GMP Requirements of HVAC Systems in Oral Solid Dosage Form Manufacturing Facilities

A well-designed heating, ventilation and air-conditioning (HVAC) system is essential in a pharmaceutical manufacturing unit to ensure all operations are carried out in accordance with current good manufacturing practices (cGMP) to produce quality pharmaceutical products and to ensure that they are stored in well-ventilated environmental conditions. From blending to granulation and compression, excess moisture can cause manufacturing inefficiencies in the production of solid oral dosage forms at almost any stage, weaken the drug product’s efficacy or can ruin an entire batch. Such environmental conditions also help production personnel carry out operations comfortably.

The basic functions of HVAC systems are maintaining the ambient temperature of a designated space; controlling airborne, dust particles and micro-organisms by regulating the movement of air; maintaining the room pressure; maintaining relative humidity by cooling air to dew point temperatures or by using desiccant dehumidifiers. Thermostats in HVAC systems enable temperature to be controlled. The system automatically maintains the necessary configured temperature depending on the environment. Humidity is controlled using humidifiers are used in the facility.

GMP requirements for HVAC facilities encompasses a number of aspects beginning from selection of building material and finishes, the flow of equipment, personnel and products, determination of key parameters like temperature (67-77°F, control point – 72°F), humidity (RH of 50 ± 5%), pressures, to filtration, air-flow parameters and classification of cleanrooms.

Oral solid dosage manufacturing facilities typically fall under Class 100,000 area (particle count not exceeding 100,000 particles per cubic foot of a size 0.5 micron) and are considered as controlled (non-sterile) areas. They require side access HEPA-filter housing and cleanroom approved, vinyl covered panels or blank aluminium panels as their ceiling system. These areas must have 12 ga hanger wires to the ceiling grid and 10 ga hanger wires to the filters as ceiling grid supports.  The area is generally equipped with non-unidirectional air-flow with supply air outlets at ceiling level and return air at floor level. This flow helps maintain satisfactory control over cleanliness levels in Class 1000 and above areas.

The air is supplied at a much higher volume than the surrounding area to ensure higher velocity and pressure in the clean zone relative to the perimeter. Air quality in controlled areas is maintained by such an airflow which is sufficient to achieve at least 20 air changes per hour and a pressure differential of at least 0.05 inch of water gauge (with all doors closed). In addition, it governs the level of control of distinct parameters for quality assurance, regulating the acceptance criteria, validation of the facility and documentation for operation and maintenance.

Planned maintenance of the HVAC system should be carried out regularly to prevent sudden breakdowns that can affect production. Maintenance activities should not have any negative impact on product quality.  They should ideally be scheduled outside production hours.

With well-designed HVAC systems, it should be possible to maintain temperature, relative humidity and ventilation conditions appropriately and in no way should these adversely affect the quality of pharmaceutical products during their production, storage, or the functioning of any equipment.

Optimised HVAC systems can immensely help pharmaceutical facilities conform to regulatory expectations and remain cGMP-compliant.


  1. Bhatia, A. (2010). HVAC Design for Pharmaceutical Facilities. CED Engineering, 877, 2–57.

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