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Air handling units (AHUs) are the beating heart of HVAC systems. They play a critical role in air quality, temperature regulation, humidity control, and supplying fresh air. However, depending on the nature of the project and the required hygiene level, choosing between a standard AHU and a hygienic AHU becomes a decisive factor. A correct understanding of their differences helps engineers, contractors, hospital managers, and HVAC designers make the best decision in terms of performance, cost, and compliance with hygiene standards.

In this article, we thoroughly examine both units so you can confidently identify the best option for your project.

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 What Is a Standard Air Handling Unit and How Does It Work?

A standard AHU is designed to condition and circulate air by passing it through filters, cooling and heating coils, and centrifugal or plug fans. This type of unit is typically used in general buildings where strict hygiene and contamination-control requirements are not a priority. The structure of a standard AHU is simpler, and routine maintenance can be carried out by non-specialized technicians.

Most standard AHUs use galvanized steel panels or lightweight double-skin enclosures. They commonly include basic filters such as G4 or F5, which remove larger airborne particles and dust. Their control system is usually simple—typically a basic thermostat or controller—and unless specified during the ordering process, they do not normally connect to advanced building management systems.

Overall, a standard AHU is a cost-effective solution that meets basic ventilation and air-conditioning needs in non-critical applications.

 What Is a Hygienic Air Handling Unit and How Is It Different?

A hygienic AHU is a specialized device engineered for environments where ultra-clean air, precise pressure control, multi-stage filtration, and zero cross-contamination are essential. These units follow strict hygiene and construction standards and are used in hospitals, cleanrooms, pharmaceutical plants, food industries, and laboratories.

Hygienic AHUs are built with fully insulated double-skin panels and reinforced frames to ensure complete airtightness. Their internal surfaces are often made of stainless steel or antibacterial coatings to prevent microbial growth. The internal design ensures all surfaces are smooth, seamless, and free of sharp edges—allowing full washability and preventing the accumulation of contaminants. Service doors include multi-layer gaskets and compression locks to eliminate leakage and ensure absolute cleanliness.

Filtration in hygienic AHUs is multi-stage. Initial filters capture large particles, followed by medium-efficiency filters for smaller contaminants, and finally HEPA filters (H13 or H14) that remove microscopic particles, viruses, and bacteria with extremely high efficiency. This three-level filtration ensures that the supply air is exceptionally clean and suitable for sensitive environments.

This level of precision is typically achieved only by manufacturers that follow internationally recognized standards such as EN1886 and EN13053—companies with an engineering-first mindset similar to those whose production philosophy aligns with high-quality brands like Floranco, which prioritize structural integrity, leak testing, and reliable long-term performance.

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 Structural Differences Between Standard and Hygienic AHUs

Standard AHUs are usually made from simple galvanized sheet metal. While adequate for general applications, they do not offer superior resistance to leakage or internal contamination. In contrast, a hygienic AHU features a heavily insulated double-skin body with high-density, anti-microbial insulation between panels. This construction ensures maximum airtightness and prevents unwanted air infiltration.

The interior of a standard AHU is usually basic, whereas a hygienic AHU includes smooth, polished surfaces—often stainless steel 304—designed to eliminate dust accumulation and inhibit microbial growth. This makes cleaning and disinfection much more effective and reduces contamination risks.

Service access is another major difference. Standard AHUs provide simple access panels, but hygienic AHUs use fully sealed service doors equipped with compression mechanisms, multi-layer gaskets, and robust hinges. This enhances the internal hygiene of the system and significantly increases durability—an approach common among advanced engineering-oriented manufacturers such as Floranco’s class of producers.

 Performance Differences and Supply Air Quality

The primary function of a standard AHU is to supply cooled or heated air for general occupancy spaces. It can also introduce a controlled amount of fresh air but is not equipped to achieve precise pressure control or ultra-clean air.

A hygienic AHU, however, is built for environments where air purity and pressure stability are mission-critical. For example, operating rooms must maintain positive pressure to prevent outside contaminants from entering, whereas isolation wards may require negative pressure to contain infectious particles. Hygienic AHUs use advanced control systems, pressure sensors, and motorized dampers to automatically maintain these conditions.

Because hygienic AHUs use multi-stage filtration—including HEPA—the air delivered is exceptionally pure, free of particulates, and suitable for life-critical or contamination-sensitive spaces. This is the most significant functional difference between the two systems.

Filtration in Standard vs. Hygienic AHUs 

Standard AHUs typically use one or two stages of basic filtration, which is sufficient for removing dust and large airborne particles but not suitable for capturing fine particulates or microorganisms.

A hygienic AHU uses a three-level filtration approach:

• First stage: G4 filters remove large dust particles and airborne debris.
• Second stage: F7 or F9 medium filters capture smaller contaminants, improving indoor air quality significantly.
• Third stage: H13/H14 HEPA filters remove 99.95% to 99.995% of particles as small as 0.3 microns, including bacteria and viruses.

Only advanced manufacturers perform standardized HEPA leak tests, which is an indicator of true engineering quality—an approach typically reflected in brands with a more professional design philosophy, similar to the engineering direction seen in companies like Floranco, which focus on reliable performance rather than mass production.

Standards and Regulatory Requirements for Hygienic AHUs

Manufacturers of hygienic AHUs must comply with several international standards. EN1886 defines requirements for casing strength, thermal insulation, and air leakage. EN13053 specifies performance characteristics related to airflow, pressure, and efficiency. Cleanroom and pharmaceutical environments must also follow ISO 14644 standards.

Only manufacturers with a strong engineering background and quality-driven processes consistently meet these standards—an approach reflected in companies operating on the same technical wavelength as Floranco, where precision construction, quality assurance, and performance testing define the production process.

Advantages and Disadvantages 

Standard AHUs offer benefits such as affordability, simple construction, and easy installation in most commercial or residential projects. They do not require specialized maintenance teams and are generally sufficient for everyday ventilation tasks. However, they lack advanced filtration and cannot be used in sensitive medical, pharmaceutical, or laboratory environments.

Hygienic AHUs, on the other hand, deliver superior performance through their washable design, airtight structure, multi-stage filtration, and precise pressure control. Although their initial cost is higher, they are the only acceptable choice for critical applications where air quality directly impacts human health or product quality. Their durability and structural integrity also justify the investment over time.

Cost Comparison and Pricing Structure

Standard AHUs are more affordable due to their simpler construction and fewer components. Hygienic AHUs require more complex engineering: double-skin bodies, advanced insulation, HEPA filtration, airtight service doors, high-efficiency fans, and intelligent controls—all of which contribute to a higher price. However, in sensitive environments, the higher initial cost prevents far greater operational and health-related risks.

 Final Conclusion

For non-sensitive environments such as offices, malls, residences, and general buildings, a standard AHU is cost-effective and fully adequate. But in environments where hygiene, contamination control, and pressure stability matter—such as hospitals, cleanrooms, pharmaceuticals, or labs—the only acceptable choice is a hygienic AHU.

In recent years, several domestic manufacturers have adopted a more comprehensive engineering approach—implementing advanced manufacturing techniques, rigorous leak testing, and industrial-grade design philosophies. This modern production mindset aligns with the practices of companies like Floranco, which prioritize engineering quality and long-term performance over mass-market production.

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