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Air handling units - Hygienic
Certification manual
Certification Manual
Appendix for Hygienic AHU


The Eurovent Certified Performance (ECP) programme scope for Hygienic Air Handling Units (HAHU) applies to hygienic ranges of Air Handling Units (AHUs). It is an additional certification option for AHUs already in an ECP certified range. 

The hygienic aspect of the AHU is certified based on 3 levels of classification, dependent on different applications:
Level 1: Is suitable for commercial applications including offices, commercial buildings, schools and hotels.
Level 2: Is suitable for use in hospitals and healthcare.
Level 3: Is suitable for applications including pharmaceutical, food processing, white rooms, operating theatres and equivalent.

For the full programme scope please view the Technical Certification Rules.


Hygienic air handling units provide ventilation and indoor air quality for buildings. Hygienic AHUs provide the same functions as traditional AHUs but are suitable for applications requiring a high hygienic standard. The main differences between a standard AHU and hygienic AHU, is that hygienic AHUs are easy to clean and disinfect, featuring access to all internal surfaces, and constructed in such a way as to reduce places where dirt can accumulate. The materials used in construction are designed to prevent fungal and bacterial growth, be resist corrosion and abrasion, and are odourless and emission free. 

Hygienic AHUs are factory made encased assembly units. The supply AHU comprises a model box (housing or casing), fan(s) and at least one other component for processing the air. Hygienic AHUs can include multiple components such as a filter, heater, cooler, energy recovery component, humidifier, dehumidifier, or mixing section. 

Hygienic AHUs use a ductwork system to deliver conditioned air into an area. Typically a fan pulls ventilated air into the AHU, where it is then conditioned and distributed into the space. Hygienic AHUs use a return AHU to pull in exhaust air and expel it to outside of the building. 


While exploring our certified products you’ll come across a number of technical terms relating to certification. The below definitions help explain the search criteria in our certified product directory.

All certified product types in the hygienic AHU programme have the following search criteria in common:

Brand name of the manufacturer.

Listing of models with some common features.

Model name.

Maximum Hygienic Level
This is the maximum hygienic level achieved by the range, measured from Level 1 to Level 3. Level 1 offers the lowest hygiene rating for projects suitable for commercial settings, while Level 3 offers the highest hygiene rating for specialist applications.

CAL class @ -400 Pa
Means casing air leakage under negative pressure at -400 Pa. The casing air leakage class (CAL class) relates to the amount of air leaked through the casing. L1 offers the lowest leakage and L3 the highest.

CAL Class @ +700 Pa
Means casing air leakage under positive pressure at +700 Pa. The casing air leakage class (CAL class) relates to the amount of air leaked through the casing. L1 offers the lowest leakage, L3 the highest.

TBF class
Is the thermal bridging factor class. It is the ratio between the lowest temperature difference between any point on the external surface and the mean internal air temperature, and the mean air-to-air temperature difference. TB1 offers the best thermal bridging factor, while TB5 is the worst.

Supply Filter class
Is the class of filter used in the supply AHU. 

Extract filter class
Is the class of filter used in the return AHU.

FBL class
Is the filter bypass leakage class. It shows the air bypass around filter cells, and casing between the filter and the fan, as a percentage of rated air volume flow. F9 offers the highest tightness class, with the lowest filter bypass leakage:

Filter class   G1 to F5   F6    F7   F8     F9
Maximun filter bypass leakage rate k in % of the volume flow rate   6   4   2   1    0.5

Number of filters on the supply side
Is the number of filters used in the supply AHU.

Fin thickness
Is a measure of the thickness of the fins in mm. 

Minimum distance between fins (cooler)
Is the measure of the distance between fins of the coolers in mm.

Minimum distance between fins (heater)
Is the measure of the distance between fins of the heaters in mm.

Factory country
Country of manufacture.

Factory city
City of manufacture.

Software version
Version of software selection tool.

Software name
Name of software selection tool.

Search for a certified hygienic air handling unit via our certified product directory.


Services characteristics:
The following services characteristics are certified :

  1. Manufacturing
  2. Maintenance
  3. Quality Management System
  4. IOM (Installation and Operational Manual)
  5. Shipment

Hygienic characteristics:
The following hygienic characteristics are certified :

  1. Materials
  2. Casing performance
  3. Components arrangement and performances (filters, coils, heat recovery systems, fans, humidifiers, dehumidifiers and silencers) .

All these above characteristics are listed in the Appendix for Hygienic AHU and are checked every year through audits. The audit consists of visual checking of the unit/components available during the audit of the factory, review of the software and technical documents with the manufacturer.

Search for a certified products in our Hygienic AHU programme via our certified product directory

Find out how to apply for the Hygienic AHU programme

💡 For information

When using the Advanced Search Criteria function you can search via maximum hygiene level, supply filter class, extract filter class or filter bypass leakage class (FBL class).


Search for certified products in our Hygienic AHU programme

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