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CONTENT
Chapter 1
01
Chapter 2
06
Introduction
Good Industry Practices - Procurement
• Early involvement of contractors and MEP specialists
• Tender requirements and specifications
Chapter 3
Good Industry Practices - Design
11
• Key considerations including transportation, lifting and handling, availability of
confirmed detailed design, ease of maintenance and material wastage
• Requirements for different module types
• Establish a workflow to develop Co-ordinated Services Drawing (CSD)
for prefabrication
Chapter 4
Good Industry Practices - Fabrication at the Manufacturing Plant
•
•
•
•
•
•
20
Adopt good management practices to improve productivity
Ensure quality control
Align MEP modules properly before delivery to site
Protect modules against weather elements
Facilitate transport, handling and installation
Refer to inspection checklist for delivery of modules
Chapter 5
24
Good Industry Practices - Installation
•
•
•
•
•
•
Adopt Just-In-Time (JIT) concept
Plan for logistics in advance
Conduct visual inspection of modules delivered to site
Mark and set out modules’ position
Install and connect modules and to the mains
Testing and commissioning
Chapter 6
26
Chapter 7
30
Appendix
36
Roles of Different Project Parties
Overseas and Local Projects
Final inspection checklist for prefabricated MEP modules
FOREWORD
A strategic focus of the Construction Industry Transformation Map (ITM) is to champion
widespread adoption of Design for Manufacturing and Assembly (DfMA) technologies.
DfMA transforms construction into a manufacturing process. It involves moving construction
activities from worksites into a controlled factory environment. Building components are
prefabricated off-site before being brought on site for assembly. This means that construction
projects can be completed faster with better quality, and in a cleaner and quieter manner.
Prefabricated Mechanical, Electrical and Plumbing (MEP) systems is identified as a game-changing
technology under the DfMA continuum.
The MEP GIP Guidebook serves to provide simple and practical guidance to practitioners on how
prefabricated MEP systems could be designed, fabricated and installed to achieve its functional
requirements and high workmanship standards. Good practices such as upfront planning,
procurement and maintenance will be covered in the guidebook. The MEP GIP guidebook also
features projects that adopted prefabricated MEP systems overseas. This allows Singapore
consultants and builders to draw reference and learn from these overseas projects.
This guide is not meant to be a definitive publication on how prefabricated MEP systems must be
designed, fabricated and installed. Industry practitioners are encouraged to innovate and improve
further on the prefabricated MEP systems. Professional advice should always be sought from
designers and suppliers when adopting prefabricated MEP systems. We gratefully acknowledge the
contributions of key technical agencies and practitioners in the production of this guide and trust
that the industry will find this publication useful. We welcome any contributions from readers to
improve subsequent editions of this guide.
Neo Choon Keong
Deputy Chief Executive Officer
Industry Development
Building and Construction Authority
ACKNOWLEDGEMENT
This Prefabricated Mechanical, Electrical and Plumbing (MEP) Systems Guidebook was developed
by the working committee in close collaboration with key technical agencies and industry
representatives comprising developers, architects, builders, consultants, MEP specialists and
industry associations.
A technical committee, comprising members from various industry associations and organisations,
was formed to review the content.
We wish to thank all members of the technical agencies as well as the technical and working
committees for their valuable contributions:
Technical Commitee
Mr Ramamoorthy Rajendran
Er Teo Yann
Mr Tan Hui
Mr Kenneth Loo
Mr Yeo Eng Choon
Mr Thomas Ang
Mr Adrian Ting
Er Matthew Ngan
Er Soh Meng Tiong
Mr Eric Man
Mr Tan Hee Wee
Dr Jang Sejun
Er Joseph Toh
Er Darren Woo
Building and Construction Authority (Chair)
Association of Consulting Engineers Singapore (ACES)
Real Estate Developers’ Association of Singapore (REDAS)
Singapore Contractors Association Ltd (SCAL)
Singapore Institute of Architects (SIA)
Specialists Trade Alliance of Singapore (STAS)
CapitaLand Limited
Changi Airport Group
CPG Consultants
Dragages Singapore Pte Ltd
Gammon Pte. Limited
Hyundai Engineering and Construction Co. Ltd
MOH Holdings
Surbana Jurong Private Limited
Working Commitee
Mr Daniel Wang Yue Bin
Ms Go Hui Jing
Ms He Ye (Gloria)
Mr Ho Dalun (Darius)
Mr Louis Chong Jia Jun
Mr Zhang Sheng (Colin)
Mr David Goh
Mr Louis Ng
Technical Agencies
Housing & Development Board
Jurong Town Corporation
Land Transport Authority
Singapore Civil Defence Force
Building and Construction Authority
Building and Construction Authority
Building and Construction Authority
Building and Construction Authority
Building and Construction Authority
Building and Construction Authority
DLE M&E Pte Ltd
Powen Engineering Pte Ltd
1. INTRODUCTION
The construction industry has been moving towards the adoption of Design for Manufacturing
and Assembly (DfMA) where most of the work is done off-site in a controlled manufacturing
environment, and are then transported and assembled on site. With more prefabrication,
manpower and time needed to construct buildings are reduced, worksites are safer and more
conducive, and there is less impact on the surrounding environment.
Prefabricated Mechanical Electrical and Plumbing (MEP) modules is one of the game-changing
technologies that can significantly improve productivity. It adopts the DfMA concept where
components in MEP services and equipment are integrated into a sub-assembly off-site, for easy
installation on site.
This guidebook helps developers, consultants, builders, subcontractors and MEP prefabricators
have a better understanding on prefabricated MEP modules, its benefits and good industry
practices on such systems.
Integrated
Assemblies:
Game-changing
Improvement
Components:
Incremental
Improvement
Prefab
Components
Integrated with
architectural/structural
components
Include MEP
services only
Pre-insulated
plastic piping
Integrated assemblies
Sub-assemblies
Prefab horizontal module Prefab horizontal module
or vertical riser
with ceiling board
Prefab plant room
Prefab plant module
Prefab vertical riser
module with catwalk
30%
45%
60%
Figure 1: DfMA continuum for MEP services
01 | Prefabricated MEP Systems
Manpower Savings
(Trade Level)
70%
1.1. Benefits of prefabricated MEP modules
Increases productivity significantly
• Construction is faster as the production
of prefabricated MEP modules/systems in
the factory is done concurrently with other
activities on site
• Installation of prefabricated MEP modules/
systems on site is easier and quicker, and
leads to significant manpower and time
savings of up to 60%, depending on the
complexity of projects
Improves workplace safety
• Construction sites are safer and more
conducive as most work is done off-site, and
less time is spent working at height
Reduces impact to the environment
• Dust and noise pollution, as well as other
dis-amenities to the surroundings are
minimised as more activities are done off-site
• Less construction waste is generated as there
is less rectification work
Enhances quality control
• Higher quality control is achieved
as most work is done in a controlled
factory environment
• Sequence of work can be planned more
efficiently with better logistics co-ordination
02 | Prefabricated MEP Systems
1.2. Types of prefabricated MEP modules/systems and their applications
MEP technologies at the higher end of the DfMA continuum such as advanced prefabricated
systems and integrated sub-assembly systems can achieve higher productivity improvement.
Examples of the types of prefabricated MEP modules/systems and their applications are
illustrated below.
PREFABRICATED COMPONENTS
MANPOWER SAVINGS
(TRADE LEVEL):
Up to 30%
APPLICATIONS:
All development types
1
3
2
4
Examples: 1) Flexible water pipe 2) Prefabricated pre-insulated aircon
duct 3) Plug and play cable 4) Flexible sprinkler dropper
SUB-ASSEMBLIES (INCLUDING MEP SERVICES ONLY)
MANPOWER SAVINGS
(TRADE LEVEL):
Up to 45%
APPLICATIONS:
All development types
1
2
Examples: 1) Prefabricated horizontal or vertical ceiling modules with
pipes, cable trays, trunking etc. 2) Prefabricated plant modules with
pump, compressor etc.
03 | Prefabricated MEP Systems
SUB-ASSEMBLIES (INTEGRATED WITH ARCHITECTURAL/STRUCTURAL COMPONENTS)
MANPOWER SAVINGS
(TRADE LEVEL):
Up to 60%
1
APPLICATIONS:
Commercial,
healthcare, industrial
and institutional
developments
2
3
Photographs courtesy of Laing O’Rourke, United Kingdom (Picture 1 and 2)
and Balfour Beatty PLC, United Kingdom (Picture 3)
Examples: 1) Prefabricated MEP modules integrated with catwalk
2) Riser module with platform 3) Prefabricated horizontal module with
ceiling board (and even lighting, exit signs etc., where practical)
FULLY INTEGRATED ASSEMBLIES
MANPOWER SAVINGS
(TRADE LEVEL):
Up to 70%
APPLICATIONS:
Commercial, residential,
healthcare, hotels etc.
Examples: MEP systems integrated into Prefabricated Prefinished
Volumetric Construction systems
04 | Prefabricated MEP Systems
Did you know?
To recognise the consultants’ initiative to adopt prefabricated MEP modules with higher
productivity gains, the Buildable Design Appraisal Framework (BDAS) was enhanced in May 2017.
Additional points will be given for a minimum 65% coverage of prefabricated MEP modules/
systems in a project.
COP on Buildability 2015
System
Prefabricated pre-insulated duct
(mandated)
Flexible sprinkler dropper
Flexible water pipes
Common M&E brackets
COP on Builability 2017
Points
System
Points
4
Prefrabricated pre-insulted duct
1
(mandated)
2
Flexible sprinkler dropper
1
1
Flexible water pipes
1
2
Common M&E brackets
1
Prefab MEP modules integrated with
5
work platform/catwalk
Prefab MEP modules e.g. pipes, cable
4
trays, trunking etc.
Prefab MEP plant modules e.g. pump,
4
compressor etc.
Figure 2: Comparison of points allocated for prefabricated MEP modules/systems
(for coverage of 80% and above) between Code of Practice on Buildability 2015 and 2017
In the next chapter, we explore good industry practices on the procurement, design, production
and installation of prefabricated MEP modules/systems.
(Photograph courtesy of DSG Modular)
2. GOOD INDUSTRY PRACTICES - PROCUREMENT
2.1. Early involvement of contractors and MEP specialists
It is important to engage the MEP specialists and main contractor early upfront during the design
stage of the project. By incorporating their inputs into the design, a more effective technical
solution can be achieved. Design clashes and structural safety concerns due to co-ordination issues
can be eliminated. The design of MEP systems will also be more holistic and take into consideration
the ease and accessibility of maintenance, replacement and upgrading of such systems.
The Design and Build (D&B) and Design Development and Build (DDB) procurement models
facilitate early involvement of the main contractor and MEP specialists during the design stage.
This significantly improves the buildability and constructability of the prefabricated MEP design,
leading to higher construction productivity.
Design and Build (D&B) model
D&B is a procurement method where the functions of design and construction are placed entirely
with the main contractor. Based on the design brief provided by the client, the main contractor
will engage his own consultants and the MEP specialists to fully design, develop and construct the
development, including the design and installation of prefabricated MEP systems.
Design Development and Build (DDB) model
The DDB model is similar to the D&B model, except that the client will engage his own consultants
to develop the conceptual design first. Based on this design concept, the main contractor will work
with his own consultants and the MEP specialists to develop the full design and construct the
development, including designing and installing the prefabricated MEP systems.
Besides the above procurement models, the consultants, main contractor and MEP specialists can
also team up to submit their design to tender for projects.
In the event when early contractor involvement cannot be adopted, the client can consider the
following options:
Typical Design Bid Build (DBB) Project
Calling of Consultants
• Client may call for MEP
specialists to assist the
client’s consultants to
develop the MEP design
• Client may engage
these MEP specialists as
nominated subcontractors
for the MEP works
Construction
Calling of Contractor
Client may call for a:
• main contractor with the relevant MEP
expertise to tender and carry out all the
works, including MEP works;
• main contractor to form a team with MEP
specialists to tender. The main contractor
will lead and co-ordinate the MEP works
carried out by MEP specialists; or
• main contractor to tender together with
a first-level subcontractor registered
under CRS ME15 workhead. The firstlevel subcontractor will co-ordinate the
MEP works, while the main contractor will
co-ordinate the overall works
Figure 3: Suggestions for a typical DBB project
06 | Prefabricated MEP Systems
Below are examples of overseas procurement models and best practices from the United Kingdom,
Japan and Korea.
07 | Prefabricated MEP Systems
2.2. Tender requirements and specifications
The requirement to adopt prefabricated MEP modules cannot be an afterthought and needs to be
incorporated upfront in the tender documents, starting from the project brief. The early decision to
adopt MEP modules in the project allows greater continuity of design and maximises
productivity gains.
Project milestones are different when prefabricated MEP modules are adopted in a project. As such,
the contract provisions of a project adopting prefabricated MEP modules should take into account
the following considerations:
2.2.1. Allow sufficient time to consider
design options
2.2.2. Have Co-ordinated Services Drawings
(CSD) endorsed by all relevant project parties
During planning, it is important to allocate
sufficient time to consider a range of design
options for prefabricated MEP modules with
the help of BIM software, and avoid rushing
into details which can limit the design options.
Once prefabrication is completed, only minor
changes are allowed. Any design changes or
re-routing causes a lot of disruption.
Hence, it is important that the designs of the
MEP services are confirmed early. Since all
modules are manufactured based on BIM
co-ordinated models, the process of approving
the shop drawings is critical and must be robust.
For example, a detailed design of a building’s
services may pre-determine the construction
sequence or limit the scope for preassembly.
The use of a vertical riser in a frame passing
through multiple floors may be more efficient
than having a smaller assembly for each floor
or fitting components in a traditional in-situ
manner. However, lifting restrictions on the
site may prevent this option from being used.
As various design options require inputs across
the construction value chain, the client should
allow adequate time for design in BIM software
and collaboration among its consultants, builder,
MEP trade specialists and prefabricator of MEP
modules, before construction starts.
The CSD needs to be endorsed by all relevant
project parties i.e. the consultants, builder and
relevant MEP trade specialists, according to a
pre-agreed schedule.
Clients are also encouraged to require the main
contractor and MEP specialists to provide more
detailed BIM drawings to facilitate off-site
prefabrication of MEP systems.
08 | Prefabricated MEP Systems
2.2.3. Approve materials and mock-ups prior to
mass production of MEP modules
2.2.4. Ensure workers are trained and defects
are rectified at the factory
Unlike cast in-situ works where there is a
sequence for materials to arrive on site, upfront
material planning is critical for prefabricated
MEP modules as all materials are needed at the
same time for prefabrication.
The skills of the trade workers deployed at
the factory play a critical role in ensuring the
smooth installation of modules on site.
To avoid potential disputes, the tender can
include requirements for MEP specialist
contractors to provide training for workers in
the factory, and to rectify defects found in the
modules installed on site.
Consultants are required to approve the
materials used early, so that prefabrication of
modules can proceed on schedule. Mock-ups
of the most typical prefabricated MEP modules
used in the development should also be
produced for the consultants’ approval, prior to
mass production of the modules in the factory.
09 | Prefabricated MEP Systems
To minimise defects in the modules due to
poor workmanship, an engineer’s representative
should be engaged by the consultant to inspect
the works done in the factory. The engineer’s
representative must be an independent party
from the prefabricator to avoid conflict
of interest.
(Photograph courtesy of DSG Modular)
2.2.5. Improve co-ordination on site and in
the factory
2.2.6. Adopt a different payment
certification methodology
Clients can specify to engage firms under the
CRS ME15 workhead as the first-level
subcontractor to co-ordinate the installation of
prefabricated MEP works. The firm should have
a relevant track record in the co-ordination and
installation of prefabricated MEP modules.
With a different work sequence, the contractor’s
pricing methodology will change and the
consultants’ payment certification methodology
and the bill of quantity, or schedule of works in
the case of a lump sum contract will also have to
be tailored accordingly. For example, if the MEP
specialist contractor is also the prefabricator of
MEP modules, the MEP specialist contractor
can claim part of the contract amount for the
modules completed in the factory, before the
installation of these modules on site.
In addition, the tender should specify a
dedicated firm or personnel to lead and direct
the co-ordination among various trades on
site and in the factory. The lead co-ordinator is
preferably the builder that is well placed to
co-ordinate logistics and activities of all trades
on site.
The flowchart below shows a possible workflow to implement prefabricated MEP modules in a
project. The next few chapters will explore the good practices for each phase of the flowchart.
DESIGN PHASE
MANUFACTURING PLANT
ON SITE
Figure 4: Workflow for prefabricated MEP modules. All the processes indicated are applicable to
multiple trades that are integrated within the modules.
10 | Prefabricated MEP Systems
3. GOOD INDUSTRY PRACTICES - DESIGN
3.1. Key considerations
3.1.1. Transportation
The length of each module is subject to the project requirements and standard sizes of materials
supplied. In overseas projects, the typical length of each module is either 6 metres or 12 metres
because pipes are supplied in these lengths.
Should the MEP modules fall outside the below parameters, police escorts are required under LTA’s
traffic regulatory requirements.
• Height: < 4.5 metres (inclusive of truck height)
• Width: < 3.4 metres
• Weight: < 80 tons
*Subject to prevailing requirements by LTA.
3.1.2. Lifting and handling
For large MEP modules, a tower crane may
be required to lift the modules.
Careful consideration must be given on how
modules are lifted and installed in congested
areas e.g. narrow corridors, etc.
Early advice from a specialist can help to identify
key issues when developing the design concept.
As the design progresses, analysis software such
as AutoTURN can be used with the BIM model
to determine swept paths, and logistics software
can be used to plan the delivery programme, site
access and installation routes.
Figure 5: Lifting of vertical riser module
(Photograph courtesy of Laing O’Rourke)
11 | Prefabricated MEP Systems
3.1.3. Availability of confirmed detailed design
In some zones, design changes or missing details might be inevitable, such as the retail space of a
commercial project which is subjected to changes in tenancy. Consultants can identify these zones
from the outset. The designers of MEP modules will then be able to include additional provisions
during the design stage, to prevent reworks downstream.
For example, if the function of a particular zone cannot be confirmed before fabrication of modules
commences, the horizontal ceiling module in the typical corridor should allow space for potential
additional services to be installed on site at a later stage.
3.1.4. Ease of maintenance
The design of prefabricated MEP modules should consider the entire building lifecycle, including
downstream maintenance. Maintainability of MEP systems should be considered during the
design stage.
Inputs from the facilities management team on the orientation of valves, accessibility and future
addition and alteration requirements should be incorporated in the design as early as possible.
For example, valves should be placed in a common fixed location to ensure all modules are
accessible. Consultants should also provide clear access routes to the modules in the design,
for example by allowing access space between the main services route and partition walls for
installation of services into the rooms adjacent to the corridor.
Modules should be designed with ease of access for servicing and replacement of components.
These include providing a ‘red zone’ of a minimum width of about 600 mm at the centre of the MEP
services for workers to access both edges of the ceiling modules, or installing a cat ladder in the
middle of module if there is space. The width of services on each side of the ‘red zone’ should be
kept within one arm’s length to allow access from the ‘red zone’.
3.1.5. Material wastage
Material wastage can be minimised through optimal routing of services.
SS
CE
AC
Figure 6: Allow working access between
the services within the module for further
interfacing works, future maintenance, repair
and replacement. (Photograph courtesy of
DLE M&E Pte Ltd)
12 | Prefabricated MEP Systems
3.2. Requirements for different module types
Prefabricated MEP modules generally fall into three types: horizontal ceiling module, vertical riser
module and plant module, depending on the location of the services. The design of different
modules types can be guided by the following principles:
1
The structural requirements of the MEP
modules including the weight of the
modules and their dynamic loading should
be provided to the Qualified Person (QP)
Structural to design the building structural
requirements.
5
If welded connections are used in the
assembly of the support system, measures
to prevent corrosion to the welded
connections are required, e.g. painting
with cold galvanizing zinc.
2
The support system of the modules
must be firmly installed, according to
the approved shop drawings endorsed
by Professional Engineer engaged by the
main contractor.
6
The overhead components should be
independently supported.
3
Structural design of supports should
utilise standard strut components and
hardware, with all mechanical connections
and bridging from the modules.
As much as possible, the supporting frame
should allow a certain level of flexibility
in adjustment, should more space be
required between tiers.
7
Modules can be linked in tandem for a
continuous service run.
4
The supporting system should be as
lightweight as possible to allow easier
installation, reduce loading on
building structure and minimise
material wastage.
13 | Prefabricated MEP Systems
3.2.1. Requirements of horizontal ceiling modules
A ceiling module should aim to include most if not all of the MEP services in the ceiling.
Typical services that can be included are listed below:
a) Sprinkler
b) Chilled water supply and return pipe
c) Condensate drain pipe
d) Sanitary drain
e) Plumbing
f) Town gas
g) Medical gas systems (if applicable)
h) Electrical and extra low voltage cabling system with trunking, tray or cable ladders (it is typical for
cables to be drawn only after the installation of modules on site to minimise cable jointing which
affects the performance of the system)
i) Air-conditioning/mechanical ventilation ductwork
j) Light fixtures
Figure 7: Designing module with an overhang of services to save material for the module frame
(Photograph courtesy of Hyundai Engineering & Construction Pte Ltd)
Fire safety
Sprinkler piping can be pre-installed in the same horizontal ceiling module as other services. If the
height of module exceeds 800 mm, a second layer of sprinklers must be in place, subject to the
complexity of modules. Consultation with SCDF should be sought for any non-compliance to the
fire safety requirements.
In addition, if a fire-rated duct runs through the module, the entire module frame and associated
supports must be fire-rated. If the horizontal ceiling module is used in fire-rated spaces such as
smoke stop and firefighting lobbies, a fire-resistant board must be incorporated, in accordance with
the Singapore Standard CP 52:2004 Code of Practice for Automatic Fire Sprinkler System and Code
of Practice for Fire Precautions in Buildings.
14 | Prefabricated MEP Systems
Water leakage
The arrangement of services within a horizontal ceiling module should take into account the
potential risk of undesirable leakages from mechanical services e.g. sanitary waste pipe and potable
water pipe.
For example, in corridors with limited width, electrical services should always be installed above
any plumbing and sanitary services. Additional acrylic/zinc sheet can be installed between water
pipe joints and electrical services above or nearby. If the width of corridor accommodates, electrical
services can be installed on one side of the ‘red zone’ in the module while mechanical services e.g.
sanitary and plumbing can be installed on the other side, as shown in the diagram below.
Access provisions
The distance between vertical tiers of the module should be at least 100 mm to allow access for
further works – such as drawing cables and interfacing between modules, and future maintenance.
If welding works for pipe jointing are to be carried out, more clearance around the pipes will
be required.
Figure 8: Elevation view of horizontal ceiling module (if ceiling height allows)
(Photograph courtesy of DLE M&E Pte Ltd)
The horizontal ceiling modules should comprise components that allow adjustment to the height
of services to compensate any offset due to unevenness of the structural ceiling. Examples of such
components are vertical threaded rod and flexible coupling which accommodates misalignment of
jointing pipes, as seen on the next page.
15 | Prefabricated MEP Systems
Hanging accessories
Lateral displacement solution
Supporting accessories
Pipe offset tolerance
Mechanical coupling
Adapter-module joints
Angular deflection tolerance
Figure 9: Examples of accessories to facilitate fabrication and
installation of prefabricated MEP modules on site
(Photograph courtesy of Gripple Limited, Georg Fischer Pte Ltd and Teekay Couplings Ltd)
3.2.2. Requirements of vertical riser modules
A riser module comprises vertical riser ducts and
pipes. The vertical services in each riser module
can be installed horizontally at ground level in
the factory, and branch out to multiple floors.
A riser module can be installed prior to, and
independently of, the erection of block walls of
the riser shaft. Another method of installation
is to lower the riser modules into the riser shaft
through designated openings in the top floor.
Therefore, lifting lugs and bracketry should be
incorporated in the design of vertical
riser modules.
Figure 10 (right): Vertical riser module
placed in position (Photograph courtesy of
Balfour Beatty PLC)
16 | Prefabricated MEP Systems
3.2.3. Requirements of plant modules
Prefabricated MEP plant modules are fully pre-assembled with control panels, and instruments
mounted on skids with lifting eyes for piping connections, valves cable termination for power
supply, and interfaces for building automation system and fire alarm system, where applicable.
The pre-assembled and pre-wired equipment with control panels include:
a) Water services pump sets for boosting and transfer including hydro-pneumatic tank
b) Fire hose reel pump set including hydro-pneumatic tank
c) Vacuum pump sets
d) Air compressor including air receiver
e) Cooling towers
f) Chillers
g) Chilled water and condensing water pumps
h) Air-condensing unit
i) Air handling units (AHUs)
j) Fan coil units (FCUs)
Figure 11: Prefabricated plant modules fitted and lined up in factory
(Photograph courtesy of Seikei factory, Japan)
17 | Prefabricated MEP Systems
Two or more modules can be combined using
flexible connections on site to complete the
installation in a plant room. All the valves/
pipework connections to the equipment can be
pre-installed in the factory including the control
panels and internal wiring.
When the equipment is delivered to site,
contractors will only need to connect
the pipework and the incoming power
supply, then the system is ready for testing
and commissioning. As compared to the
conventional way of installing plant and
equipment, prefabricated MEP plant modules
save time on site, and reduces the number
of trips to deliver individual materials and
components such as valves, pipes and control
panels to the plant room for assembly.
The site will also be neater and material waste
can be minimised.
Figure 12 (Top): Prefabricated condensing
module (Photograph courtesy of
Seikei factory, Japan)
Figure 13 (Right): Prefabricated pump
module (Photograph courtesy of Crown House
Manufacturing, United Kingdom)
18 | Prefabricated MEP Systems
3.3. Establish a workflow to develop Co-ordinated Services Drawing (CSD)
for prefabrication
The design of the modules should be generated from the CSD which is produced in BIM.
The contents and level of detail in BIM to be delivered at each project stage, as well as the role of
each project member, should be clearly defined before commencement of design. The following is
an indicative workflow for the development of CSD and should be modified to suit various
project requirements:
a) The architect provides the BIM of building layout to the MEP
consultants for development of the concept design and schematic
design of the individual services.
b) The builder, respective MEP trade specialists and prefabricator of
MEP modules collaborate to develop the CSD in BIM with detailed
design where elements are defined with specific assemblies, precise
quantity, size, shape, location and orientation. The deliverables at this
stage should include elevation views at selected locations including
common corridors, turning points in the routing of services, and
incoming of new services etc. The appointed lead co-ordinator may
be most suitable among the project members to integrate the BIM
models from various disciplines to form the final CSD.
c) The CSD is reviewed and endorsed by relevant project
members, including consultants, builder and respective MEP
specialist contractors.
d) The endorsed CSD is further developed with more details
for fabrication and assembly, including elements of the modules’
supporting frame, flanges, corners etc.
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4. GOOD INDUSTRY PRACTICES
- FABRICATION AT THE MANUFACTURING PLANT
4.1. Adopt good management practices to improve productivity
Before production commences, detailed manufacturing drawings for each module are produced
and finalised by all key parties. After the MEP modules have been produced in the factory, the
manufacturing drawing should be pasted on the respective modules and the services labelled*
accordingly for reference by other trades. Radio frequency identification (RFID) or a barcode system
can also be used to track the modules in the factory and facilitate installation on site.
The production schedule and manpower planning are also critical. The adoption of automation and
mechanisation e.g. robotic welding machine, CNC pipe cutting machine etc. in factory can help
improve productivity and reduce reliance on manpower.
*The labels should be positioned at the location of ceiling access panels or maintenance panels,
according to the ceiling plan.
20 | Prefabricated MEP Systems
Figure 11: Ensuring quality control at the MEP factory
(Photograph courtesy of Crown House Manufacturing, United Kingdom)
4.2. Ensure quality control
Inspection test plans should be developed for all modules by the prefabricator and endorsed by
MEP trade specialists and consultants to ensure that they are applicable for the project.
Tests and inspections of the individual services and support system e.g. steel frames of the
modules, should be conducted according to the respective technical specifications and codes
of practice. These include the material’s compliance with regulatory requirements, project
specifications, pipe pressure test, air tightness test for ductwork, and gradient of condensate drain
pipe, sanitary waste pipe and kitchen waste pipe.
Factory acceptance tests should be verified by an engineer’s representative to ensure that the
modules have achieved their performance requirements. Should the modules fail to meet the
performance requirements, rectifications should be carried out accordingly, prior to the delivery of
the modules.
A mock-up should also be produced for inspection and approval by the Qualified Person (QP) prior
to mass production.
21 | Prefabricated MEP Systems
4.3. Align MEP modules properly before delivery to site
To ensure a smooth installation on site, a template or jig could be used when lining up the modules
in the factory to check for proper alignment.
Figure 12: Alignment of modules in a factory. Prefabricated MEP modules are fitted out in the
factory, prior to delivery and installation on site (Photograph courtesy of DSG Modular)
4.4. Protect modules against weather elements
Modules should be covered with shrink wrap, tarp etc. to protect them against exposure to
weather, prior to delivery to site. Alternatively, the modules can be kept in a sheltered condition at
all times.
22 | Prefabricated MEP Systems
4.5. Facilitate transport, handling and installation
To ease transport and handling, modules can be pre-installed with castor wheels that can be taken
off after installation. Equipment such as pallet jacks and forklifts also facilitate the manoeuvring and
lifting of modules in the factory and on site.
Sometimes, to facilitate the installation of MEP modules in tight working spaces, the builder and
prefabricator can work together to integrate other works into the MEP modules. For example, part
of a partition wall can be integrated with the MEP modules, as shown in the diagram below.
Figure 13: A horizontal ceiling module integrated with drywall partition wall
to facilitate installation in tight working space.
4.6. Refer to inspection checklist for delivery of modules
A checklist should be used to verify the condition of modules before they are delivered to site,
minimising unnecessary waste and time. An example of the checklist is as shown in the Appendix.
23 | Prefabricated MEP Systems
5. GOOD INDUSTRY PRACTICES - INSTALLATION
5.1. Adopt Just-In-Time (JIT) concept
Adopting a just-in-time (JIT) concept, where MEP modules are delivered according to the
construction sequence, eliminates congestion in the factory and minimises damages to the modules
on site. BIM can be used to simulate the actual on-site installation to identify potential problems in
the access route.
Close co-ordination between parties at the project site and factory is critical to ensure a smooth
supply of modules to the site and minimise downtime due to missing modules on site.
5.2. Plan for logistics in advance
The method statements and risk assessments
for lifting, installing and storing (if applicable)
the modules on site require the builder’s inputs
on the capacity of cranes, availability of access
platforms on each floor for landing of modules,
delivery routes of modules to their designated
positions, and other logistics constraints.
Delivery of large pump skid and modules that
may require traffic escorts should be planned in
advance.
Figure 14: Lifting of modules on site.
(Photograph courtesy by DSG Modular)
5.3. Conduct visual inspections of modules delivered to site
Visual inspections should be conducted by an engineer’s representative to ensure there are no
defects to the modules during transportation, prior to moving the modules to their designated
location for installation.
5.4. Mark and set out modules’ position
The positions of the supporting rods on the modules, as shown in the BIM drawings, can be marked
out on the slab soffit or columns using laser marker equipment. This will ensure faster and proper
alignment of supporting rods with module frame eyelets as well as connections between modules.
24 | Prefabricated MEP Systems
5.5. Install and connect modules and to the mains
The installation of MEP modules should be carried out by workers who are familiar with the
connection details of the modules, and have been trained by the MEP prefabricators.
A lifting plan should be developed to ensure the carnage, hoist, module and lifting fixture are
positioned correctly. Final positioning is critical to achieve the levelling tolerance of the MEP
services.
The horizontal ceiling modules can also be pre-assembled on the floor on site, before
simultaneously lifting multiple connected modules to the ceiling.
Figure 15: In Korea, prefabricated MEP modules are connected on the floor at the job site
and lifted as a complete module for final installation.
Synchronised wireless jacks are used to maintain alignment when lifting the module.
(Photograph courtesy of Hyundai Engineering & Construction Pte Ltd)
5.6. Testing and commissioning
A testing and commissioning plan should be developed and the Qualified Person (QP) or his
representative should be present to witness the testing and commissioning of the MEP system.
A distribution system such as full system pressure testing for pipework and air tightness test for
ductwork shall be commissioned on site.
Commissioning can take place by zones and a full system-wide commissioning should be done
when the building envelope is made weather-tight.
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6. ROLES OF DIFFERENT PROJECT PARTIES
STAGE 1:
Tender to engage consultants, builder, subcontractors and MEP prefabricator
Developer
Consultant
Builder
Subcontractor MEP
(including architect,
Prefabricator
structural, MEP etc.)
Specify the following
• Consider potential cost increase in the tender bids due to different
tender requirements:
work activities associated with the prefabricated MEP system
where applicable:
• Adopt Early Contractor
- Development of detailed BIM models
Involvement (ECI)
- Additional resources and time required for collaborative design
procurement models
processes such as adoption of virtual design and construction
and decide which
(VDC)
party to undertake the - Supervision of works at manufacturing facility offsite and
scope of full design
project site.
• Specify the following
upfront in the tender:
1) A maximum amount
of prefabricated MEP
modules / system to
be incorporated in the
tender proposal
• Identify the areas where MEP modules can be applied
• Review the schedule and deliverables for progress
claim certification
2) Proper handover of
BIM model in the design
value chain
3) Co-ordinated services
drawings (CSD) must be
endorsed by relevant
project parties prior to
production of modules
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STAGE 2: Design
Developer
Consultant
Builder
Subcontractor
MEP
(including architect,
Prefabricator
structural, MEP etc.)
• Embrace the
• Establish the time and resources required for the process of VDC
mindset of building
including on-site installation processes, design development of
virtually before
prefabricated MEP modules and producing BIM with high level
actual construction
of details
through BIM and
VDC, and allow a
• Establish the cost required for the process
longer period for
collaborative design • Collaborate closely to develop the design to ensure the following are
achieved:
• Communicate
- Understanding of workflow and software across firms are aligned
detailed project
- Access routes and headroom clearance for the delivery routes and
goals and
installation of MEP modules are made available
considerations to
- Maximum streamlining and standardisation in the routing of services
the project team
- Maximum productivity improvement and cost efficiency by studying
thoroughly before
the feasibility of integrating MEP services with other disciplines,
finalising the design
e.g. drywall, platform and catwalk
- Ease of production of modules and connections between modules
off-site and on site
- Access to services within the modules during downstream
maintenance is available
- The MEP design is finalised upfront together with architectural and
structural design
• Develop co-ordinated services drawings (CSD) that are endorsed by
the relevant project parties prior to the production of modules
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STAGE 3:
Production of prefabricated MEP modules offsite in a manufacturing facility
Developer
N.A.
Consultant
Builder
Subcontractor
(including architect,
structural, MEP etc.)
• Workers might need
to be deployed at the
manufacturing facility,
depending on the
procurement model
MEP
Prefabricator
• Engage detail-oriented
personnel trained in BIM
to develop production
drawings of MEP
modules based on
the CSD
• Obtain endorsement from
the Professional Engineer
• Equip manufacturing
on both the structural
facility with adequate
design of the module as well
space for fabrication
as the installation support of
and storage of modules,
the module to the building’s
and necessary tools and
soffit. This should also
equipment such as jigs
include any other services
and welding machine
that are attached to the
respective modules.
• Maintain minimum
inventory of frequentlyused and pre-approved
materials such as cable
trays, conduits, pipes/
fittings etc. to ensure
no disruption due to
shortage of materials
• Production should
comply with a robust
quality assurance and
control plan which
includes factory
acceptance tests on
individual modules and
integrated modules
• An engineer’s
representative should
be deployed before
production to verify the
tests and inspections.
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STAGE 4: Construction on site
Developer
N.A.
Consultant
Builder
Subcontractor
MEP
(including architect,
Prefabricator
structural, MEP etc.)
• Work closely to ensure just-in-time delivery of modules to
project site
• Install modules on site and integrate systems
• Provide accurate site measurements for prefabrication of
interfacing between modules and elements of the building
structure, if applicable
STAGE 5: Overall testing and commissioning of services
Developer
N.A.
Consultant
Builder
Subcontractor
(including architect,
structural, MEP etc.)
Consultant and their • Conduct testing and
site team to oversee
commissioning of services
the testing and
according to the performance
commissioning (T&C)
requirements and regulations
of services.
• Rectify defects
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MEP
Prefabricator
• Provide maintenance
manual to developer
containing guidance for
facilities maintenance
team on the following:
i. How to access and
maintain the services
within the modules
ii. Dos’ and don’ts
compared to
conventional
installation
7. OVERSEAS AND LOCAL PROJECTS
7.1. Crossrail Tottenham Court Road Station
Figure 16: Crossrail Tottenham Court Road Station (Photograph courtesy of Laing O’Rourke)
7.1.1. Background
Tottenham Court Road is one of the most complex stations in London as it is in the heart of
London’s most popular shopping and entertainment areas, as well as the interchange of two
Underground lines and numerous bus routes.
Laing O’Rourke undertook the structural, building and MEP works for the new station since 2012.
The project involved major structural work and fit-out of the station’s Western Ticket Hall, station
tunnels and Goslett Yard box, which links the new Crossrail station to Tottenham Court Road
Underground station.
Tottenham Court Road Crossrail station is directly connected to the neighbouring tube station
allowing passengers to move seamlessly between Crossrail and London Underground services.
The total length of its station platforms is 220 metres.
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7.1.2. Motivation for adopting prefabricated
MEP modules
The adoption of prefabricated MEP modules
improved safety on site, as workers have less
exposure to high-risk work environments such
as tunnels 25 to 30 metres below ground.
Prefabrication of MEP modules also enables
better quality control and workmanship in a
conducive and controlled factory environment.
7.1.3. MEP modules adopted
a) Vertical riser modules comprising air
conditioning ductwork, drainage, fire mains
riser pipework and cable management
systems (ladder racks)
b) Horizontal ceiling modules comprising cable
trunking, cable tray and fire mains pipework.
(The cables are pulled after installation of the
modules on site)
Figure 17 (Top): Hoisting of vertical riser module.
(Photograph courtesy of Laing O’Rourke)
Figure 18 (Top): Prefabricated modules in the services tunnel.
(Photograph courtesy of Laing O’Rourke)
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7.1.4. Design and installation
The specialist MEP contractor developed the detailed BIM based on the model provided by the
consultant. The MEP specialist contractor also designed the supports and frames, which was
reviewed and endorsed by a structural engineer.
Just-in-time concept was adopted due to space constraints on site. The programme co-ordination
ensured that the MEP design was sufficiently developed to allow detailing of the services in the
modules. A typical lead time of 12 weeks for prefabrication of modules was incorporated into the
construction schedule to ensure that the modules were delivered to site on time. Depending on
the services, the tests on some systems were carried out at the factory.
Cranes, tower or mobile cranes were used to hoist the large risers on site. Pallet trucks and site
lifters were used to lift the modules to the ceiling for installation. The modules included services
under the scope of works by system-wide contractors. Besides installation of modules on site,
Laing O’Rourke also put the cables under the scope of works by system-wide contractors, e.g.
communications system.
7.1.5. Similar practices as traditional projects
Despite the differences in project milestones and methods of installation of MEP services, some of
the practices in traditional projects, such as structural requirements of the main building structure,
tracing liability and resolving system issues during testing and commissioning, are still applicable to
Crossrail Tottenham Court Road station project which adopted prefabricated MEP modules.
Artist’s impression courtesy of Global Switch
7.2. Global Switch Data Centre, a six-storey project in Woodlands, Singapore
7.2.1 Motivation for adopting
prefabricated MEP modules
The data centre project involved extensive and
complex MEP systems. In order to meet the high
quality standards required by Global Switch as
well as a tight project schedule, prefabricated
MEP modules were used for this project as the
conventional way of MEP system construction
could not meet these requirements.
The prefabricated MEP systems not only
improved the quality of the finished product, but
also increased on-site trade productivity by up
to 70%.
Figure 19 (Right): Workers on site connecting
the services between modules through the
working access space provided within the
module. (Photograph courtesy of Gammon
Pte. Limited)
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7.2.2. MEP modules adopted
a) Chiller plant room modules comprising pump modules and high-level horizontal piping modules
b) Cooling tower modules and roof service modules
c) Underfloor service modules
d) FCU and AHU modules
e) Corridor horizontal modules
f) Vertical riser modules
g) External services around the building modules
1
2
3
Figure 20: Modules pre-assembled in the factory
1) Plant module 2) Corridor horizontal module 3) Vertical riser module
(Photograph courtesy of Gammon Pte. Limited)
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7.2.3 Design, manufacturing and installation
The main contractor developed the detailed BIM based on the system design by the consultant.
A MEP prefabrication factory was set up to produce all the modules by the main contractor,
while a registered structural engineer was engaged to design the support and frame of the modules.
The on-site installation, testing and commissioning of the MEP systems were undertaken by the
main contractor and specialists engaged by them.
SCOPE OF WORK
PARTIES INVOLVED
1) Provide schematic design
2) Develop CSD in BIM, and
modularise the services to
produce the manufacturing
shop drawings
3) Fabricate steel frames of
prefabricated MEP modules
4) Install the services in
the modules
5) Transport and hoist
the modules to position
for installation
6) Install the modules
to building structure via
proprietary method
7) Complete the services in
between modules, if required.
These may include cabling work
e.g. drawing cables through the
cable containment system
pre-installed in the modules
off-site
*In the project, Gammon Pte. Limited is the main contractor, MEP module prefabricator and
MEP subcontractor for most services.
Figure 21: Scope of work by different project parties for MEP modules at the
Global Switch Data Centre
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APPENDIX
Final inspection checklist for prefabricated MEP modules
Tick when completed
1. General Checklist
Adequate clearance between different MEP services
All open ends are capped and free from damage
All debris are removed from modules
Final visual inspection of all welded joints
Final visual inspection for physical damage (corrosion, damage, paintwork, insulation)
Module reference code and weight are clearly indicated
Transit supports (bolts, nuts) are in place
Labels are affixed on respective services, and in positions where any ceiling access panels or maintenance panels is located
2. Support System
Correct specification of bolts and nuts
Correct sequence and torque of bolts and nuts
All brackets are installed as shown on the shop drawings
Inertia bases and vibration isolators are secured for transport
3. Accessories (Flange, Valve, Damper, Test Points)
Flanged joints have standard bolts fitted and correct torque specification
Directional valves are fitted correctly
Valve handles have clearance to operate fully and be maintained properly
Tested points are fitted and accessible by test probe
36 | Prefabricated MEP Systems