A game-changing shift in building services – MiMEP in government buildings

By the Architectural Services Department and the Electrical and Mechanical Services Department

Challenges of building services installation in construction industry

Work activities in a traditional construction mode are linear, which means that each work activity must be finished before the next can begin. Building services (BS)/Mechanical, Electrical, and Plumbing (MEP) installations often begin after the majority of the building construction work is completed. They are always placed in a passive position since their task can only begin after a series of builders work activities are completed. As a result, any delay in the previous work trade will have a substantial impact on the development of MEP installations, which are always in the final construction stage, causing a cascading effect and imposing immense time pressure on project completion. At this stage, the site is frequently more crowded, with many trades operating concurrently inside a limited space. This results in a difficult coordination process. The working environment is often more unpredictable, which complicates MEP installation progress and jeopardises labour safety. All the above factors have triggered the move of MEP installation towards the adoption of offsite prefabrication, in which the MEP components can be integrated effectively into modules prefabricated in an offsite controlled factory, before transporting to the construction site for final assembly, testing and commissioning.

The HKSAR Government has promulgated Construction 2.0 to enhance the industry’s sustainability through innovation, professionalisation and revitalisation. Wider adoption of High Productivity Construction (HPC) methods, such as Modular Integrated Construction (MiC) and Multi-trade Integrated Mechanical, Electrical and Plumbing (MiMEP), is encouraged to uplift on-site productivity and to enhance performance of works quality, site safety and environmental sustainability.

Multi-trade Integrated Mechanical, Electrical, and Plumbing (MiMEP)

Following the three major principles of HPC, MiMEP adopts off-site prefabrication, multi-trade integration and module maximisation as well as a plug-and-play approach. The multi-trade of MEP components is modularised and prefabricated off-site in a factory environment, then transported to the site for connection of modules to complete various trades of BS installations to minimise the on-site works. MiMEP can sometimes integrate with structural elements, Architectural Builders Works and Finishes (ABWF) to form an advanced assembly, such as false ceiling unit and so on.

Some common examples of MiMEP include the plant modules, the multi-trade horizontal ceiling modules, vertical MEP riser modules, modular pump set, modular condensing pipework for cooling tower, modular pump set with control panels, integrated air-handling units, panelised electrical modules, and so on. Horizontal ceiling modules may comprise multi-trade MEP components such as electrical trunkings, cable trays, lighting fittings, air conditioning ductwork, air terminal boxes and water pipes, etc. They are suitable to be applied in areas with standardised and repetitive space layout, such as open-plan offices and service corridors. Vertical MEP riser modules comprising vertical riser ducts and pipes, which may be used in multi-storey buildings. Modular pump set is constructed as a self-contained packaged module consisting of pump, motor, header pipes, sectional pipework, power supply connection, motor control panel, control and metering accessories, skid plate and mounting framework. Modular condensing pipework for cooling tower includes components such as condensing pipes and fittings, valves, vibration isolators, etc. It can be used in buildings with cooling tower installation for air-conditioning system. A skid-mounted packaged equipment with a control panel, entirely pre-assembled, pre-wired and self-contained in a built-in frame, is referred to as a plant module. The integrated air-handling unit integrates major components including the air-handling chamber, electrical supply and control module, and water pipe connection. Panelised electrical module comprises MCCB/MCB board, power quality meter, trunkings and cables. With the proliferation of ideas and innovations, it is expected that more types of MiMEP will be further developed and elaborated in various types and forms in the near future.

Common examples of MiMEP

Innovative technologies to facilitate MiMEP

Although prefabricated MEP components and equipment have been adopted for decades, three-dimensional (3D) coordination among MEP systems, structural and building elements remained a challenge and thus the extent of MEP prefabrication was confined in the past. The recent remarkable development in Building Information Modelling (BIM) provides an exceptional chance for MiMEP to be widely adopted. By capitalising on the iteration of building sequences and limitations, BIM enables well-coordinated and successful execution of off-site prefabrication of multi-trade components. It allows for the simulation of a precise virtual 3D model with perfect geometry and technical data for large-scale integration of multi-trade equipment or components into a single assembly of the prefabricated module.

The recent remarkable development in Building Information Modelling (BIM) provides an exceptional chance for MiMEP to be widely adopted. By capitalising on the iteration of building sequences and limitations, BIM enables well-coordinated and successful execution of off-site prefabrication of multi-trade components.

At the design stage, BIM can assist in capturing rules for MiMEP adoption such as floor height, spatial relationship, optimised modular size, manufacturing processes, delivery route planning, and design for disassembly. Through BIM, 3D computer models are created, allowing multi-trade prefabrication work to be efficiently done while taking into consideration construction sequences and limits through design iteration. Information such as the number of each component, its dimension and weight, and so on could also aid quantity take-off and material procurement.

During the pre-construction stage, the 3D BIM model can be translated into an immersive environment via Virtual Reality (VR), allowing the designer and maintenance team to visualise the installation details of MiMEP (such as whether sufficient working space and appropriate maintenance facilities have been allowed for and the location and orientation of valves, etc.) before building begins. Design details can be refined to include the requirements for operation and maintenance.

With the fast advancement of digitalisation through BIM, the MEP industry has begun to practise the notion of Industrialised Construction – with more mechanised, automated, and robotics-based machineries introduced to aid the MEP throughout the design, prefabrication, assembly, and delivery processes.

Radio Frequency Identification (RFID), QR Code tagging, Virtual Reality (VR), Augmented Reality (AR), among other technologies, have introduced comprehensive solutions to MiMEP. Using RFID or QR tagging, every component can be traced throughout, from the manufacturing process to the testing and commissioning process. BIM models also make it much easier for the project team to organise the logistics of module delivery in a 3D virtual environment, particularly the delivery route and on-site module hoisting. Following the completion of the project, the digitised BIM model can incorporate a tablet computer or other mobile devices to supplement AR. As-built information can easily be retrieved to facilitate asset management. The information-rich model may also be used to plan routine maintenance and plant replacement.

All of the aforementioned I&T applications have smoothened the path for MiMEP’s bringing about a technological transformation in the construction industry. With such a revolutionary transformation, the MEP installation reaches new heights.

Successful stories on MiMEP projects

Some new government building projects, as well as a chiller plant replacement project, have adopted MiMEP approach for MEP installation in order to reap the full benefits of such techniques. North Lantau Hospital Hong Kong Infection Control Centre, Fu Shan Mortuary, Tai Lung Veterinary Laboratory, and others are among them.

North Lantau Hospital Hong Kong Infection Control Centre (HKICC)

The HKICC, with over 800 isolation beds to receive COVID-19 patients, was built in four months from scratch using MiC and MiMEP with the assistance of full-scale BIM, VR and AR technologies. The project was completed in January 2021. It currently admits COVID-19 confirmed patients with suitable clinical conditions.

To expedite the BS installation, a large number of installations were done using MiMEP approach, so that the majority of the installation works were conducted outside site area with the final assembly of MiMEP modules completed on site. MiMEP approach was used for most of the BS installation, which include the horizontal ceiling modules, integrated AHU/PAU, panelised electrical modules and so on.

Solutions to challenges

MiMEP technology significantly improved the quality of site coordination, sped up and simplified the installation and increased the accuracy in the construction stage. BIM technology was one of the tools used for design from the beginning of the project and during construction to facilitate real-time monitoring of on-site fixing in accordance with the plan. VR and AR technologies were used in finalising the details of MiMEP for accurate mass production and positioning for on-site installation.

MiC and MiMEP method with full BIM technology

Horizontal ceiling modules were manufactured in a factory outside Hong Kong and delivered to site in an orderly and efficient manner. As most of the installation works had been completed off-site, this led to efficient quality control and reduced overall construction waste, as well as enhanced site safety. By overlapping on-site building structure construction with off-site MiMEP production, construction progress was significantly accelerated. It enabled thousands of workers to work concurrently at both on-site and off-site factories.

Site installation with MiMEP application

VR and AR for installation appropriateness

With the assistance of AR, the productivity of on-site inspection was substantially enhanced. The AR application enabled the combination of the virtual image of a BIM model and the actual site condition for easy assessment and verification. Detailed information of each BS component could be displayed on the screen, and each trade of BS could also be arbitrarily switched on or off to suit the installation progress. It provided great convenience and flexibility during inspection, and any deviation from the design could be easily identified on the screen. In the future, BS components above false ceiling could be located by a screen without the need to open a single acoustic ceiling panel for smoother Alterations, Additions, Repairs and Improvements (AA&I) works. MiMEP is not just an assembly of BS parts and components: if properly designed, it can also help improve the environmental quality with better acoustical performance and aesthetic outlook.

MiMEP is not just an assembly of BS parts and components: if properly designed, it can also help improve the environmental quality with better acoustical performance and aesthetic outlook.

Testing & commissioning

Testing & commissioning (T&C) for BS systems in a hospital project typically takes months. Adopting MiC and MiMEP at HKICC allowed some essential quality assurance procedures to be completed in the factory, such as air-tightness test for the isolation ward enclosure. This approach reduced the testing time to weeks as it was pre-commissioned at the factory for delivery to site for quick installation. The advantages of factory testing could improve production efficiency as well as construction site safety.

Fu Shan Mortuary

The re-provisioning project for Fu Shan Public Mortuary is a new five-storey building with construction floor area of approximately 18,500 m2. Its main facilities include eight body cold rooms with a total storage capacity of up to 830 bodies, several autopsy suites, laboratories and administrative office, among others. The project was completed in June 2022. It is now the largest public mortuary in Hong Kong.

MiMEP was not a required construction method in this project. However, the values of MiMEP were recognised, and the project team was eager to accomplish the mission with MiMEP. A considerable amount of BS plant design was identified as being repetitive to some extent, such as header pipework for water-cooled chillers and cooling towers, electrical distribution boards and wall-mounted trunking riser in switch rooms on each floor, duty and standby pump sets for fresh water, flushing water, fire services systems, and so on. The alignment and installation details of such equipment were relatively simple to be standardised and modularised. MiMEP adopted in the project included chilled water plant room and pipework, modular water pump set for Fire Service transfer pumps and sprinkler transfer pumps, integrated AHU, modular electrical wiring system.

“Successful implementation of MiMEP requires early input from the project team members in order to establish key strategies for plant locations and spatial allowance.” says Ir Lok Ka Wai, Gary, Senior Building Services Engineer of the Architectural Services Department (ArchSD). “It is also important to engage the construction team and the supply chain upfront during the design stage of the project. Supports from the Main Contractor, such as hoisting by tower crane, temporary openings, coordination of on-site delivery route, are always commendable. At the early stage of construction, project team consulted the maintenance agent about the idea and plan of MiMEP so that their views could be obtained to ensure the equipment maintainability. Project team worked with the construction team to jointly set up some criteria or rationales to select suitable plans for the application of MiMEP.”

A highlighted application of MiMEP in this project was the BS installations in the Air Handling Unit (AHU) Room on the ground floor. This example vividly demonstrated that the concept of MiMEP was so versatile and open to multi-trade. The chilled water pipes, air duct, electrical trunking, motorised valves set, etc. that constitute this AHU room were all put into a number of modules. The key to successfully modularise this AHU plant relied on factors including a neat plant layout, accurate BIM of the whole room and plant position, detailed drawing per module with precise dimensions of supporting frame and setting out of plant equipment, off-site rehearsal of connection among modules and precise planning of delivery route within the site, etc. Project team had also adjusted the inspection procedures to suit the material delivery to off-site MiMEP workshop, tests were carried out and witnessed off-site, and semi-finished modules with components were pre-inspected.

Adaption of BIM to facilitate precise dimension coordination in the implementation of MiMEP

To cope with the tight completion deadline, horizontal ceiling modules at common corridor ceiling were also implemented in this project. The development of MiMEP in this project was continually matching the overall construction progress, and interacted with various stakeholders.

Chiller plant replacement at Tai Lung Veterinary Laboratory

The Electrical and Mechanical Services Department (EMSD) has recently completed the first MiMEP pilot project for chiller replacement at Tai Lung Veterinary Laboratory. The client of the laboratory building is the Agriculture, Fisheries and Conservation Department.

Challenges of this Repair, Maintenance, Alternation and Addition (RMAA) project

The role of the veterinary laboratory is to provide veterinary laboratory testing services. Uninterrupted chiller operation and round-the-clock air conditioning provision are therefore essential for the equipment set-up inside the building. Chiller replacement must be carefully planned, with installation completed as soon as possible to have the least possible impact on the chilled water supply to the air-conditioning system.

As with other RMAA projects, another challenge for this project was the lack of available space. To meet the growing demand for air conditioning, four existing air-cooled package-type chillers were replaced by three chillers of larger capacity with additional chilled water pump sets to be installed at roof level. This equipment needed to be installed in two stages to ensure a non-stop chilled water supply for 24-hour operation. The extra requirement to accommodate the additional equipment made the space more congested and the installation more difficult.

Solutions to the challenges

This project applied MiMEP approach, BIM and other advanced technologies to overcome these challenges. During the site planning stage, 3D scanning with drone flying was conducted to capture the on-site environment and identify the site constraints that could arise during replacement. This information was also used to determine the plant delivery route.

Chiller plant design overview by BIM technology

4D animation on the logistic and installation arrangements

To ensure that the modules were feasible for installation within the time frame specified, BIM model was converted into a 4D animation with time-related information. The inclusion of time-related attribute data could help visualise how it would be installed and how the surrounding site would appear at each stage. This greatly benefited work planning in a safe and logical manner, as well as maximising efficiency on site. It also allowed the team to discuss the overall engineering plan, module design, logistical considerations, workflow streamlining, works progress monitoring, maintenance details and other related arrangements to ensure the project development was on track.

A further combination of BIM and AR technologies was used to overlay the established BIM model onto the real-world environment, allowing spatial constraints or soft clashes to be more clearly displayed. It also helped open up new possibilities for effectively anticipating constraints that might arise during construction and maintenance, as well as figuring out solutions to such challenges.

MiMEP Modular Design for the new chiller plant

Upon fabrication, 3D scanning of the assembled modules was conducted to compare with the design intent to check if all the dimensions were within acceptable tolerance. With over 80% of high modularisation ratio, the project had shown that MiMEP approach could benefit both new projects and the RMAA project. Another merit for using MiMEP approach in this RMAA project was that it could minimise the installation works on site and the disturbance, in particular air and noise pollution, to those who were still working in the building.

At the post-project stage, BIM model was connected with the asset management system so that the digitalised project information could be retrieved through RFID to fully realise smart Operations and Maintenance (O&M) system with digitalisation features.

Completion of the Chiller Replacement Project at Tai Lung Veterinary Laboratory

“In this RMAA project, MiMEP technology was accomplished with the use of precise BIM model, resulting in a reduction of construction time by more than 50% as compared to the conventional approach. The time required for the project was sharply reduced to 38 working days.” says Ir Ma Chun Yue, Senior Building Services Engineer of EMSD. “The project has proved that the application of MiMEP and other technologies are not limited to new deployment, but also facilitate smoother future RMAA projects.”

Concluding remarks – recognised benefits of MiMEP

The use of MiMEP in these three projects has demonstrated significant improvements in the economic efficiency in various aspects including increased labour productivity, enhanced construction quality, improved works safety and site management, accelerated construction speed, and reduced material consumption with improved environmental sustainability through the lowering of construction waste, carbon emissions, noise pollution and water pollution on the construction site, all of which contribute to carbon neutrality.

These projects have shown that the use of technological applications such as MiMEP is not limited to new construction, but can also benefit RMAA works. It has demonstrated that the works have a minimal impact on the clients’ daily operations.

Feedbacks on MiMEP collected from stakeholders in these projects are summarised below:

1. Construction time

   BS installation and builder’s works can be done simultaneously so that the construction time can be reduced. When MiMEP is used in parts that are on the critical path of the construction programme, the impact will be more noticeable. For instance, the cooling tower plant installation on the roof is labour intensive work that is on the critical path.

 
2. Economy of scale

   For layouts designed in a repetitive manner, it would be a good opportunity to mass produce the same modules in a controlled factory environment to enhance the economy of scale. The project preliminaries can also be reduced due to a shortened programme.

 
3. Labour productivity and quality control

   On a construction site, workers’ movements may depend heavily on the builder’s lift, particularly on a high-rise construction site where frequent movements may lead to decrease in productivity. The ability to shift installation to a factory or temporary factories close to the site (such as a flying factory) will increase labour productivity and improve quality control.

 
4. Health and safety

   Factories contribute to a cleaner and safer environment with fewer demands for site labours and reduced number of accidents. The risks related to working at height can be reduced.

 
5. Capacity and resilience

   Factories are weather-proof and provide a better work environment. It is also with the use of innovative technologies that the younger generation can be enticed to join the workforce, thereby increasing capacity and resilience.

 
6. Sustainability

   Accurate assembling helps reduce, recycle and reuse construction waste. Construction sustainability can be achieved through the improvement of workflow. In addition, the reduced on-site works and shortened construction programme will result in a reduction of on-site energy consumption as well as carbon emissions during construction, which contributes towards meeting the target of carbon neutrality. Various forms of efficient construction methods, such as offsite fabrication, MiC and MiMEP can also score the Modular and Standardised Design (MW2) and Prefabrication (MW3) credits under the BEAM Plus version 2.0.

 
7. Revolutionary coordination

   Apart from the conventional services coordination, the installation team will consult BIM models to ensure the fabricated modules are well-coordinated with efficient service combination and minimal iteration. In addition, the coordination on the module interconnection, logistics, adopting the “just-in-time” concept (with MiMEP delivered according to the construction sequence), can eliminate factory and site congestion and minimise damages to the modules on-site.

 
8. Design for maintenance

   Design for maintenance is essential. Heavy-duty MiMEP service racks for holding the services intact to facilitate transportation and installation may, however, raise maintenance concern. Under the application of horizontal ceiling module installation, the left-in of heavy-duty rack inside the already congested ceiling void would aggravate the ceiling maintenance difficulty. Temporary supports shall be designed for easy identification and dismantling after installation.

 
9. Flexible joints and connections

   Appropriate selection of joining method of services among MiMEP modules are to be carefully considered in the course of design.

Acknowledgement

The ArchSD and EMSD would like to thank the following for their collaborative effort with the project teams in delivering the projects with the use of MiMEP, a productive, innovative, safe and sustainable approach: user departments of the three projects, namely the Hospital Authority, the Department of Health, and the Agriculture, Fisheries and Conservation Department; the Contractor, China State Construction Engineering (HK) Ltd (HKICC); and the BS sub-contractors, ATAL Engineering Ltd (Fu Shan Mortuary) and REC Engineering Company Ltd (Tai Lung Veterinary Laboratory).