Modular cleanrooms

A modular cleanroom is built from prefabricated components, such as wall panels, ceiling grids, doors and fan filter units, rather than conventional construction. Modular systems range from a simple softwall enclosure over a workbench to a complete multi-room pharmaceutical suite made of insulated metal panels. They are popular because they can be installed quickly, modified as needs change and sometimes relocated.

Modular does not mean simple, though. A modular cleanroom still sits inside a building with its own HVAC, fire protection and code requirements, and it still must be tested and certified. This guide explains the options and the issues owners most often overlook.

Types of modular cleanroom

Softwall

Softwall cleanrooms are the least expensive and fastest to install. The vinyl curtains do not form a sealed enclosure; air escapes at the bottom of the curtains, which helps sweep particles out. Pressure control is limited, and temperature control relies on the surrounding building. They suit local protection rather than regulated environments.

Hardwall

Hardwall cleanrooms have rigid walls that allow positive pressure, pass-throughs and better sealing. They are often freestanding, with fan filter units in the ceiling and air returning through wall openings or out under the walls. They can achieve good classes but may need additional cooling.

Panelized systems

Panelized systems use flush, cleanable panels that are often similar in performance to conventional cleanroom construction, with integrated doors, windows, light fixtures and filter housings. They can form complete suites with airlocks and pressure cascades and are common in GMP facilities. A walkable ceiling allows maintenance access from above without entering the cleanroom.

HVAC options

Fan filter units with building air

The simplest arrangement draws air from the surrounding room through ceiling fan filter units and returns it to the surrounding room. The cleanroom then relies on the building's HVAC for temperature, humidity and outdoor air. This works only if the building can handle the extra heat from the fans, lighting and processes, and if the surrounding room's conditions are suitable.

Fan filter units with a dedicated plenum

A more controlled arrangement places fan filter units below a sealed ceiling plenum. Air returns through wall chases to the plenum and recirculates. A dedicated makeup air unit supplies conditioned outdoor air for pressurization and humidity control, and sensible cooling coils in the return path or plenum remove heat. This approach gives independent control of temperature, humidity and pressure. The trade-offs between fan filter units and ducted systems are covered in fan filter units vs ducted HEPA systems.

Ducted HEPA systems

Panelized cleanrooms can also use ducted terminal HEPA filters fed by a central air handler, with low-wall returns, just like conventionally built cleanrooms. This is common in pharmaceutical suites.

Heat is the most common problem

Fan filter units, lighting, process equipment and people add heat inside the enclosure. A freestanding cleanroom inside a warehouse can easily overheat if this is not addressed. Calculate the full cooling load and decide early where the heat will be removed: by the building system, by a dedicated cooling unit or by coils within the cleanroom's recirculation path. See temperature and humidity control in cleanrooms.

Building code and fire protection

Modular cleanrooms are usually treated as part of the building under the National Building Code of Canada or the applicable provincial code. Common issues include:

• Permits. Many modular cleanrooms require building permits, and the HVAC, electrical and fire protection work may require engineered drawings. Requirements vary by municipality and province. See mechanical permits and engineering seals in Canada.
• Combustibility and flame spread. Panel cores and finishes must meet the code requirements for the building's construction type, including flame-spread and smoke-developed ratings tested to CAN/ULC-S102. Some plastic and foam core panels may not be permitted in noncombustible construction.
• Sprinklers. In sprinklered buildings, a solid cleanroom ceiling usually requires sprinklers inside the cleanroom, and sometimes in the plenum above. Sprinkler heads must be compatible with cleanroom ceilings.
• Fire alarm and detection. Smoke detection may be needed inside the cleanroom and in plenums.
• Exits. Exit routes, door swing and travel distance must meet code, including from inner rooms through airlocks.
• Fire separations. If the cleanroom must be part of a rated separation, the modular system must be listed for that purpose; most are not.
• Seismic restraint. In seismic regions, freestanding structures, ceiling grids and suspended equipment may need restraint designed by an engineer.

Integration with the building

• Structure. Walkable ceilings and ceiling-mounted equipment add load to the cleanroom frame or the building structure.
• Floor. The existing floor must be flat, cleanable and sealed, or a new floor finish installed with coved bases.
• Utilities. Electrical, compressed air, process gases and water must enter through sealed penetrations.
• Makeup air and exhaust. Outdoor air intakes, exhaust discharges and roof penetrations need coordination.
• Building pressure. A cleanroom at positive pressure exhausts air to the surrounding space, which the building system must accommodate.

What to ask before buying

1. What class is needed, in which occupancy state, and is it a regulated environment?
2. What is the full heat load, and where will the heat go?
3. How will humidity be controlled, especially in Canadian winters?
4. Do the panels meet code requirements for the building's construction type?
5. Does the design need sprinklers, smoke detection or exits inside the cleanroom?
6. Who will provide engineered drawings and obtain permits?
7. How will the room be tested and certified, and who will do it?
8. Can the system be expanded or reconfigured later?

Testing and certification

Modular cleanrooms are tested in the same way as conventionally built cleanrooms: airflow, filter leak testing, pressure, particle counts and other tests as specified. Supplier factory testing does not replace on-site certification after installation. See cleanroom certification and testing.

Key takeaways

• Modular cleanrooms range from simple softwall enclosures to complete panelized GMP suites.
• Heat from fan filter units, lighting and processes is the most common performance problem; plan where it will be removed.
• Building codes still apply, including permits, panel flame-spread ratings, sprinklers, detection and exits.
• Dedicated makeup air and sensible cooling give the best control of temperature, humidity and pressure.
• On-site testing and certification are required after installation, regardless of factory testing.