Understanding HSE Coronavirus Ventilation Recommendations for UK businesses (Part. 2)

Understanding HSE Coronavirus Ventilation Recommendations for UK businesses (Part. 2)

24 August 2021
coronavirus particles entering an air conditioner

In the first article of the series, we discussed a number of key points to help you assess poor ventilation within your business facility. In case you missed it, you can find it here.

The second article discusses the specific steps you can take to ensure that you are in line with the HSE’s recommendations for coronavirus ventilation.

There are a number of factors to take into account when determining optimal ventilation for your work spaces. As with any workplace, you need to ensure that there is sufficient fresh air circulating through all areas. You can do this in two ways, which we also briefly touched upon in the first article:

  • Natural ventilation – where fresh air flows in through open doors, windows and air vents.
  • Mechanical ventilation – a more thorough solution where fans and ducts are installed in strategic areas to draw in fresh air from the atmosphere.

It always helps to come up with a list of areas in your office or business facility, and how they’re ventilated. Floor or design plans can definitely help.

Alternatively, you could take a stroll around your facility, noting how each area is ventilated. Remember to include all rooms, such as canteens and those used for breaks. If you’re having trouble determining how well an area is ventilated, then it’s probably because it has poor ventilation to begin with.

Questions to ask yourself when determining the quality of ventilation

How many people occupy the space?

The more people occupy any given space, the higher the likelihood of an infected person being among them, which means an increased risk of aerosol transmission. This risk further increases if the space already has poor ventilation and is occupied by multiple persons.

Consider how many people occupy any of the spaces at any given time – e.g. is there a fixed number of people in that space each day, or does the number vary?

How large is the space?

Larger areas will have a lower risk of aerosol transmission because:

  • There’s more air which helps in diluting the virus particles
  • Larger areas are typically designed with optimal ventilation rates in mind
  • It takes longer for aerosols to accumulate in larger areas

What activities/tasks take place in the space?

Activities which increase the heart rate, and therefore, the rate of breathing – such as shouting or moving heavy objects around, for instance – will increase the number aerosols generated in the air and subsequently, the risk of transmission. Unfortunately, activities like the above will continue to increase the risk of transmission, even if there is adequate ventilation.

As a precautionary measure, you can always ask your workers to cut down on these activities as much as possible in order to reduce the risk. Alternatively, you can move some of these activities outdoors or ask workers to work on their own, if possible. If none of these are feasible, then it’s best to consult a mechanical ventilation systems engineer, who will come up with a bespoke solution to your ventilation needs.

Are there specific workplace features which affect ventilation?

Large machinery, equipment or certain kinds of physical features like pillars or posts can prevent air from circulating properly in the workplace. Stagnant air means a higher risk of aerosol transmission.

Consider moving things around or modifying the physical features in order to improve airflow.

Are desk or ceiling fans being used?

Desk or ceiling fans are generally not recommended in poorly ventilated areas, so avoid these whenever possible.

Is there local exhaust ventilation (LEV)?

LEV is often used in offices to control certain workplace health risks such as those associated with dust or welding fumes. If your LEV system is discharging the air out into the atmosphere, it will improve ventilation in that space.

Is there a formal ventilation system installed?

Business facilities which have a formal or complex ventilation systems installed may include:

  • Old buildings
  • Buildings which have several floors and rooms, all using different kinds of ventilation systems according to the occupants’ needs
  • Specific systems designed for product manufacturing floors as these often include additional recirculation

In order to have the most optimal ventilation system for your office or business facility according to the layout and number of occupants, it is best to consult with a ventilation engineer.

Steps to take for improving natural ventilation

You can facilitate better ventilation in your workplace through partly or fully opened doors, windows and air vents although you should avoid propping fire doors open.

Buildings are typically designed with adequate ventilation in mind, and you should open whatever windows and/or vents you can to let fresh air in. Should you identify any areas which need ventilation (such as those where doors, vents and windows cannot be opened), then you must first determine if the area is safe to use for your workers before making any changes.

It’s always a good idea to never fully close the doors, windows and vents in areas where there’s plenty of natural ventilation. During the cooler and windier months, you can open any trickle vents if they have been installed, as there won’t be much of a need to keep the doors and windows open.

When your spaces are unoccupied, for example, during non-business hours, it’s always a good idea to purge the rooms. Airing rooms frequently by fully opening all the doors and windows can maximise natural ventilation in any given 24-hour period.

Finally, make sure that you sit down with your workers and have an honest conversation about how to improve ventilation. When it comes to sufficient fresh air in each room, your workers must play their part. So, explain how important it is to keep each room well-ventilated according to the best practices discussed above – this will allow everyone to play their individual part in reducing the spread of coronavirus.

Steps to take for improving mechanical ventilation

Mechanical ventilation systems are designed to draw in fresh air from the atmosphere. It would be helpful to speak to the ventilation system engineer or the person responsible for maintaining and managing the mechanical ventilation system. This is important because:

  • You should gain an understanding of how they work and how to operate them efficiently
  • You need to ensure that the system is supplying fresh air into any given area and according to the required quantity
  • You must ensure that the system is maintained according to the manufacturer’s specifications or instructions

It’s never a good idea to lower the mechanical ventilation setting if the total number of occupants is reduced for the time being. Therefore, ventilation rates should be based on the maximum normal occupancy of any given area.

Mechanical ventilation systems always provide optimal ventilation when they are set to maximum fresh air draw-in and minimise recirculation of the existing air in the room. You should also know the volume of fresh air your system draws in each day and whether this is enough to provide the optimal level of ventilation. If in doubt, it’s always best to consult with your ventilation systems engineer.

In any case, if you discover that the rate of draw-in is not sufficient, then you must either increase this rate or supplement it with natural air by opening doors, windows and vents. You might also consider increasing the operating timeframe of your system before and after business hours.

Lastly, as a good rule of thumb, it is best not to recirculate air from one room to another, as some businesses do. Heating/cooling recirculation units which are not designed to draw in fresh air will only continue to operate as long as outdoor air is being supplied to it – which means leaving windows and doors open.

Therefore, recirculation systems, including air conditioners, tend to mask poor ventilation levels, as they merely make a space feel more comfortable, and not necessarily well-ventilated.

Can air cleaning and filtration units help?

Under specific circumstances – for instance, when it isn’t possible to maintain adequate levels of ventilation – you might use local air cleaning and filtration units to cut down the risk of aerosol transmission. However, it should be kept in mind that these units are not primarily designed for ventilation.

Therefore, you should always prioritise any spaces identified as ‘poorly ventilated’ for improvement via other methods, before considering an air cleaning device – as such, this should always be a last resort.

If you do decide that an air cleaning unit may be beneficial, then the most suitable types to use are ultraviolet-based devices and high-efficiency filters.

Any unit you decide to use must be in accordance with the area’s size so that it works as intended. If you’re considering installing CO2 monitors in an area with air cleaning units, then you may want to reconsider as they are not effective – while filtration units do remove contaminates like coronavirus from the room, they do not remove CO2.

Closing thoughts

Hopefully, these two articles have served to equip you with the knowledge and knowhow needed to ensure adequate ventilation in your place of business.

Atmostherm has more than four decades of experience, serving as an experienced HVAC contractor in Manchester. For further professional advice and guidance on mechanical ventilation systems for your facility  please call us.