Crucial Developments in 3D Building Services Design and Coordination Field

Building services projects have benefited from many developments that have occurred in the last decade. Whether in the areas of MEP (M&E) systems design, 3D building services coordination, or interdisciplinary collaboration, the major advances seen in this field have emanated both from within the industry as well as from other sources, such as government regulations and economic developments.

·      Intelligent BIM Software for Planning and Design of Projects

One of the biggest changes in the modern building services industry is the use of intelligent building information modelling (BIM) software tools that allow for the creation of accurate and detailed representations of mechanical, electrical, plumbing, and fire protection systems using computable data. The fact that there are BIM tools more intelligent than ever and also which work across disciplines, such as architecture, structural engineering, and building services engineering, increases interdisciplinary coordination and reduces construction waste and rework.

For instance, the BIM models created using Autodesk Revit Architecture and Revit MEP can be used by building service designers for developing concept designs, schematics, and tender drawings. The same parametric model can be worked upon and used by contractors to create detailed installation and 3D MEP (M&E) coordinated drawings, including services-specific as well as multi-service coordinated plans, sections, and elevations. Furthermore, fabricators and installers can use the BIM model in conjunction with FAB MEP, a fabrication tool, to manufacture pre-assembled modules for installation on-site.

Not only does BIM allow creation of a coordinated 3D model, it also allows for information to be added to the model that can be used for project-critical purposes, including schedule creation, cost estimation, energy analysis and facilities management.

·      Greater Interdisciplinary Collaboration

Due to the growing adoption of BIM tools industry-wide complemented by the availability of sophisticated hardware systems and online collaboration channels, there is a far greater degree of interdisciplinary coordination between different stakeholders involved in AEC projects. As a result, architects, structural engineers, MEP consultants, MEP engineers, main contractors (general contractors), cost estimators, and fabricators can seamlessly collaborate during the design and planning stages and avoid costly rework during the construction stages.

For instance, large-scale construction projects generally have a complicated project structure comprising diverse project teams based in different geographical areas. During the pre-construction stage, sharing and interlinking the BIM model prepared by architects, structural engineers, MEP specialists and contractors enables respective designs to stay coordinated. Due to cloud-based collaboration tools, team members can hold review sessions online without having to be physically present together.

·      Higher Degree of Pre-Fabrication and Just-In-Time Delivery for Installation

With the widespread use of parametric modelling techniques in MEP design and planning, a major trend is to use BIM models forpre-fabrication purposes with a view to enhance the logistical cycle on the construction site. When used in conjunction with CNC fabrication applications, such as FAB-MEP, the BIM design data can be used to create fabrication drawings that can be recognised by CNC machines. Such a BIM-led prefabrication can streamline the installation process on site and avoid costly miscalculations.

Taking into account the complexities of the MEP (M&E) systems industry, BIM-driven prefabrication and modularisation has led to multifaceted benefits: reduced rework, in-time project completion, cost savings and increased efficiency.

·      Government Intervention 

Another critical development from outside the industry is the government policies in different parts of the world either promoting or mandating the use of BIM in varying levels for government-funded or private projects. In the US, the General Services Administration (GSA), through its Public Buildings Service (PBS) Office of Chief Architect (OCA), established the National 3D-4D-BIM Program in 2003. GSA mandated the use of spatial program BIMs as the minimum requirements for submission to OCA for Final Concept approvals of all major projects receiving design funding in 2007 and beyond.

In Europe, the UK Government has made Level 2 BIM compulsory for all publicly-funded projects from 2016 onwards with a view to trim the cost of public-funded projects and to reduce carbon emission to meet its EU commitments. Government agencies from the Scandinavian nations have played an important role. Senate Properties, Finland’s state property services agency, required the use of BIM for its projects since 2007. Neighbouring Norway and Denmark have also made sufficient headway towards adopting BIM practises in their public-funded projects. Statsbygg, the Norwegian government agency that manages public properties, including heritage sites, campuses, office buildings and other buildings, employed BIM in all its projects by 2010.

In Asia, Singapore was in the forefront of driving the adoption of BIM. After implementing the world’s first BIM electronic submission (e-submission) system for building approvals, the Building and Construction Authority (BCA) mapped the BIM Roadmap with the aim to adopt BIM for 80% of construction projects by 2015. In Hong Kong, the Housing Authority (HA) not only developed a set of modelling standards and guidelines for BIM implementation but also stated its intent to apply BIM to all its new projects by 2014-15. South Korea’s Public Procurement Service, which reviews designs of construction projects and provides construction management services for public institutions, has made BIM mandatory for all projects worth more than S$50 million and for all public sector projects by 2016.

3D MEP Coordination: An Effective Way to Reduce Rework and Increase Efficiency

As the architecture, engineering and construction (AEC) industry faces tremendous pressure to deliver optimal projects within stringent deadlines, improving process efficiency and reducing rework is certainly the need of the hour. The design and construction-related rework is one of the critical factors that adversely affect productivity, profitability and timely completion of projects for both contractors and owners. Besides, it impacts designers, subcontractors, MEP (M&E) engineers, consultants and the entire downstream chain. In comparatively larger and more complex projects, the design-build rework can negatively influence the entire project workflow, delay project delivery, and cost more than what was originally estimated.

As mechanical, electrical, and plumbing systems account for a significant value of the project, the prudent use of building information modeling (BIM) tools to effectively coordinate MEP (M&E) systems helps reduce rework and increase productivity. On the other hand, the lack of well-planned interdisciplinary MEP (M&E) coordination results in duplication of efforts, major interferences and design clashes on site, as well as fabrication changes and errors.

Since BIM requires comprehensive pre-construction planning and multidisciplinary coordination, its adoption by the MEP (M&E) team increases technical interoperability among various members during building services coordination. In BIM-led MEP (M&E) coordination, building services designers, consultants, and subcontractors are involved during the design and planning stage. One of the most crucial factors for an effective and accurate coordination exercise is to decide on a specific protocol for creating virtual architectural, structural, mechanical, electrical, plumbing and fire protection models of the same facility. Subsequently, the team should agree on mechanisms to merge the models from different trades and create a combined coordinated services MEP model.

For instance, the designers use Revit Architecture application to prepare architectural BIM models that accurately represent elements, such as walls, doors, windows, ceilings, and casework. Furthermore, each of these elements has a range of parameters, including thickness, height, materials, and texture, among others. Using this architectural model as a reference point, a structural model will be created using Revit Structure which features vertical and horizontal structural framing, foundations, and slabs.

Subsequently, the MEP (M&E) contractors and subcontractors design separate models for mechanical, electrical, and plumbing systems using 3D MEP modeling software (such as Autodesk MEP and Revit MEP). Usually, the mechanical models include HVAC ducts, piping assemblies, hangers, diffusers, and pipe insulation, to name a few. The electrical models will represent details concerning conduits (feeder and underground), junction boxes, lighting systems, cable/wire bundles, and cable trays, amongst others. The plumbing system model includes storm and sewage lines, plumbing assemblies, hot/cold water piping, and other specialty equipment.

Once the respective architectural, structural, and building services models are in place, they have to be merged and taken into a clash detection application and specialist interference-checking application, such as Autodesk Navisworks. Any clashes and inconsistencies, including the geometry-related hard clashes, the clearance clashes, and workflow clashes are detected. Post clash detection, the combined services models and drawing sets have to be prepared to show how MEP (M&E) systems fit together in the same space.

As a result, the MEP (M&E) installers and fabricators receive well-coordinated and clash-free building services drawings on site, which drastically reduces the number of installation conflicts in the field. Additionally, MEP (M&E) BIM coordination leads to a greater number of assemblies being prefabricated off-site in a controlled factory environment, which in turn improves the logistical flow on site. Moreover, another positive outcome of BIM-driven MEP (M&E) coordination exercise is relatively lesser number of change orders and RFIs (request for information).

All the above positive effects of MEP (M&E) BIM coordination make the design-build process more efficient by increasing project’s schedule compliance whilst reducing design and construction-related rework.

The Two Methods of MEP Coordination

MEP is an acronym used for Mechanical, Electrical and Plumbing systems for building projects.  With the increasing complexity and functionality of each system, MEP activities are not confined to the traditional mechanical, electrical and plumbing system but also include fire protection, gas piping, process piping, pneumatic tubing, data systems etc.   This article assumes that the design has been completed by ‘Design Consultants’ to a certain stage and then handed to ‘Installation Sub-Contractors’ who will validate the design and value engineer the design through the process of spatial coordination and procurement of components to meet the requirements of the design.  The coordination of Mechanical, Electrical and Plumbing (MEP) systems amongst themselves and with other building systems including architectural and structural disciplines is a critical, challenging and time consuming task, especially in complex building projects with intense MEP requirements.  The coordination process of Mechanical, Electrical and Plumbing (MEP) systems involves defining the exact location of each building system component throughout the building within the constraints of the envelope defined by the architectural and structural systems to comply with diverse design and operations criteria avoiding any interferences/clashes amongst building systems. Assuming that most companies undertake the task of MEP Coordination, without which the site installation from a ‘design only’ set of drawings would be too much of a risk, there are two ways by which the following process takes place:

2D MEP Coordination: The process starts with the design from the Design Consultant.  The Sub-Contractor team will manually update the 2D CAD drawings or create their own set from the start.  In creating these drawings a number of sections will be drawn and frequent attention given to ceiling void spaces in which the systems and services are being laid out.  In an ideal world 2D MEP Coordination can work as long as all services and systems are assessed adequately and then drawn into a 2D drawing.  The sizes of the systems would need to be manually added as would the heights and distances from gridlines or walls.  The contractor will have teams of people for each system (HVAC, plumbing, electrical etc) creating their drawings based on the architectural ceiling void.  In this method, there is no automated system to identify the conflicts in the MEP system and therefore there is a high degree of reliance on the intuition, imagination, technical knowledge and experience of the team members to lay out the services without site teams experiencing clashes.  Visualizing the potential clashes is made more difficult due to changes in ceiling profiles, not to mention the challenge of having to understand the impact of all systems as well as structural and architectural elements that may impede or impact a system or service route.  What makes things worse is that a third party cannot easily review the drawings for any errors, nor can the design be easily reviewed or communicated with a project team.  Additionally, if there are changes to the design or procurement-led changes then the process of undoing and re-doing 2D MEP Coordination projects becomes very cumbersome.  The inherent weaknesses of 2D CAD software also come into play; one can draw something of one size and label it as something completely different.  As the systems and services drawings are not checked in some form of automated method there is no guarantee that the 2D MEP coordination process will generate a clash free drawing. During the time of complex projects, it requires multiple section viewings which consume a lot of time.  These time commitments come with additional costs to each contractor.

3D MEP Coordination : This process is more collaborative and allows the ability to communicate the progress of the project quickly and easily, providing 3D visuals that resemble the final system and service installation.  It starts with a clear direction in terms of spatial zoning which is then used as the basis to start modeling the HVAC, piping, plumbing and electrical services.  As the architectural and structural models form part of the model, it is easier to insert services and systems without creating clashes.  Once the model is complete and all systems and services have been added, the ability to identify problems becomes much easier compared to the 2D Coordination method. Firstly, one is able to walk through the model using roaming software to review the model and, secondly the use of clash detection software, such as Navisworks, highlights all clashes whether these are systems against other systems or systems against structure or architecture.  Once highlighted, all clashes can then be corrected during the coordination stage of the project.  Only once the model is interference free are drawings created.  This leads to another set of benefits, unlike 2D coordination where each section must be drawn, the 3D software allows creation of sections that are directly taken from the model.  Additionally, as the 3D software is so intelligent, the sizes of systems are directly taken from the 3D model and therefore there is no chance of services or systems being modelled as one size and then labelled as another.  Beyond the coordination stage, there are several other benefits from the 3D model, including use during facilities management, energy analysis and so on.

Irrespective of the MEP Coordination method used, the need for MEP Coordination arises due to the lack of detailed coordination during the design stage.  Additionally the need for fabrication and installation of building systems in accordance with industry and Sub-Contractor best practice requires MEP Coordination to be carried out by them.  The 2D MEP Coordination process provides a limited interference-checking capability and therefore can and will result in more problems on site including additional re-work, change orders and inflating budgets.  All of this makes 3D MEP Coordination a more efficient and the increasingly preferred method for the long term.

Typical Stages Involved in MEP Coordination

One of the most integral practices undertaken in the pre-construction phase, MEP coordination demands special attention from all the AEC professionals involved in a project. This process ensures that the building’s architectural design and its structural framework don’t interfere or clash with its Mechanical, Electrical, Plumbing or Fire Protection systems. While the MEP coordination process may vary from firm to firm depending on the client’s requirements and the level of details (LOD) sought, following are the typical stages involved in the same:-

1. Review of Consultant Design Drawings and Architectural/Structural Plans

In this preliminary stage, the firm responsible for MEP coordination normally receives single-line drawings from MEP consultants or contractors. Additionally, the architectural and structural plans are analysed in detail. Apart from evaluating these drawings and layouts for consistency with schematics, their MEP specifications are studied. Based on this analysis, the MEP coordination services provider lays out a coordination roadmap.

2. 3D Model Creation

Using the consultant design drawings received in the initial stage, the MEP coordination services provider creates an accurate 3D model, by either using Revit or AutoCAD. This model shows all the MEP services within the architectural and structural limitations of the building. The 3D model completed here lays the groundwork for several other important construction-related drawing sets -- plans, sections or elevations. Furthermore, this 3D model will be used for client inputs and for creating detailed walkthroughs.

3. Clash Detection and Resolution

In this stage, the MEP coordinating services provider evaluates the 3D model, created in the previous stage, for conflicts and clashes between the architectural elements and the MEP systems. This is done using Navisworks, a specialist interference-checking software application. Any inconsistencies, including the geometry-related hard clashes, the clearance clashes, and workflow clashes, if any, are detected here and feasible alternatives for the same are provided to the client.

4. Creation of Coordinated Drawings and Sections

Once the 3D model is tested for horizontal and vertical coordination and clearance, coordinated drawing sets are prepared to show how mechanical, electrical, plumbing, and fire-protection systems work together in the same space. Besides, to make sizes clear for each discipline, additional notes may be added. The coordinated drawings form a ready reference for individual service-by-service drawings. In addition to this, firms responsible for handling MEP coordination may take section, elevation and isometric views from the same 3D model and use them to explain to the clients and detail the layouts.

5. Creation of Detailed Service Drawings

At this stage, each of the single service-by-service drawings are created and details related to their sizes, heights, and distances from gridlines, are added for further clarity. While these drawings are used by site installation teams, they also form the basis for fabrication drawings.

6. Creation of Fabrication Drawings, Spool and Hangar Drawings

In case the scope of work requires, then the individual services drawings are used to create fabrication drawings by either using traditional detailing or using FAB-MEP software. These drawings display fabrication details for ductwork and can be directly recognised by the CNC machines for production purposes.

If needed, the MEP coordination team also details elements of the model to create spooling data for production teams. Apart from this, the firm may also map out and then detail the hangers for each drawing. Once mapped out, the hangar details are shown on a schedule for the production teams.

Depending on the scope of the project, some of the above stages may be excluded by the MEP coordination services providers. However, each phase is crucial for a smooth completion of the project without any delays, cost overruns, and abrupt design changes.

7. As-Fitted Changes

This final stage involves making changes to the model and the drawings due to any site based changes or deviations from the construction drawings.  In cases where the coordination exercise has been well executed and the installation has followed the construction drawing instructions and layouts, the changes to the as-fitted (also known as as-built and as-installed) drawings are minimal.