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The importance of air conditioning systems (RLT systems) extends to a wide variety of modern special buildings such as meeting places, restaurants, underground car parks and office buildings. In this context, the topic of hygiene is of paramount importance. Inadequate hygiene in air conditioning systems creates ideal conditions for the growth of microorganisms. The consequences can be diverse: from irritation of the mucous membranes to headaches and poor concentration to asthma, allergies and infections. It is therefore crucial that HVAC systems are regularly maintained and operated in a hygienic manner to ensure the health and well-being of the people who use these spaces.
According to the Industrial Safety Ordinance and the Workplace Ordinance, operators are obliged to have the functionality of their air conditioning systems checked regularly. It is important to prove that the air conditioning systems supply air that is harmless to health and function reliably. In VDI 6022, this test corresponds to the so-called hygiene inspection. It must be carried out for the first time when commissioning and recurring every 2 years (RLT systems with humidifier) or 3 years (RLT systems without humidifier).
RLT systems according to VDI 6022 Special design properties are important for air conditioning systems that are used in areas with special hygiene requirements (e.g. hospitals). Our experts support manufacturers and evaluate air conditioning systems, components, materials, the design implementation and suitability for the stated purpose based on VDI 6022.
The hygiene inspection according to VDI 6022 as well as the maintenance of air conditioning systems must be carried out for all devices that influence the quality of the supply air. For exhaust air systems, these regulations only apply if they also influence the quality of the supply air, for example through a rotary heat exchanger or a recirculating air flap.In addition, the hygiene inspection according to VDI 6022 is mandatory for all rooms in which a single person stays for more than 30 days a year or regularly for more than 2 hours a day.
Initial hygiene inspection
Before a new HVAC system is put into operation, an initial hygiene inspection is required by law. Such an inspection is also required if significant changes have been made to the system.
Regular hygiene inspection
After the initial inspection, further hygiene inspections must be carried out at regular intervals, every 2-3 years. Any deficiencies are identified and measures are taken to correct them.
Hygiene controls
In addition, hygiene checks should be carried out throughout the year. These may consist of visual inspections or microbiological sampling of the humidifier water. The aim of these controls is to identify and correct possible defects at an early stage.
1. Indoor air technology, hygiene and hygiene maintenance
The HVAC systems (RLT systems) function as vital heart and lung machines in the pharmaceutical clean rooms. They condition the air, create the required air purity and distribute it throughout the room. The planning, construction and operation of air conditioning systems are subject to strict requirements, particularly with regard to air purity. Compliance with these requirements is proven by proof of qualifications and checked during GMP inspections. Various aspects in the cleanroom are monitored, such as the number of particles in the air, the air exchange rates, the recovery times and the direction of flow. Microbiological controls using contact tests and air samplers are also standard in the GMP world. The interface between the air conditioning system and the clean room is formed by the terminal HEPA filter in the supply air ceiling of the clean room. Despite regular integrity checks, leaks or damage can go unnoticed and affect cleanroom quality. Uncontaminated exhaust air is usually cleaned immediately via a central filter in the air conditioning unit before it is released into the environment as exhaust air. Re-contamination cannot therefore be completely ruled out. The air conditioning technology itself must not be a source of contamination and must ensure that the air in the building is safe to breathe. This requires a high level of operator and personal protection responsibility. A hygiene-compliant RLT system ensures that no microbiological risks arise for the products manufactured in the cleanroom, which also ensures product protection. The VDI 6022 series of guidelines "Indoor air technology, indoor air quality" addresses these requirements through a hygienic design as well as hygienic maintenance and hygiene inspections of the system, as described in VDI 6022 [Sheet 1].
Compliance with the hygiene requirements can be checked and documented via the hygiene inspection according to VDI 6022. This is an essential component for the hygienic operation of air conditioning systems. When it comes to hygiene inspections according to VDI 6022, a distinction is made between “initial hygiene inspection” and “repeat hygiene inspections” (known as hygiene inspections for short).
2. Initial hygiene inspection
The initial hygiene inspection should be carried out in accordance with the guidelines by qualified specialist personnel with at least category A according to VDI 6022 Sheet 4.
The initial hygiene inspection is an essential step and should be carried out in the following situations: For new systems: After construction work has been completed, but before the system is actually used, it is crucial to carry out an initial hygiene inspection. This ensures that the system meets the required hygiene standards before it is put into operation. After significant changes to air conditioning systems: In the case of significant modifications to existing air conditioning systems, it is advisable to carry out an initial hygiene inspection before further use. In this way, potential risks to air quality and the health of users can be identified and eliminated at an early stage. On existing systems without prior inspection: For existing systems that have not yet undergone an initial hygiene inspection, it is important to do so. This ensures that even older systems meet current hygiene requirements and do not pose any risks to users. Carrying out an initial hygiene inspection is also strongly recommended, especially if the system operator changes at the beginning of his activity. This ensures that the new operator adheres to the required hygiene standards right from the start, thus ensuring the health and safety of users.
In addition to the content of the repeat hygiene inspections, the initial hygiene inspection includes the following key points: Control of implementation and compliance with requirements: It is checked whether the planning, design, manufacture, execution and assembly of the air conditioning system meet the specified requirements and have been implemented correctly. This is crucial to ensure that the facility meets the required hygiene standards from the outset. Determination and documentation of the minimum test locations: The minimum test locations for the hygiene controls and repeat hygiene inspections are determined and documented. This ensures that all relevant areas of the system are monitored regularly and systematically in order to identify potential risks at an early stage. Checking the tightness of the air duct system: It is recommended to also check the tightness of the air duct system. An existing protocol can be used and optionally measurements can be taken to ensure that there are no leaks in the system. This is important to ensure that airflow within the facility is controlled and not contaminated. The initial hygiene inspection is therefore a comprehensive process that ensures that the air conditioning system meets the highest hygiene standards right from the start and that the health and safety of the users are guaranteed.
3. Periodic hygiene inspections of air conditioning systems
The hygiene inspection should be carried out in accordance with the guidelines by qualified specialist personnel who correspond to at least category A according to VDI 6022 Sheet 4. The inspection must be carried out as follows: - For air conditioning systems with humidification: The inspection should take place every two years. - For air conditioning systems without humidification: The inspection should be carried out every three years. For buildings with more than 20 similarly constructed, similarly operated decentralized devices or terminals, it is recommended that inspections be carried out using a representative selection. If critical findings occur during the inspection of several devices, either all devices must be subjected to thorough cleaning and disinfection or the inspections must be carried out for all air conditioning devices at least for this cycle. The aim of hygiene inspections is to identify fundamental deficiencies and initiate measures to rectify them. The inspection includes the following activities: Advanced visual inspection An extended visual inspection of the air conditioning system for hygiene defects such as contamination, rust formation, limescale deposits, damage and lubricant leakage must be carried out. If microbial contamination can be visually detected during the visual inspection, this is a critical finding. Checking the air distribution system for leaks VDI 6022 Sheet 1 recommends a specific tightness class depending on the desired cleanliness class of the air ducts and components. These recommendations relate to planning, but a leak test during property handover and hygiene inspections is strongly recommended for the following reasons: - Creation of a reference value for the risk assessment - Ensuring optimal operation of the system upon handover - Ensuring the hygienic function of the system For an on-site leak test, a supplementary measurement in accordance with DIN EN 12599 is recommended. The result of a leak test should be a results report that provides the operator with information about the cause of a leak. Any leakage problems must be remedied by the operator or removed by an external company.
4. Documentation of activities
It is important that sampling locations are permanently marked and accessible to allow easy and rapid sampling during sanitary inspections.
All hygiene inspections carried out must be documented and archived reproducibly by the operator. This documentation is crucial for traceability of inspections, identification of deficiencies and planning measures to improve the hygiene situation.
The date for a necessary review of the implementation and success of the recommended measures should be set depending on the urgency. The same applies to notification of the elimination of possible hygiene deficiencies. Timely review and communication are critical to ensure safety and hygiene in the facility.
In the event of a critical finding, the operator should call in additional specialist personnel. This may be necessary in order to carry out a comprehensive assessment of the situation and take appropriate measures to correct the deficiencies
In the event of complaints or health problems among personnel working in the rooms supplied by the air conditioning system, a company doctor must be consulted. If necessary, the system should be shut down and short-term remedial measures carried out to protect the health of employees.
A risk assessment in accordance with VDI 6022 Part 1 Appendix B should be carried out with regard to people who are exposed to the supply air of the ventilation system and for the activities of maintenance personnel. This serves to ensure compliance with relevant laws and regulations such as the Occupational Safety and Health Act (ArbSchG), the Industrial Safety Ordinance (BetrSichV), the Workplace Ordinance (ArbStättV), the Hazardous Substances Ordinance (GefStoffV) and the Biological Substances Ordinance (BioStoffV).
Publications / specialist literature / treatises
[1] VDI 6022 Blatt 1 Raumlufttechnik, Raumluftqualität - Hygieneanforderungen an Raumlufttechnische Anlagen und Geräte (VDI-Lüftungsregeln), Ausgabedatum: 2018-01[2] VDI 6022 Blatt 3 - Raumlufttechnik - Raumluftqualität - Beurteilung der Raumluftqualität, Ausgabedatum: 2011-07[3] VDI 6022 Blatt 4 Raumlufttechnik, Raumluftqualität - Qualifizierung von Personal für Hygiene-kontrollen, Hygieneinspektionen und die Beurteilung der Raumluftqualität, Ausgabedatum: 2012-08[4] VDI 6022 Blatt 4.1 Raumlufttechnik, Raumluftqualität - Qualifizierung von Personal für Hygienekontrollen, Hygieneinspektionen und die Beurteilung der Raumluftqualität - Nachweisverfahren zur Qualifizierung in Schulungskategorie A und Schulungskategorie B, Ausgabedatum: 2014-03[5] VDI 6022 Blatt 6 Raumlufttechnik, Raumluftqualität - Luftbefeuchtung über dezentrale Geräte - Planung, Bau, Betrieb, Instandhaltung, Ausgabedatum: 2018-01[6] VDI 6022 Blatt 7.1 Raumlufttechnik, Raumluftqualität - Branchenspezifische Leitfäden - Abfall-behandlungsanlagen, Ausgabedatum: 2013-10
Our company consistently implements the above-mentioned requirements for customers. By adhering to the guidelines, standards and recommendations, we not only ensure the proper function and hygiene of the air conditioning systems (RLT systems), but also the safety and health of the users. Through regular hygiene inspections, documentation of all measures carried out and close cooperation with qualified specialist staff and partners, we ensure that all systems comply with current standards. In addition, we set dates for review and implementation of corrective actions based on the urgency of the issues identified. In the event of critical findings, we immediately call in additional specialist personnel to carry out a comprehensive assessment and find quick solutions. We are committed to the health and safety of everyone involved and always strive to ensure the highest standards of hygiene and air quality.
