With over 20 years in cleanroom engineering, working with hundreds of factory owners, equipment managers, and project leaders, I've found the most widespread and costly misconception: Any cleanroom must have a constant temperature and humidity (HVAC) system.

Many cleanroom salespeople exploit this information gap, defaulting to including constant temperature and humidity units in all quotes. Many clients sign blindly, leading to a 30% surge in upfront costs and high electricity bills post-production. The ten-year operational energy cost of such a system can even match its purchase price.

Let's clarify the fundamentals: a cleanroom's primary mission is dust control, microbial control, and maintaining pressure differentials; constant temperature and humidity is a process-specific requirement, not a mandatory cleanroom standard. The only criterion for inclusion: whether the production process or regulatory audits impose strict constraints on temperature and humidity fluctuations.

Here's a little-known industry fact: Cleanroom HVAC ≠ Constant Temperature and Humidity HVAC Standard cleanroom HVAC: core functions – air filtration, maintaining positive pressure, basic heating and cooling, ensuring basic comfort and preventing condensation. Constant temperature and humidity cleanroom HVAC: adds independent humidification, dehumidification modules, and high-precision controls for narrow-range stability, significantly increasing cost and energy consumption.

Many peers conflate "cleanroom HVAC" with "constant temperature and humidity units," a common sales tactic in the industry.

1. Red Lines! These Industries and Processes Absolutely Require Constant Temperature and Humidity (Saving = Product Scrap, Failed Audits)

Don't swing to the other extreme. Optimize where possible, but never cut what's essential. Cutting corners has severe consequences.

1. Semiconductor, Chip, Optical Lens, Precision Microelectronics Core Processes Photolithography, wafer packaging, optical coating, sensor assembly. Low humidity causes electrostatic discharge damaging components; minor temperature fluctuations cause material expansion/contraction, crashing yield rates. Typically requires temperature fluctuation within ±1°C and humidity 45%–60% RH, mandating a full constant temperature and humidity system. Note: standard electronic assembly and simple wiring harness assembly are excluded, detailed later.

2. Lithium Battery, Solid-State Battery Electrode Manufacturing, Dry Rooms Electrode coating, calendering, and electrolyte injection are highly sensitive to dew point and humidity. Moisture causes battery swelling and safety hazards. Requires not only constant temperature and humidity but also deep desiccant dehumidification in some sections.

3. Sterile Pharmaceutical GMP A/B/C Core Production Areas, Sterile Medical Device Filling Workshops Per GB50457 pharmaceutical cleanroom standards, regulatory audits require continuous temperature and humidity records. Fluctuations affect airborne and settle plate microbial control, promoting microbial growth. Core processes for sterile preparations, injections, and implantable devices mandate stable temperature and humidity ranges; constant temperature and humidity control cannot be omitted.

4. Precision Testing Labs, CNAS-Accredited Labs, Stability Test Chamber Supporting Clean Areas Experimental data requires reproducibility; significant environmental fluctuations lead to third-party audit failure.

2. Key Insights! These Industries Can Often Skip Full Constant Temperature and Humidity Systems (Where Many Factories Waste Hundreds of Thousands)

Note: "Skipping constant temperature and humidity" here means not using integrated units with automatic humidification, deep dehumidification, and high-precision controls. Standard cleanroom cooling/heating HVAC is sufficient, allowing reasonable temperature and humidity fluctuations.

1. General Food Cleanrooms (SC Certification)

Baked goods packaging, cooked food repackaging, snack packaging, frozen food outer packaging, nut sorting in Class 100,000 clean areas. Per GB14881 food hygiene standards, regulations only require microbial control, not narrow-range constant temperature and humidity. ✅ Feasible solution: Standard cleanroom HVAC for cooling/heating, maintaining 18-28°C and 40%-70% humidity, without automatic humidification/dehumidification. ⚠️ Exception: Chocolate production, powdered milk dispensing, highly hygroscopic raw material areas should consider independent dehumidification.

2. General Cosmetic Non-Sterile Production Lines (Color Cosmetics, Skincare Packaging Workshops)

Cream filling, lotion packaging if raw materials don't rapidly hydrolyze or degrade; powder product packaging. Many cleanroom companies default to sterile pharmaceutical solutions, mandating constant temperature and humidity, but cosmetic regulatory standards don't require high-precision stability.

3. General Medical Device Class D Clean Areas, Non-Sterile Consumable Production

Disposable gloves, standard medical dressings, plastic medical component assembly (non-implant, non-sterile). Static and dynamic testing focuses on particle and microbial counts. Temperature and humidity only need to ensure personnel comfort and prevent condensation, not precise ±2°C control.

4. General Light Industry Packaging, Printing, Plastic Dust-Free Assembly, Food Machinery Parts Dust-Free Processing

Class 100,000/300,000 dust-controlled workshops, solely to prevent surface dust on products. Materials are unaffected by temperature/humidity changes, requiring only basic cooling/heating cleanroom HVAC, no constant temperature and humidity needed.

5. Modern Agricultural Tissue Culture Supporting Clean Buffer Rooms, Seedling Sorting Clean Areas

Seedling sorting and packaging sections; only the tissue culture room itself requires stable temperature and humidity; buffer zones can use simplified HVAC.

6. General Electronics Back-End Assembly, Simple Wiring Harnesses, Plastic Housing Dust-Free Assembly

Distinguish: Core chip and circuit board processes require constant temperature and humidity; simple product assembly and housing assembly, without exposed precision components, can rely on anti-static flooring and ionizers, avoiding the investment in a full constant temperature and humidity system.