Ventilation and COVID-19

Ventilation and the supply of fresh air is a topic that has always been crucially important and this has been highlighted and reinforced by the recent global pandemic.  It is likely that a large proportion of people didn’t previously think about ventilation within a building, but we are now all much more aware of its importance in the maintenance of a healthy and safe environment.

Scientific research shows that good ventilation dilutes and reduces the concentration of airborne viruses and germs, thereby reducing the risk to the occupants of contracting illness.

The importance of ventilation is summed up in this sentence from the government website:  “Ventilation is the process of introducing fresh air into indoor spaces while removing stale air. Letting fresh air into indoor spaces can help remove air that contains virus particles and prevent the spread of coronavirus (COVID-19).”

How can I ventilate my workplace?


There are two main types of ventilation – natural ventilation, and mechanical ventilation.  Natural ventilation is self-explanatory – it is simply the introduction of fresh, outside air, mainly through open windows.  Opening a window is a very effective and quick way of providing ventilation to a space, however, the challenge comes in more extreme weather – in summer you tend to keep the windows shut to allow the air conditioning to cool the space and in the winter to keep the heat in!  This simply illustrates the drawbacks of natural ventilation.

Mechanical ventilation is the supply of fresh air through a dedicated system, drawing in fresh air and extracting stale air from a space.  This can be as simple as a series of fans, ranging up to a complete, packaged HVAC solution for a large building.

For the purpose of this article, which is aimed at commercial clients rather than residential, we will focus on two main types of ventilation equipment – Air Handling units and packaged MVHR units.

An Air Handling Unit (AHU) is used to provide a complete ventilation solution for a building or part of a building.  Air handling units are typically large and therefore installed on a roof deck or plant room.  Ductwork then runs from the unit, throughout the building to provide fresh air to each area.

A typical air handling set-up includes a supply and extract fan, which works simultaneously to supply fresh air and extract the stale air at the same time.  In some instances, there is a cooling coil and/or heating coil installed within the air handling unit – in this case, the air is supplied to the space cooled or heated, depending on the requirement.  Air handling units typically house a series of filters, ensuring that the air travelling through the ductwork is filtered and clean.  Normally you would expect to find a coarse filter (pre-filter) and a fine filter on the supply air handling unit and just a coarse filter on the extract air handling unit.

Packaged MVHR (mechanical ventilation heat recovery) units offer a similar solution to an air handling unit, in fact, arguably they are the same thing but just scaled down to a smaller size.  These units can be installed above a suspended ceiling and would typically serve an area rather than a whole building.  Heat recovery is the process of energy saving by pre-heating the incoming cold air, with the extracted stale warm air.  This can result in a very impressive efficiency rating of up to 80%.  It works the same in the summer, i.e. cooling the incoming warm air from outside with the extracted stale but cool air.  The supply air does not mix with the extracted air, the transfer of energy happens via a heat exchanger.  Packaged MVHR units are often referred to as VAM units (the Daikin brand name) or Lossnay units (this Mitsubishi Electric brand name).

What is the best ventilation solution for my workplace?


There is no single answer to this question.  Every office, school, hotel, or other types of the building has its own unique parameters to consider.  Modern buildings tend to be designed to be very airtight which has advantages from an efficiency point of view, but it means that they don’t ‘breathe’ and will almost certainly need some form of assisted ventilation.  There are also a number of factors that influence the ventilation you may require in addition to the size of your building.  Most importantly is the amount of people working in the space as well as what the area is used for.  Take for example a gym, this will need an increased level of ventilation.

Especially with the recent pandemic, there is an increased responsibility on building owners to do more than they absolutely have to by law.  For example, a business owner with small premises may not be required to provide mechanical ventilation – building regulations stipulate that as long as the windows open, there is adequate natural ventilation.  However, if there are 25 people working inside the premises and the windows are kept closed during the winter months, the right thing to do would be to install some form of mechanical ventilation.

What does it cost to install a mechanical ventilation system?


As with any HVAC system, the cost of installation will vary considerably depending on the size of the premises and the complexity of the installation.  Installing a mechanical ventilation system is typically more intrusive than installing an air conditioning system.  One of the main reasons for this is due to the installation of ductwork – the network of large pipes that carries the incoming fresh air and the extracted stale air.

For small commercial premises, you could look to pay £10-20k for a basic mechanical ventilation system, assuming good access and a straightforward ductwork arrangement.  Any costs mentioned are correct at the time of writing and are subject to VAT at the standard rate.  The cost of HVAC systems and parts has been subject to significant price increases and in short supply, so please contact us for a bespoke quotation for your requirement.

As with any HVAC installation, we would recommend a site visit and survey, to determine the full extent of your requirement, in order to recommend the best overall solution.  Salix can provide a free of charge and no-obligation consultation at your premises, including a priced proposal and recommendations.

The benefits of ventilation


While the focus on ventilation has largely been centred around negating the spread of airborne germs and viruses, there are plenty of other benefits of ventilation, which are often overlooked.  One of the main additional benefits is staff performance – the impact that a well-ventilated workspace can have is significant and proven, boosting concentration, and mental and physical performance.  Good ventilation contributes to staff wellbeing and reduces the amount of time off due to sickness.

Speak to Salix today to book your FREE VentCare survey.

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Rob Tuffin