MEP Design for a Pharma Plant: HVAC Classification, Utilities and Qualification Documents

MEP design for a pharma plant starts from the product and dosage form, not the building. The revised Schedule M requires the HVAC system to be designed, installed, qualified and maintained to GMP, so the design basis must fix room grades, pressure cascades, temperature and humidity limits and clean-utility quality before layouts are drawn. Each choice must then trace through design, installation and operational qualification.

What does Schedule M require of the MEP design?

The revised Schedule M to the Drugs Rules, 1945, notified by G.S.R. 922(E) on 28 December 2023, is the regulatory frame. Its main principles give MEP engineers four direct instructions:

• Electrical supply, lighting, temperature, humidity and ventilation must be appropriate and must not harm products or equipment.
• The design, installation, qualification and maintenance of the HVAC system must be carried out.
• Premises must be designed to give a logical flow of materials and personnel.
• Water used in manufacture must come from a validated treatment system that yields purified water to pharmacopoeial specification, stored in tanks that do not allow microbial growth.

Compliance dates were staggered by company size and extended for smaller manufacturers, so confirm the position for your unit with CDSCO or your State Licensing Authority. A new plant should assume the revised text applies from day one.

How do you set the design basis?

Write the design basis as a user requirement document before any layout. It should say which dosage forms the plant makes, whether any product is highly potent or sensitising, batch sizes, the room list with the flow of people and materials, and each room's grade. Without it, the HVAC consultant guesses, and changes after design qualification are expensive.

How are classification and pressure cascades designed?

Schedule M's oral solid dosage section sets the cascade principle: air flows from the clean corridor into the cubicles, so the corridor sits at a higher pressure than the cubicles and the cubicles above atmospheric pressure. Highly potent products work under a regime that is negative relative to atmosphere. The cascade is assessed for each facility, and the building structure must accommodate it, with sealed ceilings, close-fitting doors and sealed light fittings.

The text also gives rules that decide how a design is detailed:

• Pressure ranges of adjacent rooms must not overlap. Its example is 5 to 15 Pa in one room and 15 to 30 Pa in the next, which can fail when one room is at its highest limit and the other at its lowest.
• Pressure instruments are calibrated and qualified, linked to an alarm set by risk analysis, and read out in each room with alert and action limits displayed.
• Airlocks may be cascade, sink or bubble types, and doors open towards the high-pressure side with self-closers, or are interlocked where a risk assessment says so.
• Temperature and humidity tolerances should not be made too tight, because tight bands add installation and running costs.

For sterile products, Part II defines Grades A to D. Grade B is the background to Grade A; adjacent rooms of different grade keep a differential of approximately 10 to 15 Pa as a guidance value; classification follows ISO methods at rest and in operation; and installed HEPA filters are recommended to be leak-tested every six months and not beyond twelve. Sinks and drains are excluded from Grade A and B zones. For products with hazardous substances such as sex hormones, steroids or cytotoxics, Part III requires air to be exhausted through HEPA filters rated at least H13 and not re-circulated except to the same area with a further HEPA stage.

Which qualification documents does the design produce?

Schedule M defines qualification as documentary evidence in stages: design qualification shows the premises, utilities and equipment were designed to GMP; installation qualification shows they were built to the design; operational qualification shows they operate to the design; and performance qualification or process validation shows the process consistently meets specification. The programme sits in a validation master plan and is not a one-off, because significant changes need requalification.

The design team's job is to make these tests passable: access to test ports, filter housings that can be leak-tested, instruments that can be calibrated, and drawings that can be turned into as-built records. For tender wording, see our pharma MEP tender guide.

What else must the MEP design coordinate?

Clean utilities are only part of it. Process power should be kept apart from building power so critical loads have their own distribution. Potable water, process water, drainage and effluent need separate routes, and every penetration of a cleanroom wall is a sealed, controlled detail. Fire protection must cover solvent and raw-material stores, process floors and packaging with their own detection logic, and the plant needs a monitoring or building-management system that records the limits qualification relies on. Early coordination between HVAC, electrical, plumbing, fire and ELV drawings is cheaper than finding clashes in the ceiling void.

Budget reviews follow the same logic. Use the MEPF cost calculator for an order of magnitude, then replace it with a bill of quantities once the design basis is fixed.

How Secured Engineers helps

We design MEPF in-house and coordinate HVAC, electrical, plumbing, fire and ELV in one set of drawings. Fire NOC, CEIG and DISCOM approvals are filed in-house, and MEPF and solar can sit under one contract. We are executing the full MEPF package with a solar plant for a multi-storey pharmaceutical formulations facility in Ludhiana, a project in execution as of October 2026. We work from Noida (Delhi NCR) and Ludhiana, across 535+ projects in 18+ states, with 89.77% repeat clients.

If you have a pharma design or a vendor's drawing set, send it for a technical review against your design basis before it reaches site. See our design and approvals service, message us on WhatsApp, call +91 70099 85817, or ask for a free proposal.