Why MEP Contractors Change MEP Design Models

MEP Design Services | MEP Consultants | MEP Services

In the MEP environment, a building’s MEP designs are initially developed at high level and then detailed to make them clash free and installation ready. MEP designers/consultants play a significant role in design decisions, construction planning, cost estimation and documentation. While design development is typically the role of the consultant and design detailing is done by the MEP contractor, when using MEP (M&E) BIM models and Revit BIM libraries, contractors invariably need to make changes to the MEP design model created by the consultant.

To make a design installation ready, contractors may have to make several changes to the design-intent such as resizing of ducts, re-routing of pipework, adding wall penetrations, bolt locations and datum points for hangars and changing equipment. Once these changes are made by the contractor, the design would be installation ready and will need to be approved by the MEP consultant. The question that this article seeks to answer is why do MEP contractors need to make these and other changes to MEP design models?

  • To adjust invert elevations – During the installation of plumbing or drainage pipes, MEP contractors deal with the point of the bottom inside of the pipe, this is known as the invert elevations. To guide pipe design and match the invert elevation height, elevation information can be vertically adjusted at the centre of the pipe using Revit. However, if you are unaware that the elevation information is in centre of the pipe, it could cause confusion in adjusting invert elevations and create discrepancies while coordinating with other disciplines. This is the reason why MEP contractors need to manually adjust invert levels, create spot elevations for the inside bottom of the pipe and change the design models to install pipes which are coordinated with other disciplines.
  • To retrofit MEP systems into a prefabricated module environment – Planning for prefabrication of MEP components into the 3D model would not be considered by designers and therefore the contractor is the party who will make adjustments to services to allow them to fit into prefabricated modules to maximise the advantages that are gained from off-site fabrication. In several MEP projects which require prefabrication of risers, ceilings and plant room areas, MEP services drawings and modules specifically for fabricators and installers is necessary to facilitate proper installation. MEP contractors make changes in the MEP design model to ensure that services fit within modules within the ceiling or riser space to allow prefabrication of MEP components off-site allowing faster installation on-site.
  • To facilitate efficient spatial coordination – When installing MEP systems, effective spatial coordination with other building services and disciplines is imperative. A consultant may leave clashes in a model as his focus will be on getting a design issue by a due date. A contractor is more concerned with actual fitting so after conducting a clash test on the 3d model, MEP contractors will invariably change design models to ensure that all services are not clashing. The installation programme of the MEP system depends on clash free layouts and MEP contractors must make sure that MEP systems are spatially coordinated with other disciplines in the 3D model before creating M&E (MEP) Coordinated Drawings.
  • To deal with constructability issues – There are several factors that influence the constructability or sequence in which MEP systems are installed. Some of the conflicts that require a change in MEP design include routing, fitting and sequencing of large equipment within a given space, conflicting piping network and installation of MEP systems within a crowded space. As MEP contractors need to tackle several conflicts and constructability issues before installing MEP systems, a change in MEP design usually occurs.
  • To install MEP systems economically and efficiently – While the MEP design intent may seem to be perfectly coordinated, it need not necessarily be economic or efficient when it involves installation. There are several costs involved when changes need to be made after installation such as re-routing pipes to reduce bends, re-positioning ducts to allow supply and extract in the correct locations, changing equipment or adding wall penetrations, bolt locations and datum points for hangars. To make sure that MEP systems are installed economically and efficiently, MEP contractors must make changes to MEP design models.
  • Changes in materials and components – In some cases the MEP model from a consultant is accurately modelled with specified parts, materials and components. However, in some cases projects do not have specified parts and a consultant may use library elements from Revit leaving the contractor to update the model using his planned procurement schedule. This will result in changes due to sizes and access requirements for new components such as a change from copper to plastic pipe which is thicker or a change from one set of pumps to another that may be larger and may have different valve arrangements. The knock-on effect of such component changes can mean that other systems also need to be changed.

Given the many reasons why MEP contractors need to change MEP designs and with the adoption of MEP (M&E) BIM practices, there is an overlap in the scope of MEP contractors and consultants during the planning phase. To know more about how you can reduce the duplication of efforts, additional costs, manage project schedules and reduce scope overlap, read more in this post to find out the possible routes that can be taken.

To ensure MEP design models are installation ready for MEP contractors to use on site, a viable solution would be to work with a 3D BIM coordination specialist or MEP engineering design service provider. At XS CAD, our experienced team of MEP designers in India provide BIM support and spatially coordinated building services drawings for key stakeholders in the MEP (M&E) industry, from MEP (M&E) consulting engineers and MEP (M&E) building services contractors. In our spatially coordinated MEP building services models, we use the latest 3D MEP (M&E) modelling software (Revit MEP) and clash detection technology (Autodesk Navisworks) to provide 3D M&E (MEP) coordinated drawings which adhere to engineering standards, the structural and architectural elements within a building.

MEP Design and MEP Installation Challenges

In the MEP (M&E) industry, the smooth progression of an MEP consultant’s design into well-coordinated constructible drawings and models is fundamental to the project’s success. Compared with the architectural and structural engineering disciplines, the structure of a typical MEP project team is typically more complex. It comprises an MEP consultant, an MEP contractor, trade-specific subcontractors (for mechanical, electric, plumbing and fire fighting disciplines), fabricators, and installation and maintenance specialists.

Often, the contractor is responsible for fabrication and installation; however, in larger projects, there are distinct parties commissioned for each task. Furthermore, all these key players are highly interdependent on each other right from when the building services are conceptualised to when they are detailed, fabricated and installed on site.

It is paramount that the 3D M&E (MEP) coordinated drawings/model passed on by the consultant to the MEP contractor is not only free of clashes but also allows for ease of fabrication, efficient installation, and post-completion maintenance. But this remains a challenge partly because MEP design has traditionally been a two tier system wherein the MEP consultant develops plans and schematics which are then passed on to the contractor for detailing, spatial coordination, fabrication and installation.

As a result, though the consultant’s MEP design drawings/model will show no clashes vis-à-vis the architectural and structural models/drawings, the MEP contractor will, in many cases, have to change consultant’s issue drawings to suit his requirements with respect to ease of fabrication, installation efficiency, insulation allowance, and lagging. Ducts will have to be resized. Pipework will have to be re-routed. Datum points for hangers, wall penetrations, and bolt locations will have to be added. Electrical ladders will have to be split. Equipment will have to be changed. This means the MEP design-intent will undergo a slew of changes before a detailed coordinated installation-friendly version is ready to be approved by the MEP design consultant.

In essence, the fact that the MEP contractor has to adapt consultant’s design model/drawings or in many cases redraw them not only leads to scope overlap but also negatively impacts project deadlines and schedule. The growing adoption of building information modelling (BIM) has seen a greater level of engagement from the MEP contractor in the initial design stages; however, adopting and implementing 3D BIM coordination and detailing have their own set of challenges.

Firstly, an MEP (M&E) BIM project starts with the design-intent model created by the MEP consultant. This design-intent acts as a reference model which is extended by respective parties during coordination (and detailing) phase to create a constructible model with all the details pertaining to fabrication, installation, and services maintenance. As the BIM model progresses from schematics to detailing, 3D building services coordination, fabrication, and installation phases, MEP contractors and other trade specialists contribute their respective versions to the base model.

Furthermore, the model contributed by each discipline (HVAC, electrical, mechanical, fabrication, installation) will have different levels of detail (LOD). Since each trade reuses existing elements and extends them with information relevant to their particular area of responsibility in the project, success depends on how smoothly the BIM model is extended with minimum redrawing of the earlier version model.

At XS CAD, we understand the key nuances involved in an MEP project because we have experience of working with key participants of the MEP supply chain: MEP consultants, MEP contractors, fabrication specialists, and installers. We provide pre-construction planning support during all phases of MEP design from inception and detailing, to coordination and installation.

To find out more about how your MEP (M&E) project can benefit from our 3D building services coordination, MEP modelling and MEP CAD outsourcing services, contact us.

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 for pre-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.

BIM-Enabled IPD: A Win-Win for Owners and Project Stakeholders

The building and construction industry is faced with a multitude of challenges in areas, ranging from design planning, construction administration and budgeting, to scheduling and facilities management. To add to this, the demands from owners’ regards to timely completion, cost efficiency, constructability and energy performance are becoming increasingly stringent. As a result, multidisciplinary coordination between all the parties involved in an AEC project right from design planning through to on-site construction, administration is paramount to meet these demands.

Integrated Project Delivery (IPD) framework, if implemented appropriately, can ensure ongoing collaboration between diverse stakeholders, including the client, the architect, the main contractor, the MEP designer and the MEP contractor at all the stages of the project from conception to completion. As defined by the American Institute of Architects (AIA), Integrated Project Delivery (IPD) is a process that “collaboratively harnesses the talents and insights of all the participants to optimize project results, increase value to the owner, reduce waste and maximize efficiency through all phases of design, fabrication, and construction.”

A crucial element of the IPD approach is the adoption of building information modelling (BIM) technology. Unlike traditional project delivery methods, the essence of BIM technology is the central parametric model that is developed using 3D input, often times separate BIM models, from different parties involved in an AEC project. By enabling greater collaboration and information-sharing between different participants, data-rich BIM models drive the IPD framework and improve decision-making ability that can positively impact the project’s outcome. Following are the compelling reasons as to why AEC project teams must employ a combination of IPD and BIM and how this approach delivers positive value propositions for all stakeholders:

  • The IPD contractual agreements establishes clarity and dismisses ambiguity amongst all the project stakeholders with regards to decision-making, detailed responsibilities of each party, and risk/reward-sharing mechanism for each task. As a result, major participants, including the architects, MEP engineers and main contractors are clear about their respective roles and timeframes.
  • Employing parametric BIM models structures the project team in a way that encourages clear, open, and horizontal communication. This facilitates diverse disciplines to seamlessly coordinate during the pre-construction design planning and construction phases.
  • IPD necessitates mapping out comprehensive workflows and protocols for developing, sharing and updating the digital BIM models. These plans clearly delineate procedures for intra-discipline as well as inter-discipline design data management and communication.
  • Due to an integrated design management structure facilitated by BIM and IPD, the cost and time benefits experienced by the primary project team members spill over to secondary chain participants, including fabricators, installation experts and facility managers.

So, if your firm operates in the AEC industry and is looking for a highly recommended IPD support services provider to handle initial consultation to complete project management, contact us.