
team carried out two optimizations to solve the problem. On one
approved by the Finance Committee of the Legislative Council.
hand, the trusses in the middle of the modules were canceled to
These two pilot projects from Hong Kong’s public sectors are
expected to demonstrate the feasibility of modular construction
method in tall buildings in local environment.
A large number of workers can move away from risky site ac-
tivities, bringing about better safety, productivity, and quality.
Modular construction is expected to achieve green construction
because of reduced waste and site nuisance.

5.2. The completed modular construction projects

Case 3. Lan Mountain residential building in Nanjing: The case of

residential building in Nanjing firstly applied modular construction Fig. 6. (a) Module system, (b) Typical plan layout.

Table 4
: Completed and on-going modular construction project overview.

Project overview

1. Disciplined Services Quarters for the Fire Services DepartmentC Address: Pak Shing Kok,
Tseung Kwan O, Hong Kong
C Number of floors: 16 to 17 floors
C Number of Quarters: 5 quarters blocks, 648 units
C Commencement Date: September 2018
C Expected Completion Date:2021
2. Student Residence at Wong Chuk Hang Site for the University of Hong KongC Address: Wong
(image via the University of Hong Kong) Chuk Hang,
Hong Kong
C Number of floors: 20 floors
C Number of rooms: 1224 hostel rooms
C Commencement Date: 1st Quarter, 2019
C Expected Completion Date: before 4th Quarter, 2023
3. Residential building in NanjingC Address: Jingtian Road, Nanjing, mainland China
C Number of blocks and floors: 3 blocks, 11 floors
C Number of Modules: 1285 modules
C System: light concrete modules with conventional core
C Duration: April,2015eApril 2018
4. Residential Halls at Nanyang CrescentC Address: Nanyang University, Singapore
(image via the BCA) C Number of blocks and floors: 4 blocks, one 11-storey and three 13-storey 16 floors
C Number of Modules: 676 modules
C System: steel modules with conventional core and podium floors
C Duration: December 2014eJune 2017
C Performance: 25% manpower reduction; 40% improvement in productivity; the total cost was
$132.003 million, equivalent to $2719 per square meter.
10 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861

ensure the net height up to 2700 mm. On the other hand, the modular construction did not save time in this project. The benefit
elevation of the surrounding trusses around the module was of reduction in time did not be materialized in this project for two
increased by 15 mm. The module units are integrated with struc- reasons. First, it can be derived from Fig. 9(a) that more than 50% of
ture system, envelope system, MEP system and interior decoration the time was spent in the wet trade, i.e. the construction of the core
system. Hence, the installation and usage of central air conditioning and the façade. In order to construct a reliable anti-lateral system,
were greatly affected by this change. The technical personnel had to the core is complicated with high the content of the steel bar. At the
recalculate the bearing capacity of the trusses. same time, the construction is not easy to operate due to the nar-
row working space. Second, a large number of finished products
(2) Waterproof were reworked and repaired due to the poor protection and the
unreasonable decoration processes, which somewhat affected the
Compared with the traditional cast-in-place building, pre- schedule.
fabricated building is prone to water seepage. Hence the balcony, The cost of each module consists of three parts: module pro-
toilet and kitchen were well designed to tackle this problem. For duction and interior decoration, lifting and external insulation, and
instance, the floor elevation of the balcony was lower than that of façade decoration. Module cost drivers are presented in Fig. 9(b)
the living room, as shown in Fig. 7(a). Additionally, in order to avoid The façade of the module adopted ceramic plate for reliable
water seepage between modules, the root of the wall also took waterproof with high price. Hence, it is necessary to study a more
waterproof measures. Moreover, ceramic plates were laid on the economical facade method, such as paint and integrated board.
façade of the buildings so that the water seepage was solved Sustainable construction was achieved using modular con-
effectively, but the ceramic plate is expensive. struction technology with less construction material wastage and
carbon emission in Lan Mountain residential buildings. Construc-
(3) Arrangement of pipeline tion material wastage is reduced by 85%, carbon emission reduced
by 51.7 kg/m2, which is equivalent to saving 19.88 kg of standard
The position of the pipe was accurate to the millimeter and was coal. At the same time, the improvement in the airtightness of the
fully compound with the module structure to avoid conflicts. In window modified the thermal insulation performance of the
addition, the pipelines were orderly arranged for ease of mainte- enclosure structure and reduced the expenditure of using air
nance, as shown in Fig. 7(b). The pipeline between modules did not conditioning.
go through the wall, and its connecting hinge is located above the Due to the lack familiar projects for reference, this project
door. As shown in Fig. 7(c), a hole was reserved above the door to encountered many challenges. The first challenge is difficult
provide operating space for the secondary connection of the pipe at approval, from drawing approval to acceptance. Secondly, there is
site. massive coordination work for more than 4 design teams. Intel-
Designers fully recognized that the thickness of materials, even lectual property is also a serious issue. The module supplier pro-
construction methods will affect the elevation of the ground. Thus, vided the module’s drawings as their own intellectual property,
the floor elevation, thickness of materials, as well as construction which affected the communication between participants. Another
methods were confirmed before modules were manufactured to challenge is the layout of pipes, lines and equipment, which is
ensure that the height difference between rooms (e.g., the core caused by reduced floor-to-floor height. In addition, a high pro-
floor and the indoor floor) is reasonable. portion of factory decoration led to an increase in the cost of
Modules were manufactured and prefabricated in Zhenjiang, finished product protection and secondary maintenance. Finally,
approximately 100 km from the construction site. In order to economy of scale has failed to materialize. The gross floor area of
discover problems promptly, two mock-up modular apartments the in-site work is only about 10,000 m2. On one hand, the owner
were produced before the manufacture of modules. The inter- cannot find a strong contractor and on the other hand, it is
viewee also highlighted that the inspection carried out by the impossible to organize the flow construction similar to the tradi-
owner at the manufacturing factories was a crucial factor in tional construction mode.
ensuring that the completed modules meet the requirements of the
Case 4. The Residential Halls at Nanyang Crescent: Nanyang
contract.
Technological University took the challenge to be the first institu-
Module manufacture and the on-site construction were carried
tion to use PPVC in 2013 in Residential Halls at Nanyang Avenue.
out simultaneously. The modules were assembled after installing
Subsequently, Residential Halls at Nanyang Crescent continued to
foundation beam. Fig. 8 describes how the modules were hoisted
adopt PPVC in 2015. PPVC construction method has been imple-
and assembled in the Lan Mountain residential buildings. It took
mented successfully in the Residential Halls at Nanyang Crescent
187 days to install 1285 modules. The entire construction duration
with higher quality finishes, less labor-intensive activities on site,
lasted 665 days. Compared with the traditional construction, using
better housekeeping and reduction of wastage. The C has won the

Fig. 7. (a) Balcony manufacture in the factory, (b) Pipeline arrangement, (c) Pipeline connecting hinge.

(4) Elevation
 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861 11

Fig. 8. The steps of module installation in Residential buildings (Nanjing, China).

Fig. 9. Related statistics on modular construction.

Construction Productivity Awards (CPA) for its outstanding per- guarantee that the quality of modules could satisfy the requirement
formance in improving productivity. of the contract. Meanwhile, transnational transport and quality
The modules were modularity with high repetition and low inspection dramatically increased the project’s construction cost.
variation in types to reap the full benefits of DfMA. However, the The transportation, prefabrication and supervision account for 15%
facade was customized with a view of designing a unique and non- and 70% of module costs, respectively, as shown in Fig. 9(c).
monotonous facade design. The connections between modules no The modules were massive with maximum dimensions of
longer required welding, but only a bolt and tie plate assembly. 3.25 m width, 10.76 m length, and 3.14 m height. The largest mod-
As shown in Fig. 10, the conventional podium floors were con- ules weighed 17.6 tons, and the mean steel tonnage of each module
structed to handle sloping terrain; the transfer slab was con- was 4.8 tons. Therefore, the contractor selected the crane with high
structed to connect conventional podium floors and steel-type bearing capacity, which take up 15% of PPVC cost as shown in
modules; the lateral stability was offered by centralized conven- Fig. 9(c).
tional core. Noise and pollution are significantly reduced at the construction
The construction duration was only 6 months with the floor site. Due to less need for on-site workers and short construction
cycle shortened to approximately 4 days. It is estimated that only 7 time, a corresponding reduction in the likelihood of injury is real-
workers were required to install a module in 30 min. ized. At the same time, less work-at-height also reduces fall acci-
The steel chassis of modules were manufactured in Zhangjia- dents. Although there is no precedent for the removal and recycling
gang, China. After the modules were imported into Singapore, the of modular buildings, the potential for steel reuse is still exists
rest of external and internal finishes such as lighting, windows and because the modules can be easily detached.
fans were carried out in fit-out factory. Hence, inspections carried The reduced floor-to-floor height, intellectual property, and
out periodically at the local and overseas manufacturing factories to massive coordination work issues are also existed in the case of
12 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861

Fig. 10. 3D view of the residential Halls at Nanyang crescent (image via chain).

Residential Halls at Nanyang Crescent. In addition, design and further pursue the balance of sustainability construction.
submission needs to be completed within a tight 20-month period.
Another challenge is the high transportation and supervision costs. 6.2. Challenges of adopting modular construction
Besides, PPVC modules needed to be stored elsewhere due to
Fitting-up Yard with limited storage space. The increase in crane The three challenges identified in the case study, namely intel-
capacity is accompanied by a significant increase in operation costs. lectual property, reduced floor height and finished product pro-
The comparison of the two cases is captured in Table 5. tection, are not mentioned in previous literature reviews, which
should be considered in future studies. Besides, the challenges vary
from region to region. There are still lots of barriers exist, which
6. Discussion
need champions of the industry to lead with innovative, economic,
sustainable, and clean production solutions.
6.1. Sustainable construction performance

The economic dimension of sustainable construction is pri- 6.3. Effectiveness of policy system
marily concerned with construction time and cost (Kamali and
Hewage, 2017). According to the case studies, the hoist speed was Currently, in mainland China and Hong Kong, the authorities do
undoubtedly rapid. However, modular construction needed longer not have mandatory regulations and sufficient incentive measures,
preparation before construction. Additionally, the results of the which are specific to modular construction, to encourage practi-
case studies reveal that the cost premium ranges from 15% to 20%. tioners to embrace modular construction method. In contrast, the
From economic perspective, modular construction did not perform Singaporean government has issued obligatory regulations that
well as traditional construction method. PPVC should be adopted in the selected areas and launched
However, the merits of modular construction in the environ- ambitious package of measures to fully implement PPVC. What’s
mental and social dimensions cannot be ignored. The environ- more, Singapore’s policy system is more effective. In the case 4, the
mental advantages of modular construction are clear, which three challenges, namely tight timeline for design and submission,
include the reduction in wastage, greenhouse gas emissions, noise transportation and supervision costs, and crane, can be addressed
and dust. It is estimated that material wastage was reduced by 85%, to some extent through corresponding economic incentives and
greenhouse gas emissions reduced by 51.7 kg/m2. supporting activities, such as subside, Inter-Agency Coordinating
While there are different perspectives on the criteria of the Committee and ICPH masterplan.
social dimension (Zuo et al., 2012; Goel et al., 2019), workforce The Singapore sets a model for other countries to establish their
health and safety is one of the main principles (Hill and Bowen, own policy system for implementing modular construction.
1997; Kamali and Hewage, 2017). Adopting modular construction Nevertheless, modular construction is not yet mature and require
can improve workers’ health and safety because of less work-at- strong support from governments, including Singapore, to promote
heights. The construction industry is unattractive among young greater progress and breakthroughs in critical technologies.
people because the construction industry is perceived as boring
and dangerous. This phenomenon is expected to change when the 6.4. Guidance of specifications
construction industry is actively embracing innovative technolo-
gies like module construction. The “Guidebook” provides the elaborate but optional practical
Economic sustainability is intricately linked to the social and tips. On the contrary, the PNAP ADV-36 only imposes mandatory
environmental dimensions (Chang,2016). According to Hill and requirements on quality control and supervision. Though mainland
Bowen (1997), despite the initial cost premium, the two cases can China has released association’s standards in January 2018, the
be economically sustainable, as environmental and social sustain- certain content of specifications does not conform to the charac-
ability can bring long-term benefits for stakeholders. In the future, teristics of modular construction. It indicates that the modular
the construction industry should work with the government to construction is still in its infancy, and the mature and instructive
 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861 13

Table 5
The comparison between Residential buildings in Nanjing and Residential Halls at Nanyang Crescent.

Item Case 3: Residential buildings in Nanjing, China Case 4: Residential Halls at Nanyang Crescent, Singapore

Gross Floor Area and Percentage GFA

Gross Floor Area (entire development) 38,695 m2 48,550 m2
Gross Floor Area (using PPVC) 28,401 m2 20,600 m2
Percentage GFA (entire development) 73% 42%
Percentage GFA (floor areas above 81% 53%
podium levels)
Technology system
Technology system Conventional core þ module Conventional core þ module
Module
Material Steel modules with light weight concrete floors Steel module
and walls
Dimension W: 3.79 m on average W: 2.97 m on average
L: 5.36 m on average L: 8.1 m on average
H: 2.9 m H: 3.14 m
Total number of modules 1285 676
Total type of typical modules 10 8
Production processes Factory 1 (production and internal Factory 1 (production of the steel chassis)/Factory 2 (fit-out of external and
decoration)/delivery internal finishes)/Delivery
Decoration ratio (factory/on-site) 60%/40% 70%/30%
Time
Duration 37 months 31 months
Hoist speed 4-8 modules a day 6-8 modules a day
Floor cycle construction 3.5 days 4 days
Cost
Construction Cost $ 865.11/m2 $ 2548/m2
Cost premium 16%e18% cost premium 15e20% cost premium
Manpower
Manpower 9-10 workers were required to install a module 7 workers were required to install a module (40% saving)
(20% saving)
Challenges
Common challenges 1. Floor-to-floor height
2. Intellectual property and 3. Massive coordination work
Regional challenges 1. Difficult approval 1. Tight timeline of design and submission
2. Finished product protection cost 2. Expensive transportation costs and supervision costs
3. Lack of economy of scale 3. Limited storage space
4. Initial crane cost

standards or specifications are vacant. construction especially module production and supervision. Sec-
ondly, many barriers are distinguished through the comparative
analysis of practices, which need researchers make efforts to tackle.
7. Conclusions
Acknowledgements
Modular construction has been improving constantly to make
the modules better meet the specific requirements of each project Financial supports from National Natural Science Foundation of
and region. This paper aims to conduct a comparative analysis China (71302138) and Priority Academic Program Development of
focusing on modular construction practices among three regions, Jiangsu Higher Education Institutions (1105007002) in China are
Hong Kong, Singapore and main land China. gratefully acknowledged. This is also to acknowledge that the
The policies related to modular construction are further divided project leading to publication of this paper is partially funded by
into four categories, namely goal, control and regulation, economic the Hong Kong branch of the Chinese National Engineering
incentives and supporting activities. Combined with the challenges Research Centre for Steel Construction (CNERC), China.
identified in the case studies, it shows that Singapore has estab-
lished a fairly comprehensive policy system to encourage the con- References
struction industry adopt modular construction, albeit less support
for technical innovation. Additionally, it reveals that no mature and Annan, C.D., Youssef, M.A., El Naggar, M.H., 2009. Seismic overstrength in braced
authoritative standards and specifications, which can guide the frames of modular steel buildings. J. Earthq. Eng. 13 (1), 1e21.
Abdul Rahim, A., Qureshi, S.L., 2019. A review of IBS implementation in Malaysia
practitioner to use modular construction method. The case studies and Singapore. Planning Malaysia 16 (2), 323e333.
provided a comprehensive analysis focusing on sustainable per- BCA, 2010e2019. 1st Construction Productivity Roadmap surfed at July. 30. https://
formance, technology system, challenges and lessons. It indicates www.bca.gov.sg/newsroom/others/pr03032011_CPA.pdf.
BCA, 2011. The Building Control (Buildability and Productivity) Regulations 2011.
that the merits in economic dimension is not significant as those of BCA, 2015e2019. 2nd Construction Productivity Roadmap surfed at July. 30. http://
social and environmental dimensions due to cost premium and www.nas.gov.sg/archivesonline/data/pdfdoc/20170307002/Annex%20A%20-%
slight time advantage. The construction industry should work with 202nd%20Construction%20Productivity%20Roadmap.pdf.
BCA, 2019a. Prefabricated Prefinished Volumetric Construction (PPVC). https://
the government to further pursue the balance of sustainable
www.bca.gov.sg/BuildableDesign/ppvc.html, surfed at Mar. 22, (2019).
construction. BCA, 2019b. Construction Productivity and Capability Fund. https://www.bca.gov.
The research has several implications for the research commu- sg/CPCF/cpcf.html, surfed at Mar. 22, (2019).
nity. Firstly, it shows that the implementation of modular con- BCA, 2019c. Building Innovation Panel (BIP). https://www.bca.gov.sg/cpc/BIP.html,
surfed at Mar. 22, (2019).
struction needs lots of support from governments. Meanwhile, BCA, 2019d. Project Productivity. https://www.bca.gov.sg/productivity/site_
practitioners still need to heightened awareness of modular productivity_statistics.html. surfed at July. 30, (2019).
14 Z. Xu et al. / Journal of Cleaner Production 245 (2020) 118861

Berardi, U., 2013. Clarifying the new interpretations of the concept of sustainable Li, C.Z., Hong, J., Xue, F., Shen, G.Q., Xu, X., Luo, L., 2016a. SWOT analysis and Internet
building. Sustain. Cities Soc. 8, 72e78. of Things-enabled platform for prefabrication housing production in Hong
Building Department, 2017. PNAP ADV-36. https://www.gov.hk/en/theme/bf/pdf/ Kong. Habitat Int. 57, 74e87.
PNAPADM-19.pdf. Li, C.Z., Hong, J., Xue, F., Shen, G.Q., Xu, X., Mok, M.K., 2016b. Schedule risks in
Chain, P., 2018. Prefabricated prefinished volumetric construction (PPVC) in prefabrication housing production in Hong Kong: a social network analysis.
Singapore: NTU case studies. In: International Conference on Modular Inte- J. Clean. Prod. 134 (15), 482e494.
grated Construction, Kowloon, Hong Kong. Liu, S., Qian, S., 2019. Evaluation of social life-cycle performance of buildings:
Chang, R., Soebarto, V., Zhao, Z., Zillante, G., 2016. Facilitating the transition to theoretical framework and impact assessment approach. J. Clean. Prod. 213,
sustainable construction: China’s policies. J. Clean. Prod. 131, 534e544. 792e807.
Chen, Z., Liu, J., Yu, Y., Zhou, C., Yan, R., 2017. Experimental study of an innovative Lopez, D., Froese, T.M., 2016. Analysis of costs and benefits of panelized and
modular steel building connection. J. Constr. Steel Res. 139, 69e82. modular prefabricated homes. Procedia Eng. 145, 1291e1297.
Elo, S., Kyngas, H., 2008. The qualitative content analysis process. J. Adv. Nurs. 26 (1), Lu, W., Chen, K., Xue, F., Pan, W., 2018. Searching for an optimal level of prefabri-
107e115. cation in construction: an analytical framework. J. Clean. Prod. 201 (10),
Fathieh, A., Mercan, O., 2016. Seismic evaluation of modular steel buildings. Eng. 236e245.
Struct. 122, 83e92. Mak, Y., 1998. Prefabrication and Industrialization of Housing in Hong Kong[D]. The
Financial Secretary, 2019. Modular Integrated Construction. https://www.fso.gov. Hong Kong Polvtechnic University, Hong Kong.
hk/eng/blog/blog130119.htm, surfed at Mar. 22, (2019). Quale, J., Eckelman, M.J., Williams, K.W., Sloditskie, G., Zimmerman, J.B., 2012.
Goel, A., Ganesh, L.S., Kaur, A., 2019. Deductive content analysis of research on Construction matters: comparing environmental impacts of building modular
sustainable construction in India: current progress and future directions. and conventional homes in the United States. J. Ind. Ecol. 16 (2), 243e253.
J. Clean. Prod. 226, 142e158. Rahman, M., Sobuz, B.H., 2018. Comparative study of IPS & PPVC precast system- a
Gunawardena, T., Ngo, Tuan, Mendis, P., Alfano, J., 2016. Innovative flexible struc- case study of public housing buildings project in Singapore. In: Proceedings of
tural system using prefabricated modules. J. Archit. Eng. 22 (4), 1e7. the 4th International Conference on Civil Engineering for Sustainable Devel-
Hammad, A.W., Akbarnezhad, A., Wu, P., Wang, X., Haddad, A., 2019. Building in- opment (ICCESD). KUET, Khulna, Bangladesh.
formation modelling-based framework to contrast conventional and modular Ren, Z., Chen, M., 2018. A new exploration of construction method on the design of
construction methods through selected sustainability factors. J. Clean. Prod. the temporary office area for enterprises at Xiong’an civic service center.
228, 1264e1281. J. Archit. (08), 10e13. In Chinese).
Hill, R.C., Bowen, P., 1997. Sustainable construction: principles and a framework for Rodrigues, E.E.C., Rodrigues, J.P.C., da Silva Filho, L.C.P., 2017. Comparative study of
attainment. Constr. Manag. Econ. (3), 223. building fire safety regulations in different Brazilian states. J. Build Eng. 10,
Ho, K.M., Lam, J.P., Max, S., 2019. Pre-Fabricated Pre-finished Volumetric Con- 102e108.
struction (PPVC) for Residential Projects. Threesixty Cost Management Pte Ltd. Ronchi, S., Salata, S., Arcidiacono, A., Piroli, E., Montanarella, L., 2019. Policy in-
Web. https://surbanajurong.com/wp-content/uploads/2018/08/1.-PPVC-Final-. struments for soil protection among the EU member states: a comparative
pdf. surfed at Jan. 28(2019). analysis. Land Use Policy 82, 763e780.
Hong, S.-G., Cho, B.-H., Chung, K.-S., Moon, J., 2011. Behavior of framed modular Sanches, R., Mercan, O., Roberts, B., 2018. Experimental investigations of vertical
building system with double skin steel panels. J. Constr. Steel Res. 67, 936e946. post-tensioned connection for modular steel structures. Eng. Struct. 175,
Hong, J., Shen, G.Q., Li, Z., Zhang, B., Zhang, W., 2018. Barriers to promoting pre- 776e789.
fabricated construction in China: a costebenefit analysis. J. Clean. Prod. 172, Seny Kan, A.K., Adegbite, E., El Omari, S., Abdellatif, M., 2016. On the use of quali-
649e660. tative comparative analysis in management. J. Bus. Res. 69 (4), 1458e1463.
Hua, K., Wang, Z., 2017. Research and application of structural system in high-rise Shen, L., Hao, J.L., Tam, W.Y., Yao, H., 2007. A checklist for assessing sustainability
modular building. Low Temp. Arch. Technol. 39 (05), 31e33 (in Chinese). performance of construction projects. J. Civ. Eng. Manag. 13 (4), 273e281.
Huang, B., Mauerhofer, V., Geng, Y., 2015. Analysis of existing building energy saving Spence, R., Mulligan, H., 1995. Sustainable development and the construction in-
policies in Japan and China. J. Clean. Prod. 112, 1510e1518. dustry. Habitat Int. 19 (3), 279e292.
Hwang, B.-G., Shan, M., Looi, K.-Y., 2018. Key constraints and mitigation strategies Tam, K.L., 2018. Are we ready? Pilot modular integrated construction (MiC) project
for prefabricated prefinished volumetric construction. J. Clean. Prod. 183, of student residence at Wong Chuk Hang site for the university of Hong Kong.
183e193. In: International Conference on Modular Integrated Construction, Kowloon,
Jaillon, L., Poon, C.S., 2009. The evolution of prefabricated residential building Hong Kong.
systems in Hong Kong: a review of the public and the private sector. Autom. Tam, V.W.Y., Fung, I.W.H., Sing, M.C.P., Ogunlana, S.O., 2015. Best practice of pre-
ConStruct. 18 (3), 239e248. fabrication implementation in the Hong Kong public and private sectors.
Jaillon, L., Poon, C.S., 2014. Life cycle design and prefabrication in buildings: a re- J. Clean. Prod. 109, 216e231.
view and case studies in Hong Kong. Autom. ConStruct. 39, 195e202. Tavares, V., Lacerda, N., Freire, F., 2019. Embodied energy and greenhouse gas
Kamali, M., Hewage, K., 2016. Life cycle performance of modular buildings: a critical emissions analysis of a prefabricated modular house: the "Moby" case study.
review. Renew. Sustain. Energy Rev. (62), 1171e1183. J. Clean. Prod. 212, 1044e1053.
Kamali, M., Hewage, K., 2017. Development of performance criteria for sustain- Ting, S.K., Jin, H.F., 2019. Prefabrication in the Singapore Construction Industry.
ability evaluation of modular versus conventional construction methods. White paper. https://pdfs.semanticscholar.org/9450/
J. Clean. Prod. 142 (4), 3592e3606. 18d67bc8865b855f081d10435a5e5bf37cd2.pdf, surfed at Mar. 22.
Kim, D., 2008. Preliminary Life Cycle Analysis of Modular and Conventional Housing Xu, G., Zhong, R.Y., Yang, H., Huang, G.Q., 2015. Cloud asset-enabled prefabrication
in Benton Harbor, Michigan. University of Michigan, Ann Arbor, MI, USA. transportation service for public housing production in Hong Kong. In: IEEE
Lacey, A.W., Chen, W., Hao, H., Bi, K., 2018. Structural response of modular buildings International Conference on Automation Science & Engineering. IEEE.
e an overview. J. Build Eng. 16, 45e56. Zhang, Y., Wang, J., Hu, F., Wang, Y., 2017. Comparison of evaluation standards for
Land Transport Authority, 2016. Administration of Oversized Heavy Vehicle green building in China, Britain, United States. Renew. Sustain. Energy Rev. 68
Movement. (1), 262e271.
Lawson, R.M., Richards, J., 2010. Modular design for high-rise buildings. Proc. ICE Zhang, W., Lee, M.W., Jaillon, L., Poon, C.S., 2018. The hindrance to using prefabri-
Struct. Build. 163 (3), 151e164. cation in Hong Kong’s building industry. J. Clean. Prod. 204, 70e81.
Lawson, R.M., Ogden, R.G., Bergin, R., 2012. Application of modular construction in Zuo, J., Zillante, G., Wilson, L., Davidson, K., Pullen, S., 2012. Sustainability policy of
high-rise buildings. J. Archit. Eng. (2), 148. construction contractors: a review. Renew. Sustain. Energy Rev. 16 (6),
Li, Z., Shen, G.Q., Xue, X., 2014. Critical review of the research on the management of 3910e3916.
prefabricated construction. Habitat Int. 43, 240e249 in Chinese.