Clean Air. Controlled Processes. Reliable Production.
Why HVAC Is at the Heart of Every GMP & Cleanroom Facility
Pharmaceutical plants, medical-device facilities, electronics cleanrooms and many food-processing environments may manufacture completely different products — but they all share one critical requirement: control.
Control of particles. Control of microorganisms. Control of temperature and humidity. Control of pressure. And, ultimately, control of the air itself. This is the foundation of Good Manufacturing Practice (GMP).
And behind virtually every controlled GMP environment is a system that often remains invisible — yet determines whether the entire process can operate safely and reliably: the HVAC system.
In a cleanroom, ventilation is no longer simply about comfort. Air becomes part of the production process.
What Makes a Cleanroom “Clean”
A conventional HVAC system is primarily designed to keep people comfortable. A cleanroom HVAC system has a much more demanding job: to protect the product, the process and, in many applications, the people working inside.
That means maintaining precise control over airborne particles, microbiological contamination, temperature, relative humidity, airflow direction and velocity, room pressure, filtration and air-change rates.
More air. Much more air.
A typical office may operate at approximately 3–6 air changes per hour. A cleanroom can require dramatically higher airflow rates — in some applications approaching 100 air changes per hour, depending on the process, room classification and contamination-control strategy.
Why? Because contamination control is fundamentally a game of dilution, displacement and removal. The faster contaminants are captured, diluted and removed, the easier it becomes to maintain the required cleanliness level.
HEPA filtration — the final barrier
Cleanrooms rely on high-efficiency filtration, with H13 and H14 HEPA filters commonly used as final filtration stages. These filters capture extremely small airborne particles before the conditioned air reaches the controlled environment.
Air must move in the right direction
In critical production zones, airflow is carefully engineered. For the most sensitive processes, unidirectional — often referred to as laminar — airflow can create a controlled stream of clean air across the critical working area. The principle is simple: do not allow contamination to travel towards the product.
Grade A, B, C or D? Understanding GMP Cleanroom Classification
For sterile medicinal-product manufacturing in Europe, one of the key regulatory references is EU GMP Annex 1. It defines four cleanliness grades: Grade A → Grade B → Grade C → Grade D.
These grades can be related to cleanroom classifications under ISO 14644-1, depending on whether the room is considered “at rest” or “in operation”. Grade A represents the critical zone; Grade B typically provides the background environment for Grade A operations, while Grades C and D are used for progressively less critical stages.
The Invisible Barrier: Pressure Cascades
Without controlled pressure, air — together with dust, particles and microorganisms — can move in either direction when doors open or leakage occurs. GMP environments therefore use controlled pressure relationships so that air naturally moves from the cleaner zone towards the less clean zone.
A typical cascade might look like: Grade A → Grade B → Grade C → Grade D → Uncontrolled Area.
Pressure differentials of approximately 10–15 Pa between adjacent areas are commonly used as a design reference, although final values must be determined according to the process, facility design and risk assessment. This creates an invisible air barrier against contamination.
The pressure cascade must remain stable during operation and, where required, be continuously monitored and documented as part of the facility’s Contamination Control Strategy (CCS).
ISO 14644 and GMP Are Not the Same Thing
ISO 14644 tells us how clean the air is in terms of airborne particle concentration. GMP requirements go considerably further, considering microbiological contamination, production processes, personnel, cleaning procedures, pressure relationships, temperature, humidity, airflow and contamination risks.
Simply achieving an ISO cleanroom class does not automatically mean that a facility is GMP compliant. A successful cleanroom HVAC design must bring all these requirements together into one controlled system.
Clean Air Requires a Clean HVAC System
How can you supply clean air from equipment that is itself difficult to clean? This is where VDI 6022 becomes particularly important.
The German guideline addresses hygiene requirements for ventilation and air-conditioning systems throughout their lifecycle — from design and manufacturing to installation, operation, inspection and maintenance.
A comprehensively revised edition of Part 1 was published in early 2026, consolidating previous Parts 1.1–1.3, adding more detailed requirements for air measurements and hygiene risk assessments, and updating filtration classifications.
A useful way to understand the relationship is: EU GMP Annex 1 and ISO 14644 define the required controlled environment. VDI 6022 helps ensure that the HVAC equipment creating that environment does not itself become a source of contamination.
A GMP Air Handling Unit Is Not a Standard AHU
From the outside, two air handling units may look similar. Inside, they can be completely different. An AHU intended for GMP and hygienic applications must be designed around one fundamental principle: everything that comes into contact with the air should minimise contamination risk and allow effective inspection, cleaning and maintenance.
1. Hygienic casing and internal surfaces
GMP-oriented AHUs typically use rigid double-skin sandwich-panel construction with thermal and acoustic insulation. Internal surfaces should be smooth, corrosion-resistant, accessible and easy to clean. Edges, joints, drain pans, access doors and internal components should minimise areas where dust, moisture and microorganisms can accumulate.
2. Precise cooling and temperature control
Clean manufacturing processes frequently operate within narrow temperature and humidity limits. Chilled-water and water/propylene-glycol systems are widely used because they provide stable and precise control. Direct-expansion (DX) cooling systems can also be used where appropriate.
3. Energy recovery — without compromising hygiene
GMP facilities can consume enormous amounts of energy. High air-change rates, large quantities of outdoor air and continuous operation make energy recovery extremely attractive — but it must not introduce an unacceptable cross-contamination risk.
One of the safest concepts is the run-around coil system. A coil is installed in the extract air stream and another in the fresh/supply air stream, with energy transferred through a closed glycol circuit. The major advantage is complete physical separation of the two air streams.
Plate air-to-air heat exchangers can also be considered where appropriate, provided their leakage characteristics, construction and application are assessed as part of the project’s contamination-risk analysis.
4. Separate AHUs for separate processes
Manufacturing, coating, tableting, inspection and packaging can generate very different contaminants. Critical production areas or processes are therefore often served by separate air-handling systems. Separate the processes. Separate the air. Reduce the risk.
5. Keep extract ductwork under negative pressure
Extract fans can be positioned towards the discharge end of the system so that critical sections of extract ductwork remain under negative pressure. If leakage occurs, air tends to be drawn into the duct rather than contaminated extract air leaking into surrounding areas.
6. Hygienic ductwork
Where particularly high hygiene levels are required, round stainless-steel ductwork can offer smooth surfaces and easier cleaning. Downstream of final HEPA filtration, materials and construction methods should minimise corrosion, particle generation and secondary contamination.
7. Steam humidification
When humidity needs to be increased, isothermal steam humidification is often an excellent solution for hygienic applications, enabling precise humidity control while avoiding many hygiene concerns associated with standing or recirculated water.
8. When 30–35% RH is required
Some pharmaceutical processes involve highly hygroscopic materials and require very low relative humidity. In such applications, the AHU may be combined with a desiccant dehumidification system capable of maintaining conditions around 30–35% RH or even lower, depending on the process.
TANGRA AHU — Engineered for Hygienic Applications
For more than three decades, TANGRA has been developing and manufacturing ventilation and air-conditioning equipment for demanding applications. For hygienic and cleanroom environments, TANGRA offers its dedicated TANGRA AHU HYG range — hygienic air handling units engineered specifically for HVAC systems serving clean and controlled environments.
TANGRA became the first Bulgarian manufacturer to certify hygienic air handling units in cooperation with TÜV Germany in 2014, followed by certification with Eurovent Certita Certification in 2018.
The objective is simple: to give designers, contractors, operators and investors documented confidence in the performance and construction quality of the equipment installed at the heart of their clean-air system.
What Makes TANGRA AHU HYG Different?
TÜV & Eurovent certification
TANGRA air handling units have been evaluated and certified according to relevant European requirements and standards, including hygienic requirements such as VDI 6022 and DIN 1946-4, together with applicable AHU construction and performance standards.
Multi-stage filtration — up to HEPA H14
TANGRA AHUs can be configured with multiple filtration stages — from conventional pre- and fine filtration to H13/H14 HEPA filtration. Modern filter selection can be based on ISO 16890 for general ventilation filters and EN 1822 for HEPA filtration.
Plug & Play control
A modern GMP AHU should not only condition air. It should measure, control, communicate and document. TANGRA AHUs can be supplied with integrated automation, prepared for BMS connection and remote monitoring and control.
Depending on the project, the system can monitor temperature, relative humidity, filter pressure drop, airflow, fan operation, alarms and operating status. Units can be factory-tested and configured before delivery, reducing commissioning time on site.
Where Are TANGRA AHU Units Used?
The range is designed for environments where air quality, hygiene and contamination control are critical: pharmaceutical manufacturing, GMP facilities, cleanrooms, hospital operating theatres, intensive care units, isolation rooms, emergency departments, medical and laboratory facilities, electronics and precision-component manufacturing, optical and information-media production, and food and beverage manufacturing.
Different industries. Different processes. The same requirement: controlled, clean and reliable air.
Who Is Responsible for What?
TANGRA — HVAC engineering and equipment
With more than 37 years of experience in ventilation and air-conditioning, TANGRA develops AHU solutions for demanding hygienic and controlled environments. The team can support projects with technical consultation, AHU selection and configuration, HVAC engineering, manufacturing, supply, installation support, automation and control solutions, and technical documentation.
TÜV and Eurovent certification, combined with comprehensive technical documentation, have helped TANGRA products gain acceptance in more than 18 European countries.
GMP Designer / Consultant — defining the environment
The project’s GMP specialist and HVAC designer determine what each production area requires: GMP Grade A, B, C or D; required ISO cleanliness class; airflow rates and air-change strategy; room pressure relationships; temperature and humidity limits; air-distribution concept; AHU zoning and separation; and contamination-control strategy.
Facility Operator — keeping the system compliant
Compliance does not end when the building is commissioned. The operator must ensure that required environmental conditions continue throughout the facility’s operating life, including monitoring of pressure, particles, temperature, humidity, airflow and filtration performance, together with personnel training, qualification, hygiene inspections, filter replacement, cleaning and preventive maintenance.
Because in a GMP environment, performance on Day 1 is not enough. The system must continue performing on Day 1,000.
Clean Manufacturing Starts with Clean Air
Designing HVAC for a GMP facility is much more than selecting a “powerful” air handling unit. It requires the integration of cleanroom classification, contamination control, air filtration, pressure management, temperature and humidity control, hygienic equipment design, energy efficiency, monitoring and automation.
Standards and guidelines such as EU GMP Annex 1, ISO 14644, VDI 6022 and DIN 1946-4 provide the framework. Engineering turns that framework into a working environment.
TANGRA combines more than 37 years of HVAC experience with TÜV- and Eurovent-certified air-handling technology to provide hygienic AHU solutions for pharmaceutical, medical, food-processing and other sensitive clean manufacturing environments.
Because in critical manufacturing, air is not simply something we condition. Air is part of the product quality.
Technical Consultation
TANGRA
Tel.: +359 700 70 555
E-mail: office@tangra.bg
Web: www.tangra.bg
