Want to know how to improve Indoor Air Quality (IAQ), reduce staff Sickness and save money on energy bills?


Following the recent announcement from World Health Organisation (WHO) via The Building Engineering Services Association (BESA) https://www.thebesa.com/media/837569/updated-9the-april-refcom-tb-48-4-covid19-ac-systems.pdf the time is now to ensure your Indoor Air Quality (IAQ) is of a high standard. According to WHO officials “evidence was emerging” that Covid-19 can spread through the air in confined spaces such as the buildings Heating Ventilation and Air Conditioning (HVAC) systems and potentially cause a second wave of the pandemic. For further evidence, the below link is discussing the proof that the virus can be transferred through the air.


Why Install UVC?

Considering the above, there are three reasons for installing UVC disinfection lighting within your HVAC systems. The first and most important during the current pandemic is the health benefits, all viruses and bacteria, including Covid-19 will be killed by UVC light as it disrupts the DNA and kills it off, leaving good IAQ. The second is the economic cost savings seen with clean coils and the third reason is a reduction in staff sickness and an increase in productivity. Staff sickness is very closely linked to the first two benefits, meaning as the improved IAQ is provided within the office space so is a reduction in staff sickness by as much as 5 – 25%, HR managers would love to cut sickness by just 1.5%!

How do viruses and bacteria get into HVAC systems?

Bacteria such as Legionella can enter the building via the outside air, viruses and other bacteria can enter the building with people. Once the bacteria and viruses are present within the building they are picked up and spread around the building via the A/C ducts, they get through the first wave of filters and get stuck on the coils of the air conditioning system. Once on the coils it is open season for germs and bacteria, as HVAC coils are the perfect breeding ground, they turn into a mouldy biofilm.


Doesn’t regular maintenance clean the coils?

The coils within the air handling units will always become dirty as the particles pass through the filters and get trapped on the coils. Once the particles get trapped, they quickly turn into harmful mould and Fungai which grows at incredible rates on the coil. The condensate is supposed to wash this away and keep the coil clean, but, as the Mould and Fungai create a sticky biofilm the condensate fails as a tool to clean the coil and allows the Mould to keep multiplying. During a maintenance visit an engineer can often spray the coil with a disinfectant which can be potentially harmful and again fails to remove the biofilm from the coil.

How does this effect the efficiency?

The build-up of biofilm and dust on the coil, even as small as 1.5mm will cause an efficiency loss of roughly 16%. This reduction in efficiency then begins to cost a lot of money in the operating costs of the HVAC system and coil cleaning maintenance programs.

Health and Safety

Unlike UVA and UVB, UVC does not make it through the earths ozone layer and is therefore not present on earth in its natural form. It is recommended not to expose yourself to UVC as it can cause sore eyes and skin if exposed for too long, although it is not known to cause any long-term damage. The use of PPE is recommended and when installed in AHU’s the doors to the coils are further protected by installed micro switches that automatically switch the UVC bulbs off when the doors are opened, this enables work to be carried out in a safe controlled environment.


As we walk around supermarkets and different shops, we all notice the obvious new safety features and measures that are in place to try and help keep people safe. Limited numbers of people allowed in at the same time, hand sanitising gels, 2m separation to name a few. But it appears we all are happy with the IAQ or we never even give it a thought! The HSE website recently published an article on disinfecting premises using several different methods, see below link. https://www.hse.gov.uk/coronavirus/disinfecting-premises-during-coronavirus-outbreak.htm

UVC installed within your HVAC systems can save up to 20 – 30% in running costs. A case study was completed at Auckland airport where the running costs of the airports HVAC systems was reduced by over 20%, saving them £178,000 in yearly electric bills and £52,000 in yearly HVAC maintenance costs. On top of that the total Carbon Footprint was reduced by over 10%. As we have discussed throughout this blog, we cannot stop viruses and bacteria entering buildings, but we can kill them once they have entered.


Clean coils equal a much improved IAQ, which in turn improves staff sickness and productivity whilst saving money on energy bills.
The use of UVC in HVAC systems in some US government buildings is mandatory as directed by the US government Services Agency (GSA).
Is it now time to start treating IAQ with the same precautions we do with frequent touch points?
Please contact if you need further information or to discuss further.
Many thanks to Hilary Spicer of E-Co our technology partner for the information.