We are often asked when should the ventilation ducts of a housing association or residential apartment be cleaned...
At IVAeris Oy, we know the answer: ventilation ducts should be cleaned when they are genuinely dirty. There isn’t a one-size-fits-all schedule. Some claim cleaning is essential for health reasons, but there is no definitive evidence to support this. Dirt that accumulates in ducts typically stays there and does not spread into indoor air – so even if the ducts are dirty, it doesn’t automatically mean the indoor air is polluted.
Why clean them anyway? Duct cleaning is a smart way to ensure that the system operates optimally, lasts longer, and saves energy. An unmaintained system consumes more energy and requires more repairs. The law is also clear: in certain places like hospitals, schools, and restaurants, ventilation ducts must be cleaned regularly – often every five years, but in professional kitchens, even annually.
So, don’t buy into the health hype, but don’t skip maintenance either. The schedule depends entirely on the specific needs of your property and legal requirements. A smart property owner ensures regular maintenance of ventilation systems to keep them in good condition and running efficiently.
What does the law say about ventilation cleaning?
Ventilation duct cleaning in Finland is regulated by several laws and decrees designed to ensure safe and healthy indoor air and prevent fire hazards. Here’s an overview of the key regulations:
Rescue Act (1078/2018, Section 13)
Building owners and operators are responsible for ensuring that ventilation ducts and devices are maintained and cleaned regularly to prevent fire hazards. This law applies to all buildings and obligates stakeholders to ensure fire safety in ventilation systems.
Ministry of Defence Decree (712/2017, Section 63)
This decree concerns the industrial handling and storage of hazardous chemicals. It requires that ventilation ducts involved in chemical handling are regularly maintained to ensure safety during chemical storage and handling.
Ministry of the Interior Decree on Cleaning Ventilation Ducts (802/2001)
This decree applied to all ventilation ducts, whether natural or mechanical. It specified cleaning intervals:
Annually cleaned ducts: Ventilation ducts in professional kitchens, carpentry shops, bakeries, and other industrial premises where flammable substances accumulate had to be cleaned at least once a year.
Ducts cleaned every five years: Ventilation ducts in hospitals, schools, hotels, and restaurants had to be cleaned at least every five years.
Note: This decree expired on January 1, 2007, and has not been replaced. Ventilation duct cleaning is now governed by the general principles of the Rescue Act.
The Ministry of Social Affairs and Health regulations
The Ministry of Social Affairs and Health (STM) has established several regulations related to indoor air quality in both workplaces and residential environments:
HTP values (STM 538/2018): The permissible levels of air impurities in workplaces are strictly defined, such as the allowable concentration of carbon dioxide during an 8-hour work shift, which is set at 5000 ppm.
Residential ventilation (STM 545/2015): This regulation mandates that ventilation must be sufficient to ensure proper indoor air quality and moisture control, although it does not specify particular cleaning intervals.
In summary, regular maintenance of ventilation ducts is a legal obligation, but cleaning is only required at specific intervals if there is a particular need. Cleaning is especially important for fire safety since accumulated dirt in ducts can increase fire risks. Legislation also refers to indoor air quality, but there is currently no scientific evidence that duct cleaning directly improves indoor air quality. In exceptional cases, such as mold in supply air ducts, cleaning must be done immediately to eliminate health risks.
What does the industry say about duct cleaning?
The ventilation industry has various recommendations and views on duct cleaning, but contractors often cannot provide a clear answer to the question: how often should ducts be cleaned? This is because regulations for residential buildings do not clearly specify cleaning intervals. The industry is traditionally accustomed to having legal clauses for every procedure, but for ventilation ducts, the situation is less clear – especially regarding residential buildings.
If you examine the legal texts mentioned above, you’ll notice there are no direct legal mandates on cleaning intervals for residential apartments, housing cooperatives, or consumer properties. This has led to a common misconception that a five-year cleaning interval is the "standard" for all buildings. This belief is incorrect. While the previously valid Ministry of the Interior Decree (802/2001) specified exact cleaning intervals for hospitals and restaurants, this decree expired on January 1, 2007. Since then, legislation has relied more on general maintenance requirements, and cleaning intervals for residential buildings are still not legally regulated.
It’s important to note that ventilation duct cleaning needs vary based on the property’s purpose and conditions. For example, industrial facilities and professional kitchens, where grease and dust accumulate heavily, require more frequent cleaning, while residential buildings usually require less frequent inspections and cleaning.
Indoor Climate and Ventilation Guide (June 11, 2024)
Talotekniikkainfo published an updated Indoor Climate and Ventilation Guide (June 11, 2024), and here’s the straight talk. This guide was produced by Talteka (Finnish Building Services and Trade Association) and is based on the collaboration of industry experts. It summarizes everything you need to know about duct cleaning.
Here are a few key points you can’t ignore:
Assessment of cleaning needs: The need for duct cleaning must be checked at least every five years. Highly demanding spaces, such as commercial kitchens, require cleaning at least once a year to ensure the system operates safely and efficiently.
Cleaning access doors: A sufficient number of access doors must be installed in the duct system to ensure proper cleaning. In horizontal ducts, access doors are recommended every 10 meters. In more demanding environments, they should be placed every 3–5 meters.
Cleaning certificate: A cleaning certificate is an important document that must be kept, for example, in the kitchen’s self-monitoring file. It serves as proof that the ducts have been cleaned according to regulations.
Cleaning methods: It’s essential to ensure that the cleaning process doesn’t damage control devices, silencers, or other components. Every cleaning must be done in a way that maintains system performance and avoids any damage to the ducts.
Cleaning ventilation ducts: Bottom line
When looking at ventilation ducts, many panic at the sight of dust in exhaust air ducts, thinking the indoor air is contaminated. But here’s the crucial point: exhaust air ducts carry air outward from the apartment, and the dust in them does not re-enter indoor air. So, no need to panic. The question is whether the accumulated dust affects the ventilation system’s efficiency and energy consumption. If yes, then cleaning the ducts is a sensible measure.
Supply air ducts could potentially affect indoor air quality, but supply air always passes through a filter, so the ducts rarely get dirty. In fact, supply air ducts are often nearly clean even after decades, although many don’t believe it. Dust rings often form around supply air vents, leading to the mistaken belief that the ducts are full of dust. This dust ring is caused by airflow turbulence, and the dust originates from indoor air, not the ventilation duct.
Regular cleaning is legally mandated in many cases and crucial for fire safety and efficiency. However, unnecessary cleaning without a real reason is wasteful if not legally required. If you’re unsure whether cleaning is necessary, contact us – we’ll gladly help assess your situation. You can also book an air ventilation assessment, where our experts will check your system and provide recommendations.
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IVAeris Oy
010 206 3000