HKIE TRANSACTIONS2018, VOL. 25, NO. 4, 273–280https://doi.org/10.1080/1023697X.2018.1537813

A BIM-based approach to automate the design and coordination process ofmechanical, electrical, and plumbing systems

Qiqi Lu∗ and Yuen Hung Wong

Building Information Modelling Section, Hip Hing Construction Co Ltd, Hong Kong, People’s Republic of China

ABSTRACTThe design and spatial coordination of mechanical, electrical, plumbing, and fire protection sys-tems (MEP) have become a major challenge for successful project delivery. Traditionally, MEPcoordination has been conducted based on overlaying 2D drawings from different trades todetect functional and spatial interferences betweenMEP systems. Such coordination is time con-suming and of low efficiency. Recently, the advent and development of Building InformationModelling (BIM) have significantly changed this process by affording a visual and collaborativemanner. However, it still needsmuchmanual work andmany rounds of coordination as the con-ventional 2Ddesignwas still used. Therefore, this paper proposes awell-defined approach basedon BIM to improve the workflow and automate the process by developing an MEP rule-basedautomated engine usingRevit Application Programming Interface (API) tool. The engine is devel-oped primarily to help analyse available ceiling zone forMEP elements in the first phase and thenextended to facilitate rule-based routing in the second phase. The proposed approach is verifiedand validatedby an illustrative example, followedby a real-lifeMEPdesign case. The result showsthat with the help of the proposed approach, clashes and the number of coordination iterationare reduced substantially.

ARTICLE HISTORYReceived 15 March 2018Accepted 13 August 2018

KEYWORDSBIM; MEP design; MEPcoordination; rule-basedrouting; automation

1. Introduction

Design coordination of mechanical, electrical, plumb-ing, and fire protection systems (MEP) is an integralpart of setting up and laying out the designs acrossthe construction project. It serves as the key process inconnecting various building elements and making thefacility functional and operational.Many industry prac-titioners regardedMEP coordination as one of themostchallenging tasks in the construction project delivery.There is plenty of room for continuous improvement inthe existing MEP coordination between various partiesincluding designers, main contractor and trade-specificsub-contractors. In addition, the coordination processinvolves locating equipment and routing connectingelements of all building systems in compliance witharchitectural and structural design, construction andoperations criteria [1].

The conventional MEP coordination is conductedafter specialty engineers complete their individual tradedesign. It is the main contractor’s responsibility tomake the design buildable and functional. Therefore,the main contractor usually takes the lead in coordina-tion, with professionals from each trade to attend. Byoverlaying drawings for different systems and sequen-tially comparing them, multi-disciplinary representa-tives work together to detect and resolve the spatial

and functional interferences among MEP systems [2].In order to solve these clashes, MEP components oreven architectural and structural elements are re-routedand re-designed.

Iterative in nature, such manual clash detectionand coordination process usually involve several revi-sions before finalisation of coordinated drawings. Inaddition, it becomes more difficult to conduct MEPcoordination based on 2D drawings with increasingcomplexity of the design. Therefore, this way of coordi-nation is error-prone, time-consuming, and is regardedas one of the major challenges in the project delivery.

2. Conventional BIM-based process

Building Information Modelling (BIM) is the digitalrepresentation of physical and functional characteris-tics of a facility [3]. With the advent of BIM tech-nologies, the conventional MEP coordination processhas been changed and improved with various potentialcoordination issues addressed. 3D BIM models enableengineers to visualise the size, location and routingsof different building systems. BIM also allows smoothintegration of MEP systems to the architectural andstructural envelope. The spatial interferences can bequickly identified in the 3D environment, which cannot

CONTACT Yuen Hung Wong froky_wong@hiphing.com.hk∗The first author who was at the age of 35 or below on the closing date of submission for the HKIE Outstanding Paper Award for Young Engineers/Researchers 2018.

© 2019 The Hong Kong Institution of Engineers

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be easily identified for traditional 2D based coordina-tion, reducing actual reworks onsite. In addition, someBIM software platforms like Autodesk Navisworks pro-vide a comprehensive solution to conduct automatedclash detection.

Design based on 2D drawings, although is not rec-ommended in any BIM guidelines/standards, is stillcommonly included in the current BIM-integratedprocess. Therefore, in this BIM-based process, BIMis normally used to provide a 3D environment forclash detection and spatial coordination. The tradi-tional coordination process with the integration of BIMis described in Figure 1.

Main contractor BIM team develops MEP mod-els based on the preliminary shop drawings provided

by specialty sub-contractors. Coordination meetingsare led by main contractor building service (BS) teamand BIM team, and are attended by all specialty sub-contractors. 3D coordination is conducted based onthe integrated BIM models. However, the specialtysub-contractor only insures that the routings proposedin the design only reach the location and functionalrequirements of that system, it cannot ensure all thesystems that combined together will actually fit withinthe building. Therefore, they generally do not considerother systems [4]. During spatial coordination, MEPsystems elements are re-routed or relocated to avoidinterferences. Finally, upon the completion of coordi-nation, a set of coordinated shop drawings can be pre-pared for the design engineer’s approval [4]. Based on

Figure 1. Traditional BIM-based process.

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the coordinated shop drawings, specialised contractorsconstruct the systems onsite.

Although the manual clash detection and coordina-tion efficiency can be improved by BIM, the number ofcoordination iteration cannot be reduced significantly.Since common routing rules are seldom achievedbefore individual trade develops their own branch ofthe system. There are so many clashes need to be coor-dinated and resolved. Iterative in nature still existswhich cannot reduce the number of revisions. There-fore, it is important to have the agreed common rulesready before each trade develops their own systemdrawing to reduce iteration times. In addition, althoughintegrating with BIM, the whole coordination processis not intelligent and automated, which requires muchmanual coordination work. The current issues havenecessitated the development of a well-organised andautomated solution for MEP coordination. Therefore,this paper proposes a BIM-based approach to satisfythe need by developing an MEP rule-based automatedengine (called Autoroute) using Revit Application Pro-gramming Interface (API) tool. Since the conventionalBIM-based process still emphasises on the input from2Dwhich resulted in complicated and tedious checkingin the workflow and it is difficult to completely elimi-nate the 2D process. The development of the proposedapproach is divided into two phases to progressivelychange the current 2D status. Phase 1 still keeps 2Ddesign, with 3D coordination included; while Phase 2is a true BIM process. In Phase 1, the engine is devel-oped primarily to help analyse the available ceilingzone forMEP elements, whichwill help engineers iden-tify the critical/congested ceiling zone easily and thusworking out the routing rules. The engine will then beextended to facilitate rule-based routing in Phase 2 tohelp automate the whole design coordination process.

3. Proposed BIM-based approach

3.1. Phase 1 – automated ceiling spacedemarcationmap generation

As stated before, common routing rules ready beforeeach trade develops their own systemdrawing is impor-tant to reduce coordination iteration. On the one hand,engineers usually work out routing rules based on themost congested ceiling zone. On the other hand, it ishelpful to have available MEP space analysed for engi-neers to quickly identify critical ceiling zone. However,such available ceiling zone analyses are traditionallyconducted by overlaying architectural and structuraldrawings, based on which engineers calculate the avail-able zone manually room by room, and floor by floor. Itis very time-consuming and tedious to manually mea-sure headroom clearance based on 2Ddrawings. There-fore, it is important to automate available ceiling zoneanalysis process to reducemanual work. In this phase of

development, an automated MEP ceiling space demar-cation map generation function is developed to helpanalyse the free space available for MEP elements withthe restrictions of architectural and structural design.The map uses different colours to represent variousceiling height clearance. For example, the height clear-ance of 3.0m–3.5m may use a lighter colour than3.5m–4.0m, which indicates the available space leftfor locating MEP routings. Based on the demarcationmap, engineers can easily identify the critical zone forlocating MEP elements.

With the integration of MEP ceiling space demar-cation map generation engine, the conventional BIM-based process can be revised as Figure 2. Based on theconstraints provided by the architectural and structuralmodel, a ceiling space demarcation map is generatedto facilitate the analysis of available ceiling zone forMEP routings. “Big Room” Meeting among the maincontractor, designers and all MEP sub-contractors isconducted prior to the production of any preliminaryshop drawings. During thisMeeting, engineers can eas-ily identify the most congested ceiling area with thehelp of the demarcation map. All trade-specific sub-contractors work together to locate routings in thesecongested areas and try to work out MEP routing rulesfor developing their initial shop drawings. For example,higher MEP zone should be used for Fire Service (FS)routings, while the bottom MEP zone is used to locateAir Conditioning (AC) elements. For another exam-ple, clearance of fire rated duct enclosure should bemore than 200mm. Based on common rules, specialtysub-contractors develop their own system drawing forcoordination. Since common rules have been achievedbefore design, major clashes can be avoided. Therefore,the number of design changes and coordination itera-tion can be reduced significantly, saving time and cost,compared to traditional BIM-based process.

3.2. Phase 2 – rule-based routing

The use of BIM and automated ceiling space demar-cation map generation can save time and cost to someextent, but cannot save the overall design and coordina-tion time as the 2D design is still involved [5]. In orderto streamline the coordination process, design based on2D should be removed. Therefore, in Phase 2 develop-ment, the 2D design step will be removed and a trueBIM process will be adopted by integrating rule-basedrouting function.

With the advancement of BIM technologies, rule-based systems are developed to automate and improveproject delivery [6]. The most widely used rule-basedapplication by practitioners in the construction indus-try might be “clash detection” tools (e.g. to detectdesign interferences of MEP elements). Many otherrule-based checking systems are also explored by schol-ars for different purposes in the academia, e.g. for

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Figure 2. Proposed BIM-based approach Phase 1.

safety planning and simulation [7], for green build-ing design [8], etc. However, all these systems are usedfor checking a design that has already been completed,while in fact, the design process itself is usually themost iterative part, as it includes tedious and repetitive

rule checking tasks. Traditionally, such rule checkingtasks are performed manually by designers. Rule-basedmodelling or integration of rules with BIM authoringtool can enhance the design process and allow design-ers to create elements within the rules’ requirements

Figure 3. Proposed BIM-based approach Phase 2.

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and automate the design process [9]. But such rule-based modelling is seldom developed by researchers.It is believed that if MEP coordination rules can beintegrated with the design authoring tool to providerule-based routing function, the time for design andcoordination will be significantly reduced.

Therefore, in order to automate the MEP coordina-tion process, the Autoroute Add-In will be extended toinclude the function of rule-based routing for users toinput rules before modelling. This function will allowthe user to create models within the agreed commonrules and do not need to waste time referring to paper-based standards/rules. For example, if an FS pipe isplaced under an AC duct, an error will be reportedto the user since it betrays the rule that “pipeworkshould be located higher than ductwork”. An auto-mated 200mm offset will be given to the user if he/shewants to model a pipe near fire rated duct enclosure tofollow the rule “clearance for fire rated duct enclosureshould be more than 200 mm”.

Proposed BIM-based Approach Phase 2 is describedin Figure 3. Main contractor BIM team will help inputthe routing rules worked out by all trades’ engineersin the engine. Specialty engineers can design withinthe restrictions from the pre-defined rules. Since engi-neers do not need to frequently refer to 2D papers tocheck rules, the design process is more systematic andless tedious with the help of ceiling space demarca-tionmap generation and rule-based routing. Therefore,design efficiency and accuracy are improved, and thenumber of clashes is reduced, saving much design andcoordination time.

4. Illustrative example

Due to time limitation, only Phase 1 development ofthe automated engine (MEP ceiling space demarcationmap generation) has been developed and validated inthis section. Phase 2 development (rule-based routing)is still under progress and will be contained in future

work. The proposed approach should be verified andtested before implemented in real projects. Therefore,a sample project was created, which consists of fouroffice rooms, two meeting rooms and one corridor, asshown in Figure 4. The floor height of the project is4100mm. The ceiling height/headroom clearance offour office rooms, meeting rooms 01, 02 and corridorare 2800mm, 3200 m, 3000 m, and 2500mm, respec-tively. Six beams will be constructed for the project.

The Autoroute Add-In application has been devel-oped for Autodesk Revit 2018 under the Add-Ins Tab(Figure 5). As shown in the interface, only head-room editor is contained in this engine currently. Rule-based routing editor is under development and will beincluded in future.

The headroom editor displays several columns forthe analysed rooms in the project. The columns withvalues in black colour are system columns, which can-not be edited by users; while those with values in blueare editable columns. Since ceilings have been cre-ated for all rooms in this project, Detect Ceilings arechecked by default. If users want to have custom head-room for some rooms, they can input value under the“Custom Headroom” (mm) column and tick the “UseCustom Headroom” for that room. Then the systemwill use custom headroom instead of detected ceilingheight to run the analysis. After all necessary infor-mation has been input, users can click the “Generate”button to start the analysis. MEP ceiling space demar-cation map will be generated within a second as illus-trated in Figure 6. The map uses different colours torepresent the available ceiling zones. For example, theroom with darker or red means the headroom heightis smaller. The result shows that the engine is able toconduct a quick analysis of the available ceiling zone forMEP elements, which is extremely useful for large-scaleprojects with complicated design and space require-ments. It can help reduce engineers’ time in identifyingthe critical ceiling zone to work out rules for MEProutings.

Figure 4. Typical floor plan and structural plan of the sample project.

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Figure 5. Auto-route Add-In interface.

Figure 6. MEP ceiling space demarcation map of the sample project.

5. Case study

The proposed approach has been verified by the illus-trative example, it is necessary to apply the approach ina real-life MEP design case to evaluate the effectivenessand benefits achieved. The developed engine was firstlyapplied to facilitateMEP coordination of a seven-storeyclubhouse project due to its complexity inMEP coordi-nation and different headroom requirements for eachfloor.

The seven-storey clubhouse has a total gross floorarea of 290,388 ft2 (26,978m2), with a two-level

basement carpark, a swimming pool, a gym, a foodcourt, a bowling lounge, tennis courts and severalrestaurants. Conducting MEP design and coordina-tion are extremely difficult for this multi-functionalproject, with different requirement of floor height andheadroom for each floor. Therefore, the proposed BIM-based approach with automated ceiling space demar-cation map generation was adopted in this project toenhance the MEP coordination.

In the early design stage, BS engineers and trade-specific sub-contractors should conduct MEP designbased on the constraints provided by architectural and

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Figure 7. L2 ceiling space demarcation map.

structural models, as well as the headroom require-ments from the client. The automated ceiling spacedemarcation map generation engine quickly helpedthem facilitate the analysis of available ceiling zone forMEP routings and identify the congested ceiling zonefor each floor. For example, there are 60 rooms accom-modated on level 2, and it only took up to nine minutesto finish available ceiling zone analysis and demarcateceiling space with different colours. Usually, it wouldtake almost one day to conduct such analysis manuallyfor the same floor area.

As shown in Figure 7, the middle right area (Grid10-13, Grid G-E) was identified as the most congestedarea for level 2. All BS engineers and specialty sub-contractors worked together to locate routings in thiscongested area and tried to work out common MEProuting rules for developing their initial system draw-ings. Initial BIMmodel for each tradewas created basedon the shop drawings provided by sub-contractors.MEP coordination was conducted on the combinedtrade BIM models. Since common rules had beenachieved before design, major clashes were avoided;the number of coordination iteration and designchanges were reduced dramatically, saving much timeand cost compared to the conventional coordinationprocess.

6. Summary and future work

The conventional BIM-based process for MEP coor-dination is conducted based on 2D drawings, whichis time-consuming and needs many rounds of coordi-nation before developing coordinated shop drawings.No common rules achieved before each trade develops

their system is one of themost critical reasons for a largenumber of coordination iteration in the current pro-cess. To reduce coordination times, the conventionalprocess should be firstly revised to have common rulesworked out by all trades at the beginning of design andcoordination. In addition, in order to automate the pro-cess, this paper describes a well-defined approach basedon BIM by developing an MEP rule-based automatedengine using the Revit API tool. Since it is difficult tocompletely change the conventional process and elimi-nate the 2D process, the development of the proposedapproach is divided into two phases to progressivelychange the current 2D status.

In Phase 1, engineers still conduct MEP coordi-nation based on 2D drawings with automated MEPceiling space demarcation map to help them analyseavailable space for MEP elements and identify con-gested ceiling zone to make common rules achievedbefore design. Phase 2 is a true BIM process with rule-based routing to help engineers automate the designand coordination process. Due to time limitation, onlyPhase 1 development of the automated engine (MEPceiling space demarcation map generation) has beendeveloped and validated by an illustrative example. Theresult shows that the engine is able to conduct a quickanalysis on available ceiling zone for MEP elementsand help reduce engineers’ time in identifying the crit-ical ceiling zone to work out rules for MEP routings.With the help of the proposed approach, the num-ber of clashes and coordination iteration are reducedsignificantly compared to conventional BIM-basedprocess.

Although the use of BIM and automated ceilingspace demarcation map generation can save time and

280 Q LU AND Y HWONG

cost to some extent, it cannot save the overall design andcoordination time as the 2D process is still involved.In order to streamline the coordination process, the2D design should be eliminated and the engine shouldbe developed to include rule-based routing to auto-mate the process, which will be included in futurework.

Acknowledgements

The authors take this opportunity to thank Hip Hing Con-struction Co Ltd to fully support, and continuously fund thisresearch project and developmental works that have beendescribed and presented in this paper. The authors appreciatethe guidance and suggestions from the directors, Mr DerekSo and Mr K H Mok. In addition, the authors are gratefulto Mr Joseph Lo and his building services team, who pro-vided professional engineering knowledge and expertise thatgreatly assisted the research.

Funding

This research is conducted and sponsored by Hip Hing Con-struction Co Ltd.

Notes on contributors

MsQiqi Lu is an experienced BIMEngi-neer with a strong background in engi-neering and a demonstrated history ofboth BIM research and working expe-rience. She has obtained a Master ofPhilosophy degree in Civil Engineeringfrom The Hong Kong University of Sci-ence and Technology. After joining HipHing for more than two years, her team

and she haswonmany awards, e.g. AutodeskHongKongBIMAwards 2016, Silver Award for Incubation Circle 2016/17, etc.

Mr Yuen Hung Wong a professionalmember of The Hong Kong Instituteof Building Information Modelling andManager and Head of BIM Section inHip Hing Construction Co Ltd, wholeads his team to win an AutodeskHong Kong BIM Awards 2016. He hasobtained a Master’s degree in IntelligentBuilding Technology and Management.

He is experienced on BIM implementation, development andmanagement in AEC industries with 10 years solid experi-ence which includes the BIM projects in Hong Kong, Shang-hai, South Korea, Australia, United Arab Emirates and Qatar.

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