Controlled Mechanical Ventilation and its benefits for indoor air quality

August 2021

With the outbreak of the Covid-19 pandemic, it has become clear how important it is to carry out good ventilation to maintain levels of CO₂ levels and air quality in the buildings where we live and work.

Current regulations, focused on achieving greater energy efficiency, have promoted the construction of buildings that are increasingly airtight to the outside, making ventilation more and more necessary.

But how to ventilate properly, is it enough to open the windows for 10 minutes, and is it better to do it naturally or mechanically?

Traditionally, ventilation in buildings has consisted of opening the windows wide to create a draught and thus renew the stale air inside. Over the years, new ventilation systems have been developed to improve indoor air quality and energy efficiency. Controlled Mechanical Ventilation (CMV) systems are those in which the renewal of air in a building is generated by the action of a fan, without the need to open windows.

Among the controlled mechanical ventilation systems, the most efficient is the double flow system, which incorporates a heat recovery unit. This system extracts the air inside the building and introduces new air from outside, which is captured by a fan, filtered and passed through a heat exchanger to ensure that we lose as little of the dwelling's thermal energy as possible.

In this way, Mechanical Ventilation offers many advantages compared to traditional ventilation:

  • Improved air quality by filtering the outside air. When we open the windows to ventilate in the traditional way, we think that the incoming air is pure air from nature. But unfortunately this is not always the case, as the outside air contains pollution typical of developed cities: pollution from traffic as well as from industry in general. By means of mechanical ventilation, the outside air is purified through special filters that remove dust and impurities. In this way, the air that is introduced into our buildings is of much higher quality, improving the well-being of the occupants and reducing the risk of illnesses and allergies.
  • Elimination of high relative humidity. Mechanical ventilation systems cause balanced air movement , preventing condensation and mould growth.
  • Elimination of draughts inside the building: As the windows do not need to be opened for ventilation, no draughts are generated. This has an impact on comfort and also on the health of users, as the risk of cooling is reduced.
  • Reduction of noise pollution. Another advantage of not having to open windows is the elimination of disturbing noises from outside such as vehicle traffic or people passing by. With mechanical ventilation we prevent these sounds from interfering with our daily routine, increasing our general well-being as well as concentration and performance in work spaces.
  • Reduced energy costs. With mechanical ventilation, no energy is lost by opening the windows and losing the heated air in the home in winter or cooled air in summer, avoiding the subsequent need to re-temper the air in the room and its consequent energy costs. On the other hand, the heat recovery unit further optimises the ventilation by using the heat from the outgoing air and transferring it to the incoming air in winter and vice versa. It brings fresh air into the building at a temperature close to the indoor temperature, which also greatly increases the comfort in the rooms.

Controlled mechanical ventilation

In short, with dual-flow mechanical ventilation, ventilation is optimised for the best health, energy efficiency and comfort results.

However, these controlled mechanical ventilation systems generally operate in a completely manual manner, so that we are the ones who have to change the fan's mode of operation, without a clear reference as to when it is necessary to do so. Some are programmed according to a pre-set schedule, which is not necessarily in line with actual use either, but will always provide significant improvements over supplying a fixed amount of outside air.

Ideally, for more efficient and intelligent mechanical ventilation, the system should be combined with sensors that measure the parameters affecting indoor air quality, so that the ventilation regulates itself according to actual needs.

It is therefore essential to have devices that continuously monitor indoor air quality as a tool to check the efficiency of ventilation. Our devices MICA offer simple and intuitive information on air quality, which helps the user to optimally manage ventilation in order to guarantee high levels of health and comfort at all times. In addition, they are compatible and integrable with mechanical ventilation systems, allowing on-demand air flow rates to be regulated in a fully automated, intelligent and healthy way.

In our next post we will tell you more about Intelligent Ventilation or DCV Systems (Demand Controlled Ventilation).

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