Hygienic - Air Supply

Air Supply & Extract Ventilation Ductwork

Services we can provide;

As a member of the B&ES (formerly HVCA - Heating & Ventilation Contractors Association) with trained Duct Hygiene Operators we can offer the following services;

  • System Testing (inspection/ Monitoring), recommended to be repeated at intervals not exceeding 12 months to include;
  • Deposit Thickness Test (DTT) – this method determines the mean surface deposit in terms of micro thickness for measuring internal duct floor deposits.
  • Microbiological testing – swab test are sent to an independaent laboratory for bacteria, fungi & yeast to determine the levels present. These results combined with the surface deposit results will determine whether the system requires cleaning. Testing can reduce the need for cleaning where the levels are acceptable.
  • Cleaning – carried out as per HVCA Guide to Good Practice TR/19 to include cleaning, disinfection, testing and installation of access panels.

Why Clean Ductwork

It is recommended that systems are monitored for cleanliness, many ventilation systems have never been cleaned nor had a regular maintenance schedule in place to an Approved Code of Practice (ACOP) as detailed by HVCA Cleanliness of Ventilation Systems. Maintaining the efficiency of your ventilation system will not only ensure that you meet all Health and Safety and insurance requirements, it will also show your staff that your business takes Health & Safety seriously. The above photographs clearly identify contaminated and cleaned ductwork to include DTT testing. Remember every time you notice a dirty grille or diffuser, you are breathing in that dirt!

Legal requirements

Building services and their operation are expected by current legislation to provide a comfortable and safe indoor environment for occupants. Relevant legislation includes;

  • The Health and Safety at Work 1974
  • The Management of Health and Safety at Work Act Regs
  • The Workplace (Health, Safety and Welfare) Regs
  • The Control of Substances Hazardous to Health Regs

Health and Safety to employees

Biological agents such as bacteria, fungal spores and pollen grains can enter buildings from outside and particles generated indoors can include human skin scales, bacteria, viruses and fungi, faecal material from the house dust mite, vermin or paper dust present. Many indoor pollutants can be harmful to human health either through their potential to cause infection, their toxic nature, or their potential to cause allergic reactions in susceptible individuals this is commonly referred to as ‘Sick Building Syndrome’.

System efficiency

With a build up of dust etc the system will not function efficiently. The following components should be subject to cleanliness inspection as a minimum: Fresh air intakes, air handling units, fire dampers, heat exchangers, volume control dampers etc.


  • Accreditation Certificate
  • Rospa
  • FSB
  • HVCA
  • HAS
  • Constructionline