UV-C Germicidal Irradiation

UVGI uses UV-C light to damage the DNA or RNA of bacteria, viruses, moulds and yeasts so they can't reproduce. It's been used to disinfect air, water and surfaces since the 1940s, and today it's a well-established way to control airborne pathogens in commercial buildings, particularly anywhere air is recirculated.

Wherever possible, we recommend installing it in the air handling unit, since slower-moving, enclosed air there gives UV-C far more contact time with pathogens than in ductwork, and one installation covers every space the AHU serves.

Where AHU space is limited or you're retrofitting an existing system, in-duct units are a good alternative. We'll assess your system and recommend the right fit.

No — UVGI only inactivates biological contaminants. If particulates or VOCs are also a concern in your building, we'll typically recommend combining it with filtration or bipolar ionisation as part of the same specification, so all three contaminant types are covered.

Yes. UV-C lamps are housed inside the AHU or ductwork, away from occupied spaces, so people in the building aren't exposed to the light directly. It's a purely physical process — no chemicals or by-products are introduced into the airstream — and it's named alongside HEPA filtration in UK Approved Document F as an approved method for disinfecting recirculated air.

UV-C light is both powerful and dangerous, therefore all of our systems are fitted with safety interlocks to disable them if someone gains access to the AHU.

Production of ozone (O3) is possible with UV lamps. Some applications for UV are specifically designed to produce ozone for odours control. UVGI systems selected for pathogen reduction use a 254nm wavelength which does not produce ozone.

Very little. The lamps need replacing every two years, and our systems come with a BMS interface that notifies of any faults. The UV-C also keeps coils and drip trays free of biofilm, therefore offsetting the need to clean those components, instead replacing the bulbs every two years.

They solve different problems, so it's rarely an either/or decision. UVGI is highly effective against bacteria, viruses and mould but doesn't touch particulates or VOCs; bipolar ionisation reduces VOCs and clusters particulate matter but isn't a substitute for pathogen-specific disinfection. Many of the buildings we work on use both — we'll assess your pollutant profile and recommend whether you need one, the other, or a combination.

Yes. UVGI is named in Approved Document F as an accepted way to disinfect air in systems that recirculate between spaces, and the design approach we follow is based on ASHRAE 241, the closest equivalent design guide, since there isn't yet a UK-specific standard.