Air duct cleaning in schools

Frisse Scholen ventilation: what does the programme of requirements ask?

The Frisse Scholen programme of requirements has three ambition levels: C is sufficient, B is good and A is excellent. Each level comes with a maximum CO2 concentration in the classroom.

An installation that reaches class B on paper only does so if enough air actually flows through it. Dirty filters and ducts restrict the airflow. In a laboratory study of an MVHR unit, heavily fouled filters delivered 37 percent less supply air. Less fresh air means CO2 rises faster in a full classroom, and you can read that on the meter.

Which legal rules apply to ventilation ducts in school buildings?

None of these rules states a cleaning frequency. According to a trade article on EN 15780, schools fall into the medium risk group, together with offices and hotels, with a dust limit below 3.0 g/m² and up to 4.5 g/m² for secondary ducts. Those values come from a trade publication; the text of the standard itself was not consulted for them.

How the standards fit together is explained under VDI 6022 ventilation hygiene.

Construction dust in new schools: inspect at handover

A new school building looks clean, but the RVO process manual for Frisse Scholen (RVO is the Netherlands Enterprise Agency) warns that air ducts in newly delivered schools turn out to be contaminated with construction dust. That dust goes straight into the classrooms during the first weeks of heating. A handover inspection prevents you from starting with a dirty installation.

• Have a camera inspection carried out before occupation, covering the main ducts and a sample of classroom ducts.
• Agree in the construction contract that ducts are capped during building work.
• Have demonstrably contaminated sections cleaned before the school accepts the building.
• Keep the inspection report as a baseline for later maintenance.

A handover inspection costs little time compared with the weeks of complaints that follow when a new building blows construction dust into fresh classrooms. It also gives the school board a clear document to discuss with the contractor if cleaning turns out to be needed.

Central or decentralised: what does it mean for education ductwork cleaning?

Schools broadly have two kinds of system. With a central system, one air handling unit sits on the roof or in a plant room, with long ducts to all classrooms. With decentralised ventilation, every classroom has its own unit with short ducts to the facade.

The RVO manual points out that with decentralised ventilation the installer has to visit every classroom to replace filters. Combine that visit with a check of the valves and the short duct, and you only need to enter the classroom once.

How to plan school ventilation duct cleaning in the holidays

Schools are the only buildings with long, predictable periods without users. Make use of that. An annual schedule that works well:

1. Autumn half term: filter check after the first weeks of heating.
2. Christmas holidays: camera inspection of the central ducts.
3. Spring half term: replace filters in decentralised units.
4. Summer holidays: the major work: cleaning the ducts where the inspection indicated it, with sealing caps and extraction.

Afterwards, compare the CO2 data from the first school week with the data from before the holiday. That shows whether the work had an effect, without extra measuring equipment.

Keep the schedule in one shared document that the caretaker, the installer and the school board can all see. When the same file holds the inspection photos, the filter dates and the CO2 readings, the next maintenance round starts from facts instead of memory.

Which equipment suits air ducts in schools?

For the long ducts of a central system, the DC4 duct cleaner for cleaning contractors is suitable: ducts from 100 to 600 mm, round and square, up to 30 metres and through 90 degree bends. For the short ducts of decentralised units, the PD4 duct cleaner for cleaning contractors works well; you drive it with a cordless drill, which is handy in classrooms without a socket in the right place. The compact PD2 duct cleaning tool is another option for maintenance work; request its specifications from Lamers.

During the work, put a dust tight screen around the work area and keep the duct under negative pressure. The materials for this are listed under duct sealing and extraction for cleaning contractors. In addition, choose ventilation duct brush based on the duct material: soft for duct board and sheet metal, Tynex for stubborn dirt. An overview of all machines is available under air duct cleaning tools for cleaning contractors.

Fictional example: a primary school with twelve classrooms

Fictional example. A primary school with twelve classrooms and decentralised units often sees CO2 levels above 1,200 ppm in winter, the limit of class C. The caretaker notices the filters have not been replaced for a long time. In the spring half term, the installer replaces all filters and cleans the short ducts per classroom with a compact cleaner. In the weeks that follow, the school reads out the CO2 meters and compares them with the period before. The costs depend on the number of units and the contamination, so the price is on quotation.

How to estimate the costs of such a project is covered under air duct cleaning prices. For similar buildings see air duct cleaning in offices, and other sectors are listed under ductwork cleaning per industry. If you are unsure about the right machine, you can request a quotation for cleaning contractors through a callback request or a question.