The importance of ventilation in indoor environments

The COVID emergency has caused a drastic change in our lifestyle. The risk of contagion has led society as a whole to acknowledge the importance of responsible behaviors, starting from social distancing.

All this has led to prefer places that are not crowded, and particularly outdoor spaces, especially now that we are entering the summer season. This is because outdoor spaces, with a lower density of people, are the places that present the lower risk of contagion. In fact, if the virus were to be present outdoors, it would be "diluted" in an almost infinite quantity of air, and therefore its concentration would be close to zero.

Getting out of lockdown

Reopening businesses after COVID-19

However, it is not possible to always live outdoors and, as we are getting out of lockdown, we have the possibility and the duty to return to the previous lifestyle, or rather, to a new normality.

This means we must be able to go back to living indoor environments safely, both at work – at the offices – or in our private lives – shops, shopping centers, gyms, restaurants, cinemas.

While outside any virus naturally dilutes in the air, in indoor environments this dilution process must be ensured by proper ventilation.

This is nothing new, but rather a good habit that we have always put into practice, at home for instance, changing air in domestic environments by simply opening the windows.

The importance of mechanical ventilation

In indoor environments, however, ventilation cannot always be guaranteed by simply opening the windows. Sometimes these are not even present and, when they are, they cannot be kept constantly open, except at the expense of the thermal comfort of the building occupants.

Prevent the spread of Coronavirus

In such situations, the ventilation of the premises is guaranteed through a mechanical ventilation system that introduces properly filtered air from the external environment and simultaneously extracts the internal air, expelling it outside. This allows proper ventilation and air exchange in indoor environments, also diluting the possible presence of bacteria, viruses, CO2 and other contaminants.

This technology has been used for many years in the Northern European countries, where they usually design very well thermally insulated buildings to minimize heating consumptions during the winter season. That is possible using ventilation products with heat recovery systems on-board. This type of design, excludes the use of windows as a natural ventilation system, requiring the use of a mechanical ventilation system, which guarantees adequate air exchange and the dilution of any contaminants load in the indoor environment, as naturally occurs outdoors.

We should be aware of the benefits of mechanical ventilation in indoor environments

In Southern Europe, on the other hand, and especially for medium and small size applications, the aspect of proper ventilation of the rooms is not always addressed in the most appropriate way. Usually in these applications, priority is given to room temperature control and therefore to those solutions that guarantee thermal control during the summer (cooling) and winter (heating) seasons.

Daikin Air Handling Units Modular P

This can be achieved in different ways, the most common are based on hydronic systems (combination of chiller units and fan coils) or on direct expansion systems (split, multi-split, variable refrigerant volume systems) – both excellent solutions to ensure the comfort and well-being throughout the year.

Although heating and cooling are adequately guaranteed by air conditioning systems, it is still essential, as already explained, to ensure the proper ventilation of the rooms.

Combining AC with mechanical ventilation

To do this, it is recommended to pair up the air conditioning system – whether it is hydronic or direct expansion – with a mechanical ventilation system that ensures adequate air exchange and ventilation of the indoor environments.

This is recommended not only by industry associations (REHVA and ASHRAE), but also by the Italian National Health Institute – Istituto Superiore di Sanità (ISS reports COVID-19 • n. 5/2020 Rev. 2 and ISS COVID-19 • n. 33/2020).

Experts recommendations

The ISS, in fact, points out the importance of "ensuring proper air exchange (through mechanical or natural means) in all environments where workstations and personnel are present" and that "The principle is that we need to introduce outdoor air into the workplace as much as we can, to get clean fresh air and, at the same time, to reduce or dilute the concentrations of specific pollutants (VOC, PM10, etc.), CO2, odors, humidity and bioaerosol which can carry bacteria, viruses, molds and, consequently, to reduce the risk of exposure for staff and users of the building".


In conclusion, the combination of air conditioning and ventilation systems ensures the achievement of thermal comfort, and at the same time, allows to provide premises with high air quality levels.

Daikin is a leader in the design of air conditioning and ventilation systems and provides the most advanced technologies, meeting the most stringent system design requirements, and ensuring health and well-being in all indoor environments.

In particular, the Modular L offered by Daikin is an innovative product, ideal to ensure proper ventilation in medium-sized environments. It is a compact, efficient and versatile solution whose main features are

Daikin Air Handling Unit Modular L

  • Flexibility. It can ventilate spaces of different sizes, from 50 to 600 m2 of surface.
  • Air-flows separation. The separation of the air flows granted by the aluminum counter-flow exchanger, which, as it is not permeable, makes the contamination between the air flows entering and leaving the unit impossible.
  • The highest level of air filtration. The Modular L ensures the maximum quality of the air introduced into the rooms thanks to a double filtration stage, which has an efficiency of 90% on the smallest and most dangerous particles such as bacteria, molds or other pollutants (PM1).
  • The highest hygiene standards according to the German TUV Nord certification. This, thanks to stringent tests conducted on the unit materials, to verify the effectiveness in counteracting the proliferation of bacteria and molds and the ease of product cleaning and sanitizing activities.
  • The extremely high efficiency, which is guaranteed by the counter-flow heat exchanger capable of recovering up to 90% of the heat and allowing savings on heating bills for more than 25%.
  • Quietness. Low noise operations are ensured by the unique design of the unit, which makes it much quieter than other units in the same segment. This guarantees greater comfort in the rooms.
  • The ease of installation. The full integration with various systems, plus the plug & play approach with factory mounted controls make this unit ready for immediate start-up.
  • In addition, the Modular L is a very compact solution and allows installation in any false ceiling, avoiding waste of floor-space and allowing easy integration in any environment.

For more information on Daikin solutions for mechanical ventilation, get in touch using the form below.