VDI 6022-1 Ventilation and Indoor-Air Quality
Hygiene Requirements for Ventilation and Air-Conditioning Systems and Units (VDI Ventilation Code of Practice)

The VDI 6022 series of guidelines applies to all rooms or areas and equipment used in rooms intended to be occupied by people for more than 30 days per year or regularly for more than two hours per day. VDI 6022 Part 1 applies to all ventilation and air-conditioning systems and air handling units, including their central or decentralized components (such as recooling systems), which affect the quality of supply air.

VDI 6022 also applies to exhaust air systems if they influence the quality of supply air through recirculation.

Existing ventilation and air-conditioning systems operate in a state of non-compliance within a continued permit framework comparable to structural fire protection. To maintain hygiene quality,

As short-term compensatory measures, these systems will undergo more frequent hygiene inspections and hygiene audits, and simple reconfiguration measures will be immediately initiated.

For the long-term and complete implementation of VDI 6022 Part 1, it is recommended to define a step-by-step program if the construction allows it.

Terms and Definitions

• Workplace: Any area occupied by employees for more than 30 days per year or regularly for more than two hours per day is considered a workplace.

• Outside air volume flow: The volume flow of air entering a system from outside or flowing directly into a room without conditioning.

• Swept clean: The condition of a surface that has been cleaned using a broom or brush and can be described as clean under visual inspection.

  • Note: In case of disputes regarding dust surface density and the classification of "swept clean" on surfaces in contact with handled air, measurement is recommended.

• Disinfection: A method aimed at reducing the number of living organisms.

• Decentralized air handling unit: Unlike a central air handling unit, this unit is dedicated to a single room and supplies it with secondary air or outside air.

  • Note 1: Examples of such units include:

    • Fan convectors/fan-coil units

    • Cabinet units

    • Air/cooling units/split units

    • Similar units

  • Note 2: See the following limitation → decentralized façade-mounted unit

• Air control unit

• Decentralized façade-mounted air handling unit: This is a unit mounted on or near the façade, allowing for a short air path to intake outside air, e.g., from the façade or a window.

  • Note: Examples of such units include:

    • Façade units

    • Window railing units

    • Underfloor units

    • Window air conditioners

    • Similar units

• Terminal device: This device operates with air from central air-conditioning systems and, if applicable, secondary air but does not have its own mechanical drive for air processing.

  • Note: This means that each terminal device is assigned to a single room. Examples of such devices include:

    • Volume flow controllers

    • Induction devices

    • Chilled ceilings and all silent cooling components, such as cooling partitions, cooling convectors, suspended cooling panels, etc.

  • Additionally, the following may also be considered terminal devices:

    • Mixing boxes outside the central air-conditioning system

    • Final coolers and final heaters outside the central air-conditioning system

    • Volume flow controllers assigned to a single room

• Harmless to human health: A condition in which health is not expected to be affected by the methods and technical systems used, their operation, and maintenance.

  • Note: This also means that the assessment considers possible synergies and mutual reinforcement. If necessary, an expert report from a recognized independent institution is obtained.

• Hygiene: Measures that serve to prevent diseases and protect and promote health.

• Hygiene Inspector: A medical doctor or microbiologist specialized in hygiene (and/or environmental medicine), knowledgeable about the operation of ventilation and air-conditioning systems at least to the extent provided by Category A training, and experienced in assessing and inspecting these systems for hygiene.

• Hygiene Auditor: A person qualified beyond Category A through advanced training according to VDI 6022 Part 4, Category RLQ, to conduct inspections of ventilation and air-conditioning systems and assess indoor air quality up to Class 2 according to VDI 6022 Part 3.

• Hygiene Specialist: A person with in-depth knowledge in hygiene and microbiology through relevant university studies and, if possible, professional experience in medicine, with at least the level of knowledge provided by category training in the operation of ventilation and air-conditioning systems and practical experience in inspecting and evaluating these systems for hygiene.

• Hygiene Inspection: A qualified investigation of the hygienic condition of ventilation and air-conditioning systems.

• Hygiene Control: Periodic monitoring of the hygienic condition of ventilation and air-conditioning systems at short intervals.

• CFU (Colony-Forming Unit): A unit expressing the number of culturable microorganisms. [DIN EN 13098]

• Critical Result: Examples of critical results include:

  • Repeated exceedance of permissible total colony-forming units in humidifier water (standard value: 1000 CFU/ml) or recirculating water of a recooling system (standard value: 10,000 CFU/ml)

  • Excessive Legionella concentration (>100 CFU/100 ml in humidifier water or >1000 CFU/100 ml in recirculating water of a recooling system)

  • Repeated mold contamination in humidifier water

  • Higher CFU counts downstream of air handling units compared to the upstream direction

  • Visible mold or other microbial growth on surfaces in contact with handled air in ventilation and air-conditioning systems

• Air Hygiene: A branch of hygiene concerned with interactions between inhaled air, people, and the environment concerning health and well-being.

• Microorganisms: In the context of ventilation and air-conditioning systems, this term includes bacteria (such as Legionella), algae, and molds that can proliferate in water or on moist surfaces (such as humidifier water or condensate).

• Ventilation and Air-Conditioning Systems and Air Handling Units: The total of all components required for the fan-driven ventilation of one or more rooms.

  • Note: For the purposes of this guideline, this also includes system-specific assemblies such as → central and → decentralized air handling units, → terminal devices, etc.

• Existing Ventilation and Air-Conditioning System: For the purposes of this guideline, any ventilation and air-conditioning system installed before the publication of the relevant edition of VDI 6022 is considered an existing system.

• Small Ventilation and Air-Conditioning System: A ventilation and air-conditioning system with compact overall dimensions, owned and operated by the same user, consisting solely of "filtration" and/or "heating" air-conditioning functions.

• Secondary Air: The volume flow of air extracted from a room and returned to the same room after conditioning. [DIN EN 13779, Table 2]

This document has been updated to reflect the most precise translation of the original Turkish text into English, ensuring full compliance with the technical terminology and structure of VDI 6022 guidelines.