Hygiene inspections in accordance with VDI 6022

VDI 6022, hygiene inspections, rules;  state of the art

Hygiene inspections in accordance with VDI 6022 ensure that your ventilation technology complies with current guidelines. With our clear documentation, we provide you with an overview and transparency: This minimizes your follow-up costs!

For several decades, VDI 6022 has been the standard guideline in the field of hygiene for ventilation and air-conditioning technology. Within the scope of a hygiene inspection according to VDI 6022, the complete air handling system including the air duct network is subjected to a functional test and the microbial growth is determined at representative points.

As an operator of a ventilation system, you will benefit in the long term if hygiene inspections are carried out in accordance with VDI 6022. The maintenance of a ventilation system according to the guidelines of VDI 6022 represents a continuous process, which is associated with investment costs, but ultimately ensures comprehensive hygiene safety!

Services of hygiene inspection according to the highest possible standard:

Overall microbiological assessment of ventilation systems

Conformity inspection

  • Visual inspection of air handling units for compliance with specified requirements and hygiene deficiencies
  • Inspection of accessibility of air handling units, individual components and parts
  • Documentation by means of a VDI checklist with 104 detailed questions on the condition of the entire air handling system

Physical assessment

  • Determination of broom cleanliness by visual assessment. The following representative locations are to be inspected: Supply air duct, floor in the central unit, recirculation air duct, secondary air duct, exhaust air duct (if supply air quality is affected); in addition to the visual impression, the negative assessment of dust contamination is to be confirmed by a wipe test with the palm of the hand (with glove) and photo documentation.
  • Extended visual inspection of the AHU for hygiene defects such as dirt, corrosion, deposits, damage (fiber discharge, etc.), belt abrasion, condensation, visible mold growth.
  • Photo documentation and description of physical defects.

Constructional assessment

  • Photo documentation and description of apparent or obvious design deficiencies such as non-sealing filters, housing leaks, non-existent accessibility, improper condensate drainage, etc.

Microbiological sampling

  • Microbiological surface sampling of hygiene-relevant individual components and parts such as: Heat exchangers, condensate trays, droplet separators, humidifier chambers, silencers, etc. by means of impression plates.
  • Determination of sampling points and marking in the outside area of the air handling unit
  • Microbiological surface sampling to determine the surface colony count:
    - RLT systems with humidification: 6-8 sampling points (total 18-32)
    - RLT systems without humidification: 4-6 sampling points (total 12-24)
  • For the determination of bacteria and molds (with differentiation on genus level), 1 x Caso agar, 1 x DG-18 or 1 x malt extract agar must be used per sampling point.
  • Airborne germ measurement in one supplied room per RLT system plus a comparison air measurement (reference measurement) of the outside air, or room air. For each airborne germ measurement or measuring point, 1 x Caso agar must be used to determine the total colony count of bacteria and 1 x malt extract agar must be used to determine the total colony count of mold. For each airborne germ measurement or measuring point, the molds are to be differentiated at the genus level.
  • Microbiological examination of the humidifier water (evaluation according to total germ count, Legionella spec. and pseudomonads)

What does cleaning according to VDI 6022 mean?

Swab samples are given to a laboratory for examination
Microbiological sampling on a filter

Both clients and contractors adhere to the execution of cleaning work on ventilation systems in accordance with VDI 6022. Therefore, it should be clear what exactly is included in this execution  .


  • The guideline VDI 6022 makes little or no reference to the execution of cleaning.
  • The guideline VDI 6022 gives information about planning, transport, installation, operation and inspection, but NOT about the cleaning procedure! 
  • A "Cleaning of the ventilation system according to VDI 6022" serves as a basis that an air handling system after treatment withstands a hygiene inspection according to VDI 6022.
  • A "Cleaning of the ventilation system acc. to VDI 6022" must always be preceded by a hygiene inspection acc. to VDI 6022 in order to record the condition of the system according to the same criteria of repair.  
  • A "Cleaning of the ventilation system acc. to VDI 6022" basically deals with the entire ventilation system including air ducts.

    In addition, it should be noted that a cleaning "according to VDI 6022" does not fulfill the requirements that a cleaning according to VDI 6022 does! Here it is necessary to consider corresponding quality differences among the providers.

Our services:

  • Initial hygiene inspections according to VDI 6022 .
  • Hygiene inspections of  air handling units according to VDI 6022
  • Microbiological surface and air examinations
  • Water examinations according to VDI 6022
  • Marking of sampling points
  • Constructive evaluation of the air handling unit according to VDI 6022
  • Individual report after evaluation of all samples
  • Meaningful objective recommendations for action  .
  • Sample evaluation by an independent laboratory accredited according to DIN EN ISO/IEC 17025
  • Modern validated measurement technology for air handling units

Clear documentation of our hygiene inspection

System diagram, evaluation, analysis
System diagram for hygiene inspection of an RLT system
  • Transparency with the Gesec® signal system: The clear documentation of our hygiene inspection shows you the summary of all results at a glance! After the hygiene inspection, you know immediately where everything is in order in your air handling units (white), where, according to the guideline, a defect rectification is due soon (yellow) or where immediate action is required after the hygiene inspection (red). 

Your benefit:

  • We strictly adhere to all regulations: Always up to date due to our active memberships in the Fachinstitut Gebäude-Klima e.V. (FGK) and in the German Professional Association for Air and Water Hygiene e.V. (DFLW).
  • TÜV certification: Gesec is certified by TÜV. Only companies that comply with current quality standards can be certified according to the criteria catalog of the TÜV.
  • Authorization: We are a specialized company according to the Water Resources Act. Only authorized companies are allowed to carry out services on plants with water-polluting substances.
  • Membership in the Employer's Liability Insurance Association for Health Services and Welfare (BGW): The BGW verifies the specialist company status as a hygiene specialist company. Normal cleaning companies are not members of the BGW.


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