Current trends, as caused and effected by the pandemic, are moving us into new
territories of compliance, requirements and support for human factors.
There are certain insights and products that can help with these human and health
challenges that may be experienced today.
Key topics covered in this paper are:
- Mechanical Engineer Perspectives (HEPA)
- HEPA Product Technical Overview
- Global Project Insights – Healthy Working
Mechanical Engineer Perspective
- An ongoing challenge of the SARS-CoV-2 virus which causes COVID-19 is that it can linger in the air as an aerosol, attached to human
expulsions, for several hours.
- HEPA Filters are a current hot trend as they are an ideal localised way to filter out these small particles containing virus and then neutralize
them through various means.
- HVAC (Heating, Ventilation and Air Conditioning) is designed for human comfort and efficiency – NOT infection control.
- Up-to-date HVAC systems are not any better for transmission than older systems, in fact they can be worse as the modern strive is for
- Elsevier Environmental Research V. 195 “Estimating aerosol transmission risk of SARS-CoV-2 in NYC public schools during reopening”:
“Surprisingly, schools located in older buildings … had lower transmission probabilities, likely due to the greater outdoor airflow associated
with older, non-renovated buildings … (i.e. draughty buildings).”
Problems with Mechanical Ventilation:
- Generally low ventilation rates
- Designed to efficiently mix air in a room which could contribute to distribution of virus
- Can easily move contaminated air in a room to other spaces
- Expensive to change
- Changes that may seem beneficial don’t necessarily change or resolve infection control, especially without extensive engineering
- No regulations/requirements to maintain or change
How do HEPA Purifiers Work?
- Studies within Melbourne University concluded ‘Air purifiers are very effective at removing aerosols from a room’. Further studies showed SARS-CoV-2 was eliminated with an air purifier.
- HVAC effectively distributes SARS-CoV-2 throughout the building, as any airflow needs somewhere to escape – i.e. return air duct. Air purifiers actively clean air without distributing pathogens and other impurities.
- HEPA filtration is best in places where people collaborate. We can be smart about where we place purifiers. Lifts and large spaces with very high ceilings, such as warehouses, would not be best suited to purifiers. Open-plan offices fall into a more in between category where HEPA filtration may still be somewhat useful.
- We need to CLEAN air, not just ventilate
- Portable air cleaners are a great solution, the evidence is out that they work.
- Only HEPA filters recommended (not UV-C, ionisers, or plasma). These methods need further research.
Product Technical Overview
- Recent case study in a workplace identified SARS-CoV-2 infections were caused in the tearoom where masks were being removed for drinking and eating, despite COVID safe measures being in place. Adequate HEPA filtration would have dramatically reduced risk.
- An example of a highly effective modern HEPA filter is the Aeris aair 3-in-1 Pro HEPA Filter, which is distributed by Westlab.
- Swiss engineered
- 0 System Leakage
- Anti-microbial coating on exterior housing and filters destroys viruses, bacteria, spores, and mould
- Wi-Fi Connectivity & Fleet Control
- Inbuilt air quality sensor which gives you an idea of how quickly they work
HEPA Setup Options
MONO-POLAR: Mono-polar involves a single unit and there is potential for dead spots.
MULTI-POLAR: Multi-polar involves multiple units and can create a clean air roller effect where these units are passing air between each other, working very effectively together.
Aeris remote control app
- A complete app and fleet system to back them up
- Real-time monitoring of indoor air quality
- Unit management by zone / individual unit.
- Review of history and filter life status.
Frequently Asked Questions
Whilst UFAD systems may be a little better than conventional, the advantages of portable HEPA filtration remain relevant in modern HVAC systems, which are not designed for infection control.
In addition, since both of conventional ventilation system and the UFAD systems have a high infection risk at the front of the classroom, novel method to reduce the infection risk from students to teachers should be considered (Cheong et al., 2021).
In comparison to portable HEPA filtration, an UV-C energy solution requires more engineering and installation and associated costs
could be more extensive.
Portable HEPA filters act at a localised level, within the room of concern. UV-C systems have specific locations away from people where
pathogens are targeted.
Aged care providers advise SARS-CoV-2 control measures such as HEPA and rapid antigen testing will remain key points into the
foreseeable future as these are truly life-saving for the elderly, who are susceptible to severe COVID-19.
Indoor locations of high people density are the main focus point for HEPA filtration and there are many settings matching this criteria
within aged care homes.
Filter life-time is by manufacturer, generally under normal working conditions.
Inconsistencies may be present. Erring on the safe side is advisable given the cost & effort of filter changes is not major.
Aeris filters are highly engineered with plenty of filter media, containing pre-filters of both active carbon and alumina as well as the H13
Correct, simulations based on entirely filling a space with particles yields a conclusive display of performance.
Constant explusions don’t ‘fill’ the space so may be quickly and readily extracted, or may take time, depending on location and air flow in
the space. It is difficult to establish a controlled test model for this.
The safest way to work with HEPA is to be conservative by ensuring at least or more than enough units for the square metres of space.
Engineering of existing AHU demonstates most won’t be able to cope with a HEPA filter, nor will virus circulated through the HVAC
system likely remain at infectious levels.
The real need is filtration at a local level, hence the room could be more effectively purified with portable HEPA filters.
Filter change monitoring is typically based on just an hour counter.
The aeris HEPA filter has an inbuilt logarithm that looks at indoor air quality versus time that it’s been switched on and the expected life
New replacement filters are cost-effective and user replaceable, so it is sensible to apply frequent replacements to get the best out of
HEPA is really essential in enclosed spaces of high density with people close together and likely to be interacting.
Examples are hotels, hospitals, all types of meeting rooms and staff kitchens.
HEPA is ideal for meeting rooms as often the ventilation is set based on an ACPH (air changes per hour), but this doesn’t pay attention to how many people are in the room.
HEPA filters are less relevant in lifts or places with large, high ceilings such as a warehouse where the draw of air does not occur effectively with such a large volume.
This is in development stage and is unlikely yet available for sale. Information is limited so it is worth speaking directly with a known
At this stage you can’t put a HEPA filter on a split system air conditioner as the small fan can’t cope. We are unaware of a different split
system that may allow it, but you certainly can’t retrofit.
CO2 monitors can be useful for peace of mind and identifying places that are out of the ordinary.
It is a tool to tell you there’s a problem which can be valuable, however it doesn’t provide a solution. HEPA filters are an ideal solution to tackle the problem.