MEP Coordination In Building Construction
MEP coordination presents an unusual challenge for practice and research. Advanced plant design systems can provide models to assist in coordination, but they are not used in hospitals, laboratories, semiconductor wafer, or biotech manufacturing facilities. Detailed design and construction of these complex facilities are fragmented because specialty design consultants and contractors perform this work. The cause of the MEP coordination problem is not the lack of technology but the need to apply available technology tailoring to a particular set of business and technical conditions. Object-oriented 3D models could allow a revised process of coordination.
However, capturing the distributed knowledge concerning the different types of systems and tailoring the software to meet the particular needs of MEP coordination remain significant challenges. Success with this activity would support significant improvements in design, coordination, construction, commissioning, operation, maintenance, and retrofit for new uses.
The specifications assign responsibility for coordination of the specialty or trade contractors, including checking for clearances, field conditions, architectural and structural conditions. The process of MEP coordination involves locating components and branches from all systems in compliance with design, construction, and operations criteria. The old process of sequentially comparing 1/4 inch/foot scale transparent drawings for each system over a light table adds significant cost to many projects and can add significant duration.
Improving the coordination process for mechanical, electrical, and plumbing (MEP) systems on complex buildings and light industrial projects present an excellent opportunity to improve project performance through increased integration. Coordination involves defining locations for branch components of systems in congested spaces to avoid interference and comply with diverse design and operations criteria.
Several problems in current practice create the need to improve. Limited building space for MEP systems makes efficient design and construction much more challenging. On many plans and specs projects, accelerated schedules and decreased designers’ fees do not allow detailing MEP systems by design consultants. The scope of work for specialty contractors on these projects increasingly includes “design assist” to complete the design for fabrication and installation. Design-build contracting, with different specialty contractors responsible for various systems, decentralizes design responsibility and increases the potential problems and the need for effective coordination between the various types of systems. Fast track projects increase the challenge.
MEP systems must satisfy multiple objectives and criteria for design, installation, commissioning, operation, and maintenance. Different types of specialty contractors (e.g., process piping, HVAC piping, HVAC duct-work, plumbing, electrical, fire protection, controls) are responsible for these systems. An example of different criteria for system design includes spatial (avoiding interference), functional within a system (flow or gravity drainage), adjacency or segregation, system installation (layout dimensions, space and access for installation productivity), and testing (ability to isolate). On complex buildings and plants, expertise and designs are required from different specialists -- essential fragmentation requiring horizontal integration between these different functions working in the same project phase.
The current work process is for design consultants or design-build contractors to develop their systems independently. Coordination responsibility is then assigned to one firm, often the general contractor, the HVAC contractor, or a coordination consultant. The resulting process is slow and expensive. One general contractor estimated coordination costs as six percent of the MEP value or two percent of the total cost on a light industrial project. An electrical contractor said that coordination cost equals design value on projects in Silicon Valley; each is about three percent of the total cost for electrical systems.
At the low-tech end of the practice spectrum for MEP coordination, drawing plan views on transparent media and using a light table to overlay routeing proposed by several contractors is easy to understand and change. However, this process often involves frequent and painful meetings. Difficulty in visualizing complex systems in congested spaces often requires drawing multiple section views to accompany the plans prepared for primary routeing. It is also tough to accommodate design change after coordination decisions.
At the other end of the spectrum, 3D CAD and other information technology offer the potential to improve this process and its results. Plant models provide significant benefits for large hydrocarbon and power projects on which the Architect/Engineer completes the entire design. However, design consultants and specialty contractors prefer systems tailored to actual information needs for detailing, estimating, fabricating, and tracking their type of work. Current use of multiple systems (e.g., Intellicad, Quick Pen, Colorado) tailored to the needs of specific disciplines and trades limits overall effectiveness. The systems are not compatible, and DXF transfer usually loses about ten percent of the database contents.
Complex configurations of MEP systems in congested spaces are tough to visualize. The less complete definition of systems in the “design assist” approach makes it tough to define the scope of work for fixed price contracts. This increases the potential need for contract changes based on the increased cost of installing the system configuration that results from the coordination process. Also, the first contractor working in an area often optimizes routeing for their Systems, requiring expensive rework if this is not compatible with other systems.
As a result of these problems with current processes, the product of MEP coordination does not fully satisfy the objectives of any of the project participants. To improve project performance, the construction segments focused on complex buildings, and high-tech plants need increased horizontal integration between design consultants or design-build contractors to improve the effectiveness of the coordination process and better meet project objectives.
This first requires a simplified method to consolidate the designs from multiple sources to visualize and easily change the configuration for initial coordination. The next critical need is to capture the knowledge required for application of different criteria in making coordination decisions. This will eventually allow partial automation of MEP systems coordination. For improved life-cycle performance of the facility, a major need is to increase vertical integration by mutual information exchange with facility managers and operators for the building or plant.