MEP Coordination and Clash Detection Explained: What a CDE Is

MEP means mechanical, electrical and plumbing. In practice it covers power and lighting, water supply, drainage, fire fighting, air-conditioning and ventilation, and low-voltage systems like CCTV and networking.

Services must fit inside a building that the architect and structural engineer have already shaped. That is why coordination is a separate job.

How services are designed

Each service has two kinds of work: calculations and layouts.

Lesson data table
Service	Calculations	Example tools	Layout output
Electrical	Loads, cable sizes, short circuit	ETAP, Excel	Power and lighting layouts, single-line diagram
Lighting	Lux levels	DIALux evo	Fixture layouts
HVAC	Heat load, duct and pipe sizes	HAP, Excel	Duct and piping layouts
Plumbing and drainage	Fixture units, pipe sizes, slopes	Excel, pipe-flow tools	Water and drainage layouts, sections
Fire	Sprinkler and hydrant sizing	Hydraulic tools, Excel	Fire layouts

Layouts are drawn in AutoCAD on most Indian houses and mid-size jobs, often by the MEP contractor rather than a separate consultant. On larger projects, services are modelled in Revit so they can be checked in 3D.

What a clash is

A clash is two things trying to occupy the same space. Classic examples:

A 600 x 400 mm duct running through a 600 mm deep beam.
A drainage pipe that needs a slope but hits a beam halfway along.
An electrical conduit cluster where a sleeve was never left in the slab.

On a 2D project, clashes are found on site, when someone is standing on a ladder with a duct section in hand. On a coordinated 3D project, they are found on screen weeks earlier.

Clash detection

Clash detection software overlays the architecture, structure and MEP models and reports every place they collide.

Common tools: Navisworks, Solibri, Revizto.
Output: a clash report. Each clash has a location, the two elements, the overlap, an owner and a status.

Not every clash is real. A pipe touching insulation may be fine. The coordinator groups clashes, discards false ones, and assigns the real ones to the right consultant.

The common data environment (CDE)

A CDE is one controlled place where every team puts its drawings and models, with clear states: work in progress, shared, published and archived. The idea comes from the ISO 19650 series on managing information in BIM projects.

Models meet in a common data environment. Each discipline shares its model or drawings into one controlled store. A clash check then finds places where two disciplines want the same space. The states follow the ISO 19650 idea of work in progress, shared, published and archived.

Examples of CDE platforms include Autodesk Forma (Autodesk renamed Autodesk Construction Cloud to Forma in March 2026; its file store, formerly Autodesk Docs, is now Forma Data Management; BIM 360 continues as an older product), Trimble Connect, and similar platforms from other vendors.

On many Indian small and mid-size projects, the CDE is in practice a shared Google Drive or a WhatsApp group. That can work if one person owns the folder and nobody builds from a forwarded copy.

A worked example: the cost of a missed sleeve

A G+4 commercial building has 12 places where drainage and AC drain pipes must cross beams. On a 2D job, sleeves were not shown on the structural drawings. They are found after casting.

Core cutting through each beam: about ₹1,500 per hole (illustrative), so 12 x ₹1,500 = ₹18,000.
Structural engineer's check of each cut location, and possible strengthening: more fees and delay.
Worse: some cuts may not be allowed at all, forcing reroutes with extra bends and false ceiling height lost.

The same 12 sleeves, shown on the GFC structural drawings, cost a few hundred rupees each in PVC pipe pieces before the pour.

What comes next

Module 4 turns to money: how quantities are measured from drawings or models, and how they become a priced BOQ.

MEP Design, Clash Coordination and the CDE