As the MEP (M&E) industry worldwide continues to turn to parametric 3d model-based building services design and coordination processes, the question of who does what between contractors and consultants has re-emerged BIM Detailer Austin
. One of the challenges in the modern building services industry concerns the effective control of BIM models between MEP Consultants and MEP Contractors.

BIM has many benefits including: greater collaboration between stakeholders, improved design performance, less constructability issues on-site and cost efficiency. However, implementing BIM requires successfully managing scope definition and delivery as well as the information flow between the MEP (M&E) consultant, the MEP (M&E) contractor, several sub-contractors and shop fabricators. However, BIM can create scope overlap (and therefore costs and delays for the project) between MEP (M&E) consultants, contractors and other downstream participants.

In the traditional system, where 2d design data is received, the MEP contractor would be responsible for services coordination and clash detection. He/she would overlay the 2d drawings of each of the services (HVAC, electrical, and plumbing) and perform a detailed coordination exercise – usually by using 3d tools or by using BIM tools. The end result would be a model that is spatially coordinated that can then be used for installation drawing creation and subsequent fitting/installation.

The traditional approach (2D drawing deliverables) did not require design consultants to think about constructability and spatial coordination. However, the BIM process calls for MEP (M&E) BIM consultants to create clash-free 3d MEP models before creating 2d design drawings for contractors to use. As the consultant is also handing over their BIM model (which is increasingly clash free and coordinated to some extent) he/she is in effect carrying out some of the scope traditionally taken on by contractors. However and more importantly, the MEP model from the consultant is not always coordinated in the way that the services would be installed or be cost effective for an MEP contractor.

Though the consultants’ BIM MEP model may be clash-free and spatially coordinated with the architectural and structural systems, the 3d model provided to the contractor by the consultant may fall short due to a number of reasons such as: I) procurement-led changes for materials and equipment; ii) it may not represent the actual installation process or layout; iii) the layouts may not be efficient i. e. allowing for too many bends and connections; iv) there may not be adequate allowance for lagging; v) there may not be adequate allowance for installation/hanging; and vi) there may not be allowance for access for maintenance purposes. In short, the consultant’s 3d model may be spatially coordinated but not adequate for installation.

Without updating the BIM model to his own fitting and installation requirements/standards, the contractor will not experience constructability issues until in the field. At that stage it is almost too late to make too many changes and the installation will be compromised as a review of the model and revised drawings at that late stage will almost certainly create additional costs and fees. Global construction practice has seen substantial changes over recent years, with the arrival of BIM being a key factor. Building Information Modelling, known as BIM, is a process that involves the creation of 3d models, which enables designers and engineers to create accurate construction scheduling, estimate costs and adapt intelligently to design changes. Accurate building information models and precise building designs are created from the outset, which benefits all stakeholders in the construction process, particularly MEP (mechanical, electrical and plumbing) designers. MEP (M&E) designers or engineers design MEP services, while MEP contractors are then responsible for spatial coordination, detailed design, fabrication and installation. Though BIM drives an effective process for MEP (M&E) design services, there are some risks involved. We look at how these risks can be mitigated.

Firstly, it is useful to understand exactly what the BIM process contributes to MEP engineering design. A BIM model helps visualise spatial MEP requirements. Detailed views are created for analysis, and any clashes of spatial requirements are identified and can be resolved at an early stage. Designs can be altered to mitigate any clashes, and these changes can be seen in the model.

The progress of the MEP design and coordination workflow process has been supported and driven by technological advancements. BIM technology has played an important role in making this possible, especially the use of 3d models through Autodesk’s BIM 360 tool. BIM 360 is a cloud-based software platform developed primarily for construction, which employs checklists, equipment tracking and the monitoring of tasks to improve quality and on-site safety. Within BIM 360, models can be utilised for 2d construction documentation and the 3d coordination of trades. BIM 360 permits the control of processes by project managers, subcontractors, designers and architects at all design stages. It enables the sharing of vast amounts of information between stakeholders and easy communication.

MEP designers can utilise architectural, structural and trade models to plan in detail from the onset of a project by designing in 3d. In general, the process involves MEP design and installation workflows that will streamline planning, designing, coordination, fabrication, installation and construction of a project. Following architectural design, the MEP design engineer develops building services design elements, such as lighting, cooling, heating, drainage, waste, fire prevention and protection services. In most cases, the design engineer is not involved with the detailed spatial design of building services. Usually, it is the MEP, or trade, contractor who carries out the detailed spatial design and installation. It falls to the MEP contractor to convert the consultant’s design into an installation-ready MEP format and provide MEP shop drawing services. At times, fabricators creating ductwork or pipework elements, electrical ladders or sprinklers in a module also contribute.